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R A D I A T I O N 

A N D 

R I S K 

ISSN 0131-3878 

Bulletin of the National Radiation a n d 

Epidemiological Registry * } 

Issue 3,1993 Radioecology 

English Translation by scientists in Obninsk 

Edited by Richard Wilson, Harvard University 

Obninsk 

Nr Moscow, Russia 

Harvard University 

Cambridge, MA 02138 

USA 

In 1995 the Registry was reorganized into the "National Radiation and 

Epidemiological Registry" and the title of the Bulletin was accordingly changed. 

In the contents of the translated issue 3, 1993 the previous title "All-Russia 

Medical and Dosimetric State Registry" (ARMDSR) has been preserved.

Scientific Editors of issue 3 

Cand. Sc., Phys.-Math. 

V.A.Pitkevich 

Cand. Sc, Tech. 

S.M.Vakulovsky 

© Medical Radiological Research Center RAMS, 1993 

in cooperation with SPC "Medinfo" 

ISSN 0131-3878 

All rights reserved. 

The authors alone are responsible for the views expressed in publications. 

The Bulletin "Radiation & Risk" welcomes requests for permission 

to reproduce or translate its publications, in part or in full. 

Applications and enquiries should be addressed to: 

"Radiation and Risk", 

4 Kordyov str., Obninsk, Kaluga region, Russia, 249020 

telephone: 

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telex: 

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We shall be glad to provide the latest information on any changes made 

to the text, plans for new editions, and reprints and translations already available 

(08439) 2-64-07, 2-17-28 

(095)956-14-40 

412633 INFORSU 

INDEP @ MRRC.OBNINSK.SU 

Address for English Translation: "Radiation and Risk", 

c/o Richard Wilson 

Department of Physics 

Harvard University 

17 Oxford Street 

Cambridge, MA 02138, USA 

telephone: 617-495-3387 

fax: 617-495-0416 

telex: 620 28332 

E-mail: WILSON @ PHYSICS.HARVARD.EDU 

"Radiation & Risk", 1993, issue 3 

Editor - in - Chief 

A.F.Tsyb 

Academician of RAMS; Chairman, All-Russia Scientific Commission on Radiation Protection; 

Director, Medical Radiological Research Center of RAMS (Obninsk) 

Deputy Editor 

V.K.Ivanov 

Corr. Member of RATS; Member of All-Russia Scientific Commission on Radiation Protection; 

Deputy Director, Medical Radiological Research Center of RAMS (Obninsk) 

R.M.AIexakhin 

A.V.Akleev 

M.I.Balonov 

V.I.Chiburaev 

I.I.Dedov 

L.A.IIyin 

I.I.Li nge 

A.M.Nikiforov 

V.A.Pitkevich 

Yu.D.Skoropad 

K.Baverstock 

G.D.Baisogolov 

W.Burkart 

E.B.Burlakova 

E.Cardis 

K.Chadwick 

M.Goldman 

V.LGrishin 

A.Kellerer 

S.Kobayashi 

T.Kumatori 

Academician of RAAS, 

Member of ARSCRP (Obninsk) 

D.Sc, Medicine (Chelyabinsk) 

D.Sc, Biology, Member of 

ARSCRP (St. Petersburg) 

Head of Board, the State 

Committee on Sanitary and 

Epidemiological Surveillance, 

RF (Moscow) 

Academician of RAMS (Moscow) 

Academician of RAMS (Moscow) 

Cand.Sc, Phys.-Math. (Moscow) 

D.Sc, Medicine (St.Petersburg) 

Cand.Sc, Phys.-Math. (Obninsk) 

D.Sc, Medicine (Obninsk) 

Editorial Coordinator 

V.A.SokoIov 

Cand.Sc, Biology 

D.Sc, Ph.D, WHO (Rome) 

Professor (Obninsk) 

Ph.D., Institut fur Strahlenhygiene 

(Munich) 

D.Sc, Professor (Moscow) 

Ph.D., International Agency for 

Research on Cancer, WHO (Lyon) 

F.lnstP., Commission of the 

European Communities (Brussels) 

Ph.D., Professor, University of 

California (Davis) 

President, Soyuz "Chernobyl" 

(Moscow) 

D.Sc, Professor, Institut 

fur Strahlenbiologie (Neuherberg) 

Ph.D., National Institute of 

Radiological Sciences (Chiba) 

Professor, Chairman Board of 

Directors, Radiation Effects 

Association (Tokyo) 

Editorial Board 

G.N.Sushkevich 

V.M.Shershakov 

Ya.N.Shoykhet 

A.D.Tsaregorodtsev 

V.Ya.Voznyak 

AJ.Vorobyov 

A.Yu.Yakovlev 

Advisory Council 

P.I.Khalitov 

K.Mabuchi 

E.G.Matveenko 

N.P.Napalkov 

D.L.Preston 

P.V.Ramzaev 

I.S.Riaboukhine 

A.V.Sevankaev 

I.Shigematsu 

R. Wilson 

D.Sc, Medicine, WHO 

(Geneva) 

Cand.Sc, Tech. (Obninsk) 

D.Sc, Medicine (Barnaul) 

Deputy Minister, Ministry of 

Health and Medical Industry, 

RF (Moscow) 

D.Sc, Economics, First 

Deputy Minister, Ministry on 

Civil Defence, Emergencies and 

Elimination of Natural Calamity 

Effects (Moscow) 

Academician of RAMS 

(Moscow) 

Academician of RANS 

(StPetersburg) 

D.Sc, Ministry of Health and 

Medical Industry, RF (Moscow) 

Professor, Radiation Effects 

Research Foundation 

(Hiroshima) 

Professor (Obninsk) 

Academician of RAMS, 

WHO (Geneva) 

Ph.D., Radiation Effects 


(Hiroshima) 

D.Sc, Professor (StPetersburg) 

D.Sc, Biology (Moscow) 

D.Sc, Professor (Obninsk) 

Professor, Radiation Effects 


(Hiroshima) 

Professor, Harvard University 

(Cambridge) 

The presented personnel of Editorial Board and Advisory Council was appointed in 1994. 

RAMS - Russian Academy of Medical Sciences RAAS - Russian Academy of Agricultural Science 

RATS - Russian Academy of Technological Sciences RANS - Russian Academy of Natural Sciences

'Radiation & Risk", 1993, issue 3 

Contents 

Preface to English Translation R.Wilson 5 

Preface -. 6 

Section 1. Normative Documents 7 

The Concept of radiation protection of population and economic activities on the 

territories affected by radioactive contamination 7 

Section 2. Materials of All-Russia Medical and Dosimetric State Registry 

The Contamination of Russian territories with radionuclides 137 Cs, x Sr, 239 Pu+ 240 Pu, 131 l 

(Published as a Supplement to this issue under the separate cover) 12 

Section 3. Scientific Articles 15 

Vakulovsky S.M., Shershakov V.M., Golubenkov A.V., Baranov A.Yu., Borodin R.V., 

Bochkov LP., God'ko A.M., Kosykh V.S., Krymova N.V., Meleshkin M.A. 

Computerized informational software for problems in radiation situation analysis 

at the territories contaminated as a result of the Chernobyl accident 15 

Pitkevich V.A., Shershakov V.M., Duba V.V., Chekin S.Yu., Ivanov V.K., 

Vakulovski S.M., Mahonko K.P., Volokitin A.A., Tsaturov Yu.S., Tsyb A.F. 

Reconstruction of the composition of the Chernobyl radionuclide 

fallout in the territories of Russia 39 

Savkin M.N. 

Features of the environmental and sanitary situation in the 30-km zone of the 

Chernobyl Nuclear Power Plant (NPP) at a late stage after the accident 71 

Ermilov A.P., Ziborov A.M. 

Radionuclide ratios in the fuel component of the radioactive depositions in the 

near zone of the Chernobyl Nuclear Power Plant (NPP) 95 

Vakulovski S.M., Shershakov V.M., Borodin R.V., Vozzhennikov O.I., 

Gaziev Ya.l., Kosykh V.S., Makhonko K.P., Chumiciev V.B. 

Radiation exposure following the accident at the Siberian 

chemical complex Tomsk-7 100 

Section 4. In All-Russia Scientific Commission on Radiation Protection (ARSCRP) 134 

Information about ARSCRP meetings 134 

Concept of rehabilitation of the population and normalization of the environmental, 

sanitary-hygiene, medico-biological and social-economic situation in the populated 

areas of the Altay Region located in the zone affected by nuclear weapons 

testing at the Semipalatinsk test site i 138 


Preface to English Translation 

This issue of 'Radiation and Risk' contains much material of great interest to the world outside Russia. 

Of most interest are the scientific and technical articles. There are four papers related to the 1986 Chernobyl 

accident and one about the 1993 accident at Tomsk-7. The paper by Ermilov and Ziborov describes the 

radionuclides believed to be in the fuel just before the accident. This, together with the fraction released, can tell 

us how much was emitted. For English readers, the recent paper by A. Sich in "Nuclear Safety" (1995) is an 

important adjunct. 

The paper by Vakulovski et al., describes the software for analysis and that by Pitkevich et al., 

describes how to interpolate between measurements of various radionuclides using the more extensive survey of 

137 CS. This gives the best information available on the actual deposition in May 1986. An understanding of the 

way in which these radionuclides proceed through the environment will be necessary for a full dose 

reconstruction but this gives the essential first step. 

The detail of the releases from the accident at Tomsk-7 in April 1993 is given to western readers for the 

first time. The measurements are obviously carefully done, and there are good estimates of the external dose. 

It is reassuring that even at the most exposed point, the village of Georgievka, the dose rate was less than 100 

milligrams per year (less than 1 milliSv per year). The statement that in several points the cesium 137 activity 

exceeds the activity from the 1993 accident is titillating. The explanation that the cesium came from previous 

operations (or accidents) of the chemical complex make us want to know more. 

Finally, the "normative' and "conceptual" documents for protection of the public from adverse effects of 

the radiation are very illuminating, and important as they show the continued good judgment of professionals in 

the Russian Federation. 

The translation and editing was made possible, and was partially funded by a grant from the U.S. 

Department of Energy. 

Richard Wilson 

Cambridge, MA 02138 

January, 1996


PREFACE 

The radionuclides that originated from the destroyed fourth unit of the Chernobyl Nuclear Power Plant 

(CNPP) and dispersed over a vast tenitory pose before scientists the concrete but not very simple question. The 

question: how will the emanating ionizing radiation from the radionuclides affect the health of current and future 

generations? 

Plenty of interrelated scientific problems need to be considered to answer the question. 

The primary task is to get the dynamic picture of distribution, migration and transformation of radioactivity 

that was released into the environment as a result of the Chernobyl accident. These processes and actions on 

evacuation and resettlement of the population from the heavily contaminated zones wiB determine the 

consequences of the Chernobyl accident for the health of the public. 

As a matter of fact, adverse consequences of the accident do not depend only on the absorbed radiation 

doses. To correctly evaluate possible radiological effects one should take into account data on the type of 

radiation, distribution of radionuclides in internal organs, exposure duration and other factors. Availability of data 

depends a great deal on how fully the radiation environmental situation was, and is, studied on the contaminated 

territories. 

Measurements and theoretical studies of the radioecological situation undertaken during the first years 

after the accident were based on the data obtained with previously developed tools, calculation and theoretical 

methods. They were successfully used for getting the information needed to take the first measures to diminish 

the exposure of the population to radiation. The results of these works have been summarized in the Report of 

the International Advisory Committee on Assessment of Radiological Consequences and Evaluation of Protective 

Measures prepared within the International Chernobyl Project, 1991. 

However, the scale and complexity of the Chernobyl accident, insufficient data on radiation parameters 

especially those related to the first days, weeks and months after the accident as well as limits of basic models 

and theoretical understanding called for more serious efforts to study and forecast the radiation situation. This 

work is actively continued in institutions of the Russian Committee for Hydrometheorology, State Committee on 

Sanitary and Epidemiological Inspection, Ministry of Health of the Russian Federation, State Committee of the 

Russian Federation for the Social Protection of Population and Rehabilitation of Regions Affected by the 

Chernobyl and Other Radiation Catastrophes and in other institutions and organizations, both in Russia and 

abroad. 

The Scientific and Production Association TYPHOON of the Russian Committee for Hydrometheorology 

contributes a lot in studying radiocontamination of the environmental media. It deals particularly with the 

reconstruction of parameters of radionuclide distributions in the early period after the accident. These 

investigations are carried out in cooperation with Medical Radiological Research Center of Russian Academy of 

Medical Sciences. They are mainly oriented at the dosimetry support of All-Russia Medical and Dosimetric State 

Registry (ARMDSR). Results of some of these joint projects have been published in the present issue of the 

Bulletin on Radiation and Risk. The other materials of the issue include results of various investigations of 

scientific and technical nature. They will be useful, of course, both for the system of the dosimetry support of the 

ARMDSR and other organizations involved in solving problems related to the consequences of the Chernobyl 

accident. 

The supplement contains results of measurements of the density of 137 Cs fallouts in a large number of 

Russian settlements affected by the radiation contamination. Reconstructed data on the density of 131 l fallout in 

the same settlements are also included. 

It should be stressed that a large volume of extremely important radioecologic information gained in the 

recent years is available in the form of reports. They are accessible for a rather narrow circle of specialists. 

Therefore, the publication of papers in the Bulletin "Radiation and Risk" has special value. The papers contain 

both a lot of primary data and detailed technical approaches. They resulted from the implementation of research 

projects aiming to provide the scientific support for the measures on mitigation of the consequences of the 

Chernobyl accident. This will enable ecologists, medical and agriculture specialists to competently estimate the 

level of the investigations and to use the published data in their practical work. 

Editorial Board 

"Radiation & Risk", 1993, issue 3 Normative Documents 

S E C T I O N NORMATIVE DOCUMENTS 

10 August 1993 N1405-p 

Moscow 

Council of Ministers - Government 

of Russian Federation 

DECREE 

By this decree is approved the proposal of State Chernobyl Committee 

and State Sanitary and Epidemiological Inspection of Russia agreed with 

the Ministry of Health, the Ministry of Nature, the Ministry of Agriculture, 

Roshydromet and other involved ministries and agencies to conduct studies 

in 1993-1994 aimed at updating the regulatory base to ensure social protection 

of people affected by radiation contamination and rehabilitation of contaminated 

territories on the basis of the concept of protection of the population 

and economic activities in the areas affected by radioactive contamination, 

presented in the supplement, which was developed by State Sanitary 

and Epidemiological Inspection of Russia together with the Russian Scientific 

Commission on Radiation Protection in fulfillment of the Decree of the 

President of the Russian Federation "On urgent measures to ensure radiation 

safety on the territory of Russian Federation" of 2 November 1991 N 70pn. 

The State Sanitary and Epidemiological Inspectorate of Russia should 

direct the indicated concept to the involved ministries and agencies of the 

Russian Federation and executive bodies of the subjects of the Federation. 

Chairman of the Council of Ministers 

of the Government of the Russian Federation 

CONCEPT 

V.Chernomyrdin 

OF RADIATION PROTECTION OF POPULATION AND ECONOMIC 

ACTIVITIES ON THE TERRITORIES AFFECTED 

BY RADIOACTIVE CONTAMINATION 

I. General principles 

1. As a result of the radiation-related accidents in the Urals, Chernobyl, and elsewhere and nuclear 

weapons testing, some areas of Russia were affected by heavy radioactive contamination. The 

inhabitants of these areas were exposed to increased radiation. The society faces the task to effectively 

protect the population living there from further major exposure and to reduce the possible health 

effects of the exposure.


Normative Documents 

2. The concept formulates the scientific principles and main routes of practical application of 

measures to protect the population on the territories contaminated by radionuclides as a result of radiation 

accidents or nuclear weapons testing. It also lays down the principles of economic activities on 

these territories in the long term after the accident (the recovery stage). 

3. The theses of this concept are based on the state-of-the-art understanding of the effects of 

ionizing radiation on the human body and the principles and methodology of radiation protection laid 

out in the publications of the International Commission on Radiation Protection (ICRP), World Health 

Organization (WHO), International Atomic Energy Agency (IAEA), UN Scientific Committee on the 

Effects of Ionizing Radiation and national experience in eliminating the consequences of major radiation 

accidents. 

II. Medical-biological framework of effects 

of ionizing radiation on man 

4. The medico-biological basis of the international recommendations on radiation protection is 

the concept of determined threshold and stochastic non-threshold effects of ionizing radiation on human 

health. By the conservative radiobiological hypothesis adopted by the world community, any exposure 

level, low as it may be, entails a certain risk of remote stochastic health effects. Among them 

are malignant tumours in exposed people (carcinogenic effect) and diseases of their offspring (genetic 

and teratogenic effects). To quantify the frequency of possible stochastic effects, the conservative 

hypothesis is used that the probability of remote implications varies linearly with radiation dose with 

risk coefficient 7x10" 2 Sv" 1 and no threshold. 

The deterministic effects - radiation induced tissue injuries and impaired body functions - are 

threshold in character and can clinically develop if the one-time acute exposure of individual organs 

of more than 0.15 Gy or a chronic exposure over many years at a dose rate of >0.1 Sv/year. 

III. Basic principles of the population protection 

5. The principles of public radiation protection on the contaminated territories are: 

1) prevention of deterministic effects by restricting exposure at the dose below the threshold of 

these effects (normalizing the annual dose); 

2) taking justified measures to reduce the probability of inducing remote stochastic consequences 

(oncological and genetic) with consideration for economic and social factors 

(optimization of protection measures). 

6. The objective of the protection measures in the contaminated territories is to ensure a high 

values health state for the population living there. 

According to the WHO concept an integrated indicator of human health includes life span, time 

integral of physical and mental working capacity, state of health and reproduction function. 

7. The indicated objective can be achieved through implementation of the following protection 

measures for the population of the contaminated area: 

- reduction of the public exposure from all major exposure sources on the basis of an optimization 

principle (radiation protection of the population); 

- restricting the adverse effect on the population of non-radiation factors of physical and chemical 

nature; 

- increasing resistance and anticarcinogenic protection of the population; 

- medical protection of the population: monitoring of the heath state and identification of sick 

people and persons of increased risk, their treatment and improving their health; 

- increasing the radiation-sanitary knowledge of the public, psychological protection of the 

population and assistance in overcoming radiophobia; 

- facilitating a healthy life style of the population; 

- increasing social, economic and legal protection of the population. 

Implementation of the above listed protection measures will permit offsetting the contamination 

consequences adverse for the public health. 

Note. SI unit of absorbed dose - Gray, Gy (1 Gy = 1 J/kg = 100 rad). Effective dose is measured in Sievert (Sv). This is the 

quantity weighted for different linear energy transfer. The weighting factor is unity for gamma rays and x-rays and is 20 for absorbed 

alpha emitting nuclides. This universal quantity is used to calculate the long term risk from chronic exposure. 

8 


8. The main measures of radiation protection to reduce exposure dose for the population of the 

contaminated area include: 

- relocation of the people; 

- exclusion of the contaminated area or introduction of restrictions on living and operations on 

this area; 

- decontamination of the area, buildings and other objects; 

- agricultural countermeasures to reduce radionuclides levels in local crop and animal products; 

- setting standards, radiation monitoring and sorting of agricultural produce and natural products 

with further reprocessing to make them free of radiation, supplying the population with uncontaminated 

food stuffs; 

- adoption in practice of special rules of behaviour and private farm management. 

The system of radiation protection measures that is presented should be presented with measures 

included to optimize hospital exposure of the population and reduction in natural exposure, in 

particular by reducing radon levels in dwellings and production buildings. 

9. Implementation of the dose-reducing measures given in item 8 involves economic expense 

and changes or disturbances in normal life and economic activities of the population, which is an intervention 

entailing both economic and environmental damage as well as having psychological impact 

on the population including adverse health effects. Therefore, when decisions on intervention are 

made, account should be taken not only of the expected beneficial effect (reduction in exposure 

level), but also negative consequences of a protection measure itself (economic damage, negative 

psychological effect, indirect health effects, exposure of those who eliminate the contamination). According 

to the ICRP recommendations, the form, scale and duration of intervention in the dose range 

below the threshold of determined effects should be optimized, i. e. be selected in such a way that the 

total damage from residual exposure and intervention be minimum. 

10. Optimization of radiation protection is to be performed for each protection measure with 

consideration of specific circumstances. In this context, it should be remembered that one stochastic 

effect associated with lethal and non-lethal carcinogenic, teratogenic and genetic effect mean, on the 

average, a reduction of life expectancy. The exposure of a group of people at the collective dose 1 

man Sv can lead to loss of about 1.5 man-years of life. [Editor's note: This is a little high. In the USA 

one would usually use about 0.5 man-years.] 

IV. Zoning of the contaminated territory 

11. Zoning of the territory is performed on the basis of the annual effective dose resulted from 

radioactive contamination. 

On the territory where the annual effective dose is not more than 1 mSv monitoring of the environmental 

media and agricultural products is conducted and monitoring results are used to estimate 

exposure dose of the population. There are no restrictions on living and economic activities on this 

territory in terms of the radiation factor. 

From 1 mSv to 5 mSv is the zone of radiation monitoring (protection). In this zone, monitoring 

of the environmental media and agricultural products is conducted and internal and external doses of 

population are measured. Measures to reduce dose using the optimization principle and other protection 

measures are applied. 

From 5 mSv to 50 mSv is the zone of optional transit (voluntary relocation). The monitoring 

and protection measures are the same as in the radiation monitoring zone. Population is educated on 

health risk associated, with radiation and, given their consent, residents are rendered help to relocate 

beyond the zone. 

More than 50 mSv is the exclusion zone. In this zone people are not allowed to live permanently 

and economic activities and nature use is governed by special regulation. Monitoring and protection 

measures for workers are added with application of individual dosimetric monitoring methods. 

Annual dose is understood as mean effective dose for a critical population group of a given 

populated point induced by man-made radionuclides during the current year, provided no active radiation 

protection measures are taken or they are stopped. A decision on relocation is to be made 

based on annual dose with allowance for radiation protection measures applied in practice. Residents 

of the contamination zone must be informed by the authorities and sanitary and epidemiological inspection 

about the radiation dose.


V. Basic principles of safe economic activities 

Normative Documents 

12. Economic activities at the territories where the annual effective dose is not more than 1 

mSv are not restricted and in the radiation monitoring zone and relocation zone such activities are 

possible provided: 

- the production is cost effective and satisfies the existing sanitary norms with respect to products 

and wastes (environmentally safe production); 

- radiation safety of workers is ensured. 

To make products meet sanitary norms, the selected raw materials, procedures and technologies 

should be appropriate for the given radiation situation and local natural conditions. The radioactive 

contamination largely affects products of those economic activities which involve the natural environment 

and local raw materials: agriculture, forestry, construction, fuel producing industry etc. For 

each activity, organization and technological methods are developed that permit products that satisfy 

sanitary norms. The criteria for application of special technologies are the level of contamination and 

radionuclide composition, plus soil and climatic conditions. An important organizational measure to 

reduce radionuclides levels is the production of such products which are least contaminated in the 

given natural and radiation conditions. 

In agriculture, along with organizational measures, technological measures satisfying radiation 

protection requirements are used. Among them are agrotechnical and agrochemical techniques, technological 

procedures for harvesting and processing, changing animal diet and maintenance practices 

etc. A compulsory measure in the radioactive contamination zone is radiation monitoring of all types 

of agricultural produce. 

The radiation safety of people engaged in economic activities in the radiation monitoring zone 

and relocation zone is ensured by applying measures of collective and individual protection from internal 

and external radiation. 

13. Construction of dwellings, production premises and public buildings in the monitoring zone 

is not restricted except for the organization of environmentally hazardous products. Construction sites 

should be in the places with the least level of radioactivity contamination after preliminary decontamination. 

During construction, measures need to be taken to restrict exposure of population to natural 

radionuclides. In the zone of voluntary relocation, new populated points and recreation facilities 

should not be built. 

14. In the radioactive contamination zone, integrated monitoring of radiation and non-radiation 

factors in the environment in relation to economic activities is to be conducted. Sanitary and environmental 

norms must be strictly observed and measures for protection of nature should be taken. 

VI. Recommendations for population on the contaminated territories 

1) Each resident of the radioactive contamination zone is entitled to know (by estimation) the 

dose he has received or can receive. 

2) The effectiveness of each protection measure including relocation should be assessed from 

reduction in dose and risk. The reduction in dose due to relocation 5 years after the Chernobyl accident 

is only 30% and in 10 years is projected to be about 15% of the total dose after the accident. 

3) Account should be taken of not only the benefits, but also the detriment of protection measures 

associated with changes in the life style. Therefore, major decisions should be made by a resident 

on his own. In terms of risk the decision to live on the contaminated area is comparable to other 

decisions in life. For example, smoking poses a greater health risk from the standpoint of oncological 

diseases, than living in the radiation monitoring zone. The exposure dose during an X-ray examination 

is greater than the dose received during a year of living in this zone. 

4) The admissible levels of radionuclides in products and in the environment should be regarded 

as a measure of dose reduction, rather than a limit above which a disease develops. One-time 

consumption of products with the radionuclide level slightly above the norm leads to an increase in 

lifetime dose of only a few millionths of one Sv. 

5) Local hotspots of radioactivity at the sites of discharge or storage of manure and ashes normally 

do not present any significant threat. Yet such spots should be removed from places frequented 

by people. 

6) To reduce radionuclide levels in meat products agrotechnical measures and fertilizer application 

has been found effective. 

10 


7) There is no need to strive for groundless food restrictions. Deficient or unbalanced nutrition 

leads to reduction in antitumorigenic and antiinfection immunity. 

8) Water-soluble and fat-soluble vitamins are effective means of preventive treatment of tumours 

and exposure effects. 

It is recommended that fruits, berries, greens and vegetables are made part of diet. 

9) Staying outdoors in the open air, in the fields, gardens and forests and swimming in water 

bodies should not be restricted. Restrictions on outdoor activity is detrimental. 

10) Radiation risk shows itself as more frequent diseases and can be made up for by reducing 

other risk factors: 

• reduction in dose from medical examinations; 

- reduction in dose from naturally occurring radionuclides (indoors radon); 

- improvement of life conditions, nutrition and working conditions; 

- giving up bad habits (smoking, alcoholism); 

- diagnosis and treatment of acute and chromic diseases, regular checks and clinical examination. 

11) The greatest threat for the health of the population living on the contaminated areas (except 

the exclusion zone) is posed by the state of permanent psycho-emotional stress associated with an 

incorrectly perceived risk from radiation. A knowledge of the real situation, with a justified and independent 

decision making, efforts to improve working and living conditions make it possible for everyone 

to live a full life which is not inferior to that of people in other areas of the country in terms of life 

span, family structure, health of children and other characteristics. 

The concept of radiation protection of the population and economic activities on the 

territories affected by the radioactive contamination has been prepared by workers of 

the Institute of Radiation Hygiene of State Sanitary and Epidemiological Inspection of 

Russian Federation (Director - Prof. Ramzaev P.V.) and All-Russian Scientific Commission 

on Radiation Protection (Chairman - Academician of Russian Academy of 

Medical Sciences Tsyb A.F.). 

Council of Ministers - By Decree of 10 August 1993 N1405-p the Government of 

Russian Federation charged the involved ministries and agencies with updating on the 

basis of the present Concept the regulatory base to ensure social security of citizens 

affected by radiation contamination and enable rehabilitation of radioactively contaminated 

areas. 

11


SECTION 2 

Materials of All-Russia Medical 

and Dosimetric State Registry 

MATERIALS OF ALL-RUSSIA 

MEDICAL AND DOSIMETRIC 

STATE REGISTRY 

The Contamination of Russian territories with radionuclides 

137 Cs, "Sr, ^Pu+^Pu, 131 l 

The materials included in issue 3 of the Bulletin are devoted to scientific and methodological 

aspects of the problem of reconstructing the space-time pattern of the radioactive contamination on 

the territories of Russia following the Chernobyl accident. Such data are required for calculation of 

absorbed internal and external doses group for population living in the contaminated areas and entered 

in the All-Russia Medical and Dosimetric State Registry. The existing methods for assessment 

of absorbed doses are based on data on specific density of deposited 137 Cs. Because of this, the first 

part of the Supplement contains data on 137 Cs contamination (Ci/km 2 ) of populated areas in Russia 

(data available by December 1992). For measurements, a standard qamma-spectrometric technique 

was used; soil samples were collected at different times in populated areas. The data base containing 

such data has been formed in SPA "Typhoon" (Roshydromet) in 1986 and information was partly 

provided by Kurchatov Institute, Fedorov Institute of Applied Geophysics, Institute of Biophysics 

(Health Ministry) and other organizations. Most of the contamination level measurements were made 

by Institute of Experimental Meteorology (SPA "Typhoon") before 1989. Since 1989 a number of radiometric 

laboratories have been set up at regional hydrometeoservice centers in Bryansk, Novozybkov, 

Kaluga, Tula, S-Peterburg, Kursk and other cities and these began to supply information to 

the indicated data base. All data about radionuclide concentration in soil samples were reviewed by 

experts. Some of the samples were analysed for ^Sr and 239 - 240 pu by radiochemical methods and 

these results are also presented in the first part of the Supplement. The presented data will be useful 

to specialists, for the purpose of absorbed internal dose assessment. The tables below include full 

attributes of municipalities, and also average, minimum and maximum levels of 137 Cs contamination 

(Ci/km 2 ) for each of them. These results were obtained by statistical processing of measurements. 

The number of collected samples varies from point to point (from 1 to 500) and, hence, the statistical 

error for the mean contamination level differs significantly. As was shown by detailed studies (see, for 

example an article by N.Savkin in issue 3 of the Bulletin) the statistical distribution of 137 Cs specific 

activity over the populated area is close to lognormal. Therefore the minimum and maximum activity 

of Cs may vary significantly which is indicative of nonuniformity in deposition over these areas. In 

the populated areas where only one soil sample was collected, the minimum, maximum and average 

activity of 137 Cs is of the same value which does not reflect the true contamination pattern. For such 

places additional studies will be (or should be) conducted. 

12 


Parti 

Data on 137 Cs, 90 Sr and 239240 Pu contamination 

of the territory of the Russian Federation 

Materials of All-Russia Medical 


The supplement to issue 3 of "Radiation and Risk" Bulletin includes experimental data on the 

density of deposited 137 Cs contamination after the Chernobyl accident over many populated areas in 

Russia and reconstructed in data on 131 l deposited contamination density in 1986. To provide the All- 

Russia Medical and Dosimetric State Registry with radioecological data, to reconstruct absorbed internal 

and external doses for the assessment radiation as well as non-radiation effects on human 

health, a radioecological subsystem RECOR (Radiation-ECOIogy-Registry) is now being developed in 

Medical Radiological Research Center of the Russian Academy Sciences which is closely related to 

the RECASS system (Radio ECological Analysis Support System) being created by SPA "Typhoon" 

of Roshydromet. The materials in the supplement present some of the results produced by the interaction 

between the above systems which is indispensable for providing the All-Russia Medical and 

Dosimetric State Registry with the necessary data. To determine the relationship between radiation 

and non-radiation factors and morbidity of people living in the contaminated areas is a long-term and 

multistage task which is carried out by the All-Russia Medical and Dosimetric State Registry together 

with organizations of Roshydromet, Ministry of Environmental Protection, National Sanitary and Epidemiological 

Inspection, Ministry of Agriculture, Health Ministry and Russian Scientific Commission 

on Radiation Protection. To analyse the Registry data on the health of people exposed to radiation 

after the Chernobyl accident it is important to have as complete information as possible on individual 

radiation doses and if it is not available group radiation doses are needed. Therefore, the methods of 

reconstruction of individualized absorbed doses based on radioecological parameters acquire a particular 

significance. The problem of obtaining radioecological parameters for contaminated areas has 

many aspects and includes knowledge of radionuclide concentrations in various media, development 

of new or adaptation of existing models for radionuclide migration and build-up, prediction and retrospective 

assessments of radiological situation. Each of the above components of the problem in 

question relies on a wide range of scientific methods and approaches. Some of them, which have already 

been tested and established serve as a basis for working out post-accident organizational, 

medical and socio-economic measures. Other are still being developed and up-dated and demonstrate 

the improvement of measurement, generation of various databases and accumulation of data 

on dynamic characteristics. The data presented in the Supplement refer to the second group of methods 

and are of interest primarily to radioecologists. There are a number of books (for example, 

"Chernobyl: radioactive contamination of the environment". - Leningrad, Hydrometeoizdat - 1990), 

collections of works and journal articles which contain data on the above mentioned problems of the 

Chernobyl accident. This Supplement is distinguished by data on 137 Cs levels (results of gammaspectrometric 

analysis of soil samples) and 131 l levels (results of analysis of radionuclide composition 

of depositions - see section 3, issue 3 of the Bulletin) for almost all municipalities of Russia that were 

contaminated by the Chernobyl accident. These data were produced by the application of the above 

mentioned methods for obtaining radioecological characteristics in order to create a computer subsystem 

to analyse population health (taking into account) radiation and non-radiation factors. Subsequent 

issues of the Bulletin will continue publishing the results of experimental and theoretical model applications 

to the description of radiological situation in specific municipalities and areas of Russia. The 

editors believe that such data will be of use to specialists as well as regulating bodies in of health 

care, sanitary inspection and other. 

13

"Radiation & Risk", 1993, issue 3 Materials of Alt-Russia Medical 


Part 2 

Data on reconstruction of specific density of deposited 131 i 

contamination over Russia after the Chernobyl accident 

The Supplement (Part 2) contains results of the reconstructions of specific deposited 131 l activity 

for the territories of Russia (with the exception of the Leningrad region) following the Chernobyl 

accident. The reconstruction method is described in detail in the paper by Pitkevich et al, page 39 of 

this issue*). This work presents results of the comprehensive statistical analysis of gammaspectrometric 

data for soil samples collected in 1986-1988 in the Ukraine, Belarus and Russia including 

the analysis of correlation and linear regression coefficients between radionuclide activities in 

samples as a function of the distance from the Chernobyl NPP over the so-called north-east "trace" 

(the northern part of the 30 km zone around the Chernobyl NPP, the southern part of the Belarus, 

contaminated territories of Russia). A statistically reliable correlation has been obtained between the 

deposited 131 l activity and the 137 Cs activity, the latter being well studied for the territory of Russia. 

This has made it possible to build a linear regression model with fixing the regression line in the point 

corresponding to the global levels of 137 Cs depositions. In doing so, a statistically reliable dependence 

of the linear regression coefficient on the distance from the Chernobyl NPP was found, the maximum 

lying in the south-eastern part of the Belarus contaminated territories. For reconstructing the density 

of 131 l contamination, use was made of the results of work *) and Roshydromet data on 137 Cs contamination 

of the Russian territory (see part 1 of the present Supplement). The tables below contain 

estimated average activity of 131 l (Ci/km 2 ) by 10 May 1986 for all contaminated populated areas of 

Russia (with the exception of the Leningrad region and other areas beyond the "north-eastern trace"). 

The date of 10 May 1986 was selected because of a short half-life 131 l (8.04 days) and a fairly common 

opinion among specialists that most of the fall-out over Russia from the Chernobyl accident had 

occurred before 10 May 1986. Had the fall-out been over at a later date, 131 l activity should have 

been considered at a later date too. It should be noted that the given reconstruction date cannot account 

for local variations in the deposited 131 l activity due to local meteorological conditions in specific 

municipalities. The tables give an averaged pattern of 131 l contamination which, nevertheless, may be 

of help to specialists when using various models for thyroid doses of the population living in the areas, 

territories, etc. When the minimum and maximum boundaries of activities were estimated, the 

results of work *) (confidence limits for regression coefficient) as well as measured minimum activities 

of 13T Cs were used. Therefore, the considerable variation of estimated activities of iodine means the 

substantial non-uniformity of depositions in a populated area. The reconstruction data were used for 

generating a map (on a PC of IBM type) of 131 l contamination over Russia which can be provided on 

request as a whole or in parts (territories, regions, districts), by the authors of the cited work (the request 

should be sent to the Medical Radiological Research Center of the Russian Academy of Medical 

Sciences, All-Russia Medical and Dosimetric State Registry). Likewise, request for the data on 

activity reconstruction for other short-lived radionuclides - 103 Ru, 106 Ru, ^Zr+^Nb, 140 Ba+ 140 La, 141 Ce, 

144 

l Ce, 125 Sb and 134 Cs can be made. 

Published as a Supplement to this issue under the separate cover. 

Pitkevich V.A., Shershakov V.M., Duba V.V. et al. Reconstruction of radionuclide composition of the fall-out over Russia after tt*» 

Chernobyl accidentZ/Radiation and Risk. -1993. - issue 3. 

14 


SECTION 3 SCIENTIFIC ARTICLES 

The Computerized informational software for analysis of the 

radiation situation in the territories contaminated as a result 

of the Chernobyl accident 

Scientific Articles 

Vakulovsky S.M., Shershakov V.M., Golubenkov A.V., Baranov A.Yu., Borodin R.V., Bochkov 

LP., God'ko A.M., Kosykh V.S., Krymova N.V., Meleshkin M.A. 

SPA "Typhoon" 

Creation and support of the radiation situation monitoring data bank as a result of the accident 

at the Chernobyl nuclear plant is a key problem. The efficiency of all further actions related to protection 

of the population health and returning of contaminated territories to normal life conditions depends 

upon the quality of its solution. Actions on liquidation of the accident after-effects required 

large-scale investigations concerned with analysis and forecasting of the environment radiation 

contamination. The studies included observations of air, soil and water contamination, modelling 

and forecast of processes of the radionuclides transport and transformation. During these investigation 

at the SPA "Typhoon" and preparation (on the basis of appropriate results) of recommendations 

on counter measures we faced the necessity to process large volumes of information and to 

solve problems in the real time regime. This initiated creation of the computerized radioecological 

analysis support system (RECASS - RadioECoiogical Analysis Support System) principles of functioning 

of which are described in the paper. The essence of this system is the interconnection between 

data on the environment, levels of the air, soil and water contamination and biots and mathematical 

models of radionuclides behaviour in all types of the environment and formation of doses on 

the bases of application of technology of Geographical Informational Systems (GIS). 

The main tasks of RECASS are collection, systematization and presentation of the monitoring 

data in the form of data of the radiation situation objective analysis and also presentation of the temporal 

and spatial picture of its variation at the contaminated territories for estimation of the living risk 

and efficiency of rehabilitation measures. 

The radiation monitoring data bank includes the following data bases: data base of measurements 

of the environment (soil, water, air) radiation contamination levels; meteorological data base; 

administrative division, economic activity and population date base; codes dictionaries that are used 

for coding of different types information. 

The structure of the data bank provides interrelation between the data bases using the network 

model of the data presentation on the basis of which a wide circle of inquiries is realized - from getting 

of generalized information on contamination levels in the chosen administrative or geographical 

region to data on definite type of measurement at one of the environment objects. Thus, the system 

allows the user to choose information proceeding from requirements of concrete radioecological 

analysis problem. 

The geoinformational system that is in the RECASS structure works either with raster, or with 

vector maps, the raster maps being used as a basis for presentation of radiation contamination and 

other data and vector graphical information being the input information for modelling. 

An automatic location with transfer through the fasset boundaries and their scaling is realized in 

the system. 

The created GIS base is a multi-layer system where each layer is a definite type of data. Overlapping 

of layers forms a model of the territory based on the selected set of parameters (soil, vegetation, 

forests and arable land, etc.). Principles of layer-by-layer displaying of geographical information 

permitted to develop software that not only formally overlaps different layers, but also provide 

possibilities to interprete and analyse the results obtained. 

RECASS includes a wide set of methods for processing (objectivization) and presentation as in 

coordinate so in territory related groups of measurements. A number of models of transport of radionuclides 

in different types of environment realised in the system allows one to solve the problems 

of the short-and-long-term forecasts of the radiation situation. 

In conclusion a joint utilization is demonstrated of some RECASS components to produce the 

temporal and spatial picture of contamination during the first days after the Chernobyl accident is 

demonstrated. 

15

1 I 


Introduction 

Calculations of levels of the environmental 

radiation contamination being made on the basis 

of continuously carrying out monitoring of territories 

are an important initial source of the 

quantitative information when analysing the 

situation and choosing measures to liquidate the 

after-effects of the radiation accidents. 

In this respect creation and support of radiation 

situation monitoring data base as a result of 

the Chernobyl accident is a key problem. The 

efficiency of all further actions related to protection 

of the population health and returning of 

contaminated territories to normal life conditions 

depends upon the quality of its solution. 

Actions on liquidation of the accident aftereffects 

required large-scale investigations concerned 

with analysis and forecast of the environment 

radiation contamination. The studies 

included observations of air, soil and water 

contamination, modelling and forecast of processes 

of the radionuclides transport and transformation 

[1-4]. During these investigation at the 

SPA Typhoon" and preparation (on the basis of 

appropriate results) of recommendations on 

counter measures we faced the necessity to 

process large volumes of information and to 

solve problems in the real time regime. This initiated 

creation of the computerized radioecological 

analysis support system (RECASS - 

RadioECological Analysis Support System) 

principles of functioning of which are described 

in the paper. The essence of this system is the 

interconnection between data on the environment, 

levels of the air, soil and water contamination 

and biots and mathematical models of 

radionuclides behaviour in all types of the environment 

and formation of doses on the bases of 

application of technology of Geographical Informational 

Systems (GIS). 

The main tasks of RECASS are collection, 

classification and presentation of the monitoring 

data in the form of data of the radiation situation 

objective analysis at the territories of Russian 

Federation, suffered from the Chernobyl accident, 

and forecast of its variation. 

Presentation of the temporal and spatial 

variation of radiation situation at the contaminated 

territories serves as the basis for evaluation 

of the risk to live at the contaminated territories, 

of rehabilitation measures efficiency. 

This information is being prepared by application 

of methods of physical and mathematical 

modelling of distribution and transformation 

processes of long-living radionuclides in the environment. 

The model results are compared with 

date of measurements for testing of correctness 

of calculation results, of reliability and representativeness 

of definite measured values. The 

models are also used to reconstruct the data of 

16 


contamination, when was not measured due to 

some reasons. The more data is obtained, the 

more complete will be the picture of the environment 

contamination. An analysis of discrepancies 

between model and measurement results 

is used in RECASS to refine the estimates of 

after-effects. Some problems can occur, if the 

discrepancies are caused by stochastic character 

of processes in the environment and thus 

reflect unavoidable uncertainties related to the 

forecast of the local radiological values. Therefore 

it is necessary to achieve a good relationship 

between model data and magnitudes being 

measured that will take into account as the uncertainties 

of the model forecasts, so the measurements 

variability. 

All the results of the subsequent analysis, 

especially selection of counter measures, their 

volume and duration with regard for their consequences, 

strongly depend on the quality of calculations 

in the system of radiational situation 

monitoring data bank. 

If the monitoring data are sufficiently complete, 

then the model forecasts can be changed 

by interpolations of the monitoring data. Or for 

radiological calculations one can use an average 

value, standard deviation or the maximum value 

of the monitoring result at the given region. 

In this paper we consider not only some aspects 

of the variety of problems related to storage 

of radiological data, their objectivization and 

preparation of forecasts of the radioactivity distribution 

in the environment. 

1. Data base management system 

and data systematization 

1.1. Principles for development of 

distributed radioecological data base 

When developing principles of creation of the 

radioecological data base organizational problems 

related to existing procedure of measurements, 

sampling and laboratory analysis were 

also solved. It should be noted that arrangement 

of interactions between different data collection 

groups and utilization of results is a difficult 

problem, the decision of which requires established 

regulations and rules. Many projects 

ended in failure not due to technical reasons, but 

because of absence of the arrangement agreements 

or in virtue of wrong understanding of the 

scientific and technical, social and economic 

importance of the problem. Requirements to the 

structure and radioecological data bank composition 

were formulated with allowance for existing 

methods of inspection at the territories 

contaminated after the Chernobyl accident [5]. 

The fact that the radioecological data bank is 

a model of reality, but not data storehouse was 

also taken into account. Thus, methods used for 


presentation of complex aspects of reality in the 

computer system gain great importance. Only in 

that case, if the reality structure in the stored 

data is modelled appropriately, one can expect 

that combination of numerous data sources and 

extraction of integrated information will provide 

significant results. In such situations one has to 

run into relations between data elements, for 

example, the contaminated zone is simultaneously 

related to the geography of the place it is 

located on, to the administrative region and 

population of that zone. Therefore there was 

developed such method for data storage and 

searching that would take into account the 

above noted relations. 

1.2. Structure of data bases for radiational 

situation monitoring 

The stationary network for observation and 

monitoring of contamination levels and movable 

operative monitoring groups are the basic 

sources of information on environment radiation 

contamination. Each source of information dictates 

its own requirements to the procedure of 

data collection and storage. 

The data bank (DB) contains the following 

data bases: 

The radiation monitoring data bank includes 

the following data bases: data base of measurements 

of the environment (soil, water, air) 

radiation contamination levels; meteorological 

data base; administrative division, economic 

activity and population date base; codes dictionaries 

that are used for coding of different types 

information. 

Structure of the data bank provides interrelation 

between the data bases using the network 

model of the data presentation on the basis of 

which a wide circle of inquiries is realized - from 

getting of generalized information on contamination 

levels in the chosen administrative or 

geographical region to data on definite type of 

measurement at one of the environment objects. 

Thus, the system permits to choose information 

proceeding from requirements of concrete radioecological 

analysis problem. 

DATA OF CONTAMINATION LEVEL MEA 

SUREMENTS. Requirements to the structure of 

the measurements data base is determined by 

advisability to store information from different 

sources in the unique format and by necessity to 

satisfy various possible inquiries related to data. 

Based on the above noted the measurement 

data are joined into sets in accordance with the 

information source and the environment type for 

which measurements were made. To relate data 

to administrative and territory division each record 

has the territory code, where measurements 

(samplings) were carried out. And finally, for 

spatial data analysis and contamination mapping 

17 


geographical coordinates of the measurements 

(samplings) place are written into the record. 

The presentation scheme for measurements 

data includes the record - description of the 

sampling (measurement) place, that stores the 

territory code, geographical coordinates and the 

coded characteristic (lodging, yard, vegetable - 

garden, etc.) of the object being investigated. 

Each record of the sampling place description is 

related to the inspection record of the given object. 

These records contain the sampling or 

measurement date and time; code of the inspecting 

service; code of the analysis type by 

means of which the sample was investigated or 

of the device type that was used during measurements. 

All measurements are fixed in the 

measurements record: code of the measurement 

type (for example, concentration of different 

radionuclides); value; measurement error; 

code of the measurement unit. Each such record 

is related to the its own record of the given object 

investigation. 

An obligatory requirement to the measurements 

data is their spatial and administrative 

and territory tie. Data of the network monitoring 

that come through the communication channels 

can be automatically processed and loaded into 

the data base. Information with the data of the 

network monitoring has the measurement point 

index by means of which coordinates of the 

measurement place are defined and it becomes 

needless to fulfil additional actions for their spatial 

and administrative and territory tie. For all 

other cases those software can be used that 

permit the operator when recording the measurement 

data into the data base to use digital 

maps of the territory to indicate the sampling 

(measurement) place. 

ADMINISTRATIVE AND ECONOMIC 

DIVISION AND POPULATION DATA. To 

evaluate the scales of the accident related to the 

radiation contamination, degree of risk and 

working out of measures to protect the population 

the administrative and territory and population 

data bases can be used. Structure of the 

bases contains the records of the territories description 

including the populated areas combined 

into a recursive set. Links of records reflect 

the hierarchy of administrative and territory 

division. Each record has the territory code and 

its name; code of the administrative and territory 

importance (for populated areas); coordinates of 

the populated area (for territories - coordinates 

of the populated area that is the centre of the 

given territory). Each such record is related to 

the population record. For records of the territories 

description this record has the amount of 

the town and village inhabitants of the given 

territory. For records of the populated areas in 

addition to data of the total amount of inhabi-


tants there is information on distribution of the 

population by sex, age, ability to work and main 

forms of activity. 

At present the above described data bases 

have information on 13 contaminated regions of 

Russia: Bryansk, Kaluga, Tula, Lipetsk, Orlovsk, 

Kursk, Smolensk, Ryazan', Voronezh, Tambov, 

Tver", Novgorod, Leningrad. 

HYDROMETEOROLOGICAL DATA. The Hydrometeorological 

data base is primarily needed 

for modelling of processes of radioactive substances 

distribution in the environment. The 

data base is assigned to localize the operative 

information that comes from the hydrometeorological 

observation network. The scheme of the 

data base is a combination of definite sets of 

synoptic observations records, of serological 

observations, fields of operative analysis and 

numerical forecast of meteorological parameters, 

meteorological stations data. 

1.3. Presentation of mapping information 

To obtain the most complete information on 

the environment state the system is provided 

with information that is necessary to present series 

of thematic maps. Each map of such series 

is related to a definite theme. The distinctive 

characteristic of such series consists in that the 

whole collected information about definite features 

of the environment is used for presentation 

of landscape and geochemical maps and data of 

the contamination levels measurements superimposed 

on the landscape and geochemical 

situation in combination with the character of the 

territory exploitation, hydrometeorological conditions 

are the basis for plotting the maps to 

evaluate the state and forecast the radiation 

situation development (variation). 

The mapping system works with a raster, so 

with vector maps, raster maps are used as the 

basis to represent radiation contamination data 

and other data obtained in the course of work in 

RECASS and the vector graphical information is 

the input data for modelling, for example, information 

about relief for programs to model the 

processes of radioactive substances transport in 

the atmosphere. 

The raster map data base is created in accordance 

with the known principle of division of 

the whole world into fassets and storage of data 

for them in the form of definite files. An automatic 

location with transition through the boundary 

of a fasset and scaling with transition to a 

fasset of the other scale is realized in the system. 

When inputting and transforming maps into a 

digital (vector) form element-by-element separation 

of the map content is made. Thus, when 

diditizing the topographic maps, definite sets are 

data on relief, geographical network and populated 

areas. The formulated data base is a multi- 

18 

scientific Articles 

layer system where each layer presents a definite 

type of data. Overlapping of layers form a 

model of the territory based on the selected set 

of parameters (soil, vegetation, forests and arable 

land, etc.). The principles of layer-by-layer 

displaying of geographical information permitted 

to create software that hat only formally different 

layers, but also provide possibilities to interpreted 

and analyse the results obtained, and 

possibilities of scaling of the region being studied 

allow the user to establish the required level 

of detailing and of exactness of the data presentation. 

1.4. Objectivization of contamination 

measurements results and meteoparameters 

Correct mathematical processing and presentation 

of measurement results often essentially 

increases their value. 

For measurements related to monitoring one 

can separate three main trends of such processing: 

- investigation and classification of distribution 

functions in dependence on the type of 

measurements, value being measured, nature of 

territory, type of deposition, etc. (problem of calculation 

of measurements statistical characteristics); 

- reconstruction of the value of the data field 

at some points or of the field itself (as function 

of coordinates) from results of measurements of 

this field values (interpolation problem); 

- reconstruction of the data field value at 

some points or of the field itself (as function of 

coordinates) from measurement results of this 

and other fields (regression problem). 

To solve such problems a number of algorithms 

were developed that are realized in the 

form of computer programs and are included 

into RECASS. 

The data bank that permits to couple contamination 

measurement results and geographical 

coordinates of the measurements place is 

their informational basis. This, soloing, for example, 

an interpolation problem using this information 

one can plot data random field - a 

function by means of which based on coordinates 

of any point at the territory where measurements 

were carried out, it is possible to estimate 

the assumed value of the parameter being 

studied and the accuracy of this evaluation. 

The description of methods used in RECASS 

to solve the interpolation problem is given in the 

Appendix. 

Data of objective analysis obtained due to 

suck processing and presented in the form of 

standard maps of the territory radiation contamination 

are the basis for calculation of the radiation 

situation and to make a decision on liquidation 

of contamination after-effects. 

"Radiation & Risk", 1993, issue 3 Scientific Articles 

1.5. Software for the system of the 

radiation situation monitoring data base 

Structure of the software (Fig. 1) includes the 

following program blocks: 

1 - data preparation block; 

2 - data loading block; 

3 - contamination DB correction block; 

4 - block for works with dictionaries; 

5 • population DB correction block; 

6 - administrative and territory division DB 

correction block; 

7 - block for data contamination data processing; 

8 - block for data interpolation, grids preparation; 

9 - block for demonstrations preparation and 

review; 

10 - block for maps preparation and their 

output. 

On one hand, the module structure of the software 

permits to adapt quickly the system to concrete 

conditions of its number of independent 

blocks that can be realized simultaneously. The 

possibility to match the communication facilities 

of the system with user's aids and his (her) 

needs allows to use it widely as an excellent tool 

for training of persons that take solutions, for 

testing of plans for actions under extreme conditions 

and as a way to attain experience in 

making up plans for extraordinary situations and 

of recommendations for long-term measures 

and rehabilitation actions. 

1.6. Forms for the output information 

To present information obtained when solving 

the problem of evaluating and forecasting 

the radiation situation development (variation) 

by means of radioecological data bank the following 

forms were accepted: 

- text files (dbf.files); 

- graphical data files (plt.files); 

- screen picture (slide) and slide film; 

N - spatial and temporal grids of radiation 

situation data (radionuclides concentration, dose 

rate, etc.) in the specially developed format. 

By means of the mentioned forms as real 

radioactivity measurements data, so model data 

can be presented. And in some cases (for example, 

when calculating doses) - their combination 

too. 

The dbf.file form of information output is 

convenient because there is a large amount of 

standard software that works with such files, in 

particular various report generators. 

Graphical data file is being prepared with 

application of HP-GL language standards. This 

form of presentation is necessary to prepare the 

output product in the form of standard nomenclature 

contamination maps assigned for preparation 

of hard copies utilizing different plotters. 

19 

Slide and slide films form of presentation 

permits by means of a computer to display in 

the dynamics the results of analysis of the radiation 

situation development (variation of the 

radioactivity concentration for different types of 

environment, doses at the territories, etc.). This 

form is convenient for visual review of situation. 

Spatial and temporal grids can serve as a 

form for information exchange between different 

blocks of the system, for example, as input information 

onto mapping block. 

2. Reconstruction of contamination 

dynamics with application of 

mathematical modelling methods 

As it was noted above, the monitoring data 

by themselves are not always enough to formulate 

the appropriate recommendations on countermeasures 

working out. However, the earlier 

described technologies for storage, comparing 

and objectivization of information of the widest 

range, supplemented by mathematical modelling 

means allows one to state and solve different 

prediction (direct and reverse) problems related 

to radionuclides distribution. 

A number of physical and mathematical 

models are realized in RECASS: air transport of 

radionuclides in the near, middle and for zones 

around the radiation dangerous object [6, 7]; 

calculation of source parameters and meteoparameters 

for working in the real time regime 

models of transport in the near zone [8]; 

long term forecast of radionuclides migration in 

the soil [9]; dose estimation, etc. 

The possibilities of the RECASS system related 

to reconstruction and refining of the radiation 

situation are illustrated by the reconstruction 

of the dose received by population during the 

Chernobyl accident. This complex problem is 

solved by firstly, direct dosimetric population 

inspection, secondly, by means of biological, 

physical and chemical methods, and lastly 

through mathematical modelling. One of the 

stages of such modelling is reconstruction of the 

temporary picture of the atmosphere and Earth 

surface contamination by different radionuclides 

during the accident. 

To get such a 137 Cs picture for the 140x140 

km zone near to Chernobyl we used the regional 

stochastic transport model (RSM) with preliminary 

source reconstruction. (Description of the 

model is given in Appendix). 

2.1. Reconstruction of some source parameters 

during the first days after the accident 

at the Chernobyl nuclear plant 

Proceeding to the solution of this problem the 

following information was at our disposal:


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"Radiation & Risk". 1993, issue 3 

Grids of the three-dimensional wind were estimated 

in every 6 h, with dimensions 40x50x10. 

Fig. 3 demonstrates the reconstructed 

source. The source data were used to model the 

atmospheric diffusion process. Fig. 4 shows the 

isolines of calculated and measured fields. As 

an additional criterion of these fields similarity 

one can consider the correlation coefficient 

0.704 estimated from the corresponding grids. 

We think that it is a high value. 

Calculation of the corresponding value for 

grids plotted based on the AGS and sampling 

data just because of this we did not optimizw the 

source by height and disperse composition. The 

rest discrepancies are, apparently, defined not 

by the source, but by uncertainties in the meteoparameters 

and some assumptions in RSM. 

3. Conclusion 

The possibilities of RECASS described in the 

paper related to reconstruction of the functions 

of collection, storage and presentation of information 

about radiation situation at the territories 

Q 


being controlled and its forecast; estimates of 

the counter measures undertaken from the point 

of view of doses received by population as a 

result of the environment radiation contamination 

demonstrate it as a good basis for solution 

of radioecological analysis problems and for 

decision support. 

The availability of a large number of adaptable 

informational and software subsystems allows 

the user to quickly develop and include into 

RECASS new possibilities as new problems occur. 

Thus, joint utilization of geanfonmational 

system (relief, basis fir output geographical 

forms), radioecological data bank (soil contamination 

data, meteodata) aids of objectivization 

(presentation of model and calculation fields 

grids, output graphical forms) and of physical 

and mathematical modelling allowed with a high 

degree of reliability to solve the problem of the 

temporal and spatial reconstruction of the contamination 

picture. 

**"• v •* v -s- 

\A A A A + *^f^> /•• y yS 

* * * >" **jHX;^ A A * * 

* r I 1 ' *~ '' '* *' * "^ * * + * A

N ' 

50 4C 


29- 0' 

52- 0' 

137 Cs. Ci.taT 2 

KOline according to the simulation resalts 

A* according to measured values 

• - L"s than 0.5 — _ 1£. _ 4Q 

I - 0.5 - 1 ilill 40 - 

5-15 

pooooij - 100 - 500 


3i- f 

P +i = - PDF* + PDF* 

(\\PDP~ 1 f 

a k+1 (D • P, P* 

= - 

1 ) 

(P +1 , CP +1 )' 

X k+1 = X" + a k+1 • P +1 . 

During calculations it is necessary to test the 

restrictions xt > 0. Therefore within each iteration 

step after estimation of a** 1 is evaluated: 

a* = mm 

i.-pfUo 

A . 

Ff +1 

If a k+1 < a k+1 , then a k+1 = a k+1 and the 

X** 1 corresponding is calculated. It is the coordinate 

which corresponded as minimum becomes 

equal to zero. Its index is included into /. Then, 

setting X° = X**', we repeat the procedure from 

the very beginning. 

When achieving the conditional minimum 

(PDF, PDF) < 10, the values of those coordinates 

of the gradient project are tested, which 

have indexes within /. If all values are more than 

zero, a minimum is attained and the process 

ends. In the contrary case, that index, to which 

the minimum value of the coordinate of the 

gradient projection corresponds, is excluded 

from / and the minimizing process is repeated 

with application of the current Xas X°. 

Convergence of this process is proved by the 

following considerations: 

1) non-generated quadratic functional has 

one conditional (at linear restrictions of the 

equality type) minimum; 

2) in the conjugated gradients method F 

strictly decreases with each step and the number 

of steps before attaining minimum or when 

xi = 0 nor more than N is fulfilled; it means that 

having determined the conditional minimum 

within any subspace (side) xt = 0 / e /, and then 

P, 

P,


continuing the process, we shall never return to 

this side; 

3) amount of sides that correspond to different 

/ is finite. 

4.2. Algorithms for reconstruction of 

contamination and meteofields 

from measurement results 

To solve problems of interpolation two approaches 

are used: 

- reconstruction of the field value at the point; 

- reconstruction of the field value as a function 

of coordinates. 

Both approaches have drawbacks and advantages: 

the first one permits quick and visual 

presentation of information; the second can be 

used as a basis for solution of regression and 

management problems. 

To use the first approach for processing of 

contamination measurement results two methods 

were developed - a speedy method that enables 

presentation of contamination fields in real 

time and a slower one which more correctly calculates 

the statistics of contamination fields. 

Introduce the following notations: 

N - number of individual measurements. 

Further this term will mean either direct measurement 

(for aerogammasurvey, for example) or 

some average value to which definite coordinates 

are given; 

Zt- values of an individual measurement; 

Si - standard deviation (in case of multiple 

measurements) or accuracy of measurements; 

D, * Si 2 - variance of individual measurements; 

frh Yd • coordinates of individual measurements. 

4.2.1. Operative reconstruction of fields 

by means of weight coefficients 

Concerning this method, measurement results 

with their respective weight coefficients are 

interpolated to nodes of the uniform grid using 

the following formula: 

* 

F ' = e x p ( - 2 - m - T), D = 

(A.1) 

where F, - weight of the value at the Mh point; 

Ri- distance from the Mh point to the node; 

d- grid step; 

k- by default is taken to be equal to 2. 

As this takes place averaging is carried out 

from the measurement values that are the closest 

to the node rectangular grid meshes down to 

the depth of If. For aerogammasurvey the data 

size of the square grid mesh is determined as a 

half of the interroute interval. 


The interpolation function for the whole area 

is reconstructed from finite elements each of 

which is the minimum parabola of the following 

form: 

26 

Z(x,y) = Z1+(Z4-Z1)x + 

(A.2) 

(Z2 - Z,)y + (Z3 -Z4+Z,- Z2)xy, 

where Z; - intensity values at the nodes of the 

grid mesh.; 

x, y e[0,1] • [0,1]- relative point coordinates 

within this mesh with an area of determination 

on the corresponding rectangular mesh. 

This form of interpolation elements automatically 

provides a continuous function over the 

interval of interest. 

The isolines are plotted as graphs of functions 

inverse to the interpolation one, each element 

of which has the following form: 

Z0-Z1-(Z4-Z1)x 

y Z2-Z1+(Z3-Z4+Z1-Z2)x 

where Zo • is the specified value of the isoline 

with the area of determination: 

[0,1] II {x: y(x,Zi& e [0, 1J}. 

Continuity of the interpolation function allows 

plotting of the isoline inside each mesh independently. 

This sort of approach can work without 

isoline tracking. 

When calculating the upper limits of the confidence 

intervals to take into account the discrepancy 

of the initial measurements distribution 

function from the normal, a training sampling 

method was used. From the initial file each point 

was subsequently removed, from the algorithm 

given above the field value for corresponding 

coordinates was evaluated and the correction, in 

comparison with the normal distribution, coefficient 

(f) for the standard deviation was calculated. 

It turned out that f = 1,2 sufficiently reliably 

(for data obtained by the aerogammasurvey 

method) defines the upper limit of the confidence 

interval, i.e., assuming a normal distribution, 

then 95% of probability corresponds to 

/ = Z+ 1,645 S, 

with allowance for the correction coefficient 

/ = Z + f • 1,645 S = Z + 1,974 • S. 

Note that the method described is highly 

flexible and adaptable to computer capability. 

Further it permits processing of files of an arbitrary 

size, is not limited by the areas being processed 

and is equally applicable for a small or 

large member of measurements. 

4.2.2. Estimation of fields through evaluation 

of auto-correlation functions 

The second method uses a procedure of the 

field values estimation at the grid nodes that is 

r 


based on the preliminary evaluation of the autocorrelation 

function. 

Let Z/ (xy yi)-be the point of measurements. 

Divide the initial area into M rings with Km equal 

thickness with the centre at fx/, yj). Let 

u? = (£z*) / /.. 

k=0 

where lm is the number of Zj : (xj, yj e K^ 

Repeating this operation for N0£N randomly 

selected points, we shall obtain M pairs of series: 

{z„u]},{z„u?},...,{z„u?} • 

Those pairs which are included into series 

have: 

/' *0 

Correlation 

coefficient 

0,957 

0,916 

0,872 

0,792 

0,772 

0,695 

0,619 

0,475 

0,487 

0,389 

0,321 

0,216 

0,187 

Criterion 

value 

3,70 

5,17 

5,99 

6,78 

6,88 

7,01 

6,83 

5,86 

5,97 

5,03 

4,26 

2,96 

2.58 

Reconstruction of the function value in the 

node is obtained from the following formula: 

\ 

s w 

Z, =*&r 

2 X 

m=1 

where values of Wm are reconstructed by means 

of the iteration formula: 

Wt=/Va s> 

wl+1=(i-i: w j) k --i' 

Here *s - is the correlation coefficient that 

corresponds to the first of the rings that contains 

measurements, lj- is the number of such rings. 

The node dispersion is evaluated in the 

manner described above: 

Degree of 

freedom 

184 

197 

197 

197 

197 

197 

197 

197 

197 

197 

197 

197 

197 

Then from these pairs of series in a standard 

manner the correlation coefficients km, m = 1, 

M, and their significance levels P are estimated 

and from the Student criterion [11]. Further, according 

to the condition P > Po we choose the 

Mo first correlation coefficients. Note that the 

total thickness of Mo rings defines the correlation 

radius. 

An example of the procedure operation is 

given in Table A.1 to which the following initial 

values correspond: 

thickness of the correlation ring - 0,72 km; 

volume of the training sample - 200; 

total amount of rings in the zone - 80; 

probability to test significance of the correlation 

coefficient discrepancy from zero - 0,99; 

significant correlation radius for this example - 

9,4 km. 

Confidence 

probability 

0,9999 

1,0000 

1,0000 

1,0000 

1,0000 

1,0000 

1,0000 

1,0000 

1,0000 

0,9999 

0,9999 

0,9982 

0,9946 

Z W - 

D(Zj) _ = m=1 

(A.3) 5 X 

m=l 

27 

Table A.1 

Ring I 

number | 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

(A.4) 

where Df is dispersion inside the m-th ring 

around the >th node of the grid. If only one 

measurement is within the ring, then as Df, the 

average dispersion, for the m-th ring, obtained 

from the auto-correlation function, is chosen. 

4.2.3. Reconstruction of fields in the form 

of analytical functions 

To solve the problem of reconstruction of 

contamination fields as a function of coordinates, 

the cubic spline interpolation method was 

used [12]. 

Let the initial zone be given in the form of a 

rectangular on the plane.

I I 

11 

I I 

II . 

If -II 

11 1 " I 

III' 

I I 

I'll 


Plot a non-uniform rectangular grid on it in 

such a way that each rectangular P; contains no 

less than nine points of initial data. Let the number 

of such rectangles be L. Inside each rectangular 

we shall search for an interpolation function 

in the form of a two-dimensional third order 

polynomial P (x, y, 3) that linearly depends on 

the coefficients of 5. These coefficients are defined 

from conditions of attaining by means of 

the functional 

-\2 

PM.y'k.aJ-z* 

z - Z 

k=1 

which is minimized. The summation above is 

made over points, the coordinates of which are 

within the given rectangle, and equalities of Pk 

and their first and second derivatives at the 

general boundaries of corresponding rectangulars 

are used as conditions. 

Let So (of K dimension) be the value of parameters 

at the point of minimum. Then the intensity 

value at the point with coordinates (Xo, 

yo) will be P (xo, yo, So), / being the index of the 

rectangle, that contains the point (x, y). Dispersion 

at this point was estimated from the formula 

given below: 

o(x0,y0) = Y\9'»( x

I '. |l 

,'fl 


(vi +v; +v; +v;-v?-v y 

(vi-v2 2 -v 3 2 +v; +v; -v; 

Indexes of the velocity coordinates correspond 

to numeration of faces and tops given 

in Fig. A.1. 

Later on condition of (A.6) for the grid 

presentation will be naturally re-written: 

U?(x„y„z,) = (0,0,0), 

at zf

.i' 

M i 


maxK'V " (^h\ < £ 

maximum variation of the wind velocity field 

coordinates 0' is the iteration number, / is the 

coordinate number; 

|fU*"%, - (u lnd ), 

\(U M )]+1 

< s 

relative variation of the wind velocity modulus 

iteration. 

The last quantity appeared to be the most 

useful. At the accuracy parameter of 0.001 the 

last condition is realized in 3-4 iterations (with 

20000 grid nodes). Fig. A.2 illustrates the results 

of calculating wind speed field meeting the 


above listed geophysical requirement for a part 

of terrain on the southern boundary of the Bryansk 

region. 

The upper part of the figure is horizontal 

cross-section of the 3-D field, the lower - the 

cross-section of the field by the vertical plane 

passing though the line (a, b) shown below in 

the horizontal cross-section. 

Based on our approaches and algorithms we 

created software which makes it possible to calculate 

3-D wind velocity fields from various initial 

data, and save, cut out, combine and visualize 

them in any horizontal and/or vertical crosssections. 

ICC SPH Typhoon i Ubniwsfc, 1992 

KMJTOVKA 

Fig A 2 Balanced 3-D field of wind velocity vector field for a section of earth surface near Vyshkov, 

Bryansk region (a picture of PC terminal screen with results of GIS which we developed). 

4.3. Regional model of atmosphere diffusion 

based on the Monte-Carlo method 

The present model was based on the requirement 

to describe both routine and emergency 

releases of contaminants into the atmosphere. 

Previously, a variety of local, regional 

and global models of transfer and dispersion of 

substances in the atmosphere have been published. 

Many of the existing models in - corpo 

32 

rate the complexity of the present problem by 

taking into account various meteorological 

conditions and a wide range of spatial and temporal 

scales of the atmosphere disturbances. 

Traditionally diffusion models are classified as 

follow: Gaussian models, models of K-theory 

diffusion, models of the similarity theory and 

statistical models. 


The Gaussian diffusion model is mostly 

widely used. It serves as a basis for almost all 

models in the EPA USA UNAMAP system and 

for models created by USA Atomic Energy 

Commission [13]. The model is based on a 

simple formula that assumes the constant wind 

velocity and complete reflection from the earth 

surface. For the case of a continuous point 

source, the Gaussian formula for a plume has 

the form: 

R = G(y,Ofay)(G(z,H,


chastic model which generates a random process 

that has specified statistical features. The 

statistical procedure for calculation of diffusion 

is based on use of an equation for random pulsations 

of the particle turbulent velocity and on 

plotting of tracks of thousands of individual particles. 

The particle motion in the wind velocity field 

is expressed by a sum of the average and turbulent 

components that are separated with application 

of the definite specific averaging time. 

The equation for the particle total velocity in the 

direction / On the system of coordinates related 

to the average wind direction at the given point) 

has the form: 

v,=vl+v;. 

As a mean wind field one can take results of 

a dynamic model or the field built from network 

measurements. In the last case, the obtained 

field of mean wind is corrected with allowance 

for meeting the equations of continuity providing 

for conservation of the material mass. At time 

scales that exceed the averaging time ail turbulent 

diffusion is described by spatial and temporal 

variations in the average wind. 

At the time scales less than the time for averaging 

the diffusion is estimated on the basis of 

assumption that the turbulent pulsations have 

two components - correlated and pure random. 

v;(t + At) = v;(t)P'L+p„ 

where At - time step; 

pt(At) - Lagrangian auto-correlation coefficient 

for the Mh velocity component. 

34 


The random component is generated is such 

a way that it has a Gaussion distribution of 

probabilities with a zero average and standard 

deviation given by 

This condition provides for turbulence energy 

conservation from step to step. To calculate 

PL (At) an exponential dependence is often used 

p'L(At)=exp(-At/ rL). 

Movement of the particle at each moment of 

time is determined by the velocity fluctuations 

that correspond to CT/ and pi!(At) values at the 

given point of space, i.e., the model allows including 

variation of these parameters into description 

of the diffusion. 

Thus, success of the statistical model application 

depends primarily on utilization of the 

most accurate experimental and theoretical estimates 

for profiles of the turbulence energy and 

velocity timescaies. The best of the up-to-date 

values of these variables [14] are used in the 

present model. Components of the turbulence 

energy and time scales in the unstable atmosphere 

boundary layer (ABL) are given by the 

following formula: 

'•r 


^ = [12 + 0,5h/ \l\X\ 

^- 

w. 

= 0,96 

h 

-(1/3 

h 

for ~ < 0,03, 

h 

^- =/n/n 0 , 9 6 ^ - M ; 0,763 

r 7-\ 0 - 207 

= ° ' 7 2 T - i 

= 0,37 

7? = VL=0,15^-, 

for 0,4 < — < 0,96, 

h 

for 0,96

'I 


ta - Earth rotation angular velocity; 

. = (0hPo/ Cp p) 1/3 

Monin-Obukhov-scale is 

L=- 

k0Po/ CpP 

where k - Karman's constant. 

The characteristic scales U., a>., L and external 

parameters h, z0, Vg of the boundary atmospheric 

layer can be determined using other 

methodologies or direct measurement methods, 

given a measurement network. 

The diurnal variation of the ABL thickness is 

described by the formula [16]: 

H = Hmx(0,54 + 0,46 cos((t -15) • 15 + X)), 

where Hmax - maximum height of the mixing 

layer, m; 

H - layer height at the moment t, m; 

t-time, h(AGT); 

X - longitude (degrees). 

1,25 Mt. for fi2_h < 0; 

0,002(M2.h) 2 +2,77M2-h-20, 

for M2-h > °- 

The dynamic velocity is determined from the 

relationship in [16]: 

for 0 < Mo-h *• 1200 

for - 600 < Mo-h < 0 

Maximum height of the mixing layer is an input 

parameter. It is assumed that outside the 

mixing layer in the free atmosphere where the 

turbulence is suppressed mixing of the particle 

in the horizontal occurs only due to the average 

wind horizontal component and in the vertical - 

due to sedimentation and the average wind vertical 

component. As this takes place, the particle 

easily penetrates inside the layer. The velocity 

vector of the particle that is within the mixing 

layer has a turbulent component too. In this case 

the particle reflects from the upper boundary 

layer when it tries to leave it. 

Interaction with the underlying surface is 

modelled with consideration of the capture coefficient 

for the probability to capture particles 

which touch the surface. The capture coefficient 

is an input parameter and can be either a single 

value over the entire surface or estimated by 

any method taking into account the variability in 

surface characteristics. 

If information on precipitation intensity is 

available, one can take into consideration 

washing out of the cloud. For this purpose, it is 

assumed that the particle is washed off with the 

probability: 

36 

p = 1 - exp (-A • At), 

where A - constant for depletion of substance 

from the atmosphere; At- time step. 

The washing off constant A is obtained from 

generalized graphs that are recommended in 

[17] and relate the washing off coefficient to 

precipitation intensity for different particle radii. 


For practical application, these graphs are approximated 

by the following formula: 

A=J1(r*exp (1-10/R 2 ), 

where J - precipitation intensity, mm/h; R - particle 

radius, m. 

The relationship between the particle radius 

R and velocity of its gravitational falling a> the 

formula given below was used [18]: 

to = 0,125 R 2 , 

where co is measured in mm/s, R • in m. 

Finally, in the practical realization of the 

model, the probability of the particle washing off 

by precipitation is estimated from the formula: 

p=1-exp (-J-10~* exp(1- 1 -^-)). 

(0 

One of the primary advantages of the Monte- 

Carlo method is the possibility to model a complex 

source. Within the framework of the model 

being described, this means generation for each 

individual particle its initial spatial and temporal 

coordinates, its velocity of gravitational settling 

and of the relative mass (or relative activity) that 

permits description of the source with arbitrarily 

changing intensity in time and with height of 

source of general magnitude and extent. The 

model enables work with several sources each 

ejecting materials of different dispersion composition 

and characteristics. For convenient description 

of these parameters, graphical input 

aids are available. 

Fields of concentration in the atmosphere or 

precipitation fields in the underlying surface are 

estimated at the arbitrary periods of time during 

the model operation. Evaluated fields can be 

stored (in standard form) on the disk and later 

be used for operation of other RECASS programmes. 

Besides, simultaneous output of data 

on material concentration in the given detection 

points is provided for. 

Input model information is prepared and 

adapted by a separate block of software permitting 

reduction in modelling time and unifying 

input information fluxes. This includes building 

3D wind fields from synoptic and serological 

measurement or results of objective analysis 

and prognosis made by specialized prognostic 

centres, correction of wind field with allowance 

for terrain and preservation of mass balance, 

calculation of stability parameters and characteristic 

scales of the atmospheric boundary layer, 

visualization of this information. 

References 

1. Borzilov V.A., Teslenko V.P., Shershakov V.M. 

Concept of GIS as a basis for development of 

tools of information support for environmental 

monitoring systems//Collection of works of IEM. 

37 

Issue 12 (154). M.: Hydrometeoizdat, 1991.-P.3- 

15 (in Russian). 

2. Kryshev I.I., Sazykina T.G. Simulation models 

for the dynamics of ecosystems under the anthropogenic 

impact of thermal and nuclear power 

stations. M.: Energoatomizdat, 1990 (in Russian). 

3. Kosykh V.S., Luksha I.S. Organization of a databank 

for network data of radioactive monitoring 

of the environment//Collection of work of IEM. Issue 

12 (154). M.: Hydrometeoizdat, 1991.-P.132- 


4. Dodonov I.N., Shershakov V.M. Computer 

equipment for geoinformation systems 

//Collection of works of IEM. Issue 12 (154). M.: 

Hydrometeoizdat, 1991 .-P. 15-29 (in Russian). 

5. Methodological recommendations on assessing 

the radiation situation in populated points. M.: 

Goscomhydromet of USSR, 1990 (in Russian). 

6. Korenev A.I., Borodin R.V. Information environment 

and specific features of programming 

implementation of accidental releases into the 

atmosphere//Collection of works of IEM. Issue 

12(154). M.: Hydrometeoizdat, 1991.-P.69-73 (in 

Russian). 

7. Borzilov et al. Some aspects of the Chernobyl 

accident consequences and post accident activities. 

In Proceeding of the Seminar on methods 

and codes for assessing the off-site consequences 

of nuclear accidents, Athens, 7-11 May, 

1990, Report EUR 13013. 

8. Aleksandr V. Golubenkov, Ruslan V. Borodin 

An Optimized Technology for More Precise Determination 

of a Source at Modelling Radioactive 

Substance Release into the Atmosphere. Third 

International Workshop on DECISION-MAKING 

SUPPORT FOR OFFSITE EMERGENCY 

MANAGEMENT, JSF, Scloss Elmau, Bavaria, 

October 25-30, 1992. 

9. Konoplev A.V., Golubenkov A.V. Modelling 

vertical migration of radionuclides in the soil 

(based on the data of the nuclear accidenty/Meteorology 

and hydrology.-1991.- 1 10.- 

P.62 (in Russian). 

10. Pshenichny B.N., Danilin Yu.M. Numerical 

methods in extremity problems. M.: Nauka, 1976 

(in Russian). 

11. Gmurman V.E. Probability theory and mathematical 

statistics. M.: Vyshaya shkola, 1977 (in 


12. Loran PZh. Approximation and optimisation. M.: 

Mir, 1975 (in Russian). 

13. Hanna S.R. Review of atmospheric diffusion 

models for regulatory applications. Technical 

Note: 177. WMO 1982. 

14. Atmospheric turbulence and modelling dispersion 

of materials. Ed. by F.T.Niestad and H.Van Dop. 

L: Hydrometeoizdat, 1991.-P.56-62(in Russian). 

15. Borodin R.V., Denkin V.A., Malkova E.V. 

Technology and methods for processing and representation 

of meteorological information//Collection 

of works of IEM. Issue 12 (154). 

M.: Hydrometeoizdat, 1991.-P.56-62 (in Russian).


16. Orlenko LP. Structure of planetary boundary 

atmospheric layer. L: Hydrometeoizdat, 1975 (in 


17. Account of dispersion parameters of the atmosphere 

in siting nuclear power plants. Manual on 

safety Vienna IAEA, 1982, STI (PUB) 549, ISBN 

92-0-423082-7 (in Russian). 

38 


18. Hrgian A.H. Physics of the atmosphere. L: Hydrometeoizdat, 


r 


Reconstruction of the composition of the Chernobyl 

radionuclide fallout in the territories of Russia 

Pitkevich V.A., Shershakov V.M.*, Duba V.V., Chekin S.Yu., Ivanov V.K., 

Vakulovski S.M/, Mahonko K.P.*. Volokitin A.A.*, 

Tsaturov Yu.S.**, Tsyb A.F. 

Medical Radiological Research Center RAMS, Obninsk; 

* - Scientific-production association "TYPHOON"; 

** - Chernobyl State Committee of Russia 

This paper presents original results of reconstruction of the radionuclide composition of the Chernobyl 

fallout in the territories of Russia. Reconstruction has been earned out by means of statistical 

analysis of the data on gamma-spectrometry of 2867 soil samples collected in the territories of 

Ukraine, Belarus and Russia from 1986 to 1988. To verify the data, aggregated estimates of the fuel 

composition of the 4-th block at the moment of the accident available from the literature have been 

used as wdl as the estinês of the radkaciivrty released into the atmosphere. Resulting correlation 

and regression dependencies between activities of radionuclides most contributing to the final dose 

( 1S7 Cs, 1M Cs, ,M I, ,40 Ba, ,40 la. "Zr. "Nb, im Ru, 106 Ru, 141 Ce, 144 Ce, 12S Sb) have been obtained. 

Statistically significant regression relations between different pairs of radionuclides (including 

analysis of "noise" contribution to the data) depending on the distance between the point of the 

sample collection and power station are presented in this paper for the "north-east track" - the 

northern part of the 30-km zone, southern part of the Gomel district (Belarus), Briansk, Kaluga, Tula 

and Orel districts (Russia). Results of reconstruction of relative surface contamination with 131 l isotope 

for about 7000 population points of Russia are given in the appendix 1, part 2 of the present issue. 

Introduction 

A knowledge of the radionuclide composition 

(RC) of depositions in Russia after the Chernobyl 

accident is not only of importance in itself, 

but is also critical for reconstruction of irradiation 

doses to the population, especially for the first 

year following the accident. It is also essential to 

complete the Russian State Medical-Dosimetric 

Registry, in which the dosimetry part lacks individual 

external and internal exposure doses over 

the first several years after the accident. 

Many studies examining various aspects of 

the Chernobyl accident have been recently published. 

Numerous organizations and institutions 

of CIS have pursued extended studies of parameters 

of environmental contamination after 

the Chernobyl accident. The results of these 

efforts are best described in [1]. The indicated 

publication presents RC of depositions in the 

near zone of the Chernobyl NPP (up to 100 km) 

as mean measured ratios of radionuclide activities 

in soil samples to ^Zr activity. In [2] RC of 

depositions in sourthem and Central Finland has 

been studied and [3], 131 l contamination of the 

territory of Russia has been reconstructed on the 

basis of statistical analysis of gammaspectrometry 

data of soil samples. Unfortunately, 

such comparisons have not been completed 

for other gamma-emitting radionuclides. 

A brief review of the published data demonstrates 

that the job of reconstructing RC in 

depositions on territories of Russia has not been 

completed. The given paper presents an attempt 

39 

to reconstruct RC of depositions on the territory 

of Russia based on detailed analysis of available 

experimental data about major doseforming 

radionuclides. 

1. Methodology for analysis and 

grouping of gamma-spectrometry 

data for soil samples 

The analysis was made using the database 

of SPA Typhoon" of Roshydromet which comprises 

gamma-spectrometry data for soil samples. 

These data have been collected by SPA 

Typhoon", institute of Applied Geophysics of 

Roshydromet, Russian Scientific Centre 

"Kurchatov Institute", Main Hydromet and Institute 

of Nuclear Energy of Byelorussia Academy 

of Science. Measurements of radionuclide levels 

in soil samples collected in the "benchmark" 

network of the 30-km zone of the Chernobyl 

plant were not used at that stage. The maximum 

measurement error in determination of the radionuclide 

level was not more than 30%. 

The available spectrometry data can be divided 

into 3 groups: 

Group 1 - measurement results with indication 

of sample code and measured specific surface 

activity for all recorded radionuclides - data 

for 295 settlements - 2654 records (measurement 

results for 606 soil samples with established 

geographic coordinates of sampling 

points). 

The next two groups have been identified in 

the data measured activities of various radi-


onuclides without indication, however, of the 

sample code. Specifically: 

Group 2 - records with the same sampling 

date to which measurements of activities in a 

settlement (populated point or PP) are referred, 

provided the number of activities of some radionuclide 

in the given settlement is equal to 1. 

However, the probability of determination 

whether activity measurement result belongs to 

the same sample is not exactly unity (but very 

close to unity, as the analysis showed). After 

verification, we received such data for 2052 settlements 

- 7534 records (2261 of "pseudosamples* 

with established geographic coordinates 

of sampling points). 

Group 3 - this group included all the radioactivity 

measurement data which are represented 


in the source file as average values with indication 

of minimum and maximum values (the 

number of values for which averaging was done 

was more than 2) and sampling dates. In this 

data array it is impossible to determine whether 

activities of radionuclides belong to the same 

sample. Thus, of the total data bulk 10707 records 

for 2558 settlements of the Russia, Byelorussia 

and Ukraine were included in Group 3. 

We have analyzed the data in Groups 1 and 

2 only. The activities of radionuclides in each 

sample were referred to the same date - 10 May 

1986. We classified the decay schemes as follows 

(Tm and 7*0 - are half-lifes of radioactive 

decay of parent and daughter nuclides accordingly): 

1 - the radionuclide in decay does not form a daughter radionuclide. For example: 

131 

98.9ô 

l.liy>J 131m Xe 

131 Xe 

134 Cs m 

141 Ce 

or the daughter radionuclide is a beta-emitter only. For example: 

143 Ce •H 143 Pr 143 Nd 

m 

= 8.04 d 

= 2.062 y 

141 Pr T m =32.6 d 

T m = 33 h 

Td = 13-66 d 

In this case, the external exposure to gamma-quanta is determined by the exposure to the parent 

radionuclide only. 

40 



2 • the decay of a radionuclide produces daughter radionuclides products with half-life considerably 

shorter than the daughter radionuclide half-life, for example: 

T m = 30y 

T d = 2.56 m. 

T m 

- 39.28 d 

T d - 66.12 m 

Tm = 28.43 d 

T dl = 17.28 m 

T d2 = 7 - 2 m 

T m = 66h 

T d|_ = 213000 y 

Td2 "6h 

T m - 78.2 h 

T d = 2.3 h 

T m 

- 36.82 d 

Tj= 29.9 s 

In this case, the external gamma ray exposure is determined by both parent and daughter radionuclides 

but the equilibrium between parent and daughter sets in rather quickly. 

3 -the decay of a radionuclide forms daughter products having the half-life of the same order of 

\ magnitude as that of the parent half-life, for example: 

T m 

T d l 

= 63.98 d 

= 35.16 d 

T^ =84h 

T n 

- 12.74 d 

T d - 40.27 h 

In this case, the external exposure with gamma-quanta is determined by both parent and 

daughter radionuclides and the equilibrium sets in fairly slowly. 

41



4 - the radionuclide decays to form daughter products with half-life much longer that of the parent 

radionuclide, for example: 

T m - 20.8 h 

T j. - 6.245 d 

The analysis depends on the category to 

which the measured radionuclide in the sample 

belongs. If it belongs to group 3, the total activity 

of the parent and daughter radionuclides is calculated. 

The spectrometry data can be available 

for the parent and daughter radionuclides separately, 

the parent radionuclide only, the daughter 

radionuclide only or the total activity of the parent 

and daughter radionuclide. For reconstruction 

of the time the relationship of parent and 

daughter radionuclides activities we took account 

of their ratio at the time of the accident 

(see Table. 1). If data about activities of both 

parent and daughter radionuclides in the sample 

were available, the total activity was estimated. 

Given total activities differed from the average 

value by more than 20% for Group 1 (30% - 

Group 2), the data of such a sample were discarded 

as unreliable. 

For further analysis we need estimated activities 

of major dose-producing nuclides, including 

short-lived nuclides that were released to the 

atmosphere by the accident at the 4th unit. 

There is an extensive literature on the problem. 

For our purposes we averaged data from different 

publications [1 ],..., [14] (column Q0 in Table 

1 together with root-mean-square deviations) 

without detailed analysis of the data (see [13], 

[14]). The activity released in the atmosphere 

(last column of Table 1) was estimated for longlived 

radionuclides by release coefficients and 

average accumulated activity. The coefficients 

of the radionuclide release to the atmosphere 

were taken from [13]: for caesium species - 

0.33, for iodine species - 0.55, for inert gases - 

1.0 and for other radionuclides - 0,035. In assessments 

of released activity of short-lived radionuclides 

(marked (*) in Table 1) the assumption 

was made that "radioactive brothers" (longlived 

and short-lived) such as 137 Cs, 136 Cs, 13 M, 

133 l; 132 Te, 144 Ce, 141 Ce, 143 Ce are carried over in 

the atmosphere on the same aerosol particles. 

The released activity of the short-lived brother, 

then, is determined by release rate of the long- 

Td2 =2.18d 

Tm 

- 10.98 d 

T d - 2.64 y 

lived brother, the decay of short-lived species 

and the ratio of their activities in fuel just before 

the accident. The proportion of 131 l and 133 l aerosol 

fractions was taken to be 70% and 132 Te - 

100%. 

For analysis of radioactive contamination 

(relationship of fuel and fall-out components of 

the deposition) one needs to know ratios of radionuclide 

activities in the fuel of the damaged 

unit. Such ratios for the accident time and 10 

May 1986 (date to which we attributed radionuclide 

activities in the analyzed soil samples) 

obtained on the basis of publications [1] [14] 

are shown in Table 2. In addition to cerium ratios 

Table 2 includes zirconium ratios, as the soil 

samples under consideration showed x Zr more 

frequently and at farther distances from Chemobyl 

NPP. Note that symbols 140 Ba and ^Zr in 

Table 2 refer to the activity of parent radionuclide 

(Except Table 2, these symbols in the work 

refer to total activity of parent and daughter radionuclides). 

The statistical error of the ratios, 

calculated with the data from the papers cited 

above, did not exceed 30%. 

For further statistical analysis, we grouped 

the data by coordinate sampling points. The best 

way to do this would be to perform data grouping 

along the trajectory of atmospheric transport 

of radioactive aerosols. Because of the complicated 

(poorly understood) and long-term nature 

of the transport of radioactive material from the 

damaged unit #4 over the territory of Russia, we 

used a cruder way of grouping - by distances 

from the sampling point to the Chernobyl NPP 

within the selected "coordinate corridor": 51.3- 

54.0° N and 28.5-31.0° E or 52.0-54.0° N and 

31.0-39.0° E. This is the so-called "north-east 

trail" - the north part of the 30-km zone, southem 

part of the Gomel region (Byelorus), Bryansk, 

Kaluga, Tula and Orel region (Russia). 

Another condition used in grouping was that the 

number of samples in each group was about and 

not less than 20. So, for each pair of radionuclides 

we selected boundaries from the condition 

42 


of more or less uniform coverage of the territory 

within the selected coordinate boundaries. With 

such a grouping of sampling points "gaps" appeared 

in the 0-650 km distance range, i.e. areas 

having no or few sampling points and for 

which the criterion of uniform filling-in is not 

met. In this work we used the cartographic system 

developed by Information-Computer Centre 

of SPA "Typhoon". Figure 1 is an illustrative 

cartographic description of the "north-east trail" 

and shows distribution of sampling points from 

the measured 137, 1J 'Cs data Groups 1 and 2. 

Table 1 

Radionuclide activities (megaCi) (averaged with literature data) accumulated (Q0) in the 4-th 

unit of ChNPP by the accident and released (Qr) in the atmosphere in April-May 1986 

Ky is ionization gamma constant with allowance for gamma-radiation of short lived 

Radionuclide 

137 Cs 

136 Cs 

134 Cs 

1311 

133| 

132 Te 

1



137, 

Fig. 1. Spatial distribution of soil samples of Groups 1 and 2 in which the 1J 'Cs level 

was measured - "north-east trail". 

2. Correlation and regression 

analysis of spectrometry data 

of soil samples 

The most complete measurements on the 

territory of Russia were made of the surface soil 

specific activity of 137 Cs which did not contribute 

significantly to the dose rate at an early stage.. 

Nevertheless, one can attempt to find correlation 

relationships between Cs activity arid 

some significant short-lived radionuclides, as 

well as other pairs of radionuclides. As an example 

of such an analysis we cite work [2] in 

which on the based of gamma-spectrometry 

data of 62 soil samples collected in Southern 

and Central Finland, correlations have been derived 

for two groups of radionuclides - 137 Cs, 

134 Cs, 131 l, 132 Te and 141 Ce, ^Zr, ^Sr, 103 Ru, 

140 Ba. There is also a loose correlation between, 

these two groups. 

Let us briefly describe the regression analysis 

of spectrometry data of soil samples. To maintain 

natural boundary conditions the linear regression 

equation "was fixed" at the origin (using 

the background 137 Cs activity from global fallout). 

This gives a relationship between activities 

of the deposited radionuclides with a positive 

44 

slope even if there is no correlation between 

them (or when the number of samples in the 

group is not enough to verify the hypothesis 

about non-zero correlation coefficient). We then 

introduce in the analysis a normally distributed 

random value G - "noise" which collectively 

describes all random effects on ratios between 

activities of deposited radionuclides and has the 

mathematical expectancy E(G) = 0. We assumed 

that a random activity value of one radionuclide 

Y with the prescribed activity value of 

the other radionuclide X is written as the relation: 

Y = b X + G X" (D 

where b is regression parameter to be estimated; 

G is normally distributed random value with 

the average 0 and unknown dispersion s 2 ; 

a is a normalizing parameter which takes 

values at the segment from 0 to 1. 

The parameter a was selected so that the G 

"noise" distribution approximated the normal 

distribution when calculating the unknown b and 

s by the likelihood maximum method. As a cri- 


tenon of conformity to the. normal distribution we 

used standardized coefficients of asymmetry 

and excess [15] and also the two-side Kolmogorov-Smirnov 

criteria for limited samples 

[16]. At a = 0 model (1) corresponds to additive 

noise and at a = 1 to multiplicative noise. The 

likelihood function was written from the condition 

that the values obtained from experimental data 

_Y,-b X, 

1 " XT ' 

(2) 

where / is the measurement number, should be 

independent realizations of normally distributed 

random value with zero average and unknown 

mean-square-root deviation s. 

Estimates of parameters b and s can then be 

written as: 

2>/ -x,-Yi 

b = J T- (3) 

where Xt, Yt are measured activity values in 

samples, n is number of samples in the analyzed 

group, 

1 

w, 

I 

= 

x 

v2a 

(4) 

f 

s *=~£wl[Yl-bXl]>, (5) 

0(b) = 

2>, X, X, 

(6) 

1=1 

D(s) =s*/ (2n). 

(7) 

The final confidence interval for the regression 

coefficient resulted from joining corresponding 

intervals estimated by minimizing with respect 

to a the above criterion that noise distribution 

conforms to the normal. For this reason, 

the confidence interval may appear to be 

asymmetric about the estimate of b. The confidence 

interval for activity Y values calculated 

with the regression equation is found using the 

variance 

0(Y) = [D(b) + s 2 • X 2(a - 1) \-X 2 . (8) 

The results of gamma-spectrometry data 

analysis using the described approach are presented 

in Table 3. The first line in the Table indicates 

the analyzed pair of radionuclides: the 

first name X (activity) is the regression equation 

argument; the second name Y is the regression 

equation ordinate. The activities of all radionuclides 

are referred to 10 May 1986. Note that the 

45 


designations 140 Ba and "Zr actually include total 

activities 1


pairs of radionuclides accumulated prior to the 

accident in the 4th unit of the Chernobyl plant. 

These ratios have been obtained by statistical 

analysis of data from Table 1. In the figures 

showing relations between activities of radionuclides 

with differing coefficients of atmos 

pheric release (see release coefficients in Table 

1), the dark horizontal band shows the ratio of 

activities of the analyzed pair in the fuel multiplied 

by the corresponding ratio of atmospheric 

release coefficients. 

Table 3 

Results from analysis of verified gamma-spectrometry data of soil samples grouped according 

to the distance to the Chernobyl plant and geographic coordinates (north-east trail) - correla 

Ri 

Rz 

Kr 

n 

r 

tr 

Ur 

a 

St 

X 

Y 

SY 

s(G) 

Ss 

sff 

tion and regression relationships between specific surface activities of radionuclides 

referred to 10 May 1986 

- is left boundary of distance interval, km; 

- is right boundary of distance interval, km; 

- is correlation coefficient which is differs from zero significantly (y) or not significantly (n); 

- is number of analysed pairs of radionuclide activity values; 

- is proportion of the total number of pairs of activity values lying outside the confidence 

interval of the linear regression model, %; 

- is correlation coefficient; 

- is Student criterion for evaluating the significance of correlation coefficient; 

- is 5 % quantile of Student distribution; 

- is exponent as a function of mean-square-root deviation of noise from radionuclide 

activity as abscissa; 

- is coefficient of linear relationship between activity of radionuclide right-hand in the table 

and that of radionuclide left-hand; 

- is relative error of the above coefficient, %; 

- is selected average activity value for the radionuclide left-hand in the table 

(abscissa), Ci/km 2 ; 

- is unbiased estimator of mean-square-root deviation of activity for the radionuclide 

left-hand (abscissa), Ci/km 2 ; 

- is selected average activity of radionuclide right-hand (ordinate), Ci/km 2 ; 

- is unbiased estimator of mean-square-root deviation of the activity for the radionuclide 

right-hand (ordinate), Ci/km 2 ; 

- is mean-square-root deviation of noise estimated by the plausibility 

maximum method, Ci/km 2 ; 

- is relative error in estimate of noise mean-square-root deviation, %; 

- is ratio of mean-square-root deviation of noise and average activity of radionuclide 

as ordinate; 

- is results of verification of conformity of noise distribution law to normal (by conformity 

tests): 1 symbol - by standardized coefficient of asymmetry, 2 symbol - by standardized 

coefficient of excess, 3 symbol - by bilateral Kolmogorov-Smimov test, 

"y" - with conformity, "n" - without conformity. 

46 

.a 

*M 

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y- T- CO CM 00 co •* 

oqqqqoo 

o" o" o" o" o" o" o" 

05 -3 : . 

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>< >. 

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c . 

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5*c 

c c 

S> 2 

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CO CO 

•* 

O 

in 

CM 

c = c = c >•; 

c c c c c c c c c >. >. H| 

c C c >• c c 

c c ! 

co CM a) 00 *- ^ r>- co 05 co *3- in ^* 

CO CO CO CO CD o> CM CM CM CM O O T- 

d d d y-^ d d d d d d d d d 

N; ID y-_ CM ^ LO >U- inm ON CJIN 

r^ co r^ 1^ 05* co 

N iri r~" N r-~' CM t 

:|:g 

• cci: 

-T-UJOSi-OCOCMOO 

qor-{\iso--'- 

moominoo5T-cM 

dooddo'dd 

q^qq^-ooT-r-. 

cd co co co cd iri T^ Tt 

m o> •* o) T- ^ o 

CM q i- i- CM T- rdddddo'd 

"i CM CO in 05 00 CM 

w •* co f~. oo in •* 

CO I s - O 00 CO O) CD 

oo J^ oq in in co w 

iri I s co — o o Tq 

•>* in •* o O CO 05 CO O) iS S fG S" °> » 

03 

CM 

y- ^1 

m 

ggoi'ttrrini N r-" iri co iri 

in en in co •* 00 •* Mnt 

q 'f 

loom 

CM 05 co m 

co •* in m a o in r~^ — 

00 CM ,— T- 

TJ- T— r- CO d 05 -^ CM cd CM ^t 

\r- m co in T- r- CM eooco,-^ 

'^; r- q CM co ^- CM 'tiqqsoi - CO CO y- y- CO •fl- y- y- CM CM 

CO 0> CO CO CM l~~ N 00 *-. 05 q CO ooajin^ f*; q CO CO O ^ CD 

^dr^d^dd d N d o5 d 05' CO'^ CO CD "f N oi cci ni 0 i\i 

CM y- y- y- y- 

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S 

CO 

in m 

CO 

in 

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in 

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in in 

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CM 

CM 

y- 

h- 

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05 

CM 

CO 

f N. •* r>» — 1*. in co in co N CM 05 

o o o o o o o co in co CM co r- in r~. r-- co CM 00 05 O CO CO CM 

y- O C3) ^t CO y- t^- tO n ~ y- y- 

coinsMnoio 

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r*~ h~ *r co co m CM co 05 co fflfflc)ai'-n» 

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co CM TJ- r-~ 05 

CM 05 ^ aa co co O) 

co co o o co CM co 

dodo d 

f*: q y~. CM q o o) o> o) a 

F*— "(Moms CD d d m d •q- d 05 d 05 nonNooo 

o) *- r^- O O O y- in TJq 

q o 

r^ 

o 

co 

— 

1-- CM 

05 r** 

o 

co 

r*- CO 

co 05 

O 

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CM 

h» 

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CM CM CM CM CM CM CM CM CM q q 05 05 05 o o 

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7- «• iv. co co in 05 

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o o o o o o o O O O O o 

CO CO f CM T- 

i- CM CO "3- 

CO 

CD 

CM 

co co in co CM 

— CM co co 

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m CM co CM 

y- CM CO 

O O O O O O CM 

co m 

y- 

o 

•— 

co co 

CM 

*r 

T 

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co 

o o o o o o o O O O O o 

CO CO "3- CM T- 

i-CM CO *J- 

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co in CM 

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O CO 

00 

O 

co 

CM 

co 

o 

in 

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CM 

y- CM t CO 

o 

t 

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CM 00 •» in 

y- y- n yf\ 

v- co05inco 

CDCOOCOiCTtCMCM 

>>>->.>,>,>, >J 

co^co*— 

oinoooooo 

•- y- 

h*N>inco 

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co ^t co 

y- 

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r*co 

05 

•ain

Table 3 (continuation 1) 

o 

30 

60 

100 

0 

30 

40 

50 

70 

150 

0 

150 

l cr 

S(G) 

s/Y 

137Cs . 14lQg^ 

30 

60 

100 

210 

y 

y 

y 

n 

52 

74 

26 

23 

5.8 

6.8 

3.8 

8.7 

0.4031 

0.6729 

0.4821 

0.0229 

2.9914 

6.8767 

2.5213 

0.1022 

2.0105 

1.9960 

2.0640 

2.0800 

0.7896 

0.1431 

0.7427 

0.6994 

10.159 

1.413 

2.531 

0.736 

14.8 

10.7 

20.9 

59.7 

36.25 

20.18 

8.64 

9.51 

62.47 

29.74 

14.39 

12.80 

273.08 

39.50 

16.10 

3.55 

472.60 

46.38 

23.18 

3.94 

20.13 

24.72 

4.22 

3.80 

9.8 

8.2 

13.9 

14.7 

0.074 

0.626 

0.262 

1.071 

37 Cs - 144 Cte 

30 

40 

50 

70 

150 

240 

y 

y 

y 

y 

y 

_y_ 

80 

m 

113 

33 

32 

2.2 

2.5 

4.5 

4.4 

3.0 

6.3 

0.3010 

0.6700 

0.2715 

0.8098 

0.6774 

0.7945 

2.8809 

7.1137 

2.8942 

11.8145 

4.5148 

5.8351 

1.9910 

1.9940 

1.9837 

1.9830 

2.0399 

2.0420 

0.8361 

0.8537 

0.8606 

0.0747 

0.1419 

0.3411 

6.082 

4.114 

2.874 

1.414 

0.761 

0.249 

12.2 

8.5 

9.8 

6.3 

15.9 

11.2 

57.25 

12.30 

17.35 

14.92 

8.46 

7.34 

108.40 

17.45 

19.96 

24.58 

13.22 

6.33 

229.48 

32.03 

35.29 

25.71 

9.12 

1.74 

422.45 

56.25 

68.32 

39.21 

10.53 

2.33 

11.85 

4.16 

4.12 

19.22 

6.44 

0.62 

7.5 

7.9 

6.7 

6.7 

12.3 

12.5 

0.052 

0.130 

0.117 

0.747 

0.706 

0.359 

137Cs . 125Sb 

70 

300 

32 

46 

6.3 

6.5 

0.9521 

0.6707 

9.9815 

5.3243 

2.0420 

2.0168 

0.4539 

0.5712 

0.065 

0.057 

4.0 

9.6 

10.40 

24.10 

14.24 

19.01 

0.67 

1.35 

0.89 

1.32 

0.05 

0.14 

12.5 

10.4 

0.081 

0.104 

131, . 140Ba 

nny 

ynn 

nny 

nnn 

nyy 

nny 

2.05 

32.92 

3.36 

0.29 

10.9 

16.2 

14.7 

18.9 

0.016 

0.597 

0.215 

0.065 

nnn 

nyy 

ynn 

yyy 

Table 3 (continuation 2) 

"/ 

0 

40 

130 

R2 

40 

75 

230 

611 

Kr 

y 

y 

n 

n 

n 

40 

40 

25 

12 

E 

5.0 

10.0 

4.0 

8.3 

r 

0.9102 

0.7790 

0.3373 

0.4509 

*r 

^ 

9.2998 

6.3425 

1.6464 

1.4573 

*cr 

2.0252 

2.0252 

2.0690 

2.2280 

a 

0.6663 

0.7105 

1.0000 

0.5185 

b 

140 Ba - 95 Zr 

1.972 

1.494 

0.381 

0.110 

»A 

20.0 

8.1 

37.2 

21.8 

X 

414.55 

61.58 

14.68 

4.66 

sx 

1254.22 

67.46 

13.17 

3.72 

Y 

692.97 

82.88 

4.85 

0.50 

Sy 

1605.5 

80.26 

8.18 

0.27 

S(G) 

15.22 

2.34 

0.70 

0.17 

ss 

11.2 

11.2 

14.1 

20.4 

S/Y 

0.022 

0 028 

0 146 

0.343 

*fl| 

«J 

yyy 

140Ba . 103Ru 

0 

42 

400 

0 

31 

42 

75 

230 

620 

31 

52 

75 

y 

y 

y 

n 

y 

y 

Y 

20 

23 

24 

13 

23 

20 

15 

0.0 

4.3 

8.3 

7.7 

4.3 

0.0 

6.7 

0.7194 

0.8337 

0.7850 

0.5994 

0.8843 

0.8777 

0.6797 

3.7368 

5.3679 

4.8491 

2.1892 

6.2386 

5.6313 

2.8700 

2.1010 

2.0800 

2.0740 

2.2010 

2.0800 

2.1010 

2.1600 

0.6410 

0.0776 

1.0000 

0.0839 

0.5965 

0.1261 

0.7198 

0.787 

1.062 

3.039 

1.848 

9.7 

7.3 

6.4 

17.5 

40Ba . 106Ru 

0.205 

0.282 

0.355 

32.1 

6.4 

23.2 

47.82 

55.28 

15.13 

4.32 

211.62 

52.41 

48.69 

32.99 

45.19 

13.25 

3.77 

432.78 

41.71 

50.88 

37.11 

62.87 

45.87 

10.06 

38.00 

14.74 

13.21 

30.77 

48.63 

52.04 

6.30 

54.77 

12.97 

9.86 

1.33 

18.42 

0.94 

5.50 

2.52 

3.03 

0.87 

15.8 

14.7 

14 4 

19.6 

14.7 

15.8 

18.3 

0.036 

0 293 

0 021 

0.546 

0 066 

0.206 

0.066 

yyy 

yyy 

yny 

yyy 

140Ba . 141Ce 

0 

0 

30 

0 

35 

409 

30 

50 

152 

30 

50 

152 

35 

50 

86 

180 

232 

650 

y 

y 

Y 

y 

y 

Y 

y 

y 

y 

y 

y 

n 

28 

30 

26 

23 

28 

23 

60 

68 

55 

83 

77 

52 

7.1 

6.7 

3.8 

8.7 

7.1 

4.3 

8.3 

2.9 

5.5 

6.0 

6.5 

7.7 

0.9042 

0.8952 

0.8114 

0.9336 

0.6698 

0.8299 

0.9388 

0.4713 

0.5272 

0.2356 

0.4545 

-0.0633 

7.4734 

7.5203 

5.4242 

7.5387 

4.0516 

5.3126 

13.0442 

4.1262 

4.2271 

2.1475 

4.2179 

0.4436 

2.0560 

2.0480 

2.0640 

2.0800 

2.0560 

2.0800 

2.0021 

1.9980 

2.0073 

1.9930 

1.9950 

2.0105 

0.4034 

0.7511 

0.7513 

0.440 

0.693 

0.769 

12.1 

7.0 

11.3 

140Ba . 144Ce 

0.2645 

0.5903 

0.6213 

0.4553 

1.0000 

-0.0691 

0.4444 

0.6827 

0.3843 

0.593 

0.704 

0.557 

95Zr . 103Ru 

0.279 

0.583 

0.440 

3.633 

12.138 

9.030 

6.9 

11.3 

12.6 

7.4 

18.5 

11.3 

8.3 

8.0 

15.9 

584.50 

56.83 

43.38 

242.7 

59.25 

47.88 

316.6 

90.50 

49.12 

8.71 

3.50 

0.66 

1473.9 

69.82 

47.88 

435.46 

71.62 

49.18 

718.85 

80.37 

56.48 

5.97 

3.22 

0.48 

286.91 

35.11 

29.33 

146.54 

39.97 

25.15 

87.97 

43.13 

30.87 

32.83 

39.19 

6.71 

495.2 

30.67 

32.46 

261.3 

41.48 

25.07 

243.31 

47.98 

33.24 

13.51 

36.43 

4.47 

14.63 

0.67 

1.03 

14.78 

2.14 

1.38 

3.87 

0.88 

38.63 

9.27 

12.20 

8.33 

13.4 

12.9 

13.9 

14.7 

13.4 

14.7 

9.1 

8.6 

9.5 

7.8 

8.1 

9.8 

0.051 

0.019 

0.035 

0.101 

0.054 

0.055 

0.044 

0.021 

1.251 

0.283 

0.311 

1.241 

ynn 

yyy 

yyy 

nny 

nny 

vw 

yny 

yyy 

yyy 

9SZr . 106R(J 

0 

40 

30 

40 

50 

86 

260 

y 

y 

y 

y 

Y 

62 

64 

85 

88 

66 

8.1 

1.6 

8.2 

5.7 

7.6 

0.8971 

0.7931 

0.9374 

0.8944 

0.5999 

11.1940 

8.4336 

15.5370 

13.3105 

5.5004 

2.0000 

1.9993 

1.9923 

1.9913 

1.9987 

0.5814 

0.7864 

0.3742 

0.0190 

0.4313 

0.122 

0.160 

0.138 

0.159 

0.710 

6.6 

16.0 

5.5 

4.5 

11.7 

560.68 

117.55 

105.27 

61.76 

4.84 

975.35 

229.33 

212.67 

114.15 

4.97 

66.33 

14.97 

15.61 

11.46 

3.62 

115.94 

21.13 

24.96 

19.16 

3.25 

0.83 

0.52 

1.46 

7.70 

1.71 

9.0 

8.8 

7.7 

7.5 

8.7 

0.013 

0.035 

0.094 

0.672 

0.473 

nny 

ynn 

ynn 

95 Zr - 141 Ce 

0 

50 

92 , 

30 

50 

92 

210 

y 

y 

y 

Y 

51 

57 

41 

23 

5.9 

8.8 

7.3 

4.3 

0.9566 

0.8855 

0.9518 

0.8953 

13.1949 

10.2914 

11.4078 

6.4765 

2.0115 

2.0052 

2.0231 

2.0800 

0.4302 

1.0597 

-0.0256 

0.3732 

0.291 

0.385 

0.364 

0.402 

5.5 

5.6 

3.2 

7.2 

854.53 

78.70 

83.35 

8.79 

1586.79 

67.83 

158.19 

9.59 

255.94 

32.28 

35.14 

3.55 

431.12 

29.97 

56.73 

3.94 

5.83 

0.13 

15.41 

0.57 

9.9 

9.4 

11.0 

14.7 

0.023 

0.004 

0.438 

0.163 

ynn 

yny 

yyy

t 

en 

i—r 

$?> 

m 

!-•. p 

If 8« C 

III oi «. g a. * 

2S 

CO „. 

3 3" 

8 • 

Ol 

F* 

m 

o 

•8 5=~ 

£ l 

CD °- 

3 

3 

CO £• 

w 5" 

3 -> 

"2. 5 

fffcl 

11II 

o 

Ol 

o 

• 

o 

o — o" 

o 

CSS 

m | 

p 

CO CO 

I" 

-Radiation & Risk", 1993, issue 3 Scientific Articles 

10 

i ;» 1" 1 

0 200 400 

R, km 

0.5 

0.1 

W a \s\J 

0.01 

325225 Qa 

SSSSH 5a 

1** 

3a 

i 2b 

—- la 

Fig. 4. The linear regression coefficient b(R) between the ratio of 137 Cs activity and 103 Ru activity 

measured in soil sample (independent variable) as a function of distance R between a sampling point 

and the Chernobyl plant. 

Symbols are the same as in Fig. 2,3. 

10 ffi$SSSS23P&!5SSSS&£^3^^ 

7.SL..&. 

1 

R, km. 

S^^^&'S&SSS&KSSSS 

SKSSSJJSJSJSKHSSKJSSS^K^ 

0.5 

0.05 

0.01 

seoss 6a 

JSgtfRYl 5a 

4a 

— 3a 

§ 2b 

--- la 

Fig. 5. The linear regression coefficient b(R) between the ratio of 137 Cs activity and 106 Ru activity 



Symbols are the same as in Fig. 2, 3. 

52 


200 

R, km 

0. 

0. 

0. 

1 

05 

01 


ss£5 6a 

sssss 

ESSES 

6a 

Fig. 6. The linear regression coefficient b(R) between the ratio of 137 Cs activity and 140 Ba + 140 La activity 

measured in soil sample (independent variable) as a function of distance R between a sampling 

point and the Chernobyl plant. 


200 

R, km 

400 

400 

1 

— 

1 

4a 

3a 

2b 

la 

jssss 6a 

Fig. 7. The linear regression coefficient b(R) between the ratio of 137 Cs activity and ^Zr + ^Nb activity 




53


•fUttSMsasmi^^ 



10 

5 

^^ss^passssB^sra 

1 

0.5 

= m § •: s .... -^ 0.5 


wm&!& 6a 

5a 

4a 

3a 

2b 

- la 

2225 6a 

§ 2b 

J 0.01 U 

«• ont MR) between the ratio of 137 Cs activity and Ce activity 

Fig. 9. The linear regression coefficienW o distance R between a sampling point 

measured in soil sample (independent vanable) as 



54 


l 

0.8 

0.6 

0.4 

0.2 

0.1 • 

0 50 100 

R, km 

150 

I 

0.5 

0.1 

SHEEE 6a 

0.05 SSS3S 

6a 

4a 

3a 

8 2b 

0.01 -— la 

200 

Fig. 10. The linear regression coefficient b(R) between the ratio of 103 Ru activity and 106 Ru activity 




- 0.05 

0.01 

5SSSSI 6a 

I 4 ' 

3a 

i 2b 

—• la 

Fig. 11. The linear regression coefficient b(R) between the ratio of 103 Ru activity and 144 Ce activity 



Symbols are the same as in Fig. 2. 

55


0.4 

0.2 

S\XXV\VS\S\.>\VS\VX\N\N\^ 

® 

1^xN^^N^^^x\^^^Nx^x^x>ôcv>^^v^^^^ 

0.1 L 

0 50 100 

R, km 

0.5 

0.1 

0.05 

ssss: 5a 

m 

4a 

3a 

S 2b 

0.01 —- la 

150 200 

Fig. 12. The linear regression coefficient b(R) between the ratio of 141 Ce activity and 144 Ce activity 




0 

0 

IBSSSKKSSSKKSSSS^^ 

^:H>.>?XNXXXXVXXXXXXXXXNXX>X\>NNX^ 

50 100 

R, km. 

0.5 

0.1 

0.05 

0.01 

0.005 

• • ! '0.001 

150 200 

sssssa 5a 

D 4 ' 

— 3a 

S 2b 

—- la 

Fig. 13. The linear regression coefficient b(R) between 106 Ru activity and 144 Ce activity measured in 

soil sample (independent variable) as a function of distance R between a. sampling point and the 

Chernobyl plant. 


56 


a 

1 

0.8 

0.6 

0.4 

0.2 

0.1 

0 

-§ f-f fr •i- 

• 

fr^v^^^ Q m Q5 

50 

1 

I I I 

100 

R, km 

150 

J 

1 

0.5 

0.1 

0.01 

0.005 

0.001 

200 


•WWW - 

6a 

4a 

3a 

S 2b 

— la 

Fig. 14. The linear regression coefficient b(R) between the ratio of ^Zr + ^Nb activity and 141 Ce activity 




a 

1 

0.8 §- ©••§!•§ i I 

m 

0.6P 

0.4 

0.2 

0.1 

I I I I I I I 

0 50 

f 

'1 

1 

0.5 

SSSSSSKSSSSS 

0.1 

0.05 

5a 

JSS25S33 

0.01 I 4a 

0.005 

"~"~ OR. 

8 2b 

,.i i 

100 

t t ' ' -' ' j 

R» km 

: 150 

' 

200 

' • • I 0.001 

250 

-— i„ 

Fig. 15. The linear regression coefficient b(R) between the ratio of ^Zr + ^Nb activity and 

ac- 

144 Ce activity 



> are the same as in Fig. 2. 

57


10 

E g » 

5 

1 

0.5 

0.1 

,^^^


a 

0.2 

0.15 

0.1 

0.05 

# 

0 

0 

i i i 

50 

i i 

100 

• 

150 

' ' 

R, km 

200 

3fti«»gi&fefefe«&y 

0.5 

0.1 


0.05 

&Z23E 6a 

ssssss: 5a 

4a 

3a 

S 2b 

J 0.01 

250 

—- la 

Fig, 20. The linear regression coefficient b(R) between the ratio of 137 Cs activity and 123 Sb activity 




a 

10r 

^Ss^sv^^,^^^^^v^^v^^^^s'•^svs^^vs^^•.^•!^^^^'^^v^^^^v.^^^^^^^^^^^'v^v^ss^^v^^^^^^•.ss^^^\^^Vl•.^•.^^^^v^^^^^y^^v^v.^v.^^^^^' 

•»^^>^^>ti^%.^\^^k^îtkit^k^t^^>xVU^\^^^^5a^Q c- 

-to.i 

0.05 

0.01 

600 

assss 6a 

ssssss 6a 

1 " 

3a 

§ 2b 

-- la 

140, 

Fig. 21. The linear regression coefficient b(R) between the ratio of 131 l activity and 1w Ba + lw La activity 




60 


a 

0.5 

5 -J!—g—i i-j L. j iM 3 

1 


0.1 -i—i—i ; i 

0 100 

• • -I 

200 

I L. -l 

300 

: 1 : ' 

400 

' J 

500 

i i_ 0.001 

600 

—- la 

R, km. 

0.1 

0.05 5sss6a 

S5S8S8 

SSSS52 5a 

IsSSBSffiSSSSSO.Ol ii â 

0.005 _ 3 a 

i 2b 

Fig. 22. The linear regression coefficient b(R) between the ratio of 131 l activity and 103 Ru activity 

measured in soil sample (independent variable) and distance R between a sampling point and the 

Chernobyl plant. 


H 0.005 

0.001 

2232 6a 

5a 

4a 

— 3a 

S 2b 

—- la 

Fig. 23. the linear regression coefficient b(R) between the ratio of 131 l activity and 106 Ru activity 




61


The analysis of data in Figs. 2-23 shows that 

in most cases the regression ratios between activities 

of radionuclides with correlation coefficients 

different from zero (statistical significance) 

agree with the fuel ratios (with correction 

for different release into the atmosphere for 

which, however, the uncertainty of estimation is 

about 100%). In the zone near the Chernobyl 

plant the regression coefficients either agree 

with fuel ratios or are close to them. At larger 

distances from the Chernobyl plant, because of 

different physical and chemical properties of 

compounds which incorporate the radionuclides 

released in the atmosphere at different times, 

the regression ratios depart from fuel ones. It 

should also be noted that the used corrections 

for atmospheric release are for the total activities 

released during 2 weeks, rather than the 

part forming the north-east trail. More detailed 

information about ratios between different radionuclides 

can be obtained by analyzing data of 

Table 3 and Figs. 2-23, taking into account the 

above comments. Since only aerosol fraction of 

131 1 was measured, data of Fig. 3 suggests a 

long-term contamination (several passings of 

the radioactive mixture of I and Cs is vary 


ing ratios) over the territories of Byelorus and 

Russia. It can be seen that the nature of 131 l 

contamination of the above territories is different. 

An in-depth analysis of the obtained ratios 

with modelling atmospheric dispersion of radioactive 

aerosols is the goal of our further studies. 

For orientation in statistical relationships between 

radionuclide activities in the depositions 

of the "north-east trail" Figs. 24-28 show correlation 

diagrams between activities of different 

pairs of radionuclides in depositions. The vertical 

scale indicates distance between a sampling 

point and the Chernobyl plant. In the boxes are 

correlation coefficients r (Table 3; r was estimated 

with the correction for the sample volume) 

between activities of radionuclides given 

in the lower part of the figure. The correlation 

coefficients that are statistically insignificant due 

to insufficient sample size are shown in the 

black boxes. The vertical edges of the box correspond 

to minimum and maximum distances to 

the Chernobyl plant in the analysed group of 

samples. The presented diagrams allow easy 

selection of the necessary regression ratio for 

reconstruction of activity of some radionuclide. 

134„ 137, 131. 137 140_ 137 95 137 103 7 106-. 137_ 

Cs CS 

Cs 

Zr Cs Ru" Cs 

Ba Cs 

Ru Cs 

Fig. 24. Correlation coefficients between activities of pairs of radionuclides in groups of soil samples 

collected at different distances R from the Chernobyl plant. 

The lower and upper boundaries of the box are minimum and maximum boundaries of distances in a group of samples. The hatched 

boxes show statistically significant correlation coefficients, dark boxes - correlation coefficients that are not significantly different from 

zero. 

62 


R, km 

600 

500 

400 J 

300 J 

200 

100 J 

01 

131 I 14 %a 13J I 95 Zr "V 03 Ru "°Ba"Zr "°Ba 103 Ru 95 Zr lo: feu 




1€1 Ce 1,7 C. 

i44 Ce 137 Cs 125 Sb 137 CS 106 Ru 


collected at different distances R from the Chernobyl plant. Symbols are the same as in Fig. 24 

63

-Radiation & Risk", 1993, issue 3 


X40„ 1060 i40_ 141 14©„ 144_ 95„ 106 95_ 141_ 95 144 

Zr Cc 

Ba Ru Ba Ce Ba Ce Zr Ru Zr Ce 




R, km 

200 J 

150 

100 

106_ 103-. 141 103 144 103-v 141_ 10*_ 14 V-° 6 r>.. 

Ru Ru Ce Ru Ce Ru Ce Ru Ce Ru 

Ce Ce 




64 


So, we believe that the obtained regression 

ratios between related pairs of radionuclides are 

well-founded and the used gamma-spectrometry 

data of soil samples and the verification method 

is acceptable which makes it possible to use 

these results for reconstruction of radionuclide 

depositions on the territory of Russia (except the 

Leningrad region and other areas lying beyond 

the "north-east trail"). Data in Table 3 will further 

be used for reconstruction of levels of shortlived 

radionuclides in those settlements in the 

Russian Federation in which their levels were 

not measured at the appropriate time. It is then 

natural to use as X in formula (1) the activity of 

137 Cs isotope which was extensively measured 

in populated areas of Russia. Indeed, the tabulated 

data suggest a high correlation between 

the activity of Cs and that of some radionuclides 

134 Cs, 131 l (correlation coefficient is not 

less than 0.7 suggesting that not less than 50 % 

of 137 Cs depositions are associated with 131 l 

depositions (whose activity on May 10 1986 is 

determined with the regression equation according 

to the distance between the settlement and 

the Chernobyl plant), depositionsjof 103 Ru and 

106, Ru (except 30 km zone) and '^Sb. Statist! 

cally significant though not very high correlation 

are also found for Ce and 144 Ce. For some 

areas one can reconstruct by 137 Cs activities of 

140 Ba and ^Zr. In all the cases a smooth 

(normally, monotonically descending) dependence 

of the regression coefficient b on distance 

R from the Chernobyl unit 4 becomes evident in 

the indicated coordinated corridor. In future it 

will probably be possible to substantiate theoretically 

the relationships found in experimental 

data using an adequate model of atmospheric 

dispersion of radioactive material. Such 

"smooth" relationships justify using regression 

ratios for those regions where correlation coefficients 

are not high or insignificantly different 

from 0, for example when reconstructing 140 Ba 

and ^Zr (with daughter products) activities by 

137 Cs. In this case the confidence interval for 

activities to be reconstructed is unfortunately, 

rather wide. Activities can also be reconstructed 

by ^Zr and 106 Ru which occur frequently in 

measured soil samples. For instance, by ^Zr 

one can reconstruct activities of 106 Ru ( Ru can 

be reconstructed by 106 Ru and reactor ratio), 

144 Ce and 141 Ce. The activities of the two last 

radionuclides can also be reconstructed by 

106 Ru. In conclusion, we describe the method 

used for interpolation of the regression coefficient 

by distance from a populated area to the 

Chernobyl plant. We found the conventional 

interpolation method - deriving and using an 

approximation function with correction for estimated 

regression coefficient - unacceptable for 

our purposes because it offers no theoretically 

65 

substantiated relationship of distance and radionuclide 

activities in depositions. On the other 

hand, usage of a precewise-constant function in 

the distance intervals of Table 3 is not proper 

either because it lacks smoothness (for two 

closely located settlements near the boundaries 

of distances to the Chernobyl plant, significantly 

different regression coefficients can be used and 

the boundaries of distances were chosen rather 

arbitrarily). For this reason, at this stage we used 

a piecewise-linear function of distances to the 

Chernobyl plant (see Fig. 2-23). For distances 

beyond the interval given in Table 3, the regression 

coefficient for the center of the last left 

or right intervals was used. 

Considering the important role of 131 l depositions 

for possible health effects, the second part 

of Appendix 1 to this bulletin "Radiation and 

Risk" includes 131 l deposition densities reconstructed 

by 137 Cs for virtually all the settlements 

of Russia affected by the radioactive contamination 

after the Chernobyl accident. The 131 l activities 

are referred to May 10 1986. 

The whole picture of 131 l contamination of 

some regions of Russia is graphically shown in 

Fig. 29-31. They present I deposition density 

isopleths for most contaminated areas of Russia 

referred to May 10 1986. The contamination 

map was constructed by average values of reconstructed 

131 l deposition density which is important 

to remember when interpolating and using 

the data because of a wide confidence interval 

for the estimated deposition density. It 

should also be noted that the isopleths have 

been contracted on a cartographic base with the 

technology developed in Information Computer 

Centre of SPA Tyhpoon" using autocorrelation 

function for reconstructing a deposition density 

in a surface point (this reconstruction technology 

and method are described in detail in one of the 

articles of this issue). Because of the high values 

of the correlation coefficient and radius 

(0.965 and 70 km respectively) estimated with 

autocorrelation functions in reconstruction field, 

it was possible to use the joining operation which 

allowed us to construct a contamination map for 

the whole area under study. The isopleths are 

incomplete on some parts near the boundaries 

of the selected area in Russia because of the 

insufficient amount of measurements of 137 Cs 

deposition density by which 131 l deposition density 

is reconstructed. For the Smolensk and Bryansk 

regions of Russia bordering Byelorus and 

Ukraine, we have incomplete isopleths because 

the values of reconstructed 131 l deposition density 

in these republics are not available to us. 

However, the reconstructed 131 l deposition 

densities on the southern border of the Bryansk 

region are in qualitative agreement with 131 l 

levels in soil for the western border of Byelorus


[17]. The results presented here allow independent 

estimation of 131 l deposition densities for 

Byelorus too and this enabled us to define more 

exactly the isopleths for both the Bryansk and 

Smolensk regions of Russia. Therefore, the pre 

• .;"'«J .!•' . l

'Radiation & Risk*, 1993, issue 3 

Another major problem is the reconstruction 

of time history of the 131 l contamination in the 

CIS countries. The preliminary studies using the 

model of atmospheric turbulent diffusion of radioactive 

material developed in ICC of SPA 

"Typhoon" (presented in the first part of the issue) 

show a significantly different nature of 

contamination of I in the territories of Byelorus 

and Russia between isotope transport in aerosol 

and gas form. Obtaining more definitive data 

about the 131 l contamination dynamics over the 

territories of CIS is the goal of our future study. 

By comparing to 137 Cs we have reconstructed 

the activities of major short-lived radionuclides 

for all the settlements of Russia (except the 

Leningrad region which was beyond the analyzed 

coordinate corridor) in which 137 Cs levels 

were measured. The activities of some radionuclides 

reconstructed from different data differ 

significantly, and in such a case we give 

preference to the regression coefficient with a 

greater correlation coefficient. 

Figs. 32-34 illustrate activities reconstructed 

by this method and confidence limits for Novozybkov 

and Zlynka, Bryansk region and 

Zhizdra, Kaluga region. In estimation of confidence 

limits for activities reconstructed by 137 Cs 

account was taken of the spread of 137 Cs activir 

ties in the settlement. 

The above mentioned figures compare 

measured deposition densities of some radi 


onuclides in these towns and reconstructed values. 

The confidence intervals for reconstructed 

deposition densities were estimated by the 

spread of measured activities of radionuclides 

used in the estimates. As can be seen from the 

figure the results of the reconstruction are quite 

satisfactory. 

The method for reconstructing the deposition 

density of short-lived radionuclides 132 Te, 133 l, 

136 141 143 M 

Cs, Ce, Ce, M6 will be presented in our 

next work. 

Thus the statistical analysis of gammaspectrometry 

data of soil samples revealed relationships 

between activities of radionuclides deposited 

on the territory of Russia after the Chernobyl 

accident. The relieved relationships allow 

reconstruction of radionuclide depositions in 

Russia which later can be used as a basis for 

reconstructing absorbed external doses for 

people the contaminated areas of Russia. 

The authors are thankful to specialists of 

SPA Typhoon" V.S.Kosykh, A.V.Golubenkov, 

R.V. Borodin, A.N.Silanfev, M.Yu.Orlov, V.P. 

Snykov, L.P.Bochkov whose developments and 

collaboration has made a significant contribution 

to this work. We are also indebted to A.M. Ziborov 

for useful discussion of some aspects of 

the problem and providing references and literature 

data on radionuclide activities accumulated 

at the Chernobyl plant by the accident time. 

Fig. 32. Comparison of measured and reconstructed deposition densities of various radionuclides in 

Novosybkov, Bryansk region. 

Measured deposition densities are shown with the spread of values left to each radionuclide; boxes which are hatched more densely 

indicate both reconstructed values and that spread. An asterisk (*) next to the name of radionuclide means that deposition density 

was estimated for parent and daughter radionuclides. Deposition densities are reconstructed primarily by 137 Cs (last box in the 

group). Additionally ,w Ba deposition density is estimated by "°Ru. 

68 


Ci/km' 

* 

103 Bu 

106 Rul 

* 


125 Sbj 


Zlynka, Bryansk region. 


Additionally 10S Ru deposition density was estimated by measured 103 Ru deposition density. 

Ci/kin 2 


Zhisdra, Kaluga region. 

Symbols are the same as in Fig. 32. Additionally ,40 Ba deposition density was estimated by measured 103 Ru deposition density. 

The results of the work should be used with 

allowance for estimated confidence intervals 

which are not small in all the cases. The authors 

would appreciate if specialists suggest additions 

or corrections to the results, since the task of 

69 

i U 

reconstructing radiation parameters at an early 

stage of the Chernobyl accident is of major importance. 

Our work has made a small contribution 

to the solution of these problems. It will take 

a lot of joint efforts to reconstruct absorbed


doses over 1986-1987 for persons included in 

the Russian State Medical Dosymetric Registry 

to make correct assessments of possible longterm 

health effects. 

References 

1. Chernobyl: radioactive contamination of natural 

environments/Ed. by Yu.AJzrael.-S.-Petersburg: 

Hydrometeoizdat, 1990 (in Russian). 

2. Jantunen M. et al. Chernobyl fallout in southern 

and central FinlanaV/Health Physics.-1991.-V.60, 

N3.-P.427-434. 

3. Makhon'ko K.P., Kozlova E.G., Silanfev A.N. 

et al. 131 l contamination after the Chernobyl accident 

and upper estimates of doses from corresponding 

exposure//Atomic energy.-1992.-V.72, 

issue 4.-P.377-382 (in Russian). 

4. Begichev S.N., Borovoy A.A., Burlakov E.V. et 

al. Fuel of the 4-th unit of the Chernobyl NPP: 

Preprint IAE-5268/3.-Moscow, 1990 (in Russian). 

5. Kirchner G., Noack C. Core history and nuclide 

inventory of Chernobyl core at the time of accident//Nucl. 

Safety.-1990.-V.29, N1.-P.1-5. 

6. Gudiksen P.H. et al. Chernobyl Source Term, 

Atmospheric, Dispersion, and Dose Estimation 

//Health Physics.-1989.-V.57, N5. 

7. Calculation of radionuclide composition of the 

fuel in the 4-th unit of the Chernobyl NPP verified 

with program WIMS-D and SHAES, Russian Scientific 

Centre "Kurchatov Institute": Reference of 

20 October 1987 (in Russian). 

8. Information about the Chernobyl accident and its 

consequences prepared for IAEA//Atomic Energy. 

-1986.rV.61, issue 5.-P.301-320 (in Russian). 


9. The Chernobyl accident and its consequences: 

Materials for IAEA meeting on 25-29 August 

1986. Part 1.-Vienna: IAEA (in Russian). 

10. Markushev V.M. Reference on nuclide composition 

of the 4-th unit of the Chernobyl NPP: Russian 

Scientific centre "Kurchatov Institute" Chernobyl. 


11. Kolobashkin V.M., Rubtzov P.M., Ruzhansky 

P.A. et al. Radiation Characteristics of irradiated 

nuclear fuel Moscow. - Moscow: Energoatomizdat, 

1983.-P.384 (in Russian). 

12. Ermilov A.P., Ziborov A.M. Radionuclide ratios 

in the fuel component of the radioactive fall-out in 

the near zone of the Chernobyl plant//The given 

issue of the Bulletin "Radiation and Risk" (in 

Russian). . * , . « • * 

13. Buzulukov Yu.P., Dobrymn Yu.L. Reeaseof 

radionuclide of ChernoDyl accidenu/ln Hne 

Chernobyl papers" (Ed. M.l. Balonov) Research 

Enterprises Publishing Segment, USA 1993. V. 

1 P 3-21 

14. Khan S.A. The Chernobyl Source Term: A Critical 

Review//Nucl.Safety. 1990. V.31. N. 3. P. 

353-374. 

15. Reference book on applied statistics. In two volumes. 

V.1 /Ed. by E.LIoid, U. Lederman. Translated 

from English under ed. of Yu. N. Tyurin.- 

Moscow: Finances and statistics, 1989.-P.271 (in 


16. Owen D.A. A collection of statistical tables 

/Transl. from English.-Moscow: Computer Center 

of USSR Academy of Science, 1966.-P.424-425 


17. A schematic map: distribution of I level in soil 

by 10 May 1986 over the territories of Byelorus.- 

Minsk: Skorina, 1991 (Glavhydromet, Centre of 

radioecological monitoring of the environment) 


70 


Features of the environmental and sanitary situation in the 30-km zone of the 

Chernobyl NPP at a late stage after the accident 

Savkin M.N. 

Institute of Biophysics, Ministry of Health of Russia 

The exclusion zone (so-called 30-km zone around Chernobyl Nuclear Power Plant) was finally 

formed in autumn 1986 according to radiation and geographical criteria. Dynamic investigations 

have been carried out in the southern and the eastern parts of zone during 1989-1991. The ranges 

of soil contamination were equal to 20-370 kBq/m 2 by 137 Cs, 15-260 kBq/m 2 by 90 Sr and 7-90 

kBq/m 2 by 144 Ce in 1991. Radioactive contamination is formed both by matrix particles and condensation 

particles. Local external and internal dose distributions and distributions of grass and foodstaff 

activities in settlements could be defined as log-normal functions with S = 1.8 ± 0.2. Annual 

effective doses for people who lived into 30-km zone were below 5 mSv/y in ^89-1991. Doze zoning 

30-km area and radiological aspects of rehabilitation of territory and resettling of points are discussed. 

Contents 

Introduction 71 

1. Brief history of the 30-km zone formation 71 

2. Objects and methods of research 73 

3. Characteristics of the dose field in settlements 75 

4. Radioactive contamination of the surface air layer 80 

5. Radioactive contamination of the territory and agricultural produce 83 

6. Internal and external exposure doses 87 

7. Radiation-sanitary aspects of rehabilitation of the territories and 

settlements in the 30-km zone 92 

References 94 

Introduction 

One of the main features of the Chernobyl 

accident was that the environmental contamination 

was not uniform in terms of levels and radionuclide 

composition. This fact and a wide variety 

of biogeochemical characteristics of the 

environment, social and economic conditions on 

the contaminated areas dictated that in the first 

years after the accident the priority is given to 

field'radiation studies on the territories and 

specific settlements (populated points or PP) 

with permanent population. 

The results of radiation-sanitary studies on 

the contaminated territories of Ukraine, Byelorus 

and Russia lying at a distance from the Chernobyl 

NPP have been described at length in publications 

of CIS specialists [1, 2, 3, 4] and evaluated 

by independent international experts [5]. 

What these territories have in common is that 

the depositions there are rich in Cs radionuclides 

occurring as part of condensation particles and 

hence low concentration of refractory radionuclides 

associated with fuel matrix. 

This work describes the radiation situation 

from the standpoint of environmental and sanitary 

requirements in the near zone of the Chernobyl 

NPP and discusses features of formation 

71 

of population doses with allowance made for 

characteristics of radionuclide depositions. The 

objects for investigation are settlements of the 

30-km zone to which residents evacuated immediately 

after the accident were returned in 

autumn 1986. 

These settlements are located on the periphery 

of the south and south-east sectors of the 

30-km zone and these territories were less contaminated 

with radioactivity. At present, more 

than 1000 people live, in the 15 rural type settlements. 

The article contains results of systematic dynamic 

radiation measurements conducted in 

1989-1991 by specialists of the Institute of Biophysics 

of Russian Ministry of Health (Moscow) 

together with Institute of Hygiene of Marine 

Transport (St. Petersburg) and Division of Dosimetric 

Monitoring of SPA "Pripyaf" 

(Chernobyl). Radiation aspects of possible rehabilitation 

of these territories are also considered. 

1. Brief history of the 30-km 

zone formation 

On 2nd May 1986 the Governmental Commission 

chaired by N.I.Ryzhkov took a decision


to evacuate the population from the zone within 

30-km around the Chernobyl NPP. 

At the end of May the USSR Ministry of 

Health set the temporary dose limit of 0.1 Sv for 

the population in the first year after the accident 

and then the USSR Goskomhydromet zoned of 

the areas by gamma-radiation dose rate (DR) 

(referred back to May 10 1986) for open areas: 

> 20 mR/h - the exclusion zone, the territory 

from which the population is evacuated for ever 

("the black zone"); 

60 

km 

3- 

i. Pripf at' «' 3 

EDR. mR/h - -A\ 

U Mai 13S6 


5-20 mR/h - the zone of temporary evacuation, 

the territory to which the population was 

expected to return as the radiation situation gets 

normal ("the red zone"). 

3-5 mR/h - the zone of strict monitoring the 

territory from which children and pregnant 

women were relocated to "clean" areas for the 

summer of 1986 ("the blue zone"). 

Fig. 1 shows a schematic map of territories 

adjacent to the Chernobyl NPP with DR isolines 

for 10 May 1986. 

40 km 

Fig. 1. Schematic map of territories adjacent to the Chernobyl NPP with Dose Rate isolines 

for 10 May 1986. 

The second group of radiation criteria for 

decision making was specified in late May 1986 

and supported with information by July 1986 

when official maps were made available for 

contamination with long-lived biologically significant 

nuclides of 137 Cs, ^Sr, 239 Pu and 2,0 Pu. By 

the surface contamination density these criteria 

were 5.55x10 5 Bq/m 2 for 137 Cs, 1.1.1x10 s Bq/m 2 

for ^Sr and 3.7x10° Bq/nrf for "*Pu + 240r Tii. 

These criteria are substantiated from the dose 

standpoint in [6]. Based on estimated doses 

from all radiation exposures, recommendations 

were proposed on relocating the population from 

the settlements in which the annual dose limit of 

0.1 Sv can be exceeded. By September 1986 

final relocations of people from the zone adjacent 

to the Chernobyl NPP, were completed. 

The main data on evacuation and relocation 

of people from the settlements of the 30-km 

zone and adjacent territories in 1986 are summarized 

in Table 1. 

Data on evacuation and relocation of people from the settlements of the 30-km zone 

and adjacent territories in 1986 

Evacuation and 

relocation zone 

Byelorus 

Ukraine 

Total 

Area, km 2 

1542 

2157 

3699 

72 

Number of Settlements 

108 

75 

183 

N 

Table 1 

Population, thousand 

24.5 

91.2 

115-7 

1 

'Radiation & Risk', 1993, issue 3 Scientific Articles 

Since the evacuation zone was formed based 

oh the geometric principle added by radiation 

criteria, in August 1986 the Governmental 

Commission put in charge Goskomhydromet, 

Ministry of Health and Ministry of Defence to 

carry out a detailed radiation survey of the least 

contaminated 47 points located in the south and 

west parts of the evacuation zone and make an 

estimate whether it is possible for people to 

return. Based on the results of the investigations 

it was recommended that 27 settlements be 

resettled after "Sarcophagus" is completed: 12 

in Byelorus and 15 in Ukraine. The main radiation 

criterion for resettlement required that in 

September 1986 two characteristics be not exceeded 

at the same time: density of surface 

contamination with biologically significant nuclides: 

5.55x10 5 Bq/m 2 for 137 Cs, 1.11x10 5 

Bq/m 2 for ^Sr and 3.7x10 3 Bq/m 2 for ^Pu + 

2 Pu and gamma-radiation dose rate of 0.2 

mR/h. It was thought that the adopted resettlement 

criteria ensured that the temporary dose 

limit of 0.03 Sv with the margin coefficient of 

1.5-2 be not exceeded in 1987. 

In compliance with the recommendations of 

Ministry of Health and Goskomhydromet, resettlement 

to 12 villages of Byelorus was carried 

out by winter 1986-1987 after the Sarcophagus 

was built and decontamination works in the settlements 

were completed. 

Andreevka 

Gorodishche 

ll'intsy 

Kupovatoe 

Ladyzhichi 

Lubyanka 

Otashev 

Opachichi 

Parishev 

M'inetskya 

Raz'ezzheye 

Stechanka 

Terekhov 

Khutor 

Zolotneyev 

Teremtsy 

The decision making authorities of the 

Ukraine concluded that it was not economically 

and socially reasonable to return the population 

to the 30-km zone. 

So, the 30-km zone, which is currently called 

the exclusion zone, consists of the Byelorussian 

part designated as an environmental reserve 

and occasionally visited by specialists and the 

Ukrainian part with the Chernobyl NPP, Sarcophagus 

and scientific bases in Chernobyl, 

Pripyaf etc. The works on the Ukrainian part of 

the zone are organized in shifts except the 

Chernobyl NPP site. The 30-km zone is fenced 

along the whole perimeter on the Ukrainian part 

and partly on the Byelorus areas. The zone exits 

for automobiles and railway transport have decontamination 

points and inspection points. The 

most contaminated part of the zone which approaches 

isolines of 20 mR/h on 10 May 1986 

and 3.7 kBq/m 2 for ^Pu + 240 Pu, the so-called 

10-km zone, has an additional fence, decontamination 

and inspection points. 

2. Objects and methods of research 

Along with the official resettlement, part of 

the population (mostly, elderly people) returned 

on their own to some points of the 30-km zone 

as soon as by autumn 1986. Table 2 includes 

data about the points on the Ukrainian part of 

the zone repopulated without authority and Fig. 

1 shows the geographical: location of some of 

them. 

Table 2 

Settlements in the Ukrainian part of the 30-km zone around the Chernobyl NPP 

which were voluntarily repopulated by evacuated residents 

These settlements used to be typical settlements 

of the Ukrainian Polesye before the accident. 

The houses are built along one street, 60- 

73 

70% of are one-storey wooden houses and the 

structures the rest-brick houses. There are utility


structures and gardens of (5-15)X10 m next to 

the houses. 

In the centre of the settlements there are 

normally administrative buildings, a shop, a 

school and a medical station. Most settlements 

lie on plane or slightly hilly area, are surrounded 

by mixed forest or lie on the bank of the rivers 

(Dnieper, Uzh, Pripyaf, Veresnya). The agricultural 

lands are ameliorated. 

In the years after the accident, the studied 

lands were not used for agricultural purposes. As 

a result, almost all cultivated lands became wild. 

On some farms (Teremtsy, Ladyzhichi, 

Gorodishche, Kupovatoe) because no amelioration 

was conducted extensive hay and grazing 

lands became waterlogged. In IPintsy the former 

peateries tend to self ignite. On the meadows 

where farm cattle used to graze (H'ynetskaya, 

IPintsy, Stechanka, Raz'ezzheye, Andreyevka, 

Terekhov) because of deadwood the fodder 

base is disturbed and there is a threat of fires. 

The production base of the former collective 

farms under went considerable changes: the 

machines were taken apart or became useless. 

In some settlements power lines were disturbed. 

As a result of lack of control in implementing the 

postaccidental measures, equipment and wastes 

were disposed in some villages (ll'intsy, 

ll'inetskaya, Stechanka, Terekhov) or their vicinity. 

The water supply system is only capable of 

meeting one demand of those living there now. 

The former centralized water supply system is 

shut down and communications have worn out. 

Yet, some houses have been occupied by the 

local population without permission. Other 

houses call for major repair. The abandoned 

private farms have been overgrown with weeds. 

In Ladyzhichi and Teremtsy a fish hatchery 

was the main productive activity before the accident. 

At present, the fish hatchery ponds are 

not used and partly swamped. Because water 

discharges are no longer regulated in these 

systems, extensive grazing lands became waterlogged. 

The population has a primitive natural way of 

life. Medical aid and services are reduced to a 

minimum. Imported food is normally supplied 

twice a week. 

So, the rehabilitation of these territories 

would require a new productive and housing 

infrastructure and, hence, significant material 

resources and financial investments. 

Comprehensive radiation-sanitary surveys 

have been conducted in all the settlements of 

Table 2 except Otashev and Khutor Zolotneev. 

When the volume and type of the radiation 

survey in a settlement was specified, it was assumed 

that internal and external exposure levels 

may result from exposure indoors - in houses 

74 


and outdoors the adjacent area within 0.5 km of 

a settlement and closely lying territories 

(agricultural lands, forest) up to 2.5 km from the 

settlement. 

The first basic survey of each settlement in 

1989 included: 

gamma-beta-survey of 20 private farms 

(houses, yards, gardens, utilities), public and 

working buildings, streets of 10-50 m, width, 

roads of 100-500 m adjoining the settlement and 

territories surrounding the settlement with the 

grid of 200-400 m spacing; 

analysis for radionuclides in water, soil, 

vegetation and food (1-2 pastures, 20 gardens 

and their produce, milk from all cows, mushrooms 

from neighbouring forests); 

determination of Cs-radionuclides in body for 

30% of the population using a mobile system; 

selective individual dosimetric monitoring in 

two most contaminated settlements for at least 

30% of population. 

In 1990-1991 the surveys were repeated on a 

reduced programme to study the dynamics of 

radiation parameters in time. 

Measurements of the gamma dose rate on 

the streets of settlements and on the roads between 

settlements were performed by specialists 

of the Research Institute of Marine Transport of 

Russian Federation Ministry of Health using a 

vehicle of radiation reconnaissance equipped 

with a dosimetric unit MKG-01T with automatic 

recording of data. 

The land-based gamma-beta-surveys in 

other parts of the settlements were conducted by 

specialists of the Institute of Biophysics with 

DRG-01T and MKS-01R type dosimeters. 

Outdoors and indoors measurements of direct 

and scattered gamma radiation spectra 

were made using a gamma spectrometer with a 

NaJfJI) based detector (40 mm diameter and 60 

mm height) and a spectrometer LP-4700 

(Finland). 

Preparation of environmental and produce 

samples for the spectrometry analysis was done 

as follows. 

Standard cylindrical rings of 145 mm diameter 

and 50 mm height were used to sample soil 

cores which were sent for measurements. 

Soil samples from gardens, collected by a 

standardized methodology, vegetation and liquid 

samples were placed in 250 ml flasks. 

For measurements of radioactivity in samples 

of food products, water etc. Marinelli vessels 

were used. 

The equipment used for gamma spectrometry 

included: two semiconductor spectrometer 

(LP 4900B analyzer with a "ORTEC" semiconductor 

GFG-SH type detector of 91 cm 3 working 

volume and 2.5 keV resolution at gamma 

quantum energy of 662 keV, Finland and NTA- 

1024 analyzer of 4 keV resolution for the above 


energy, Hungary) and two scintillation spectrometers 

(a NTA-1024 analyzer with BDEG2-23 

detector of 9.1% resolution, a ROBOTRON 

20050 analyzer with a detector of 9% resolution). 

The efficiency of gamma radiation measurements 

was determined depending on the 

type of the analyzed sample and energy composition 

of radionuclides. 

The sensitivity of semiconductor spectrometers 

was 150 Bq/kg and scintillation spectrometers 

0.37 Bq/kg. 

In the course of the work results of measurements 

were compared with data of the spectrometric 

laboratory of the Emergency Group of 

Roshydromet. 

In part of the samples, the ^Sr activity was 

determined by standard radiochemical methodology 

[7]. 

The individual dosimetric monitoring (IDM) 

was conducted by Grinev M.P. (Institute of Biophysics) 

in the time period from April to June 

1989 for most contaminated villages of 

Opachichi (45 persons) and Lubyanka (48 persons). 

Two types of thermoluminescence detectors 

- IS-7 alumophosphate glasses and 

LiF-DTG-4 monocrystals. The first were used in 

IKS kit cartridges and the second - in DPG-02 

cartridges of KDT-02 kit. For measurements 

IKS-ts panel and a 2000A type thermoluminescence 

measuring instrument with "Harshaw" 

2080 type picoprocessor. The used meassuring 

instruments were metrologically certified. The 

relative error of measurements in both cases did 

not exceed ± 20% at confidence probability of 

0.95. 

The time for carrying detectors was 55 ± 2 

days. 

To check the reliability of IDK results, the 

relation was used which had been obtained by 

M.P.Grinev for the settlements in the Byelorus 

zone of stringent monitoring 

nP1K1

"Radiation & Risk", 1993. issue 3 

r 


Table 3 

Works to measure parameters of the radiological situation in settlements of the 30-km zone 

of the Chernobyl NPP in 1989-1991 

Type of work 

Number of settlements under comprehensive study 

Number of yards 

Number of points of dose rate measurements 

Number of points of measurements of beta-particle 

flux density 

Vehicle gamma-survey: 

number of settlements 

number of points for measuring dose rate 

Spectrometric analysis: 

soil 

vegetation 

pasture soil 

pasture vegetation 

garden soil 

milk 

vegetables and fruits 

forest products, fish 

Analysis of samples for w Sr 

soil 

vegetation 

milk 

vegetables and fruit 

Analysis of aerosol samples 

Populated 

point 

Lubyanka 

Opachichi 

Terekhov 

Andreevka 

Khutor Zolotneev 

Stechanka 

Parishev 

Kupovatoe 

U'inetskaya 

Ladyzhichi 

Gorodishche 

H'intsy 

Teremtsy 

Raz'ezzhee 

Statistical characteristics of outdoors dose rate measurements 

Number of 

measurements 

598 

271 

223 

309 

99 

101 

766 

227 

240 

230 

91 

673 

335 

259 

minim. average 

31 

17 

18 

15 

17 

17 

16 

14 

16 

13 

14 

12 

11 

10 

Dose rate, u,R/h 

60.0 

42.0 

29.0 

28.5 

28.0 

27.5 

26.7 

23.3 

23.5 

23.5 

23.0 

21.2 

18.4 

17.4 

The earlier measurements [2] of gammaradiation 

levels in settlements remote from the 

Chernobyl NPP have shown that the ratio of 

dose rate in different parts of a settlement and a 

dose rate over raw land plots Kj=PJPrn*ianci is a 

76 

90%quantil 

77 

58 

37 

36 

38 

36 

32 

35 

29 

33 

28 

27 

24 

22 

139 

80 

55 

43 

45 

63 

41 

44 

35 

48 

34 

37 

31 

29 

1.28 

1.38 

1.28 

1.26 

1.36 

1.31 

1.20 

1.50 

1.23 

1.40 

1.22 

1.27 

1.30 

1.26 

Table 4 

2.30 

1.90 

1.90 

1.51 

1.61 

2.30 

1.54 

1.89 

1.49 

2.04 

1.48 

1.75 

1.68 

1.67 J 

fairly stable parameter in the case of uniform 

contamination. Table 5 compares K, obtained in 

settlements with rigorous monitoring with those 

in settlements of the 30-km zone. 


I 

Indoors 

Yard 

Garden 

Street 

Agr. tand 

Forest 

Table 5 

Kj ratio of dose rate in different parts of settlement to dose rate on raw land plots 

Object, j 

Strict monitoring zone [2], 

P. 124 

June 1987 September 1987 

0.34 

0.28 

0.69 

0.74 

0.74 

0.74 

0.72 

0.35 

0.70 

0.70 

1.07 

1.07 

It is seen from Table 5 that the values of Kj in 

the 30-km zone and in the strict monitoring zone 

are close though the gamma-survey in September 

1987 was performed immediately after decontamination 

works which was not the case for 

gamma-surveys in May 1987 and 1989-1990. 

Constant ratios of dose rates in different 

parts of settlements allows a rather precise and 

quick estimation of absorbed dose for human 

tissue using the average dose rate over raw land 

plots Prwith the formula 

1=1 

(2) 

where KT is coefficient of air absorbed dose to 

tissue absorbed dose; 

P,o is dose rate from natural gammaradiation 

sources; 

Kj is the above mentioned coefficient (Table 

5.); 

' 

30-km zone 

1989-1990 

0.29±0.04 

0.89±0.08 

0.72±0.06 

0.76±0.04 

0.80±0.04 

1.19±0.09 

cpFflPfPJ 

3.0 

7.0 

6.0 

- 

10 

10 

t) is the time during which a person stayed in 

specific parts of a settlement. 

By way of illustration Fig. 2 shows calculated 

average daily doses in the 30-km zone settlements 

in the summers of 1989 and 1990. 

The soil contamination in the 30-km zone is 

different from that in territories remote from the 

Chernobyl NPP is that along 134 Cs and 137 Cs. 

Radionuclides ^Sr, 106 Ru and 144 Ce occur in the 

zone in significant quantities. Since the decay 

energy of Sr, 106 Ru and 144 Ce is primarily carried 

away by beta-particles, the last column of 

Table 5 contains median values of the ratio of 

beta particle flux density at a distance of 2-3 cm 

from the studied object (Ffi) to dose rate at a 

distance of 1 m height minus the natural background 

(PfP-fl): a=Ffi/(P7.-Pr^. It was assumed 

thatP^=2.76x10' 11 Gys" 1 . 

It follows from Table 5 that the highest median 

value was detected in the forest. The same 

m~„ Lubyanka 

2 p r- 1 -, Opachichi 

^y 1^1 I Terekhov 

a.oio_ 

coca. 

CH 

a.aaE- i 

Q.OCU- 

0.DD2- 

«A«: 

§1 

• 

'*.*' 

/ 

&c * 'K 

•K' */• 

:*: */ 

- V 

M /.*• 

i K i '*• 

j***: f »* 

:V : Andreevka 

R. finetskaya 

Parishev 

Kupovatoe 

Ladyzhichi 

* / 

i* 

- 1989 ; 

• 

••.'*: 

Si ;:«: ;:• 

- 1990 

U'intsy stechanka 

Gorodishche 

Teremtsy 

1 Raz'ezzhee 

a»;: 

ij :•• 

Fig. 2. Daily average external exposure dose in 1989 and 1990 in some settlements 

Of the "near" zone Of the Chernobyl NPP. Y-a»s - dose mSv/day estimated with (2). 

77 

I 

|


value was obtained on raw meadow land. For 

yards and gardens because of deeper occurrence 

of nuclides the values were lower by a 

factor of 1.4 and 1.7 respectively. The estimation 

shows that the fluence of beta particles on 

the surface ground with an error not more than 

25% can be related to the surface activity of 

beta emitting nuclides ap, if 

Ofi/(tTp+oj>0AS. 

For raw land, the median value of parameter 

P= Ff/a,, is 0.27 and for ploughed garden plots - 

0.10. Then the ratio of absorbed doses for skin 

from beta- and gamma-radiations at 1 m height 

in 1990 with an error of 70%, can be found by 

the empirical formula: 

P//(Pr -P^ = 30pap/ ay37, (3) 

where Pp is beta-radiation dose rate at the depth 

of 7 mgcm* 2 s' 1 ; 

ap = a( 144 Ce) + aC^Ru) + af°Sr); 

&13T = of CS)- 

The estimation of the ratio (3) for settlements 

of the 30-km zone in 1990 shows that the betaradiation 

dose for the open skin surface is about 

3-8 times higher than the dose of external radiation 

for the whole body. This estimate, however, 

does not allow for the input of skin contafnina- 

78 


tion to the dose. If the radioactive decay of betaemitting 

nuclides of 144 Ce and 104 Ru and penetration 

of nuclides down the soil nuclides is 

taken into account, then it can be assumed that 

in the earlier time after the accident, the contribution 

of beta-radiation to the dose was even 

larger and hence it was the main kind of radiation 

exposure. 

For a man in gamma-fields, the distribution 

of radiation loads oh organs and tissues is 

strongly dependent on the energy characteristics 

of radiation. Starting from the second year after 

the accident the main radionuclides forming the 

spectrum of gamma-radiation on the contaminated 

territories have been 134 Cs and 137 Cs. The 

changes in the spectra later on are, therefore, 

mostly associated with natural decay of these 

nuclides and their behavior in the environment. 

To study how gamma-radiation spectra are 

formed field experiments were conducted on the 

contaminated territories in 1987-1990. 

The spectra measurements were organized 

on meadows, ploughed land, in the forest and 

indoors in settlements lying in different directions 

and different distances from the Chernobyl 

NPP. The results of gamma-radiation spectra 

measurements in settlements and their vicinity 

in different years after the accident are shown in 

Table 6. 


Energy spectra of gamma-radiation on the Chernobyl contaminated areas 

Energy range, 

keV 

50-150 

150-300 

300-450 

450-600 

600-750 

750-900 

900-1050 

Average energy, keV 

50-150 

150-300 

300-450 

450-600 

600-750 

750-900 

900-1050 

| Average energy, keV 

50-150 

150-300 

300-450 

450-600 

600-750 

750-900 

900-1050 


50-150 

150-300 

300-450 

450-600 

600-750 

750-900 

900-1050 


\ 

1987 

28.9±2.7 

24.8±1.5 

8.4±0.4 

9.211.1 

20.213.7 

7.611.4 

0.910.3 

370130 

40.912.2 

28.111.3 

9.210:2 

7.110.9 

10.411.4 

3.910.8 

0.410.3 

270120 

28.814.8 

25.511.4 

8.4±0.5 

9.911.5 

19.812.4 

6.811.0 

0.810.2 

360120 

45.814.4 

28.411.9 

8.910.9 

6.711.0 

7.011.4 

2.710.8 

0.510.9 

240120 

It can be seen from the table that the average 

energy of gamma-radiation on ploughed 

fields, in forest and indoors decreases with time. 

In 1987 the spectrum in the forest was practically 

identical to that on the grass covered land: 

the ratio of non-scattered radiation fluences 

(energy range of 550-900 keV) normalized over 

unit density of contamination by cesium nuclides 

in the forest and on meadows was 1.110.3. By 

1990 this ratio increased to 1.410.1 and the 

average energy of gammarradiation in the forest 

became 1.1 times higher than that on meadows. 

This effect can be explained by different distributions 

of cesium along the vertical soil profile 

on the open area and in the forest. In the latter 

case the activity proportion in the upper layer is 

Gamma-quanta 

1 1988 | 

GRASS PLANTED LAND 

30.612.7 

25.710.6 

8.710.3 

7.410.5 

18.011.6 

7.610.9 

1.810.5 

350120 

PLOUGHED FIELD 

38.813.3 

27.810.7 

9.310.5 

6.910.6 

11.711.3 

4.810.9 

0.710.4 

290120 

FOREST 

31.411.5 

25.410.5 

8.510.4 

7.610.3 

18.010.9 

7.410.4 

1.710.2 

350110 

INDOORS 

47.214.5 

28.311.5 

8.410.9 

5.410.9 

7.211.5 

2.910.7 

0.610.2 

240120 

79 

fluence, % 

1989 | 1990 

29.112.5 

19.710.9 

7.210.3 

11.010.5 

25.612.7 

6.910.5 

0.510.1 

380120 

34.910.9 

22.610.8 

9.210.7 

10.210.5 

17.611.0 

5.010.1 

0.510.1 

33013 

43.312.2 

25.310.9 

9.510.4 

8.210.7 

9.411.4 

3.410.6 

0.910.6 

270110 

27.412.9 

19.611.2 

7.310.7 

9.910.7 

28.713.2 

6.710.8 

0.410.2 

390120 

Table 6 

33.911.9 

22.510.4 

9.110.4 

9.210.2 

20.211.7 

4.810.4 

0.310.1 

340110 I 

1 

23.912.0 

17.710.9 1 

6.610.4 

9.710.6 

33.812.6 

7.810.7 

0.510.1 

420120 

• 

41.113.6 

24.911.0 

9.710.7 

8.611.2 

11.312.& 

3.510.5 

0.910.4 

280120 

higher than on the meadows because of the 

litter and organic matter. 

A year after the accident on the ploughed 

land, the average energy of gamma-radiation 

was much lower than that on the grass covered 

plots, which is associated with a considerable 

depth of nuclides occurrence. The typical distribution 

of cesium isotopes with depth was as 

follows: 0-5 cm layer - 20%, 5-10 cm - 20% and 

10-15 cm - 60% (results of the studies in Mogilev 

region). As a result of multiple ploughing of 

soil the activity of nuclides got equalized: along 

the full ploughing depth and this led to a 

"harder" energy spectrum of gamma-radiation. * 

In future, the radiation spectrum may change 

due to the changes in the ratio of Cs and

'Radiation & Risk", 1993, issue 3 Scientific Articles 

134 Cs activities. In 1990 it was equal to 7.3, but 

in 8-10 years because of 134 Cs decay the 

gamma-radiation will be practically determined 

by 137 Cs only and the average energy of 

gamma-radiation on the ploughed land, by our 

estimation will be 0.31 MeV. 

On the grass-covered land changes in 

gamma-radiation spectra may occur as a result 

of decay and vertical migration of nuclides in 

soil. As is seen from Table 6, the influence of 

these factors in the considered time period is 

insignificant. The comparison of results of 

measurements made in the same sites in 1989 

and 1990 has shown that the decrease in the 

fluence of 134 Cs nonscattered radiation over 1 

year correlates with natural decay of the radionuclide 

(the ratio between the 0.796 MeV 

gamma-radiation change obtained in experiment 

and calculated is 1.00±0.05). This suggests that 

the cesium goes down the soil rather slowly. The 

average energy of gamma-radiation in these 

sites remained almost unchanged, i. e. decay of 

134 Cs does not lead to any significant changes in 

the hardness of the spectrum. 

4. Radioactive contamination 

of the surface air layer 

In order to understand the inhalation pathway 

of radionuclides to the human body let us briefly 

discuss the phenomenological model of the 

accident. 

The release of radioactivity from the 4th unit 

of the Chernobyl NPP was formed by two major 

processes: 

- dispersion of nuclear fuel as a result of the 

explosion on 26 April 1986 which led to generation 

of aerosol particles consisting of fragments 

of fuel matrix (F-aerosols) and including the 

entire spectrum of transuranium nuclides and 

products of nuclear fission; 

- escape of vapours of radioactive materials 

from the reactor during graphite burning (27 

April - 9 May 1986) which led to formation of 

condensation particles (C-aerosols) having 

largely monoisotopic composition. 

The analysis of the release of radioactive 

materials and formation of surface layer and 

area contamination shows that the largest release 

of radionuclides responsible for depositions 

in the near zone occurred on 26-28 April 

1986 [4]. It should be noted that the activity was 

transported on rather large aerosol particles. 

A large body of experimental data shows that 

there is a significant correlation between 239 Pu + 

240 Pu and 1 *Ce both near the Chernobyl NPP 

and at a distance. Both in the fuel particles and 

soil samples the correlation factor between the 

activities of the two radionuclides was 

(6±2)x10~ 4 on 26 April 1986. This ratio was 

80 

widely used for generating maps of contamination 

with plutonium isotopes based on Ce 

gamma-spectrometry data. 

The ratio of F- and C-aerosols in depositions 

can be estimated by the fractionation coefficient 

of Cs with respect to 144, Ce: 

(4) 

f\Z = (^137 I a iu)tL I (YlST I Y 144)T> 

where faur/aÊ is experimentally obtained 

ratio of Cs and 144 Cs contamination density at 

the time of the accident; 

(YISWYI4^T is the ratio of 137 Cs and 144 Cs activities 

accumulated in the reactor by the time of 

the accident. 

The members of Complex expedition of Kurchatov 

Institute have found that the value 

(Y137/Y14JT can change in the range (0.03, 0.07) 

due to different time of bum-out of fuel assemblies. 

The average value of parameter 

(Y137/Y14JT is 0.063. 

Because of evaporation of cesium from fuel 

composition the ratio (Ai37/A144)F of 137 Cs and 

144 Ce activities in F-aerosols was decreasing in 

the course of the accidental release. By the data 

of A.Ter-Saakov the ratio (AIU/AI^F in hot 

particles formed from fuel matrix changed from 

0.022 to 0.043. Therefore, the ratio of nuclides 

in the fuel and condensation components of the 

depositions is more adequately described by the 

fractionation coefficient in depositions: 

f%(FC/ F) = (*,„/ a144)e/ 

' (A137 ' A144/F' 

(5) 

The values of this coefficient for settlements 

of the 30-km zone are presented in Table 7. For 

comparison Fig. 3 shows dependencies of 

f}%(FC/F) on distance in the north-north-east 

direction of the Chernobyl NPP. 

It can be seen from Table 7 that in settlements 

of the 30-km zone (except H'inetskaya) 

f}%(FC/F) ranged from 2 to 4, i.e. the condensation 

and fuel components of the depositions 

are in comparable quantities. At large distances, 

for example, the contaminated areas of Byelorus 

(places with "dry" or "wet" depositions have 

been identified) the depositions were primarily 

formed by C-aerosols and in the most remote 

places of the Mogilev region fl%(FC/F) was 40 

for "dry" and 150 for "wet" depositions. Thus, the 

specific feature of the 30-km zone compared to 

remote areas is that the contamination was 

formed equally by fuel and condensation composition 

of the accidental releases. In this sense, 

the 30-km zone is a unique object for investigating 

dust resuspension. 


[ Settlement 

Teremtsy 

Ladyzhichi 

Parishev 

Opachichi 

Gorodishche 

Kupovatoe 

Terekhov 

Andreevka 

Stechanka 

Raz'ezzhee 

ll'intsy 

H'inetskaya 

Lubyanka 

f%(rc/F) 

100 

5 

10 

5 

1 

1S7 Cs and 144 Ce fractionation coefficient f}?I(FC/F) 

Azimuth, degrees 

124 

127 

129 

145 

146 

149 

170 

177 

230 

229 

237 

239 

251 

=1 

• 

Distance, km 

32 

27 

20 

26 

35 

31 

29 

29 

16 

18 

20 

24 

25 

L 

10 100 

\ X 

d« km 

fffFOF) 

3.6 

2.4 

2.1 

2.4 

2.5 

2.2 

2.4 

2.2 

3.8 

4.0 

3.7 

7.7 

2.8 

Fig 3. Change in the fractionation coefficient f]%(FC/F) in the north-north-east direction 

of the Chernobyl NPP depending on distance cffrom the Chernobyl NPP. 

1 - Rosnydromet network data; 

\ 2 - "dry* depositions; 

3 - "wet" depositions (data of Institute of Nuclear Energy of Byekxus Academy of Science). 

At present, the United Nations Scientific 

Committee on the Effects of Atomic Radiation 

(UNSCEAR) [9] has adopted a model estimating 

the air concentrations of a radionuclide by the 

surface activity and the resuspension coefficient, 

R(t) 

R(t) = 1(T s exp(-4.Gt) + 

+ 1a 9 exp(-0.007t), m" 1 (6) 

where t is time since depositions, years. 

By this model R is expected to be 10' 5 m" 1 

immediately after the accident, 10" 6 m" 1 in 0.5 

year, 10" 8 in 1 year and 10' 9 m' 1 in 2 years and 

81 

Table 7 

more with the period of half reduction of 100 

years. 

The measurements made from August 1986 

to September 1987 [10] have shown that on the 

open area RslO" 8 m' 1 for 144 Ce, 137 Cs and 

Zr+^Nb and it is 2-9 times righer in a young 

pine forest with average height of trees of 5-6 m. 

No reduction in R with years have been found. 

In 1989 the mean monthly values of R 

around the Chernobyl NPP were 5x lO^-Sx 10" 9 

m" 1 and in the 5-15 km zone - 5x 10' 9 -5x 10' 10 m" 

1 [11]. The range of R in the whole 30-km zone 

in 1989 was LOxlO^-LOxlO" 10 m" 1 which 

agrees with the data of other authors. The difference 

in the coefficient >? between the indi-



cated zones can be explained by the fact that in suspension coefficient on some sites where 

the 5-15 km zone there is no intense transporta activities lead to intense dust formation. 

tion, decontamination works or anthropogenic In this connection, specialists of the Institute 

factor, hence, no technogenic component of of Biophysics (N.Startsev, A.Molokanov et al) in 

dust formation. 

1990 conducted studies of dust formation during 

The changes in R within one or two orders of 

magnitude brings in an uncertainty in the estimate 

of radionuclide intake by body and internal 

exposure doses. Besides, the measurements of 

the air concentration of radionuclides were 

mostly made with stationary instrumentation and 

they may not reflect the true values of the re- 

agricultural works. As the contamination levels 

in the 30-km zone are not high and agricultural 

activities are limited, they selected two experimental 

plots in the 10-km zone and 8 agricultural 

fields in Polessky district of the Kiev region. 

Table 8 gives brief characterization of the studied 

plots. 

Tables 

Characterization of plots on which dust formation processes 

during agricultural lands were studied 

r 

Location 

Chistogalovka 

Novye ShepeBchi 

Buda Varovichi 

Pukhovo 

Vladimirovka 

JKotovskoe 

I N. Markovka 

T 

1 

Azimuth, Distance, 

km 

6.7 

11.5 

42 

48 

60 

57 

52 

Procedure 

discing 

cultivation 

cultivation 

use of ammonia 

water 

and gathering and 

threshing 

of oats 

ploughed field 


planting perennial 

grasses 

gathering 

potatoes 


It follows from Table 8 that the plots in the 

10-km zone are primarily characterized by fueltype 

of contamination fj%(FC/F) is 1.8±0.3, 

where as the agricultural lands of the Polessky 

region have condensation contamination 

fj%(FC/F) = 27±11. That is why further comparative 

analysis was done for these two regions. 

The study of the distribution of the radionuclides 

activity by soil particles has shown that for 

the 10-km zone the distributions of 137 Cs, ^Sr 

and Pu by soil particles size are close which 

confirms the conclusion that the most part of the 

activity occur on fuel particles. In the Polessky 

district, the specific activity on fine particles 

appeared increased: the proportion of the activity 

on 0-5 UJTI particles was 5-8 times higher than 

in the 10-km zone. 

The investigation of particle size distribution 

with a 4 cascade impactor showed that the activity 

median aerodynamic diameter (AMAD) in 

the dust plume was 8.7 urn at variance #=3.1. 

In the absence of a technogenic factor of significance, 

the radioactive aerosol in the 30-km zone 

is currently characterized by AMAD of 3-4.5 u/n 

at #=3 [11]. The researchers report that the size 

82 

Specific activity of radionuclides in soil, 

Bq/kg 

f(FC/F) 

characteristics of the radioactive aerosol in the 

30-km zone are stable, which suggests a firm 

binding of fine radioactive particles with nonactive 

soil particles. 

In the Polessky district, the dust resuspension 

coefficient R measured right after the tractor 

in the 10-km zone was found to be (3- 

6)x 10" 6 m" 1 , which is in good agreement with the 

results obtained on the Nevada testing grounds 

(2x10' 6 -7x10- 5 m- 1 )[12]. 

The concentration of dust in a closed but unsealed 

cabin appeared to be 40-400 time lower 

than behind the cabin. At the same time, the 

concentration of radionuclides fell by 7-20 times 

only. The concentration of radionuclides windward 

of the ploughed field was, on the average, 

200 lower that in the plume. Thus, the daily intake 

of the radionuclide with the respirable aerosols 

(0-50 u,m) during agricultural works can be 

estimated from the ratio: 

A = Vvi'EfyijTj' (7) 

where A, is daily intake of the ^nuclide, Bq/day; 

Vis lung ventilation rate, m 3 /h; 

ov is surface activity of the i-nuclide, Bq/m 2 ; 


Rj is coefficient of secondary dust formation 

in the /-zone, m* 1 ; 

tjf is proportion of the ^nuclide activity associated 

with respirable fraction; 

7} is time a person spends in the J-zone, 

h/day. 

Parameter 

R, m" 1 

T, h/day 1 

Taking V=1.2 m 3 /h, o= 1 x 10 3 Bq/m 2 and parameters 

R, rj, T as indicated in Table 9, we 

estimate daily intake by tractor drivers - 5x 10" 3 

Bq/day, by personnel attending to trailing devices 

- 3x10' 2 Bq/day and personnel not engaged 

in works involving intense dust formation 

-2x10"* Bq/day. 

Parameters for estimation of inhalation intake of radionuclides 

worker on a 

trailing device 

5x10" 

0.8 

6 

Methodologically it is of interest to compare 

the obtained estimates with results of smears 

from nose. The smears were taken 5-7 hours 

after the start of the work from 6-9 agricultural 

workers on the field; then they were combined to 

produce one sample and subject to spectrometry 

analysis. 

Considering the part of the activity passing 

through the nose and the part of the activity 

passing into the smear, the mean inhalation 

intake of 137 Cs was estimated at 0.04-0.09 

Bq/day on the plots in Buda-Varovichi and 

Shepelichi with contamination density of 

8.5 x10 5 and 3.4 x10 5 Bq/m 2 , respectively. 

There fore, at density 10 3 Bq/m the inhalation 

intake may be expected to be 4.7x10 5 - 

2.6 xlO" 4 Bq/day. It can be seen that the experimental 

assessment of the intake is two orders 

of magnitude lower the maximum calcu 

Group 

I 

II 

III 

IV 

V 

Working zone, profession 

driver in tractor 

cabin 

worker on a field 

(wind ward) 

2.5x10-* 

1 

6 

Table 9 

Other territory 

10"" 

1 

18 

lated value for workers working the dust plume 

behind the machines. Estimates of possible 

doses from inhalation of radionuclides in settlements 

of the 30-km zone will be discussed in 

Section 7. 

5. Radioactive contamination of the 

territory and agricultural produce 

The radioactive contamination of settlements 

in the 30-km zone is summarized in Table 10. 

The settlements are divided by territorialgeographical 

principle: I - left bank of the Pripyaf 

(south-east-east), II - right bank of the Pripyat' 

(south-east), III - territories between the Uzh 

and Teterev (south), IV - territories between the 

Pripyat' and Uzh (south-west), V - territories 

between the Pripyat' and Uzh (west). 

Table 10 

Radioactive contamination of territories of settlements and pastures, kBq/m 2 

(1 May 1991) 

Populated 

point 

Teremtsy 

Ladyzhtehi 

Parishev 

Opachichi 

Gorodishche 

Kupovatoe 

Terekhov 

Andreevka 

Stechanka 

Raz'ezzhee 

H'intsy 

Rudnya 

H'inetskaya 

Settlement and its vicinity, range [131 

,J 'Cs r ""Sr I ~*Pu + * ,0 Pu 

93 1 70 

37-81 | 48-81 

48-120 | 59-89 

44-370 | 44-230 

52 I 

44-130 I 59-110 

22-160 J 85-130 

81-140 1 70-140 

15-120 | 30-56 

22-48 j 15-30 

15-78 fl 26-37 

77-200 1 22-44 

| 

Lubyanka | 370 I 260 

83 

1.4 

0.3-0.7 

0.4-2.6 

2.2-11 

3.7 

0.1-0.6 

0.1-7.0 

1.1-3.7 

0.1-0.3 

0.1 

0.4-11 

0.1-0.4 

7.4 

,s; Cs 

77 

86 

97 

240 

120 

150 

160 

110 

66 

59 

87 

130 

350 

Pasture; mean f 141 

^Sr 

59 

50 

61 

135 

24 

74 

61 

95 

37 

13 

18 

31 

260 

^Pu + 2W Pu 

11 

18 

24 

53 

52 

35 

34 

26 

9.2 

7.3 

12 

89 

65

"Radiation & Risk", 1993. issue 3 Scientific Articles 

It can be seen from Table 10 that the contamination 

levels in settlements and within 2.5 

km around them vary by 3-5 times. To describe 

quantitavely the scattering of individual measurements 

with respect to the mean value let us 

consider the function of accumulated probability 

Ff&J and parameter £j = p/pj, where £# is experimentally 

obtained parameter p in the A 

99.9 

99 

95 

80 

50 

20 

5 

1 

0.1 

F(*u>.* 

sample for the /-object, pj is mean value of p 

parameter for the /-object. So, for pj = crf is 

surface activity of 137 Cs on pastures and the 

function F(4f) looks as in Fig. 4. It is seen that 

the distribution is well approximated by a normal 

dependence with variance 0.56. 

0 0 .5 L L5 2 2 

OIJ/OJ 

•137, 

Fig. 4. Distribution of relative value of Cs surface activity on pastures. 

Y-axis - ratio of surface activity of " 7 Cs on pastures and average surface activity of a settlement; 

X-axis - accumulated probability Ffa), %. 

The 30-km zone is part of the Ukrainian- 

Byelorussian Polesye which is characterized by 

increased and varying across the area transfer 

factors of 137 Cs from soil to biological chains. 

The migration of 137 Cs was studied after the 

Chernobyl accident in much detail, but had been 

investigated even earlier-after nuclear weapons 

testing. Therefore, we restrict ourselves to 

analysis of ^Sr and 137 Cs migration along the 

main food chains critical for internal exposure: 

soil - grass - milk, soil - vegetables. 

The annual measurements of 137 Cs and ^Sr 

in pasture grass allowed determination of soilgrass 

transfer factors TFCs. TFs,. The average 

TFcs and TFSr on the studied pastures were in 

the range 3X10" 3 and 4x10 m 2 /kg, respectively. 

The highest TFcs and TFsr were reported 

on peaty-boggy soils. For example, on the pastures 

near Gorodishche because of failure of the 

84 

irrigation system after the accident the level of 

groundwaters rose and the TFcs averaged over 

three years on waterlogged lands were 2.1 x 10' 2 

m 2 /kg for 137 Cs and 2.3x 10" 2 m 2 /kg for^Sr. 

The attempts to distinguish the contribution 

of the condensation and fuel cesium to TFcs 

were no success. The influence of soil characteristics 

appeared predominant. Therefore no 

specific features of TFcs have been detected in 

the near zone as compared to remote "cesium" 

regions. 

Even within one settlement on different pastures 

the variability of TFcs could be more than 

an order of magnitude and TFsr was normally 2- 

3 times lower. Because TF changes significantly 

depending on the territory and time after the 

accident it is problematic to use this parameter 

for assessing the dynamics of decontamination 

of pasture vegetation and estimating milk con- 


tamination. The comparison of actual mean 

concentrations of 

Sr 

137 Cs and ^Sr in milk with the 

values calculated by average TFQS and TF 

confirms this conclusion (see Table 11). 

It can be from Table 11 that 137 Cs to ^Sr ratio 

in milk is about 10 except Gorodishche • 40, 

ll'inetskya and Lubyanka - 20 and Terekhov - 5. 

Therefore, for the 30-zone the intake of cesium 

8 Settlement 

Teremtsy 

Ladyzhichi 

Parishev 

Opachichi 

Gorodishche 

Kupovatoe 

Terekhov 

Andreevka 

H'intsy 

H'inetskaya 

Lubyanka 

-Radiation & Risk", 1993, Issue 3 

assumed that since 1990,12991 the main role in 

137 Cs decontamination of agricultural produce 

will be played by the "slow" component. 

The statistical distributions of specific activity 

with respect to the mean in different kinds of 

agricultural produce are presented in Fig. 5-7 

and Table 13. 

The presented data suggest that all distributions 

of activity by products and in human body 

99.9 

99 

95 

80 

50 

20 

5 

^ r 

1 f " * 

^ 

* * 

0.1 

-2.5 -1.5 -0.5 0.5 L.5 

InCAij/Aj) 


can be approximated by lognormal dependence 

with close values of fig of about 1.8. 

This is of principal importance for the scope 

and frequency of radiation monitoring. If there 

are no additional sources of activity in a settlement, 

it is enough to determine the mean value 

and then use data of Figs. 4-7 and Table 13. 

1 

Pasture grass p 

* 

V 

-"i 

r f 

^ m • 

: ^ 

2.5 3.5 

Fig. 5. Distribution of logarithm of relative concentration of 137 Cs in pasture grass samples 

in the vicinity of settlement. 

99.9 

99 

95 

BO 

50 

30 

»#»» 

Pol tato 1 

^^r i 

0.1 1! ' 

-1.6 -0.8 0.4 

„ lnCAjj/Aj) 

J . 

*—;—•— • 

Fig. 6. Distribution of logarithm of relative concentration of 137 Cs in potato samples 

in the vicinity of settlement. 

86 

1.4 

3.4 

'Radiation & Risk', 1993, issue 3 

99,9 

99 

95 

80 

50 

F.% 

20 

u9 J' 

Milk i 

1 ..-* 

f 

0.1 • 

• 

f 

•3.6 -2.6 -1.6 -0.8 0.4 L4 2.4 

ln(AM/Aj) 

! 

* * 


Fig. 7. Distribution of logarithm of relative concentration of 137 Cs in milk samples in the vicinity of 

settlement. 

Table 13 

Statistical characteristics of distribution of relative radiation parameters in the exclusion zone 

N 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

Radiation 

parameter 

Dose rate 

" r Cs soil contamination density 

" r Cs concentration in grass 

157 

Cs concentration in potato 

137 

Cs concentration in milk 

External exposure dose 

,37 

Cs concentration in body 

\ 6. External and internal 

exposure doses 

6.1. External exposure 

Distribution 

type 

normal 

normal 

tognorm. 

lognorm. 

lognorm. 

lognorm. 

lognorm. 

According to the results of IDM, in May-June 

1989 in Lubyanka and Opachichi the mean daily 

doses were practically the same - 8.3 uGy/day 

at maximum individual values of 16 ^Gy/day in 

Lubyanka and 13.7 u,Gy/day in Opachichi. 

As is seen from Fig. 8, individual doses can 

be well approximated by the lognormal dependence 

with pg = 1.52. 

Based on the results of IDM in the areas of 

rigorous monitoring [15] it was established that 

probability density fi(ln(H/)) of distribution 

of ratio of individual doses H to settlement a 

averaged is rather stable and practically 

universal for a rural settlement: 

87 

Mean 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

1.0 

Standard 

deviation 

0.224 

0.558 

0.667 

0.614 

0.784 

0.439 

0.729 

A 

1.81 

1.76 

2.00 

1.52 

1.92 

f1(ln(H/))=0.96exp{-[ln(H/)+ 

90% 

quantite 

1.29 3 

1.56 

1.64 

1.58 

1.87 

1.54 

2.00 

+0.088f/0.3S}. (8) 

If we compare the distribution variances in 

settlements of the rigorous monitoring zone and 

settlements of the 30-km zone we see that they 

are close. The analysis of the relation of nonuniformity 

of contaminations of settlements and 

distribution of individual doses shows that in the 

range of 10 to 95 percentile the form of distribution 

and its parameters (mode, median, variance) 

with 10% error do not depend on the nature 

of radioactive contamination of a settlement. 

The effect of non-uniformity of radioactive 

contamination becomes noticeable only for extreme 

values. 

For practical purposes it is convenient to use 

the distribution f^H/am) of ratio of external 

individual doses H to mean density of 137 Cs


contamination of the territory 0*37. For example, 

for 1990: 

fi(ln(H/(T13T)=0.88exp{-[ln(H/ar1„)+ 

N, 

90 

60 

30 

0.7 1.4 3.1 

Hi{/H4 

u 

where [H] = mSv/day; 

fcrf377=Bq/m 2 . 


+ 2.27f/0.41}, (9) 

2.8 3.5 

Fig. 8. Histogramme of ratio of annual individual external doses H9 

and mean doses Hjfor a settlement in 1989. 

6.2. Internal exposure to 137 Cs, i34 Cs 

The population was examined for gammaemitting 

nuclides in May-June 1989 (12 settlements 

- 248 persons), August-September 1989 

(10 settlements - 267 persons) and August- 

September 1990 (5 settlements - 69 persons). 

The mean internal doses over 1989 ranged 

from 0.3 to 1.4 mSv in different settlements, and 

their relation to external doses was from 0.5 to 

3.0 with mean geometric value of 1.1. 

The purpose of the repeated survey in 

August-September 1989 and 1990 was to 

evaluate cesium intake in summer when population 

consumed products grown on contaminated 

territories. 

The comparison of data obtained in spring 

and autumn 1989 shows that the mean concentrations 

of radionuclides in body for a settlement 

did hot practically change. 

It is of interest to assess an error in determination 

of annual internal dose with one-time 

measurement by WBC. For this purpose we 

calculated the ratio of activities in body measured 

in spring A} 05 and in autumn A; 08 1989 in 

the same people. We] performed a frequency 

analysis of the indicated ratios for a sample of 

61 measurements. Th^ results are presented in 

Fig. 9. 

88 

It can be seen from the histogram that in 

85% cases the repeated measurements do not 

differ the first measurements by more than 2 

times. So, in the first approximation the error in 

estimation of mean annual internal doses WBC 

measurements is (-50% +100%) with confidence 

probability of 0.85. 

The function F(Af/Aj) of accumulated probability 

versus the ratio of individual concentrations 

of radiocesium Aq in body to an average 

over a settlement Aj is shows in Fig. 10. The 

distribution has a lognormal form with ^=1.92. 

Let us compare doses estimated by measured 

radionuclide concentration in body with 

dose calculated by intake with food for three 

different diets: 

1. consumption of all food stuffs without restrictions 

(mean daily diet of rural population in 

the Ukrainian Polesye: miik and milk products - 

1 kg, meat including lard and poultry - 0.2 kg, 

potato - 0.5 kg, vegetables - 0.3 kg, fruit - 0.15 

kg, mushrooms dried - 0.005 kg); 

2. excluding local milk from the diet; 

3. excluding local milk and mushrooms. 

The estimates show that for all settlements 

the mean geometric value of ratio of doses calculated 

by diet 1 to the actual mean doses was 

1.4. The same parameter for diets 2 and 3 are 

0.6 and 0.2 respectively. It should be noted that 


such ratios for specific settlements different 

from mean geometric values by a factor of 3 to 

4. The obtained results permit two conclusions 

to be made: 

firstly, for the settlements of the 30-km zone 

there are no restrictions on diet existing in the 

settlements of the rigorous monitoring zone and 

the food basket is primarily formed from local 

A f / A f 

food products. But even then the internal exposure 

doses due to 134 Cs and 137 Cs are close to 

external exposure doses; 

secondly, the error in does estimated by the 

typical diet used in adopted methodology [17] in 

specific settlements may be as high as 3-4 

times. 

Fig. 9. Histogram of distribution of ratios of WBC readings in May and August 1989. 

Y-axis - ratio of concentrations of cesium isotopes in body in May and August 1989. 

99.9 

99 

95 

80 

F,% 

50 

20 

5 

1 

0.1 

-2.7 

MfTtf* r neasuremen 

. K 

1 ••* 

-1.7 -0.7 0.3 

]n(Aij/Aj) 

-1 yr 

1.3 2.3 

Fig. 10. Distribution of logarithm of relative value of 137 Cs concentration in body. 

Y-axis - logarithm of ratio of 137 Cs activity in body to average for settlement residents 

89


Me 

6.3. Internal exposure from Sr 

The annual internal doses from ^Sr due to 

food consumption were assessed for two cases: 

1 - consumption of all kinds of food stuffs 

without restrictions; 

2 - excluding of local milk from the diet. 

The dose factors per unit intake were taken 

as prescribed in Publication 1 56 ICRP [16] for 

an adult. For a settlement, the dose due to ^Sr 

intake is estimated to be 10% of the dose due to 

137 Cs, 134 Cs intake and equals 0.08 to 0.37 mSv 

for the first diet option and 0.01-0.11 mSv - for 

the second diet option. It should be noted that 

the doses calculated based on the annual intake 

in 1990 (option 1) practically coincides with estimated 

average annual effective equivalent 

doses measured in 1991 due to the intake in 

1986-1991 [17]. 

6.4. Internal exposure due to 

inhalation intake 

The determination of expected equivalent 

absorbed doses for human organs and tissues is 

based on the model proposed in ICRP Publication 

30 and further developed in US [18] and 

USSR [19]. This dosimetric model allows finding 

cfwiTi, the expected specific equivalent dose of 

organ T at inhalation of 1 Bq of radioactive material 

/. 

It was assumed in calculations that the radioactive 

materials bound with condensation aerosol 

particles, when in a body, act differently 

governed by the kinetics laws for oxides of corresponding 

elements. Fission products and radionuclides 

incorporated in aerosol formed by fuel 

matrix particles show the whole spectrum of 

fragmentary and transuranium radionuclides. 

The ratio between them changes insignificantly, 

it is due to physics of 235 U fission and can be 

described by a constant coefficient with respect 

to a radionuclide reference of fuel particles. 

The radionuclide marker of fuel matrix particles 

in the environment is the gamma-emitter 

144 Ce. In methodology [19] it was assumed that 

in barrier organs, respiratory organs and IT the 

behavior of different radionuclides from fuel 

particles correlate. After these radionuclides get 

in barrier organs they behave independently 

governed by the kinetics of the corresponding 

elements. 

Given no direct measurements, the aerodispersed 

characteristics of the Chernobyl aerosol 

particles (AMAD and 0g) may be taken to be as 

follows: 

- 1 urn for condensation aerosols including 

131 l, 106 Ru, 103 Ru, 132 Te; 

- 5 urn for other condensation aerosols and 

fuel aerosol; 

- the value of pa is taken to be 3.0. 


The calculation was made for an adult 

"standard" person with parameters specified in 

ICRP Publication 30. 

Based on the ratio of fuel and condensation 

components of the depositions in settlements 

(Table 7), effective equivalent doses of two 

types were estimated: 

1 - the dose over 50 years from annual intake 

during 1991; 

2 - the dose in 1991 from intake of nuclides 

in 1986-1991 [17]. The estimates made with 

these two doses appeared to be close and 

ranged from 0.01 to 0.08 mSv in different settlements. 

Hence, the additional exposure from inhalation 

may make 1-10% of the natural radiation 

background and is much lower the contribution 

of 137 Cs, 134 Cs and ^Sr to the total dose. There 

seem to be no grounds to say that the structure 

of dose changes significantly due to fuel composition 

in the near zone as compared to the 

remote territories. 

90 

6.5. Dose zoning of the exclusion zone 

In the law of Ukraine [20] the following contamination 

zones are specified: the exclusion 

zone, the zone of compulsory relocation, the 

zone of voluntary relocation and the zone of 

enhanced radioecological monitoring. The criteria 

for referring a settlement to the zone is the 

values of 90% quantiles of contamination density 

with cesium, strontium, plutonium 

(environmental levels) and annual effective 

equivalent dose (EED) (dose levels). 

The law does not specify radiation criteria for 

the exclusion zone. It is therefor, of interest to 

evaluate the radiological situation in the exclusion 

zone using environmental and dose criteria. 

In terms of the radionuclide composition of 

the depositions in the 30-km zone the "hardest" 

indicator is ^Sr contamination density. The 

whole exclusion zone lies within the isoline of 74 

kBq/m 2 (by 90% quantile) and the isoline of 111 

kBq/m 2 except the south-west periphery. Hence, 

by the criterium of contamination density the 

exclusion zone can be classified as the zone of 

compulsory relocation. 

The picture is different with dose zoning 

which is done in three different ways: 

1 - in accordance with methodology [17]; 

2 - with allowance for data of individual dosimetry 

and radiometry of the population in the 

30-km zone; 

3 - only external exposure is considered in 

calculations of the annual dose which is 

equivalent to the assumption that only imported 

food stuffs are consumed. 

Fig. 11-13 show the maps of dose zoning 

performed by these three options. 


It can be seen for option 1,2,3 that 55, 65 

and 52% of the Ukrainian zone lies within 

isolines of 1-5 mSv/yean 44, 30 and 13% are 

above 5 mSv/year and 1,5 and 35% are below 1 

mSv/year. 

For options 1 and 2 the isodose of 5 

mSv/year is close to the isoline of 555 kBq/m 2 

by 13 Cs. For the third variant in which internal 

exposure is not considered, the area on which 

EED of 5 mSv/year can be exceeded is estimated 

to be 280 km 2 . 

so _ 

-so 

~6- iso*»s» 5 mSvli*ar (1991] 

8 a^ |Bvelorus| I —> 

nmmrrmrrrmf ( 

lUkrainel J 

The presented estimates do not take into account 

the dose from the natural radiation background 

and possible role of local sources of 

contamination. For the studied settlements, the 

ratio of dose from cesium (external and internal) 

to total EED was from 0.75 to 0.93. Thus, by the 

dose criterium the critical contamination indicator 

in the exclusion zone is the surface density 

of 137 Cs contamination. 

-90 km 

Fig. 11. Map of zoning (by dose) of the near territories in 1991. 

Option 1 - doses by the official methodology [17]. 

km 

60 J5 — isodose 5 mSvlfeat (1991) 

86^ Kiiufci 

EED= 86.1 mEWjeSTTl: % P,lM * t ' 

I Ukraine 

Teiekhov 

>shev 

C! 

i 

—3D 50 km 


Option 2 - by results of radiation-sanitary and dosimetric studies in the 30-km zone in 1989-1991. 

91


The value of dose from 137 Cs and 134 Cs per 

unit activity can change from 4X10" 6 to 1x10" 5 

(mSv/year/Bq/m 2 ) with the average of 7X10" 6 ; for 

^Sr - from 8x10' 7 to 8X10" 6 mSv/year with the 

average of 2x10" 6 . 

This means that at equal contamination 

density of 137 Cs and ^Sr, the dose from 137 Cs is 

3 to 4 times higher than that from ^Sr which is 

the opposite of the relation of boundary values 

of contamination density adopted in the law of 

Ukraine (0.003 - 0.2). 

km 

BD 

40 

-20 

5 — isodos* 5mSvl|«ar (1391) 

(5oJ) Ki,«Us (1991) ^ ^ - " V C T - S - V ^ S 

EED - 50.4 «S»lte« ^^p t i p | af N ^ ^ ^ ^ { 


The mentioned contradiction in environmental 

and dose criteria can be solved by giving 

preference to the radiation-sanitary norms, 

rather than environmental ones: the indicators 

that affect the expected frequency of adverse 

health effects of exposure should have priority. 

In this case the dose zoning including mapping 

of contamination of environmental media and 

mathematical formalization of behavior of people 

under real and anticipated socio-economic 

and technological conditions. 

t ^ \ s ^ y 


Option 3 - by external exposure. 

7. Radiation-sanitary aspects of 

rehabilitation of areas and settlements 

in the 30-km zone 

Rehabilitation is understood as returning the 

area to economical use, and to its initial natural 

condition plus decontamination to reduce the 

personnel and population doses or to decrease 

the contamination level of the produce. 

It was proposed that the rehabilitation in the 

30-km zone should be started from the least 

contaminated areas towards the areas of higher 

contamination: 

185-555 kBq/m 2 - using for agricultural and 

industrial purposes; 

555-1480 kBq/m 2 - growing technical crops 

and forestry; 

92 

3D km 

1480-2960 kBq/m 2 - some branches of forestry; 

above 2960 kBq/m 2 - forestation with coniferous 

tree and organization of a environmentalradiation 

reserve. 

At present, however, the territory of the 30km 

zone is prohibited for use by the low of 

Ukraine. Nevetherless we assess the radiationsanitary 

situation which would occur if the 

southern part of the 30-km zone were used in 

the economy. 

The proposed criteria of rehabilitation and resettlement 

of the population are: 

1. The basic dose limit should not be exceeded 

by the population permanently living on 

the area, given no restrictions on their activities. 

According to the Ukrainian law, this limit is an 

F 

J f t . 


annual effective equivalent dose of 1 mSv 

above the dose received before the accident. 

2. The production of the public and private 

sector should meet the requirements of the 

sanitary regulation. 

3. Resettlement should be carried out on a 

voluntary basic. 

Our studies show that the highest contamination 

level of produce within a settlement in 

most cases does not exceed the mean value by 

more than 3 times. Therefore, the production of 

produce meeting the specified permissible levels 

will be guaranteed in those settlements in 

which the average concentration of radionuclides 

is 1/3 of the permissible value. Therefore, 

along with the dose zoning discussed in Section 

7.5 it is expedient to carry out the zoning of the 

territory and settlements of the 30-km zone by 

radionuclides levels in the agricultural produce, 

specifically: 

the territory of guaranteed agricultural production 

of a given crop with expected contamination 

below 1/3 of the admissible level; 

the territory of risky agricultural production on 

which the contamination of the crop makes 1/3 - 

1 of the admissible level; 

the territory on which agricultural production 

is banned as the crop contamination exceeds 

the admissible level. 

Such zoning for the 30-km zone territory by 

the main kinds of agricultural produce (milk, 

potato, cereal crops) will permit optimal planning 

of production. There are three options of reha- 

bilitation: restoration of pre-accidental farms, 

returning the territories for economic use without 

inhabiting the contaminated areas and creating 

a new infrastructure. 

By way of illustration let us consider the resettlement 

of residents of a settlement and restoring 

traditional agricultural practices. 

Based on the 1985 statistical reports of the 

collective farms of the Chernobyl district we 

analyzed demographic and economic data for 7 

farms lying in the south of the 30-km zone. Before 

the accident, the total population was 10 

thousand people and the land areas - 40 thousand 

ha. The annual volume of produce was: 

16801 vegetable and 21301 grain and legumes. 

Using results of studies in the 30-km zone 

one can assess the contamination levels of agricultural 

produce which could be produced on the 

above mentioned farms. The contamination of 

vegetables and fruit was assumed to be the 

average contamination reported on private 

farms. Multiple comparisons of contamination of 

milk from private and collective grams show that 

the "collective" milk is normally 3 times cleaner 

the "private" milk. That is why in calculations the 

milk contamination was taken to be 1/3 of the 

level reported on private farms of the 30-km 

zone. The concentration of 137 Cs in meat was 

assumed to be 4 times higher that in milk. The 

total level of 137 Cs in a hypothetical case of 7 

farms of the Chernobyl district is presented in 

Table 14. 

Total level of 137, Cs in produce produced on the farms in 1991, MBq 

(hipothetical case) 

Produce | Ceres 

Cereal crops 

Concentration of Cs in 

produce in 1991, MBq 

184 

It follows from Table 14 that the main input to 

the activity is made by meat and milk (77%). 

If we assume that the volume of production 

and structure of consumption is the same as in 

1985 and the produce is supplied by the state 

without processing to the population living beyond 

the 30-km zone, the maximum collective 

dose for them from Cs and 134 Cs for a year 

will be 25 man-Sv. Taking the half reduction 

periods for the produce decontamination to be 

14 years for the 137 Cs and 10 year for the ^Sr 

the collective dose transferred with the agricultural 

produce from the 30-km zone over 70 

years can be estimated at not more than 500 

man-Sv for 137 Cs and 50 man-Sv for ^Sr. 

Potato | Vegetables 

310 16 

93 

Milk Meat 

993 712 

Table 14 

It we further assume that the farms will be 

resettled by residents themselves (10 thousand 

people) their average EED over 70 years may 

be 0.024 Sv. In this case, the total collective 

dose will not exceed 790 man-Sv. Then, the 

maximum radiation damage over 70 years related 

to reconstruction of traditional farming 

practices (collective risk) may be 50 cases even 

if no radiation countermeasures are taken. The 

individual mean annual risk for resettled population 

is estimated at 10' 5 . 

The obtained estimates are conservative in 

nature and need to be refined. The problem of 

socioeconomic acceptance of risk related to the 

Chernobyl accident presents a scientific interest 

in itself. Yet, there are strong grounds to believe

I 

'Radiation & Risk*, 1993, issue 3 

that the radiation-sanitary situation in the south 

periphery of the 30-km zone is such that rehabilitation 

of the territories by resettlement of the 

population, in principle, is possible. 

So, in this paper we considered different radiation-sanitary 

aspects in relation to the near 

zone of the Chernobyl NPP. The data obtained 

and the methodological approaches used, however, 

can be useful for other territories as well. 

In particular, they can be used for reconstructing 

doses on the contaminated territories of Russia 

and, hence, will be useful for the Russian State 

Medico-Dosimetric Registry. 

References 

1. International Atomic Agency. Summary report of 

Post-Accident Review Meeting of the Chernobyl 

Accident, Safety Series. Vienna: IAEA. 1988. 

N75. INSAG-1. 

2. Medical aspects of the Chernobyl accident. Proceedings 

of an All-Union conference organized 

by the USSR Ministry of Health and the All-Union 

Scientific Centre of Radiation Medicine USSR 

Academy of Medical Sciences and held in Kiev 

11-12 May, 1988: Technical document issued by 

the International Atomic Energy Agency, IAEA, 

TECDOC-516, Vienna, 1989. 

3. Ilyin LA. and Pavlovsky O.A. Radiological 

consequences of the Chernobyl accident in the 

Soviet Union and measurements taken to mitigate 

their impad//IAEA International Conference 

on Nuclear Power Performance and Safety, Austria, 

28 Sept.-2 October 1987: IAEA CN-48/33. 

1987. V. 3. P.149-166. 

4. Izraer Yu.A., Vakulovsky S.M., Vetrov V.A. et 

al. Chernobyl: radioactive contamination of environmental 

media. Leningrad: Hydrometeoizdat, 


5. The Radiological consequences in the USSR 

from the Chernobyl accident: Assessment of 

health and environmental effects and evaluation 

of protective measures. International Advisory 

Committee, Technical Report Printed by the 

IAEA in Vienna ISBN 92-0129391-7, IAEA, 1991. 

6. Gordeev K.I., Barkhudarov R.M., Savkin M.N. 

Theoretical base for setting norms of population 

exposure in the early period of eliminating the 

consequences of the Chernobyl NPP //Newsletter 

of Academy of Medical Sciences, in press, Moscow, 


7. Methodological recommendations on sanitary 

monitoring of levels of radioactive materials in 

environmental media/Ed. by Marey A.N., Zykova 

A.S., Moscow, 1980 (in Russian). 

8. Norms of radiation safety NRB 76/87. Moscow: 

Energoatomizdat, 1988 (in Russian). 

94 


9. Ionizing radiation: sources and biological effects 

UNSCEAR. 1988. Report to the UN Assembly. 

V.1. New York, 1988. 

10. Garger E.K., Zhukov G.P., Sedunov Yu.S. 

About estimation of resuspension parameters in 

the Chernobyl NPP zone//Methodology and hydrology. 

-1990.-N1. (in Russian). 

11. Sukhoruchkin A.K., Kazakov S.V. Dynamics of 

radioactive contamination of the air in the 30-km 

zone of the Chernobyl NPP//Proceeding of II NTS 

on main results of elimination of the consequences 

of the Chernobyl accident/Ed by Prof. 

Senin E.V. Chernobyl, 1990 (in Russian). 

12. Transuranic elements in the environment/Ed. by 

Hanson U.S. Moscow Energoatomizdat, 1985 (in 


13. Systematizing and analysis of works performed 

by research institutions in the 30-km zone of the 

Chernobyl NPP in 1986-1989: Contract N 2/27 of 

23.03.90, "Mayak", Chernobyl, 1990 (in Russian). 

14. Results of integrated radiation-sanitary survey of 

the settlements in the 30-km zone in 1990: 

Technical document IBP N 51-10-16/90-185. 

Moscow, 1990 (in Russian). 

15. Barchudarow R., Buldakow L., Gordeew K., 

Ilyin L, Savkin M. Strahlenexposition der 

Bevolkerung, der Kontrollgebiete in der vier 

Jahren nach der Havarie in Kernkeraftwerk 

Tshernobyl. Aktuele Fragen im strahlenschutz, 

TUL Bayern 30 Jahre Strahlenschutz Simposium, 

5 October, 1990. Beim Verland TUL Bagem. 

1991. P.27-55. 

16. International Commission of Radiological Protection. 

Agedependent Dose to Members of the 

Public from intake of Radionuclides. Part 1 ICRP 

Publication 56.Pergamon Press. 1990. 

17. Determination of annual total effective equivalent 

doses of population for the monitored areas of 

Russia, Ukraine and Byelorus affected by radioactive 

contamination as a result of the Chernobyl 

accident: Methodological guidelines of USSR 

Ministry of Health N 5792-91. Moscow, 1991 (in 


18. Cristy M., Eckerman K.E. Specific Absorbed 

Fraction of energy at Various Ages from internal 

Photon Sources. ORNL/TM-8381. 1987. V.17. 

19. Kut'kov V.A. Phenomenological dosimetric 

model of the aerosol of fuel matrix. Technical 

document of Institute of biophysics N91- 

16/90/31. Moscow, 1990 (in Russian). 

20. On legal regime of the territories affected by the 

radioactive contamination after the Chernobyl 

disaster. Legislation of Ukraine of 27 February 

1991. 'The Chernobyl Newsletter" N 25(245), 

April 1991 (in Russian). 

"Radiation & Risk', 1993, issue 3 Scientific Articles 

Radionuclide ratios in the fuel component of the radioactive 

depositions in the near zone of the Chernobyl NPP 

Ermilov A.P., Ziborov A.M. 

SPA "VNIIFTRI", Mendeleevo, Moscow Region; 

Russian Scientific-practical and Expert-analitical Center (RSEC), Moscow 

This study summarizes calculations on radionuclide composition of fuel in the 4th unit at the preaccident 

moment: mean values of radioactivity ratios against the radioactivity 144 Ce have been estimated 

for a number of radionuclides. Starting from "genetic" dependence of radionuclide ratios 

(RNR) on the bum up level the scheme of the analysis of fuel component of the fallout has been 

proposed. Experimental data on radionuclide composition of the fallout fuel particles have been 

analyzed which has led to more precise calculated RNR values. 

As a result of the explosion on the 4th unit of 

the Chernobyl NPP and the high temperature 

processes going on in the damaged unit till 6 

May 1986, in the releases a complex air dispersed 

system was formed which consisted of 

aerosols of different physico-chemical nature: 

- the particles of dispersed fuel (fuel particles); 

- the particles of dispersed matter formed in 

intergranular cavities of the fuel composition 

during the live time of the reactor (hot particles); 

- condensation aerosols formed by condensation 

of radioactive vapours in the release on 

the surface of aerosol particles and on atmospheric 

condensation nuclei; 

- fractal structures which are condensation 

aerosols and conglomerates incorporating soot 

particles with volumetric density almost equal to 

the air density; 

- radioactive inert gases and different species 

of iodine isotopes. 

The studies of the releases and depositions 

immediately after the accident revealed more 

than 40 fission and activation radionuclides. The 

difference in physical and chemical properties of 

the materials incorporating radionuclides (volatility 

of vapours and oxides, in the first place) 

on the one hand and the other hand, the radical 

difference in the origin of aerosol components in 

the releases has possible a "radionuclide" identification 

of aerodispersed species in the depositions. 

The methodological approaches for doing 

this are based on the analysis of measurements 

of the radionuclide compositions and on calculation 

of the radionuclide content in the reactor 

fuel before the accident. All this enables the 

preaccidental fuel history, the data on radionuclide 

composition and released physicochemical 

species to be combined in the model 

of Chernobyl depositions [1]. 

The comparison of different calculations of 

the fuel radionuclide composition and analysis of 

experimental data is presented in work [2]. The 

preaccidental ratios of radionuclide activities to 

Ce activities averaged over the area affected 

by the accident are included in Table 1. 

Table 1 

Ratios K« of radionuclide activity to 144 Ce activity in preaccidental fuel, 26 April 1986 

J E L T 

X 

Kg 

•wr Ce 3" "Ce °Zr -se Nb "so; Sr 

2.44x10* 

1.00 

•fas 

Ru 

1.76x10" 

1.20 

X 2.13x10 

1.20 

2.13x10' 

1.40 

= Toa 

1.08x10" 

1.40 

1.98x10" 

1.40 

6.65x10" 

6.30x10" 

E Z X 

1.88x10-° 

°Rh 

3.10x10 -1 

E 

2.40x10" 

Z 

'Sb "I 

3.10x10" 1 

6.87x10-* 

5.20x10" 3 

1.21x10 W 

1.50x10-* 

3 ^ Cs 

9.23x10- 

3.60x10" 

a Sr 

1.37x10" 

7.90x10 .-1 

T3T 

8.62x10 

8.30x10 -1 

7T 

,3b 

Cs j 

.34x10' 2 I 

,70x1Q- 2 'Cs T*B 

Ba TTO Pr 

5.34x 6.31x10- 5.42x10 T 8.32 

1.70x I 6.40x10" 1.50 1.00 

95 

•a Mo 

2.52x10 

T 

1.50 

°TS 

8.00x10" 

1.30 

'Pm 

7.26x10"* 

2.00x10" 1


R^T 

x 

Ka_ 

2.16x10" 

1.50X10- 3 

R/n 7*T Am "Cm 

4.39X10" 6 

4.00x10 s 

X is the radionuclide decay constant [1/day]. 

1.05x10" 

6.30x10"* 

Within the above mentioned modelling approaches 

with respect to the samples collected 

at 3-5 km from the unit the fuel particles (FP) 

are microscopic fragments of the reactor fuel of 

several tens of jim in size. The specific feature 

of soil and other environmental samples incorporating 

several dozens of FPs is that the 

measured radionuclide ratios of non-volatile radionuclides 

such as Ce, ^Zr, ^Nb, 154, 

155, Eu, appeared to be close to corresponding 

calculated values for the 4th unit of the ChNPP 

[1]. The other words, samples may be thought of 

as representative for the preaccidental fuel. The 

activity measurements in the samples show that 

at 100 km from the ChNPP practically all the 

samples of 150 cm 2 EUi 

and more are representative. 

The activity of radionuclides in non-volatile 

compounds is governed by the relation: 

Q't = KuQi, (D 

where Kf - data of Table 1. 

For the radionuclides of volatile elements: 

iodine, tellurium and cesium, the activity in the 

fuel component of the representative sample is 

Q? = W l ' z.. (2) 

where Q J t is activity of nonvolatile radionuclide 

T in the sample; 

Zm is coefficient of depletion of fuel by radionuclide 

"m". For example, for cesium Zm=1.4- 

2.0. 

Thus, based on relations 1 and 2 one can 

make a retrospective estimate of the fuel component 

activity in the sample for any of the radionuclide 

in Table 1 using measured activity of 

nonvolatile 144 Ce ore 154 Eu etc. The condensation 

Q" ore "free" component of the activity of 

volatile radionuclide in the sample is 

Q? = Q m - Qf m , (3) 

where CF is activity of volatile nuclide "/n" 

measured in the sample; 

Q is fuel component of volatile radionuclide 

estimated from (2). 

96 

Within the proposed approaches and using 

the available experimental data we obtained 

correlation factors Kgs relating the free activity 

of nuclide "nf in the sample to the free activity 

of 137 Cs 

or = *£Q CS (4) 

Factors KJ?S allow reconstruction of the activity 

of the free component of 125 Sb, 140 Ba, ^Sr 

etc. with reasonable accuracy [2]. The model of 

the Chernobyl depositions was supported with a 

large body of experimental data both from this 

country and other country and other countries. 

Before the accident, the 4th unit contained 

1659 fuel assemblies (FA) with varying bumup 

time (operating time) which determines ratio 

between the activities of different radionuclides. 

Table 2 contains results of calculation of 

specific activity of some fission products (FP) in 

the preaccidental reactor and core-averaged 

data [1]. 

It is worth pointing to the good agreement of 

core-averaged ratios of activities in Table 2 and 

Table 1. 

In this relation we looked at the agreement 

between results of calculations presented in Table 

2 and results of gamma-spectrometric 

measurement of activity of main fission products 

in the samples of the bank of fuel particles (over 

1200) generated by VNIITFA in 1987-1989. 

It should be noted, however, that by identifying 

the data of Table 2 with the radionuclide 

characteristics of FPs formed during the explosion 

we idealize them because in calculations 

allowance is only made for nuclear-physical 

processes in fuel during the reactor operating 

time and no consideration is given to local fluctuations 

in radionuclides distribution in each FA 

due to migration of fission products in fuel. 

Nevetherless, the data of Table 2 allow us to 

determine to what extent the radionuclide Characteristics 

of FAs depend on bumup using at 

least close correlations of averaged calculated 

data of Table 2 and Table 1 on the previous 

page. 


Activity of 144 Ce in 10 Bq/g and ratios of activity of some radionuclides 

to Ce activity in FA groups with different bumup time (Mwtxday/kg U) 

| N | Number of FAS | Burnup 

J 1 1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

146 

575 

261 

131 

79 

75 

66 

35 

18 

17 

28 

15 

23 

18 

34 

74 

64 

I 14.04-14.90 

13.16-14.03 

12.28-13.15 

11.40-12.27 

10.53-11.39 

9.65-10.52 

8.77-9.64 

7.89-8.76 

7.02-7.88 

6.14-7.01 

5.26-6.13 

4.39-5.25 

3.51-4.38 

2.63-3.50 

1.75-2.62 

0.88-1.74 

0.00-0.87 

Core-averaged 

N 

Number of FAS 

Bumup 

1 146 

2 575 

3 

4 

5 

6 

7 

8 

9 

10 

11 

| 12 

1 

261 

131 

13 

14.04-14.90 

13.16-14.03 

I 14 

I 15 I 

I 16 I 

| 17 I 

79 

75 

66 

35 

18 

17 

28 

15 

23 

18 

34 

74 

64 

12.28-13.15 

11.40-12.27 

10.53-11.39 

9.65-10.52 

8.77-9.64 

7.89-8.76 

7.02-7.88 

6.14-7.01 

5.26-6.13 

4.39-5.25 

3.51-4.38 

2.63-3.50 

1.75-2.62 

0.88-1.74 

0.00-0.87 

Core-averaged 

Activity of 144 Ce| "Sr/^Ce | "Sr/^Ce 

2.04 I 

2.00 

1.96 

1.91 

1.85 

1.79 

1.72 

1.63 

1.54 

1.43 

1.31 

1.18 

1.02 

0.84 

0.64 

1.240 1 0.067 

1.265 1 0.064 

1.291 J 0.061 

1.325 

1.367 

1.413 

1.471 

1.546 

1.636 

1.748 

1.893 

2.068 

2.314 

2.631 

3.047 

0.41 1 3.634 

0.14 I 4.571 

1.73 || 1.400 

137 Cs/ 144 Ce 

0.074 

0.071 

0.068 

0.065 

0.062 

0.059 

0.056 

0.054 

0.051 

0.048 

0.046 

0.043 

0.041 

0.039 

0.036 

0.034 

0.036 

0.064 

It can be seen from Table 2 that the activity 

ratio for cesium nuclides is the most sensitive 

indicator of FA bumup. As is shown in [3], the 

relationship of the ratio of cesium isotopes activities 

and the FA bumup is close to linear, 

which allows splitting the entire range of 

134 Cs/ 137 Cs ratios into equal intervals and place 

against each of them an interval of FA bumup 

which, in turn, is matched by a certain activity 

ratio for other radionuclides (specifically, for cerium). 

For convenience, the entire range (0-0.7) of 

ratios of 134 Cs and 137 Cs activities was divided 

into seven equal intervals. Each interval was 

attached by a FAs group (see Table 2): 

0.0 - 0.1 - FAs of groups 17 and 16; 

97 

134 Cs/ 144 Ce 

0.041 

0.038 

0.035 

0.032 

0.029 

0.027 

0.024 

0.022 

0.019 

0.016 

0.014 

0.012 

0.009 

0.007 

0.005 

0.003 

I 0.007 

| 0.034 

0.058 

0.055 

0.053 

0.049 

0.047 

0.045 

0.042 

0.040 

0.037 

0.035 

0.033 

0.031 

0.029 

0.029 

0.059 

154 Eu/ 144 Ce 

xlO -3 

1.57 

1.53 

1.52 

1.50 

1.49 

1.45 

1.42 

1.39 

1.34 

1.28 

1.21 

1.12 

1.01 

0.87 

0.68 

0.46 

0.21 

1.50 


Table 2 

106 144 

Ru/ Ce 

0.235 

0.227 

0.227 

0.225 

0.222 

0.219 

0.217 

0.215 

0.212 

0.211 

0.207 

0.205 

0.203 

0.200 

0.199 

0.197 

0.194 

0.220 I 

125 Sb/ 144 Ce 

xlO -3 

5.39 

5.35 

5.31 

5.29 

5.24 

5.19 

5.12 

5.09 

5.00 

4.89 

4.80 

4.74 

4.62 

4.52 

4.37 

4.39 

5.70 

5.30 

0.1 - 0.2 - FAs of groups 13,14 and 15; 


0.3 - 0.4 - FAs of groups 8, 9 and 10; 


0.5 - 0.6 - FAs of groups 3, 4 and 5; 

0.6 - 0.7 - FAs of groups 1 and 2. 

The proposed scheme was used for radionuclide 

analysis of the fuel component of the 

depositions represented by dispersed fuel particles. 

The results of the analysis are presented in 

Table 3 which gives calculated ratios in preaccidental 

fuel and the same ratios measured in FPs 

and these are compared with calculated cesium 

ratios used as a measure of bumup. 

I


Table 3 

Experimental and calculated ratios of activities of some radionuclides to activities 

of 144 Ce and 1S4 Cs, 26 April 1986 

134 Cs/ 144 Ce 

0.0-0.1 

0.1-0.2 

0.2-0.3 

0.3-0.4 

0.4-0.5 

0.5-0.6 

0.6-0.7 

Exp. 

0.10 

0.13 

0.18 

0.19 

0.24 

0.31 

0.29 

106 Rui 

' 144 Ce 

Calc. 

0.196 

0.201 

0.206 

0.213 

0.218 

0.225 

0.231 

Exp. 

1S4 Eui 

1.6x10"* 

7.8X10 -4 

1.1X10 -3 

1.4x10^ 

2.0x10 -3 

2.1X10" 3 

' 144 Ce 

Calc. 

4.0x10 -4 

8.5X10 -4 

1.2X10 -3 

1.4X10 -3 

1.4X10 -3 

1.5X10 -3 

1.5X10 -3 

12S Sb/ 144 Ce 

Exp. | Calc. 

2.40X10 -3 

2.03X10" 3 

3.14X10 -3 

3.94X10 -3 

4.63X10- 3 

5.50X10 -3 

5.84X10 -3 

4.4x10 -3 

4.5X10 -3 

4.8X10" 3 

5.0x10 -3 

5.1X10" 3 

5.3X10 -3 

5.4X10- 3 

137 Cs/ 144 Ce 

Exp. Calc. 

0.034 1 0.034 

0.017 0.038 

0.030 0.045 

0.022 0.052 

0.034 0.058 

0.040 0.066 

0.042 0.072 

Data of Table 3 show that, on a whole, the Along with correction of estimates data on 

calculated data are close to experimental. This the radionuclide composition of fuel particles 

confirms the earlier statement that the fuel com allow some specific features of the fuel compoponent 

of the depositions and the radionuclide nent of the depositions in the near zone of the 

composition of fuel particles have genetic rela ChNPP to be identified. The comparative 

tionship with the groups of FAs from which the analysis of 

particles originate. Therefor, taking into consideration 

the processes in the reactor which were 

neglected before allows us to make corrections 

in the results. Table 4 includes calculated cesium 

ratios of some radionuclides which have 

been refined with experimental data. 

144 Ce (as one of main fuel markers) 

activity distribution in the reactor fuel and in the 

fuel component of the depositions against the 

ranges of ratio of cesium isotopes activities 

(bumup ranges) makes possible an evaluation 

of the extent to which the fuel component of the 

depositions corresponds to the reactor fuel (Fig. 

1). 

Table 4 

Radionuclide ratios in the reactor fuel and the fuel component of the depositions 

Data type 

Calculation + correction 

Fuel component 

Experiment/ 

calcul.+ correct. 

137 Cs/ 14 «Ce 

3.9x10 2 

3.3x10 -2 

0.85 

12S Sb/ 144 Ce 

5.4x10^ 

4.6x1 OI 3 

0.85 

98 

106 Ru/ 144 Ce 

2.8x10 -1 

2.4x10 -1 

0.86 

: 

154 Eu/ 144 Ce 

1.8x10^ 

1.5x10" 3 

0.83 


"•Cl< "TC, 

Fig. 1. Proportion of ^Ce activity in the preaccidental fuel of the 4th unit of the Chernobyl NPP 

and in the fuel component of the depositions in the near zone. 

Y-axis - ratio of ,S4 Cs activity to " 7 Cs activity, characteristic of the FA bumup. 

As is seen from Fig. 1, the fuel in the depositions 

of the near zone of the ChNPP primarily 

corresponds to the groups of FAs with the fuel 

bumup lower than in the bulk of the fuel. The 

qualitative appraisal suggests that the average 

values of the cerium ratios of radionuclides in 

the fuel component of the depositions may differ 

from those in the reactor fuel. This assumption 

is also confirmed by the data of Table 4 including 

average values of cerium ratios in the reactor 

fuel and in the fuel component of the depositions 

represented by particles of dispersed fuel. 

99 

References 

1. Ermilov A.P. Assessment of ratios of main radionuclides 

in the reactor fuel depending on FA 

energy production, assessment for all the reactor 

fuel. Results of investigation of size distribution 

of fuel particles: Report of VNIIFTRI, 1989. 

2. Ermilov A.P. Use of the radionuclide ratios in 

the accidental depositions of the ChNPP for prediction 

of behavior of radionuclides in the environment: 

Report of VNIIFTRI, 1991. 

3. Markushev V.M. Information about the nuclide 

composition of the fuel of the 4th unit of the 

ChNPP. Kurchatov Institute of Atomic Power, 

Chernobyl, 1987.


Radiation exposure following the accident 

at the Siberian chemical complex Tomsk-7 

Vakulovski S.M., Shershakov V.M., Borodin R.V., Vozzhennikov O.I., 

Gaziev Ya.l., Kosykh V.S., Makhonko K.P., Chumiciev V.B. 

Scientific Production Association Typhoon" 

On the basis of the work (ground investigations and gamma-aerial surveys) earned out jointly by 

the Rosgidromet organizations and Berezovgeotogiya, data on radiation exposure in Russia were 

obtained shortly after the accident of April 6, 1993 already. These data were transmitted to interested 

institutions. 

The measurements performed on April 11 and 12,1993 indicated that within the isolines of 10 

pR/h a contaminated area of up to 25 km in length and up to 6 km in width extended towards the 

northeastern direction. Thus, the contaminated area outside of the premises of the complex covered 

about 100 km 2 . The total amount of radioactive substances in this area was 530-590 Ci. Isotope 

composition of the radioactive trace was determined by 103 Ru (1%). 10B Ru (31%), ""Zr (22%), ^Nb 

(45%) and ^Pu (0.02%). 

Contamination heterogeneity is caused by the existence of "hot" particles with an activity of up to 

10-11 Ci/particte. 

In the contaminated area the gamma-exposure rate varied between 14 and 42 nR/h at 1 m 

height, yielding the maximum external radiation dose 100 mrem/year for the population of Georgievka. 

The Pu inhalation dose of the population of Georgievka when passing the radioactive 

cloud did not exceed 1.5 mrem. 

A prognosis was made with regard to water contamination of the rives Samuska and Tom during 

the flood in spring. Furthermore, contamination of the air layer adjacent to the ground resulting 

from the wind transport of radionuclides in the summer months at Georgievka was predicted. The 

values were far below the limits fixed according to the valid radiation protection regulations. However, 

that radionuclide concentration of the snow water may exceed the limits specified for drinking 

water. 

According to the data measured by the meteorological stations, the radioactive products were not 

entrained beyond the borders of the country. Source estimation was successfully obtained using 

RIMPUFF, the RisO on-line puff diffusion model, in its backfitting mode. 

Contents 

Introduction 100 

1. Measures taken by the Russian Federal Survey for Hydrometeorology and 

environmental monitoring after the accident 101 

2. Results of the isotope analysis of snow and soil samples 102 

3. Spread of the radioactive products in the atmosphere and contamination 

of the ground due to their deposition 107 

4. Prognosis of contamination resulting from secondary wind transport 112 

5. Prognosis of water contamination 113 

5.1. Estimated radionuclide concentration of the Samuska river 113 

5.2. Contamination of the flood in spring 113 

5.3. Estimation of radionuclide washout 114 

6. Supply of information for the estimation of radiation exposure in the area 

of the Siberian chemical complex 114 

6.1. Information for the taking of appropriate measures during the first hours 

after the accident 115 

6.2. Systematization of the measured values and data processing or 

an objective radiation analysis 118 

Concluding remarks 131 

Annex. Calculation of the factors of conversion of the dose rate distribution 

of the ground into the contamination density of individual radionuclides 132 

References 133 

Introduction 

According to the report about the state of radiation 

in the area affected by the accident at 

the Siberian chemical complex (Tomsk-7), 

which was submitted by the Commission of the 

Russian State Committee for States of Emergency 

[1], the N 610272 facility of the radio 

100 

chemical plant was destroyed on April 6,1993 at 

12.58. In this facility, a uranium solution had 

been prepared for extraction. During the explosion, 

part of the activity was released into the 

environment. It can be concluded from the activity 

data of the uranium solution published by 

the chemical complex that 500 Ci beta-active 

and 20 Ci alpha-active products including 19,3 


239r 

Ci Pu had been contained in the facility prior 

to destruction. 

The explosion resulted from the decomposition 

of the organic phase of the solution when 

interacting with concentrated nitric acid. 

The limited steam/gas volume that was released 

into the hall exploded. This furthered increased 

the extent of the damage. Activity release 

into the atmosphere took place via the 

ventilation system, the pressure and vacuum 

lines, the 150 m high stack of building no. 205, 

the ventilation system and stack of building no. 

201 as well as via the destroyed walls. 

Immediately after Rosgidromet had been 

notified of the accident, measurements were 

started and radiation exposure in the area affected 

was analyzed in accordance with the 

regulations regarding The measures to be taken 

by the Rosgidromet divisions in case of nuclear 

accidents". 

1. Measures taken by the Russian 

Federal Survey for 

Hydrometeorology and environmental 

monitoring after the accident 

At 18.45 local time Rosgidromet was informed 

about the accident. 

To determine the contaminated area, all hydrometeorological 

stations and aeronautical 

meteorological offices of the monitoring network 

established by Rosgidromet were ordered to 

measure the gamma dose rate and the meteorological 

parameters every hour. 

I Time | Wind j 

(h-min) j direction j 

I (decree) I 

1,x1-00 190 

11-30 

12-00 

12-30 

13-00 

13-30 

14-00 

14-30 

15-00 

15-30 

16-00 


The data obtained were then to be made 

available to Rosgidromet and other interested 

institutions. These values allowed a preliminary 

estimation of the extent of contamination to be 

accomplished. It turned out that contamination 

was entirely local. 

As far as geography is concerned, the contaminated 

area is slightly hilly with only small 

differences in altitude (30 m). In the northern 

part, the territory is mainly covered by coniferous 

forest with dense underwood. In the south, 

mixed forest as well as bushes and shrubs are 

prevailing. Population density amounts to 80%. 

Heights of 10 to 12 m are reached by the trees. 

About 20% of the territory is made up of 

swamps. Nearly 10 is under agricultural use. 

From east to west, the area is crossed by the 

Samuska river flowing in strong meanders. A 

maximum water flow rate of up to 70 m 3 /s is 

attained. The mean annual water flow rate is 10 

m 3 /s. While in the north-eastern part, the territory 

is mainly loamy (70%), soil in the southwestern 

part is found to be predominantly sandy. 

The values measured by the synoptic 

serological stations nearby, the meteorological 

data determined every 30 minutes in Tomsk 

(table 1.1) and the balloon data measured at 

Tomsk airport (table 1.2) led to the following 

conclusions: 

- the weather conditions at the site of the accident 

were stable southwestern wind (190- 

210°), speed 8-13 m/s, temperature - 3 °C; precipitation 

in the form of wet snow was recorded 

after the accident at 15-30 local time; 

- stratification - neutral. 

Table 1 

Data measured by the Tomsk meteorological station on April 6,1993 

200 

200 

210 

190 

210 

200 

210 

200 

200 

200 

Wind 

speed 

(m/s) 

8-11 

7-10 

8-11 

8-11 

9-12 

9-12 

10-13 

9-13 

8-12 

9-13 

10-13 

Air 

temp. 

(°C) I 

-4.3 

-4.0 

-3.8 

-3.5 

-3.2 

-3.2 

-2.9 

-2.6 

-2.3 

-2.0 

-2.0 

Rel. 

hum. 

(%) 

79 

80 

80 

81 

77 

77 

67 

65 

68 

71 

81 

101 

| Precipitation: 

| beginl 

end 

- 

_ 

_ 

_ 

_ 

_ 

_ 

_ 

is 18 -^ 35 

- 

Degree 

of 

cloudiness 

10/3 cirrostratus strato-cumulus 

clouds 

II 

.. 

* 

.. 

. .. 

i 

.. 

i 

_ '_ 

10/4 cirrostratus strato-cumulus 

clouds


t 

11-00 

14-00 

17-00 

t'time, h-min; 


Sample 

No. 

3 

4 

7 

8 

9 

, « 

Table 2.1 

Snow and soil samples taken in the area affected by the accident (Tomsk-7) 

Radiation 

uJR/h 

70 

120 

100 

131 

123 

77 

I 

Route 

I 

I Sample 

No. 

M-1 1 

M-1 

M-2 

M-3 

M-4 

Susp. - F 

Sol. - R 

Soil 

F 

R 

F+R 

Soil 

Total 

F 

R 

F+R 

Soil 

Total 

F 

R 

F + R 

Soil 

Total 

F 

R 

F + R 

Soil 

Total 

F 

R 

F + R 

Soil 

iuJ Ru | 

0.068 

0.004 

0.072 

0.026 

0.098 

0.106 

0.009 

1.115 

0.223 

0.338 

0.062 

0.003 

0.065 

0.061 

0.125 

0:253 

0.015 

0.268 

0.086 

0.354 

0.210 

0.006 

0.216 

0.210 

1ui Ru 

1.13 

0.07 

1.20 

0.43 

1.63 

1.89 

0.179 

2.07 

8.32 

10.4 

1.46 

0.063 

1.52 

1.36 

2.88 

4.73 

0.34 

5.06 

1.99 

7.05 

4.40 

0.23 

4.63 

4.99 

Activity, Ci/km 2 

I *Zr | 

0.843 

0.022 

0.865 

0,173 

1.040 

1.09 

0.05 

1.14 

6.08 

7.20 

0.884 

0.009 

0.893 

0.949 

1.84 

3.51 

0.09 

3.60 

1.50 

5.10 

3.24 

0.085 

3.32 

3.34 

~Nb | 

1.65 

0.024 

1.67 

0.347 

2.02 

2.08 

0.058 

2.14 

15.6 

17.7 

1.73 

0.016 

1.75 

1.98 

3.73 

6.78 

0.137 

6.91 

3.44 

10.3 

10.0 

0.311 

10.3 

Snow samples taken in the area affected by the accident (Tomsk-7) 

2 

1 

1 

2 

Georgievka, village 

boundary, field path 

Georgievka, village 

boundary, house No.6 

front yard 

Date of 

sampling 

12.04.93 I 

12.04.93 

12.04.93 

12.04.93 

12.04.93 

| 07.04.93 

08.04.93 

Radiation, 

uR/h 

30 

23 

72 

206 

96 

l< "" 

I 

- 

Susp. - F 

Sol. - R 

Total-C 

F 

R 

C 

F 

R 

C 

F 

R 

C 

F 

R 

c 

F 

R 

I c 

F 

R 

c 

F 

R 

C 

104 

lu tRu 

0.021 

- 

0.021 

0.061 

- 

0.061 

0.092 

- 

0.092 

0.137 

0.034 

0.171 

0.07 

0.007 

0.077 

0.019 

- 

0.019 

0.023 

- 

0.023 

9-8 

Activity, Ci/km^ 

| ,l *Ru 

0.286 

- 

0.286 

1.304 

- 

1.304 

2.08 

0.05 

2.13 

3.01 

0.843 

0.385 

1.62 

0.154 

1.77 

0.403 

0.032 

0.435 

0.566 

0.10 

0.666 

I ** « 

0.18 

0.02 

0.20 

0.993 

0.018 

1.011 

1.51 

0.042 

1.55 

2.11 

0.559 

2.67 

1.01 

0.098 

1.11 

0.224 

0.013 

0.237 

0.432 

0.046 

0.478 

,J 'Cs 

. 

. 

. 

0.222 

0.222 

. 

- 

. 

0.14 

0.14 

. 

- 

. 

0.435 

0.435 

- 

. 

. 

0.271 

0.271 

. 

. 

- 

0.44 

Table 2.2 

^ ~ i 

'"No 

0.465 

0.035 

0.50 

1.97 

0.028 

2.0 

2.84 

0.071 

2.91 

3.67 

1:036 

4.71 

1.90 

0.195 

2.095 

0.358 

0.027 

0.385 

0.919 

0.107 

1.03 | 


^Sr was determined in accordance with the 

methods outlined in [5]. They had already been 

applied in 1990, when SPA Typhoon" investigated 

intercalibrated IAEA samples with regard 

to their ^Pu, 240 Pu and ^Sr contents. Agreement 

of the results with the basic values was 

found to be rather good. The analytical results 

obtained with regard to the 239 Pu concentration 

of both suspensions of the particles contained in 

the snow water of the snow samples studied and 

filtered water samples are presented in table 

2.3. 

According to the values indicated for the first 

five samples, at least 90% of the ^Pu activity 

of the snow is bound to the water-insoluble, disperse 

phase of the radioactive fallout. A mean 

of 4% of the activity is found in the soluble 

phase only. For subsequent analysis, suspensions 

filtered from the snow water samples were 

applied. It is evident from the data given in table 

2.3 that the densities of ^Pu deposition on the 

snow exceeded 0.06 mCi/km 2 . However, they 

were far below the maximum permissible ground 

contamination (100 mCi/km 2 ) specified in April 

1986 after the Chernobyl accident. 

239, 

The density of surface contamination of the snow by Pu 

No. or designation n | Analysed fraction 

of the sample 

Suspension (F) 

Filtrate (R) 

F 

R 

F 

7 

8 

9 

M-1-1 

M-1-2 

M-2-1 

M-2-2 

M-4-2 

Georgievka, 6 

I 

| 

| 

y 

1 . 

i 

1 

1 

1 

1 

1 

R 

F 

R 

F 

R 

F 

R 

F 

F 

F 

F 

F 

F 

The values given in table 2.3 (last column) 

are required for the determination of the conversion 

factors. Using these factors, the 239 Pu 

content of the radioactive fallout may be calculated 

from the ^Zr activity that can be measured 

easily. The mean value of the 239 Pu/ 95 Zr activity 

ratios indicated in table 2.3 is 3.4-10" 4 . The rootmean-square 

of the distribution of the measurements 

is 8-10" 5 and the root-mean-square 

error of the mean value is 2.6-10" 5 . Otherwise 

stated, the mean value of the conversion factor 

from the ^Zr activity measured in a sample to 

its 239 Pu content, is Z.A+0.6W* and ranges from 

1.6 to 5.2-10" 4 . Thus, the most probable surface 

density at the sampling point of the snow sample 

M-3-1, the 239 Pu content of which was not analyzed 

radiochemically, was found to be about 1 

mCi/km 2 . With a probability of 0.95, the value of 

1.4 mCi/km 2 was not exceeded. The snow sample 

M-3-1 (or to be more precise, the portion 

analyzed by SPA Typhoon" was applied for 

fable 2.3 

Surface contamination 

of the snow, 

mCi/km 2 

ation U ^Pu^Zr 

activity ratio, 

% 

0.3 

0.007 

0.036 

0.15 

0.017 

0.014 

0.4 

0.045 I 

0.0032 

I 

1.2 

0.037 

0.043 

I 

1.2 

0.037 

0.023 

- 

0.06 

0.032 

0.3 

0.63 

0.03 

0.042 

0.35 

0.035 

0.35 

0.035 

0.12 

0.028 

105 

,preliminary estimation of the surface density of 

uranium deposition in the controlled area. According 

to the data published by the Siberian 

chemical complex, 8773 kg uranium had been 

contained in the N 6102/2 facility prior to the 

accident [1]. 

This value almost completely referred to 

238 U. The fractions of the other uranium isotopes 

were extremely small. The Û content of the 

sample to be investigated was determined by 

means of neutron activation analysis. It was 

found that surface density of the 238 U deposition 

on the snow amounted to 480 g/km 2 at the 

sampling point of sample M-3-1. Surface density 

of the alpha-activity resulting from 238 U was 0.16 

mCi/km . This value may be derived from the 

known specific alpha?activity of 238 U of 3.34-10' 7 

Ci/g. As the surface density of 239 Pu deposition 

on the snow amounted to about 1 mCi/km 2 at 

this point, the 238 U/ a8 Pu activity ratio of the atmospheric 

radioactive fallout was 0.16. This 

value corresponded to that of these radionu-


elides (0.15) in the source of radioactive emission 

into the atmosphere. 

The most important data obtained by the 

laboratory of the National Health Service with 

regard to the surface densities of the radioactive 

Pu and 238 U depositions on the snow are reported 

about in [1] and summarized in table 2.4. 

According to the data given in tables 2.3 and 

2.4, the surface densities of 239 Pu deposition on 

the snow at Georgievka are 0.12 mCi/km 2 and 

0.20 mCi/km 2 , respectively. Hence, a mean 

value of 0.16 mCi/km 2 is obtained. The deviations 

of the individual values measured from the 

mean value obviously result from macroscopic 

and microscopic inhomogeneities of the ^Pu 

deposition field in the Georgievka area. These 

inhomogeneities may be caused by most of the 

alpha- and beta-active products being deposited 

on the surface of the snow in the form of "hot" 

particles having beta-activities of 10" 11 

Ci/particle and more. According to preliminary 

estimates, the deposition density of these particles 

on the surface of the snow at the fringe of 

the Georgievka village (field path) amounted to 

about 4-10 2 particles/m 2 . Now, the special features 

of ground contamination by "hot" radioac 

tive particles and their physical and nuclearphysical 

characteristics shall be investigated. 

According to table 2.4, values of (6.5-7.5) 

mCi/km 2 were attained for the surface density of 

239 Pu contamination at certain points in the 

snow. These values corresponded to those of 

the sections with the highest contamination. But 

even in these cases, the values were found to 

be far below the maximum permissible ground 

contamination by 239 Pu. 

At measuring points with the gamma dose 

rate ranging from 160 to 1800 uJR/h, a mean 

value of the 239 Pu/ 85 Zr activity ratio of 

(1.0±0.34)-10' 3 was obtained with a probability of 

0.95. The individual values were found to be in 

the range of (I.OiO.&O-IO" 3 . Hence, they differed 

from the above estimates for less contaminated 

areas in the radioactive trace. It must be pointed 

out that so far only few measured values have 

been made available with regard to ground 

contamination by 239 Pu in the area affected by 

the accident at the Siberian chemical complex. 

To obtain more reliable data about the existing 

contamination, far more measurements have to 

be carried out. 

Snow contamination by alpha-active products in the radioactive trace [1] 

Sampling 

point 

Km 28 

Km 28 lefthand side 

Km 28 righthand side 

Georgievka 

Km 28 (50 m) 

Km 28 (300 m) 

Km 28 (600 m) 

18 PI. (righ-hand 

side of path) 

Date, 

1993 

06.04 

07.04 

07.04 

08.04 

09.04 

09.04 

, 09.04 

10.04 

Gamma 

exposure 

rare, 

u.R/h 

280 

400 

400 

23 

370 

350 

157 

1800 

Snow contamination 

by alpha-active radionuclides, 

mCi/km 2 

^Pu fl Û | Û 

0.60 1.151 0.172 

7.51 0.707 0.619 

5.28 0.815 0.424 

0.20 0.101 0.101 

4.53 0.437 0.306 

2.43 0.334 0.576 

0.59 0.020 0.020 

6.45 5.15 5.68 

Table 2.4 

Total alpha- | 

activity, & 

mCi/km 2 

0.93 

8.94 

6.52 

0.40 

5.27 

3.34 

0.65 

18.33* 

•*) - The share of the 235 U portion of the sample measured in the total alpha-activity 1.05 mCi/km 2 

is also taken into account. 

Thirteen snow samples and 5 soil samples 

were analyzed by SPA "Typhoon" with a view to 

determine their ^Sr content. The results are 

presented in table 2.5. In the snow, this radionuclide 

was mainly found in the dissolved fraction, 

i.e., the snow water. 13% of the ^Sr was 

bound to the suspended particles only. According 

to our data, contamination density of the 

snow by ^Sr was the highest in samples nos. 8 

and 9. Here, values of 9.2 and 7.6 mCi/km 2 , respectively, 

were reached. Analysis of seven 

snow samples by ZapSibgidromet revealed that 

106 

the ^Sr concentration of sample No. 1 (18.5 

mCi/km 2 ) was twice as high as the maximum 

value determined by SPA "Typhoon". The other 

^Sr values were in good agreement with the 

values determined by Typhoon". 

Our values do not suggest any relation between 

the ^Sr content and the content of 

gamma emitters in the samples. This can be 

explained by the fact that the latter are predominantly 

encountered in the suspended particles of 

the snow, while ^Sr is mainly found in the snow 

water. 


At the measuring points, the density of 

ground contamination by ^Sr varied between 

140 and 250 mCi/km 2 . These values were much 

higher than the contamination of the surface of 

the snow. The contamination exceeded gross 

background radiation (35 mCi/km 2 ) by a factor 

Sample No. 

3 

4 

7 

8 

9 

M-1-1 

M-1-2 

M-2-1 

M-2-2 

M-3-1 

M-4-2 

Georgievka field path 

Georgievka house No.6 

of 4 to 7. The higher ground contamination may 

result from emissions during previous operation 

of the complex. In certain areas, such emissions 

had aldready been recorded by ZapSibgidromet 

experts in 1990. 

Density of snow and ground contamination by Sr, mCi/km 

Snow 

Snowwater | Suspension I Total 

2.3 

3.4 0.26 3.6 

2.8 0.35 3.15 

8.5 0.7 9.2 

6.6 1.0 7.6 

0.3 0.04 0.34 

0.5 0.03 0.53 

0.5 0.07 0.57 


In the Tomsk area and in the 100-km zone 

surrounding the chemical complex, the radioactive 

contamination is controlled regularly by the 

measuring and meteorological stations belonging 

to the ZapSibgidromet radiometrical network. 

Twenty-three dose control stations, 13 

stations controlling radioactive fallout and one 

station for the control of the concentration of 

radioactive products in the air (Kolpashevo) are 

located in the Tomsk region. Following the accident 

at the chemical complex (Tomsk-7) with 

the release of radioactive products into the atmosphere, 

all stations of the ZapSibgidromet 

radiometrical network in the Tomsk region and 

in the adjacent areas of Novosibirsk and Kemerovo 

as well as the measuring stations of the 

Krasnoyarsk region were ordered in accordance 

with the valid regulations to carry out measurements 

of the gamma-background until April 11, 

1993. From April 6 to April 8,1993, these measurements 

were carried out every hour. As of 

April 9,1993, they took place every three hours. 

The gamma-exposure rate measured by the 

measuring stations in the Tomsk region including 

the control stations in the 100-km zone surrounding 

the chemical complex was found to 

vary between 6 and 15 ^ h on these days. 

The gamma-exposure rates measured in the 

Tomsk area before and after the accident are 

presented in table 3.1. It is evident from the data 

below that gamma-background in the 100-km 

zone did not change after the accident of April 6, 

1993. The measuring stations located in the Novosibirsk 

and Kemerovo areas also did not record 

any changes of gamma-background after 

April 6, 1993. The mean gamma-exposure rates 

determined by the measuring stations of the radiometrical 

network from April 6 to April 11, 

1993 varied between 7 and 13 nR/h and 9 and 

17 uR/h in the Novosibirsk and the Kemerovo 

area, respectively. 

The mean values determined by the measuring 

stations of the Krasnoyarskgidromet from 

108 

April 6 to April 11, 1993 are presented in table 

3.2. For comparison, the mean gammaexposure 

rates of March 1993 are indicated as 

well. It can be noticed that the gammabackground 

values measured by the radiometrical 

measuring stations in the regions adjacent to 

the Tomsk area did not change after the accident. 

The trajectories of air transport calculated for 

a period of 67 hours following the explosion are 

represented in Fig. 6.1 for three different altitudes. 

They indicate that transport took place 

towards the northern and northeastern direction 

on the first three days after the accident. However, 

an increase in the gamma-background had 

not been recorded by any of the Rosgidromet 

radiometrical network stations located in the direction 

of these trajectories. 

The most sensitive method for controlling the 

radioactive products released into the air during 

an accident is the sampling of the atmospheric 

fallout and aerosols. Radioactivity is measured 

daily by the stations belonging to the radiometrical 

network. According to the data transmitted to 

"Typhoon" by the stations determining the total 

beta-activity of the samples, a slight increase in 

the radioactivity concentration of the air and the 

precipitations was recorded by the Turukhansk 

station from April 8 to 10 only. On these days, 

atmospheric precipitation amounted to three 

times the mean value of the month of March. 

Concentration of radioactive aerosols was increased 

by a factor of 1.5-2. This, however, was 

still within the limits of fluctuation of the radioactive 

background. These increases were of no 

significance, as precipitations and concentrations 

of the same amounts had also been observed 

on some days in March. No radioactivity 

changes were recorded at the Norilsk station 

located north of Turukhansk. 


Table 3.1 

Gamma-exposure rates measured in the Tomsk region before and during the first days 

after the accident at the chemical complex, uJVh 

I Control 

station 

Molchanovo 

Kozhevnikovo 

Permomaiskoe 

Krasnyi Yar 

Baturino 

Bolotnoe 

Tomsk aeronau. 

station 

Tomsk hydromet. 

station 

Belyi Yar 

d - distance of radiation source, km; 


Road section, km 

20-28 

28 - 28.6 

28.6 - 28.9 

28.9 - 29.6 

29.6-31.1 

From these data, the high radioactive contamination 

between km 28 and km 31 is clearly 

visible. Therefore, workers of the chemical 

complex carried out decontamination at km 29 

of the road. Thus, the gamma-exposure rates in 

the most contaminated sections could be reduced 

to 120 uR/h. 

Along the fence around the complex premises, 

the gamma-exposure rate ranged between 

225 and 12 uR/h from km 28.5 to 30.5. At the 

Gamma-exposure rate, uR/h 

12-30 

30 r 510 

510-180 

180-200 

200-20 

guard house at the entry of the complex, a value 

of 12 uR/h was measured. 

At km 28.5 of the road, gamma-background 

measurement was performed up to a distance of 

700 m from the road in the direction towards the 

complex. Gamma-exposure rate varied between 

180 and 480 uK/h. Starting at this road section, 

measurements were made every 500 m until the 

village of Georgievka was reached. The results 

obtained are presented below: 

Distance, m Gamma-exposure rate, uR/h 

Of all villages located in the 30-km zone, 

only Georgievka suffered from contamination. 

The values measured there are indicated below. 

At the remaining 14 places (Malinovka, Aleksandrovskoe, 

kolkhoz "Rassvet", Kopylovo, Kuzovlevo, 

Bobrovka, Mikhaiiovka, Nadezhda, 

Dzerzhinski, Timiryazevo, Zerkaltsevo, Berezovka, 

Porosino and Nelyubino), gamma dose 

rate amounted to 7 - 14 uR/h between April 6 

and 12, 1993. At the villages of Karakozovo, 

tyukalovo, Yegorovo and Karyukina, a value 

smaller than 10 uR/h was determined. At 

Tomsk-7 and Tomsk, the gamma dose rate was 

12 uR/h which corresponded to the natural 

gamma-background. 

On the route from Naumovka to Georgievka, 

the gamma-radiation field was found to have a 

spot-like structure: 

- 3 km away from Naumovka, 3 m away from 

road 150-160 uR/h; 

- 3 km away from Naumovka, 50-100 rri 

away from road 30 uR/h; 

- 3 km away from Naumovka 17-30 uR/h; 

- 1 km away from Georgievka, on the road 

surface 70 uR/h. 

After the accident, the gamma-exposure rate 

at Georgievka increased to 28 to 42 uR/h. At 

certain points on the northern fringe of the vil 

110 

270 

270 

180 

216 

240 

200 

160 

350 

310 

280 

lage, even values of up to 60 uR/h were recorded. 

The values measured at Georgievka are" 

represented in Fig. 3.1. Here, the gammaexposure 

rates are given in uR/h for certain 

points of the village. A mean dose rate of 27 

uR/h was attained. 

The gamma-exposure rates on the streets 

were smaller, while on the untouched snow in 

the surroundings they were found to be very 

much higher. Here, values of 40 u.R/h were attained. 

In the fields outside of Georgievka, a 

value of 30 uR/h was measured. 

The measurements on the surface of the 

ground thus revealed that radioactive contamination 

of the ground was extremely heterogeneous. 

This was attributed above all to the existence 

of hot particles in the aerosol products 

deposited on the snow. 

The results of radioisotopic analysis of two 

snow samples taken at Georgievka six days after 

the accident (April 12, 1993) are obvious 

from table 3.3. According to these data, contamination 

at Georgievka was mainly caused by 

^Nb and 106 Ru, while x Zx was of minor importance. 

Contamination by 103 Ru could be neglected. 

All these isotopes are relatively shortlived 

and, hence, did not appear when determining 

the composition of the gross radioactive 


background. They merely represented accident 

products. Background contamination by X ST of 

global origin amounted to about 0.03 Ci/km 2 . 

Therefore, concentration of this isotope in the 

snow could also be neglected. It must be pointed 

out that ^Sr was almost exclusively contained in 

the aqueous fraction, while the gamma-emitting 

isotopes were bound to the suspended fractions. 

Total density of radioactive contamination at 

Georgievka was 1.6 Ci/km 2 . The contamination 

densities of the individual isotopes in the Georgievka 

area were calculated at a mean gamma 

dose rate of the entire village of N = 27 uR/h. 

They are given in the bottom line of table 3.3. 

The formulas applied for the calculation are presented 

in Annex 1. The calculations are based 

on the assumption of a natural gammabackground 

of N = 10 uR/h. The calculated results 

are in good agreement with the measured 

values. Contamination of Georgievka by 239 Pu 

(0.1 mCi/km 2 ) can hence be neglected. 

On the basis of the data given in table 3.3, 

external gamma-irradiation of the local population 

may be estimated. 

For this purpose, it is assumed that no migration 

of the population takes place. Shielding 

I GEORGIEVKA jb, "ft 

Sawmill 

Farm I 

of the gamma-radiation by the walls of the 

houses and production facilities is neglected. 

The film contamination of the ground (upper 

dose value) was calculated using the dose coefficients 

given in Annex 1 and taking into account 

the natural isotope migration into the ground. 

The calculations are obvious from table 3.4 [6]. 

Reduction of the radiation dose due to the 

penetration of the isotopes into the soil when 

digging the gardens and ploughing the fields 

was not taken into consideration. It is evident 

from the data above that external gammairradiation 

of the population is less than 1% of 

the irradiation resulting from the natural gammabackground 

even when staying permanently (for 

a period of 50 years) at Georgievka. The calculations 

were based on the assumptions of N = 10 

uR/h and 1R = 0.8 rem (cSv)=0.87 rad (cGy) for 

air. External irradiation with l03 Ru, ^Zr and *Nb 

becomes obvious within a period of one year 

after the accident. Irradiation with the longerlived 

106 Ru is steadily increasing. The shares of 

gamma-irradiation of 106 Ru and ^Zr + ^Nb in 

the external irradiation are nearly the same, the 

contribution of 103 Ru can be neglected. It may 

therefore be concluded that external gammairradiation 

does not represent any danger to the 

Georgievka population. 

5S 

W-C2 m 23: • 0:ED 

EEE3&mmmmmm mm m^:-: 

_ .^—.j. •"' : Roof:' : 

Gamma dom rate §•• hS-•'•'• 

s^- oa. April 12.1993, 3. yR/h. KRAL fi::* i'rsri "• 

i:' I Garden: 


Sampling point 

House No.6 

front yard 

Fringe of the 

village field path 

Density of snow contamination by individual radionuclides at Georgievka 

on April 12,1993, mCi/km 2 

F - suspension; 

R - water; 

C - total; 

At, Af - mean values calculated according to eguations (7) & (12) of Annex 

Analyzed fraction 

of the sample 

F 

R 

C 

F 

R 

C 

A' 

Af 

1C3 Ru 

23 

0 

23 

19 

0 

19 

21 

24 

106 Ru 

566 

100 

666 

403 

32 

435 

550 

540 

| «* 

432 

46 

478 

224 

13 

237 

360 

370 

* Nb I 

919 

107 

1030 

358 

37 

385 

710 

800 

w Sr 

0 

0.6 

0.6 

- 

T 

- 

0.6 


| » P U | 

0.12 

0.12 

- 

- 

- 

0.12 

0.13 

Table 3.3 

2y 

- 

- 

1600 

1700 

Table 3.4 

External gamma-irradiation of the Georgievka population by the radioactive products released 

during the accident and the natural gamma-background over the period indicated, 10 rem 

(cSv) 

Time, years 

1 

2 

3 

0J15-0.16 

0.15-0.16 

0.15-0.16 

106, Ru ^Zr + ^Nb Total 

6.6-8.3 

8.6-13 

10-17 

4. Prognosis of contamination 

resulting from secondary 

wind transport 

Judging from the geographical data of the 

contaminated area, about 10% of the territory is 

under agricultural use. This territory may be a 

source of air contamination, when the radionuclides 

deposited on the fields are transported by 

the wind. The greatest risk to the population 

consists in the intake of 239 Pu by inhalation. It 

therefore seems to be reasonable to estimate air 

contamination in the area under agricultural use. 

Air contamination may result from wind or mechanical 

transport of the deposited radionuclides. 

Mechanical transport takes place when 

the soil is cultivated using agricultural equipment 

or when traffic is passing. Now, air contamination 

resulting from wind erosion and mechanical 

impacts shall be estimated. According to the 

data obtained in the Chernobyl area [7], the intensity 

of wind transport of recently deposited 

radionuclides amounts to 10" 9 s' 1 . 

Assuming that the area under agricultural use 

is similar to 10 km 2 with the height of the layer 

near to the ground surface being 50 zm and the 

112 

12-14 

12-14 

12-14 

19-32 

21-27 

Nat. gammabackground 

70 

140 

N 3500 

contamination density by gamma- and betaemitters 

similar to ~ 5 Ci/km 2 (Georgievka), a 

maximum concentration of these emitters in the 

air near the ground surface of 5-10" 16 Ci/I is obtained. 

This value is smaller than the corresponding 

dose coefficients DKB of these radionuclides 

by four to five orders of magnitude. In 

our case, air contamination by 239 Pu was 6-10" 20 

Ci/I (DKB = 3-10" 17 Ci/I). This value was calculated 

at a contamination density of 8-10" 4 Ci/km 2 . 

It allowed the conclusion to be drawn that contamination 

of the air due to wind transport of the 

radionuclides was insignificant and did not represent 

any danger to the population. 

Mechanical impacts may considerably intensify 

the wind transport of the radionuclides. 

The maximum values measured for the intensity 

of wind transport of ^Pu are 10" 4 s" 1 and 10" 6 s" 1 

for passing traffic and ploughing of the fields, 

respectively [8]. 

Let us now assume that maximum air contamination 

is caused by public and agricultural 

traffic passing in transverse direction to the 

wind. Thus, a stationary active source is generated, 

the intensity of which may be estimated as 

follows: 


Q = l-r-a-L-p,, 

where / - traffic density, s" 1 ; 

r - minimum time interval between the individual 

clouds generated by the traffic; it is 

calculated using the continuity condition of a 

jet; 

a - intensity of wind transport of the radionuclides, 

s~ 1 ; 

L - width of the road in the surroundings of 

the villages, m; 

p, - ground contamination density, Ci/km 2 . 

The time rwas calculated using the following 

equation: 

In (b ux r/z


5.3. Estimation of radionuclide washout 

Prognosis of the radionuclide flow was based 

on the homogeneous distribution of the radionuclides 

in the snow water. While flowing, the 

radionuclides interact with the earth layer and 

sorption takes place. According to [9], this interaction 

layer is about 1 cm thick. It is assumed 

that a sorption equilibrium exists between the 

earth and the water flow. This equilibrium is 

characterized by the distribution coefficient K* 

Only little is known about the distribution coefficients 

of 103 Ru, 106 Ru, *Zr and ^Nb. According 

to the data published in [10], however, the behavior 

of 106 Ru in the soil practically corresponds 

to that of 137 Cs. It was therefore expected that 

the migration processes of these radionuclides 

were similar as well. It was shown in [11] that the 

distribution coefficient of the radionuclides depends 

on the water/soil volume ratio. Under the 

flow conditions outlined in table 5.2, this ratio is 

about 10. This corresponds to a distribution 

coefficient of Kd ~ 200. According to [8], the 

distribution coefficient of 239 Pu is in the range of 

10 3 -10 4 . For maximization of the estimations, 

the former value was selected. The washout 

River 

Tom 

Samuska 

DKB. water 

factors were calculated in accordance with the 

method described in [12, 13]. It was found out 

that the washout factors of the dissolved phase 

amounted to about 5% and 1% for gamma- and 

beta-emitting radionuclides and for 239 Pu, respectively, 

In the solid phase, the washout factor 

does not exceed 0.3% for all radionuclides. It 

must be pointed out that the estimated washout 

factors were too high by an order of magnitude 

at least. This was due to the assumption that all 

radionuclides were present in the exchange 

form. It is known, however, that the exchange 

form is 1-5% of the irreversibly sorted form only 

[11]. The calculated mean concentrations of the 

flood are presented in table 5.2. 

Comparison of the calculated mean values 

and the permissible concentrations (bottom line 

in table 5.2) shows that the concentrations in the 

water are smaller than DKB by a factor of 10 2 - 

10 4 even under the most unfavorable washout 

conditions. It must be taken into consideration 

that the limit value DKB was calculated for the 

annual standardized water consumption with the 

internal irradiation being 5-10" 3 Sv. 

Mean radionuclide concentration of the rivers Tom and Samuska 

Or • radionuclide concentration of the water, pCi/l 

I 

I 

,UJ Ru 

| 0.04 

1 ° 

I 

I 80000 

» 

,l *Ru 

1.0 

150 

12000 

6. Supply of information for the 

estimation of radiation exposure 

in the area of the Siberian 

chemical complex 

Supply of information for the analysis of radiation 

exposure in the area affected by the accident 

depended on the data available and could 

be divided into two stages: 

A. Analysis of the situation, estimation of the 

release parameters and determination of preliminary 

data on the possibly contaminated area 

and the radiation exposure, estimation of a possible 

transport beyond the national borders. In 

this stage, data measured at ground level were 

not yet available. Therefore, numerous calculations 

were carried out on the basis of a physicomathematical 

simulation of radioactivity spread 

in the environment using preliminary findings 

about the source. 

I 

114 

Q, 

"Zr 

0.7 

120 

62000 

I 

*Nb 

1.6 

300 

96000 

« 

Table 5.2 

1 

""Pu 

0.001 | 

0.2 I 

2900 | 

B. Systematization of the data with the aim of 

setting up a diagram of radioactive contamination 

of the environment soon after the accident 

as a function of time and space. It is the objective 

of this stage to estimate the statistical reliability 

of all values measured when investigating 

the contaminated area and to make use of these 

data when determining (more precisely) the radionuclide 

composition of the emissions and 

their quantitative ratio. Furthermore, a map of 

contamination in this area shall be prepared 

(gamma dose rate at ground level, contamination 

densities of all radionuclides identified in the 

samples). 

As ground measurements were carried out 

outside of the premises of the chemical complex 

only, calculations were performed for the entire 

contaminated area including the complex site. 

Radioactivity spread in the area as a function of 

space and time then allowed to estimate the 


possible individual doses when passing the radioactive 

cloud. 

6.1. Information for the taking of 

appropriate measures during the first 

hours after the accident 

On April 6, 1993 at about 17.00 local time, 

SPA Typhoon" was informed by Rosgidromet 

about the accident at the chemical complex. For 

information, Rosgidromet also transmitted the 

following data on the release: 

- nuclide composition: 239 Pu, 238 U; 

- total activity released: 2-5 Ci; 

- activity released into the environment via 

the destroyed walls of the buildings (height of 

release up to 30 m); 

- duration of the release about 15 min. 

On the basis of weather forecasts, possible 

trajectories were determined for the movement 

of the radioactive cloud at various heights 

(ground level, 700-800 m and about 1500 m). 

They are represented in Fig. 6.1. By simulating 

the atmospheric transport of 239 Pu, the concentration 

of radioactivity in the cloud was found to 

have decreased to insignificant values due to 

diffusion and deposition processes within a period 

of 3.5 hours after the accident. According to 

the simulation data, maximum 239 Pu concentration 

of the cloud 3.5 hours after the accident 

amounted to 1.5-10' 17 Ci/I (permissible concentration 

3.0-10" 17 Ci/I) at a distance of 110 km 

from the source and a height of 1 m. Thus, 

transport of significant radionuclide concentrations 

beyond the national borders could be excluded. 

The values of ground contamination by 239 Pu, 

which were obtained by simulating the atmospheric 

transport and deposition of the radioactivity, 

are represented in Fig. 6.2. The gammaaerial 

survey data obtained later confirmed that 

the predictions based on the simulation had 

been very precise. 

\For simulation, the "Gaussian Puff model 

developed by the data processing center of SPA 

Typhoon" according to the method described in 

[14] was applied. A simulation was performed 

for a source with a height of 30 m (building, 

where the accident occurred), a release duration 

115 

of 15 min. and a total 239 Pu activity released of 5 

Ci. 

As soon as the accident was reported, an 

"express" analysis of the accident was carried 

out by SPA Typhoon". The results were then 

processed and transmitted to Rosgidromet at 

20.00 Moscow time on April 6,1993. 

The first data on the radiation exposure were 

received by SPA Typhoon" on April 7 and 8, 

1993. Gamma dose rates at ground level at km 

28 of the road from Tomsk to Samus (300 

uR/h), and at Naumovka (14 uR/h) and Georgievka 

(40-60 uR/h) were measured by expert 

teams of Rosgidromet. 

On the basis of the first analyses of snow 

samples, the radionuclide composition of the 

release could be determined more accurately: 

^Nb - 36%; 106 Ru - 38%; 

103 Ru-1%; ^-23%. 

The following main source parameters were 

determined more precisely and recommended 

for simulation by the Rosgidromet experts: 

- release height 15-150 m (the source was 

simulated by two simultaneous releases at 

heights of 15-30 m (50% of the total activity) 

and 150-200 m (50% of the total activity), respectively); 

- deposition rate 0.01-0.19 m/s; 

- duration of the release 10-15 min; 

- total activity released 150-400 Ci. 

On the basis of the data recommended by 

the Rosgidromet experts, the density of contamination 

by the most important radionuclides 

was calculated. The map plotted for the contamination 

density of ^Nb is shown in Fig. 6.3 

(the source was simulated by two simultaneous 

releases from the building affected (release 

height 30 m, 50% of the total activity) and the 

ventilation pipe (height 200 m, 50% of the total 

activity), respectively, at a deposition rate of the 

radioactive products of 0.15 m/s and an assumed 

total Nb activity released of 400 Ci). 

The gamma dose rates at the measuring 

points (building affected, km 28 of the road from 

Tomsk to Samus, Georgievka) obtained by 

simulation at the calculated contamination 

density amounted to 10-20% of the value measured.

Russian Issue 3 - Harvard University Department of Physics

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