Booklet radioecology - IRSN

IPSN
booklets
INSTITUT DE PROTECTION ET DE SÛRETÉ NUCLÉAIRE
Radioecology
To know
and understand
the evolution
of radioactivity
in the environment.

The use of nuclear energy
in both military
and civil applications
has led scientists to study
the fate of radioactive products
called "radionuclides" (see P. 21)
released in the environment
since the beginning
of the 1940s.
This concern has given birth
to an ecological discipline - radioecology.
Both natural and artificial
radionuclides can be found
throughout the environment.

All you need to know about radioecology
1
What is radioecology?
Radioecologists seek to understand the evolution of radionuclides in the environment
and to collect data to predict their dosimetric impact.
2
Radioecology in the world and in France
Studies on radioecology have been developed from 1940 up to the present day
in parallel with military and civil nuclear activities.
Origins of radionuclides
3
Weapons testing, accidents at facilities, controlled waste have released artificial radionuclides
into the environment which are added to natural-occurring radionuclides.
Radioecology tools
4
Measurements on samples taken in the field and laboratory work are the basis
for development of software programmes used to predict dosimetric impact.
Marine radioecology
5
Radioecologists carry out assessments on the effects of dumping waste
from nuclear facilities at sea.
Radioecology of inland waters
6
Liquid radioactive waste produced by nuclear facilities located along rivers
is discharged into fresh water.
Land radioecology
7
The radionuclides in the land ecosystem affect human health mainly through
the food chain: plants animals meat or milk.
8
Radioecological studies in the field
Around a nuclear power station - Radioactivity levels are regularly controlled in the different
environments to measure the radioecological impact caused by waste from the power station.
9
Radioecological studies in the field
The Nord-Cotentin Radioecology Group - In Nord-Cotentin, an inventory of radioactive
waste from a fuel reprocessing plant was conducted.
Mercantour workshop zone - In the Mercantour area, a "workshop zone" was created to trace
the migration of the caesium-137 released in May 1986 after the Chernobyl accident.
10
A permanent observatory and instant information
1

11
What is radioecology?
The purpose of radioecology is to detect the presence of
radionuclides in the environment, to research their
origins and to understand their process of transfer and
their concentration in ecosystems.
Its aim is to evaluate the impact of both natural and
artificial radioactivity on the environment
(radioecological impact) and on the population
(dosimetric impact) (see P. 21). These studies are based
on the same approach as those relating to other
chemical polluting agents such as heavy metals (lead,
zinc, etc.) or nitrates.
Given the presence of radionuclides in all ecosystems
and the complexity of the transfer processes,
radioecologists work in three main environments in the
biosphere: the marine aquatic environment, the inland
aquatic environment and the land environment.
From the picture …
Air, land, water
and living organisms,
including human
beings, make up
the biosphere which
can be subdivided
into ecological units
called "ecosystems".
A river, a lake,
an ocean, a mountain
chain, a tropical forest,
a town or a desert
are ecosystems.
Radionuclides are scattered into the air and water, settle
on the soil and sediments, migrate into the food chains …
and thus can affect man.
transfers
liquid effluents
gas effluents
breathing
2
nutrition
meat - milk - vegetables

… to the model …
The environment can be depicted by a series of boxes
through which radionuclides circulate. Radioecologists
seek to measure the concentration of the radionuclides in
each box and understand their transfer mechanisms.
Atmosphere
Wet and dry deposits
Sediments Soils
Deposits Irrigation
Water
Drainage
migration
Root
transfers
Plants
Nutrition
Animals
… to predict the dosimetric impact
Radioecology provides data used in calculating the
dosimetric impact. Whether the waste be controlled or
accidental, radioecology helps provide answers to
potential questions from public authorities, the nuclear
industry, the media or the public at large.
3

2
Radioecology in the world and in France
The term "radioecology" first appeared in 1935 but only
became widely used during the 1950s. It probably
emerged from the combination of "radioactivity" and
"ecology". The first radioecological work was published
in Geneva in 1955 during the first international meeting
on the use of nuclear energy in the Pacific.
Significant events
in the world
… and in France
1940-1950 • First nuclear weapons tests • Divergence of ZOE reactor
• Nuclear explosions at Hiroshima (Fontenay-aux-Roses - 1948)
and Nagasaki
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
1950-1960 • Use of radionuclides in biology • Creation of an "ecology" group
and agriculture
at CEA
• Kyshtym accident in the USSR
• Beginning of scientific
and at Windscale in Great Britain
publications
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
1960-1970 • First international congress on • Creation of radioecological laboratories
radioecology in the USA (1961)
at CEA
• Radioecology congress organised
• First congress organised
by Vienna Agency (IAEA – 1966) in France (Cadarache, 1969)
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
1970-1980 • Oil crisis, rise of nuclear energy • First reference states before
• Accident at Three Mile Island
installation of nuclear power
in the USA
stations (Bugey, Fessenheim)
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
1980-1990 • Accident at Chernobyl in Ukraine • Experimental studies
(1986) on the effects of an accident
on the environment: RESSAC
programme (Cadarache)
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
1990-2001 • Development of studies • Study of the impact
on the storage of radioactive waste
of the Chernobyl accident
(Vosges, Mercantour, Corsica)
4

The two main public bodies involved in the field of
radioecology in France are IPSN and OPRI (Office de
protection contre les rayonnements ionisants). IPSN
carries out radioecological studies in the framework of its
activities in research and assessment. Its department for
the protection of the environment is organised around
themes of study and has several sites.
La Hague
Octeville
Le Vésinet
Saclay
Angers
Fontenay-aux-Roses
Orsay
•Radioecological studies
on the Atlantic seaboard
•Experimental radioecology
•Modelling and validation of transfers
of radionuclides in the environment
•Organisation of environmental data
Agen
Avignon
Cadarache
Toulon
•Studies and intervention relating
to radon and atmospheric
contaminants
• Inland radioecological studies and
research on the Mediterranean
Location of IPSN laboratories (•)
and OPRI agencies (•).
Themes of the radioecological
studies developed at IPSN.
OPRI is responsible for the supervision and regulatory
control of radioactivity in the environment. It manages
several warning networks which allow the authorities to
react immediately should abnormal radioactivity levels be
detected in France.
5

3
Origins of radionuclides
Humans are continuously exposed to both natural and
artificial radiation.
Natural radioactivity
Of the 340 different atoms (more precisely called
"nuclides") found in nature, 70 are radioactive. These
radionuclides (see P. 21) can be found throughout the
environment … including in the human body.
Sample Activity (roughly speaking) Predominant radionuclide
Outside air between 1 and 100 Bq/m 3 radon-222
Air inside houses between 10 and 10,000 Bq/m 3 radon-222
Sedimentary land 1,000 Bq/kg uranium-238, thorium-232
and their daughter products,
potassium-40
Granite 3,000 Bq/kg uranium-238, thorium-232
and their daughter
products, potassium-40
Seawater 13 Bq/l potassium-40
Mineral water between 2 and 4 Bq/l potassium-40
Milk 80 Bq/l potassium-40
Potato
150 Bq/kg
Humans 120 Bq/kg potassium-40 and carbon-14
Of the more than 2,000
nuclear weapons tests
carried out throughout
the world, 423 took place
in the atmosphere
between 1945 and 1981
(USA: 193, USSR: 142,
France: 45,
Great Britain: 21,
China: 22).
Artificial radioactivity
1. Atmospheric tests of nuclear weapons
At the time of the explosions, radionuclides (tritium,
ruthenium-106, caesium-137, strontium-90…) were
propelled into the upper atmosphere and then settled on the
continents and oceans in a relatively uniform manner. Over a
period of 35 years these atmospheric tests released a quantity
of radionuclides equivalent to 500 times the waste from the
Chernobyl accident.
6

Three accidents
released significant
quantities
of radionuclides
into the environment:
Windscale
(Great Britain, 1957),
Kyshtym (Russia, 1957)
and Chernobyl
(Ukraine, 1986).
2. Accidents at nuclear plants
When the Chernobyl accident occurred, radionuclides were
deposited over the entire European continent (iodine-131,
caesium-137, caesium-134, ruthenium-106 …).
3. Controlled nuclear industrial waste
Nuclear facilities (nuclear power stations, fuel reprocessing
plants) are authorised to release radionuclides into rivers
or the sea (liquid effluents) or the air (gas effluents).
Principal radionuclides…
in liquid effluents
in gas effluents
Nuclear reactor tritium, cobalt-60, manganese-54 krypton-85, xenon-133,
silver-110, antimony-124, iodine-131, iodine-131, tritium,
caesium-137
carbon-14
Reprocessing plant tritium, caesium-137, ruthenium-106, tritium, krypton-85,
strontium-90, antimony-125, iodine- xenon-133, iodine-129,
129, carbon-14 carbon-14
4. Fall of satellites
Several satellites powered by a nuclear source have fallen.
In 1964, the re-entry of a satellite into the atmosphere
over the Indian Ocean scattered plutonium-238 across
the world. Traces of this radionuclide were found on
French territory.
7

4
Radioecology tools
Measuring instruments are used to determine the exact
concentrations of radionuclides in samples taken in the
field (for example, from a potato and the soil in which it
is grown). It is extremely difficult, however, to determine
on site the mechanisms of transfer (how the potato
absorbs the radionuclides by drawing from the earth's
reserves). That is why radioecologists conduct
experimental work in laboratories.
The aim is to construct radionuclide transfer models
capable of quickly predicting the impact of radioactive
contamination in a given area by using a restricted
number of radioactive measurements from samples taken
in the field.
Determination
of mechanisms
to be studied
Field
Taking samples
Measuring contamination (Bq)
MEASURING
Laboratory
Reconstructing
simplified ecosystems
Understanding transfer
mechanisms
MODELLING
Validation
by comparing measurements
against predictions
computation tools
Evaluation
of the radioecological (Bq)
and dosimetric (Sv) impact
PREDICT
Formulation
of experimental
results
8

Measuring
in shielded
underground
room.
Measuring the samples
The samples taken are analysed in specialised facilities
capable of measuring radionuclides, even if there is only a
trace, from any environment: air, water, land, sediments,
plants, living organisms.
To facilitate the measuring, radioecologists choose
substances in the field which fix the radionuclides (such as
sediments) or species called "bioindicators" which
concentrate the radionuclides (as in the case of mosses,
lichens, mussels, oysters…).
Cultures
in the laboratory.
Experimental work and modelling
In order to understand the transfer mechanisms,
radioecologists reconstruct simplified ecosystems in the
laboratory. They contaminate cultures with various
radionuclides by changing the nature of the soil and the
climatic conditions.
This work results in the development of models simulating
the transfer of radionuclides between the different parts
of the environment.
Software for predicting dosimetric impact
Radioecologists build computation tools based on both
measurement results and transfer models which take into
account local ecological conditions.
In the event of accidental release of radionuclides into the
environment, these tools predict the dosimetric impact on
the population groups affected and provide invaluable
technical assistance to the "crisis managers".
9

5
Marine radioecology
Marine radioecology studies the evolution of radioactive
levels in the open sea and in coastal areas. It conducts
expert assessments on the effects of waste released into
the sea from nuclear facilities.
Naturally-occurring radioactivity in the sea is around
13,000 Bq/m 3 , basically due to potassium-40. Artificial
radioactivity is added to this, caesium-137 being one of
the main elements.
Irish
Sea
55
English
Channel
10
Estimate of the mean
distribution
of the caesium-137
concentration in Bq/m 3 .
3,3
2,5
2,4
2,5
2,0
1,5
0,7 0,8
2,5 5,4
0,4
2,3
2,9
0,1
3,0
2,6
1,9
The oceans are contaminated in a relatively uniform
manner by fallout from atmospheric nuclear weapon
testing. Seas which are not very deep and estuaries are
subject to more pronounced contamination due to the
release of waste from the fuel reprocessing plants of
Sellafield (Great Britain) into the Irish Sea and La Hague
(France) into the English Channel. These discharges have
been decreasing sharply for more than ten years.
10

Mussels.
Radionuclide transfers
Radionuclides are spread by currents. They fix themselves
to particles suspended in water which gradually settle on
the seabed and are stored in sediments which may
contain radioactivity levels 100 to 10 million times higher
than that of seawater.
Through physiological processes such as water filtering,
marine organisms can accumulate certain radionuclides
with a concentration factor of 5 to 100,000 compared to
seawater.
The bioindicators used are, for example, algae of the
fucus species, oysters, mussels, scallops, crab or lobster.
51
50
49
Atlantic
Ocean
English Channel
Distribution of tritium
in the English Channel
(measuring campaign
carried out in 1994).
Great Britain
La Hague
France
+ : Measurement points
48
-6 -5 -4 -3 -2 -1 0 1 2
7500
6500
5500
4500
3500
2500
1750
1300
1150
1050
950
850
750
650
550
450
350
250
150
Tritium
Bq/m 3
Certain radionuclides released into the sea represent
remarkable tools for oceanographers. For example, by
tracing tritium, one of the radionuclides found in the
waste released from the La Hague plant, calculations
revealed that water took 110 to 152 days to flow from La
Hague to the Straits of Dover.
11

6
Radioecology of inland waters
Bodies of fresh water that receive liquid radioactive waste
from nuclear facilities and laboratories (research centres,
hospitals) form a group of ecosystems studied in
radioecology.
La Hague
Storage centre Manche
Seine
Nogent-sur-Seine
Chooz
Meuse
Cattenom
Storage centre
Aube
Moselle
Rhin
Fessenheim
Saint-Laurent
Chinon
Belleville
Dampierre
Civaux
Bugey
Loire
Vienne
Saint-Alban
Rhône
Le Blayais
Golfech
Cruas
Tricastin
Garonne
Marcoule
In France, 15 nuclear sites
out of 19 and various
facilities concerning
the fuel cycle are located
along rivers. The others
are on the Channel
or the North Sea coast.
EDF nuclear power plants
Fuel reprocessing plants
12
Storage centres for radioactive waste

Radionuclide transfers
The same radionuclide concentration phenomena
occurring in the marine ecosystem are also found in
fresh waters. But the concentration factors in the living
organisms differ between fresh water and seawater. The
presence of heavy metals (zinc, lead, and others) in the
waterways also modify the intensity of radionuclide
fixation.
The bioindicators used are molluscs such as the Asian
Asian clams.
clam and the Zebra mussel which are very plentiful
together with water mosses.
A living organism's radioactivity results from a balance
between contamination and decontamination .
Contamination occurs through the ingestion of water
and food. Decontamination is due to the physical decay
of the radionuclides and their biological elimination.
Example
of an inland water
ecosystem
studied
in the laboratory.
Laboratory experiments are essential to understanding
transfer mechanisms. Here one can evaluate the
importance of each parameter: the type and chemical
nature of the radionuclide, the mixture of contaminants
(radioactive or not), the temperature and pH of water, etc.
Hydrobiology experimental hall (Cadarache).
13

7
Land radioecology
The land ecosystem is complex: the environments (soil,
surface water, underground water), the topography
(plains, mountains), the vegetation (grassland, cultivated
areas, forests) and the food chains (plant and animal) are
extremely varied.
The contamination of the land ecosystem is usually due
to atmospheric deposits. When the Chernobyl accident
occurred, the contaminated air masses travelled
thousands of miles. Large disparities exist in the surface
activities (in Bq/m 2 ) inside a country or a region: the
radionuclides present in the atmosphere settle gradually
according to the vagaries of the wind - deposits are more
concentrated during rainy periods 1 , when encountering
a relief 2 or high vegetation 3 .
1
2
3
14

Radionuclide transfers
Radionuclides deposited by wind gusts or rain directly
contaminate plant leaves ( 1
1
. The radionuclides then migrate
to the earth ( 2 , followed by transfers towards the roots (3). 3
The principal bioindicators studied are mosses and
lichens.
Certain animals become contaminated by the ingestion
of plants; the most common food chain is:
2
grass -> cow -> meat and milk.
3
The effects of atmospheric pollution vary notably with
the seasons, as the radionuclides can settle on cultivated
or uncultivated agricultural land, on seedlings or ripe
vegetation, while the cows are in a cowshed or grazing
outside.
Taking samples
in the field.
Culture
in the laboratory.
One of the experiments for the study of radionuclide
transfer involves taking a block of earth in the field and
placing it in a laboratory under controlled climatic
conditions. Here one can observe various cultures (corn,
vines, beans…) which can be contaminated at different
stages in their growth.
15

8
Radioecological studies in the field
In-field studies trace radioactivity levels in space and time.
Whether they involve a nuclear power station, a fuel
reprocessing plant or an area affected by deposits from
Chernobyl, these studies follow the same scenario:
•Define the scope of the study.
•Define the local ecosystem: topography, hydrology, demography,
type of soil, cultivation and animal raising, meteorology.
•Define the population reference groups (see P. 21).
•Determine the environments and the species to be taken from the
ecosystem.
•Choose the locations and frequency of sample taking.
•Take the samples and store them.
•Measure the radioactivity, register the results in a database,
interpret the results.
•Publish the results.
16

Around a nuclear power station
Before startup of a nuclear power station, a reading of the
radioactivity levels of the water, soil, plants and food
products is carried out in a circle of some 8 to 25 miles
around the site. This is the radioecological zero point
which serves as a reference.
Sediments are taken from the
bank using a "Berthois cone".
It is thrown out then brought
back, scraping the bottom.
Fish are often caught using
electric fishing methods.
Aquatic plants are collected
then washed carefully.
Agricultural products are
selected after a food survey.
Subsequently, an annual follow-up and an assessment
every ten years provides a precise measurement of the
radioecological impact of the power station's waste and
its evolution over time.
17

9
Radioecological studies in the field
Limpets
are very plentiful
on rocks where people
gather them
at low tide.
Knowledge
of their radioactivity
level can be used
to evaluate the doses
received by people
who eat them.
The Nord-Cotentin Radioecology Group
In 1997 the Ministers for the Environment and Health
decided to create a Nord-Cotentin Radioecology Group,
whose mission was to take an inventory of radioactive waste
from the nuclear plants in Nord-Cotentin (mainly the fuel
reprocessing plant at La Hague) and to assess the doses
received by the population as well as the risks associated
with leukaemia.
Over fifty specialists from extremely different fields
participated in the group's work; research and assessment
bodies, control bodies, operators, information commissions,
experts from associations and foreign institutes.
Two complementary methods were implemented. One
relied on the knowledge of wastes and on the models of
radioactivity transfer to human populations, while the other
consisted in collecting the results of more than 500,000
existing radioactivity measurements from the different
components of the environment so as to verify the validity
of the models for the population. It was thus possible to
estimate the doses and associated risks from knowledge of
the environmental contamination and the living habits of
the population groups concerned.
Bq/kg
Evolution
of the concentration
of caesium-137 2
in limpets.
4
18
1978 1988 1998

The Mercantour workshop zone
In the days following the Chernobyl accident, the passage
of contaminated air masses over the French Alps during
heavy snowfalls led to contaminated snow being deposited
at high altitude. A study has been carried out in the
Mercantour mountains (Southern Alps) to produce a map
of the soil radioactivity.
A workshop zone of 1.35 km 2 was first chosen between
the Isola 2000 station and the Lombarde pass.
Measurements of caesium-137 showed evidence of
important differences in surface activity depending on the type
of soil. Whereas the average is approximately 10,000 Bq/m 2 ,
areas of concentration of more than 100,000 Bq/m 2 were
found in basins in the grasslands and at the foot of larch
forests where the spring firn fields linger.
Partial view
of the workshop
zone above Isola
2000.
Observations made in this zone have traced the migration
of caesium-137 deposited in May 1986 and led to a
cartographic model which links the surface activities to the
type of soil (scree, forest, grassland) and to the
topography (slope, basin).
Through extrapolation, the model can also be used to
study vast mountain areas and to identify the "trouble
spots" where the concentrations of caesium-137 resulting
19
from the Chernobyl accident can be found.

10
A permanent observatory
and instant information
www.ipsn.fr/opera
The Permanent Environmental Radioactivity Observatory
(OPERA) monitors radioactivity levels in the
environment in France. It is supported by a network of
over 30 stations throughout the country (including
Papeete and Saint-Denis de la Réunion) that are
representative of the main environments. This tool offers
a significant means of informing the public, which has
Caesium-137 immediate access to the results.
activity in
1000000
atmospheric
Chernobyl
aerosols (mBq/m 3 )
100000
observed in french
sampling stations.
10000
The peak in 1998
is due to the accidental
incineration
of a caesium-137
source in a steel plant
in Algeciras.
1000
100
10
1
Atmospheric nuclear weapon testing
Algeciras
0,1
For further information
Bibliographical references
1960 1970 1980 1990 2000
Histoire de l'écologie
285 p., 1988, PUF, P. Acot.
Dictionnaire encyclopédique de l'écologie et des sciences
de l'environnement
822 p., 1993, Ediscience international, Paris, F. Ramade.
20
The collection IPSN - EDP Sciences
This collection includes several books on radioecology: the
references can be found in the library section on the website
www.ipsn.fr.

Useful definitions in radioecology
Radionuclides
atomic mass :
14 = 6 protons + 8 neutrons 14
atomic number :
6 protons 6 C
Radionuclides are atoms with a radioactive nucleus. For
example, carbon-14 is a radionuclide present in very small
amounts in carbon. The symbolic representation of the
nucleus is shown above, but it is generally written as 14 C or
carbon-14.
Radioecological impact
The radioecological impact is determined by measuring the
radioactivity of the different constituents that make up an
environment, in other words the radionuclide concentration
present in the environment. The unit of activity is a
becquerel (Bq) which is equivalent to the decay of one
radionuclide per second. In radioecology, activity is always
expressed with respect to a volume, mass or surface area.
Bq/kg
Bq/l
Bq/m2
Dosimetric impact
The dosimetric impact is determined by evaluating the
radiation to which a population group in exposed. It is
expressed in sieverts (Sv). A sub-multiple, the millisievert
(1 mSv = 0.001 Sv), is frequently used.
Reference group
A reference group is a group of people more specifically
exposed to a source of radiation due to their geographical
location, their way of life or their eating habits.
Photos by: Photothèque IPSN / Claude Cieutat D.R. - Campagne Campagne 21

IPSN
IPSN: research and expertise
The Institut de protection et de sûreté nucléaire (IPSN) carries out
research and assessments to control nuclear risk and its effect on
human health and the environment, covering such areas as safety
of nuclear facilities, the protection of workers, the public, and the
environment, and safety in transporting radioactive materials.
Although it acts mainly for public authorities, it often works in
partnership with its counterparts overseas.
Radionuclides, both natural and artificial, can be found throughout
the environment and can affect people, mainly through the food
chains. The purpose of radioecology is to detect radionuclides,
measure their concentration, understand their methods of transfer,
and supply data that can be used to estimate the radiation
received by the population.
77-83 av. du Général-de-Gaulle
92140 Clamart
Postal address: BP 6
92265 Fontenay-aux-Roses Cedex
France
Tel +33 (0)1 46 54 80 07
Fax + 33 (0)1 46 54 79 49
For further information,
visit our website : www.ipsn.fr
© 2001 IPSN - Epsim - Graphisme / Catherine Barluet