Views
3 years ago

Safety_Series_025_1968 - gnssn - International Atomic Energy ...

Safety_Series_025_1968 - gnssn - International Atomic Energy ...

This publication is no

This publication is no longer validPlease see http://www.ns-iaea.org/standards/radiation o f the public for diagnostic or therapeutic purposes shouldbe taken into account.M ed ica l irra d ia tion o f the pu blic in alm ost a ll c a s e s in v olv esp a rtia l irradiation o f the body. T h ere a re only a few excep tion a lkinds of treatm ent, including certain types of treatm ent with ra d ioisotopes which a re distribu ted g en era lly (such as p h osp h oru s-3 2 ),which involve w hole-body exposure. In all other cases the exposurem ust be view ed with re g a rd to the ra d io se n sitiv ity o f the tis s u e s .On this basis a m ajor distinction can be drawn between irradiation ofthe bone m arrow (for som atic effects) and irradiation o f the gonads(for genetic e ffe cts ). It should be born e in m ind that not a ll typeso f ra d io lo g ica l exam ination and treatm en t a re equ ally im p ortan t.T h ose involving the use o f unsealed radion u clide s o u rce s a re onlya sm a ll percen tage o f those which em p loy radiation gen era tors o rsealed radionuclide sou rces. M oreover, ca ses of radiotherapy r e ­p resen t only a sm a ll p ercen ta ge o f ra d iod ia gn ostic exam in a tion s.Finally, certain examinations contribute m ore especially to irra d iationo f the bone m arrow o r the gonads. F or exam ple, examinationso f the p e lv is and the lo w e r part o f the g a s tro -in te s tin a l tra ct a reresp on sible for the greater part of irradiation of the gonads.2.3. O CCU PATIO N AL EXPOSURE2.3.1. A tom ic energyTo study these hazards it is easiest to follow the route of radionuclidesin the atom ic industry.(1) The p ro ce ssin g o f fuels to be used in re a cto rs includes orem ining, ore enrichm ent and final p ro ce ssin g of the fuel.Uranium mines are always subject to regular hazards. Gammaex p osu re is u su ally low . T h ere is a r is k o f ex tern a l irra d ia tio n ,but it is of lim ited extent and only encountered in exceptional ca seswhen concentrations a re o f the o rd e r o f 1% and w here there is su f­ficient ore in the working gallery. However, the risk of the air becom ingcontam inated by radon and daughters o r radioactive dusts and a e ro so lsis con sid era b le. P rim a ry radioactive dusts (uranium p a rticle s ) areto be distinguished from secon d ary radioactive dusts (inert dust onwhich solid daughter products of radon are deposited). Radon a lsod issolv es in a e ro so ls resulting from w ork with water sprays; thesea e r o s o ls fo rm a m ist in the m ine. The a tm osp h eric r is k is tw o-58

This publication is no longer validPlease see http://www.ns-iaea.org/standards/fo ld : it can en tail skin con tam ination and in tern al con tam in ationfollow ing inhalation. The pollution o f mine w aters is only a se co n ­dary danger.Ore m illing plants are subject to the sam e hazards from gammaradiation and a ir contam ination. W ork ers handling o re at 20% areex p osed to sign ifican t quantities o f gam m a radiation . A ir con ta ­m ination re su lts from the radon given o ff and the dust sca tte re ddu rin g cru sh in g and grin din g o p e ra tio n s.In plants p roce s s in g m eta llic uranium o r thorium a ll daughterp rod u cts o f uranium o r thorium which a re contained in the o re areseparated and treated as w aste. This con siderably reduces the risko f irradiation , but contam ination risk s rem ain , a risin g e sp e cia llyfro m w ork on oxid es and flu orid es.In isotope separation plants there are risk s o f acciden tal contaminationfrom gases o r dust.(2) At n u clear re a c to r s the p rim a ry radiation hazards to w ork ersa re either by exp osu re to gam m a rays o r neutrons leaking d irectlyfro m the r e a c to r through the channels when these a re open o r e x ­p osu re to beta o r gam m a radiation fro m the activated m a teria ltaken out o f the r e a c to r .During n orm al operation the ris k o f ra d ioactive contam inationis alm ost en tirely confined to the coolin g fluid, slight leakage beingalw ays a p o ssib ility in clo s e d c ir c u its . M o re o v e r, such incidentsas a bu rst pipe a re alw ays p o s s ib le .The m ost se rio u s a ccid en t re su lts fro m the co n s id e ra b le in ­c re a s e in tem perature which takes p la ce when there is in su fficien tcoolin g inside the r e a c to r . Dusts fro m p rim a ry (U) o r secon d ary(Pu) fuel and gaseous fission products w ill then be released throughthe bursting o f the fuel cladding and may entail seriou s contam inationof the a ir.(3) W orkers in ch em ical or m etallurgical plants which rep rocessm aterial from re a cto rs o r b y-p rod u cts m ay be subjected to sig n ificantirradiation.;For instance when Pu is ex tra cted , fis s io n p rod u cts a re to befound togeth er with the fuel and storage is req u ired to allow sh ortlivedfissio n p rod u cts to d ecay. P e rson n e l engaged in p r o c e s s in gch em istry are su bjected to beta irradiation from the la rge amountso f 32P and 90Sr they have to handle.In m etallurgical plants, only the processin g of som e special m a­te r ia ls such as cob a lt and yttriu m en tails the r is k o f e x p o su re togamma or beta radiation. In the cou rse of routine operation of theseplants there is a risk of two types of contamination:59

Safety_Series_013_1965 - gnssn - International Atomic Energy ...
Safety_Series_006_1961 - gnssn - International Atomic Energy ...
Radiation Protection Procedures - gnssn - International Atomic ...
Safety_Series_041_1975 - gnssn - International Atomic Energy ...
Safety_Series_008_1962 - gnssn - International Atomic Energy ...
Safe Handling of Radioisotopes - gnssn - International Atomic ...
Safety_Series_016_1966 - gnssn - International Atomic Energy ...
Safety_Series_015_1965 - gnssn - International Atomic Energy ...
Safety_Series_024_1967 - gnssn - International Atomic Energy ...
Safety_Series_019_1966 - gnssn - International Atomic Energy ...
Safety_Series_004_1961 - gnssn - International Atomic Energy ...
Safety_Series_005_1961 - gnssn - International Atomic Energy ...
safety series - gnssn - International Atomic Energy Agency
SAFETY ST; NDARDS - gnssn - International Atomic Energy Agency
No.6-Suppl 1988 - gnssn - International Atomic Energy Agency
SAFETY PR A CTICES - gnssn - International Atomic Energy Agency
Safety_Series_035-S-1_1992 - gnssn - International Atomic Energy ...
LEVEL 3 - gnssn - International Atomic Energy Agency
1 - gnssn - International Atomic Energy Agency
Level 2 - gnssn - International Atomic Energy Agency
SAFETY P R A C TIC ES - gnssn - International Atomic Energy Agency
SAFETY P R A C TIC E S - gnssn - International Atomic Energy Agency
Safety_Series_028_1968 - gnssn - International Atomic Energy ...
Safety_Series_050-SG-S2_1979 - gnssn - International Atomic ...
Notes on Certain Aspects of the Regulations - gnssn - International ...
Borchardt - gnssn - International Atomic Energy Agency
Research Reactor - gnssn - International Atomic Energy Agency
Safety_Series_010_1963 - gnssn - International Atomic Energy ...
O < - gnssn - International Atomic Energy Agency
Emergency Planning and Preparedness for Re-entry of a ... - gnssn