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SAFETY \ 0»Jt SERIES

No. 18

Environmental Monitoring in Emergency Situations

INTERNATIONAL ATOMIC ENERGY AGENCY

VIENNA, 1966

This publication is no longer valid Please see http://www-ns.iaea.org/standards/

ENVIRONMENTAL MONITORING IN EMERGENCY SITUATIONS


T he follow ing S tates are M em bers o f the In te rn a tiona l A tom ic Energy Agency:

AFGHANISTAN FEDERAL REPUBLIC OF NICARAGUAALBANIA GERMANY NIGERIAALGERIA GABON NORWAYARGENTINA GHANA PAKISTANAUSTRALIA GREECE PANAMAAUSTRIA GUATEMALA PARAGUAYBELGIUM HAITI PERUBOLIVIA HOLY SEE PHILIPPINESBRAZIL HONDURAS POLANDBULGARIA HUNGARY PORTUGALBURMA ICELAND ROMANIABYELORUSSIAN SOVIET INDIA SAUDI ARABIA

SOCIALIST REPUBLIC INDONESIA SENEGALCAMBODIA IRAN SOUTH AFRICACAMEROON IRAQ SPAINCANADA ISRAEL SUDANCEYLON ITALY SWEDENCHILE IVORY COAST SWITZERLANDCHINA JAMAICA SYRIACOLOMBIA JAPAN THAILANDCONGO, DEMOCRATIC KENYA TUNISIA

REPUBLIC OF REPUBLIC OF KOREA TURKEYCOSTA RICA KUWAIT UKRAINIAN SOVIET SOCIALISTCUBA LEBANON REPUBLICCYPRUS LIBERIA UNION OF SOVIET SOCIALISTCZECHOSLOVAK SOCIALIST LIBYA REPUBLICS

REPUBLIC LUXEMBOURG UNITED ARAB REPUBLICDENMARK MADAGASCAR UNITED KINGDOM OF GREATDOMINICAN REPUBLIC MALI BRITAIN AND NORTHERNECUADOR MEXICO IRELANDEL SALVADOR MONACO UNITED STATES OF AMERICAETHIOPIA MOROCCO URUGUAYFINLAND NETHERLANDS VENEZUELAFRANCE NEW ZEALAND VIET-NAM

YUGOSLAVIA

The Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the IAEA held a t United Nations Headquarters, New York; it entered into force on 29 July 1957, The Headquarters of the Agency are situated in Vienna. Its principal objective is "to accelerate and enlarge the contribution o f atom ic energy to peace, health and prosperity throughout the world".

@ IAEA, 1966

Permission to reproduce or translate the information contained in this publication m aybe obtained by writing to the International Atomic Energy Agency, KSrntner Ring 11, Vienna 1, Austria.

Printed by the IAEA in Austria May 1966


SAFETY SERIES No. 18

ENVIRONMENTAL MONITORING IN EMERGENCY SITUATIONS

A MANUAL BASED ON THE WORK OF A PAN EL OF EX P E R T S

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, 1966


In te rn a tio n a l A to m ic E n e r g y A g en cy .E n v iro n m e n ta l m o n ito rin g in e m e rg e n c y s itu

a tio n s . A m an u al b ased on the w ork of a p anel of e x p e r ts . V ien n a, th e A gen cy , 1 9 6 6 .

122 p. (IA E A , S afety s e r i e s no. 18)

6 2 1 . 0 3 9 . 5 8 5 3 9 . 1 6 . 0 8 6 1 4 . 8 7 6

THIS MANUAL IS ALSO PUBLISHED IN FR EN C H , RUSSIAN AND SPANISH

ENVIRO NM ENTAL MONITORING IN EM ER G EN C Y SITUATIONS

IA EA , VIENNA, 1966 S T I / P U B / 1 1 8


FOREWORD

Should an accid en t leading to the uncontrolled re le a se of rad io activ e su b stan ces to the n atu ral environm ent o ccu r, it is m ost im p ortant that an adequate m onitoring sy stem be put into operation as quickly a s p o ssib le . In such a s y s te m the le v e ls of rad ia tio n and the le v e ls of rad io activ e con tam inan ts to which the public m ight be exposed should be m easu red and one of its m ain p urposes would be to provide tim ely data on which to base any n e ce ssa ry p rotective and rem ed ial action s.

This manual gives tech n ical guidance on appropriate em ergency m onitoring p roced ures to those who would have to a sse ss the situation a f te r su ch an a cc id e n t. It d oes not se t out to p rovid e e m e rg e n cy plans applicable to a ll situations, but ra th e r to draw attention to the im portant fa c to rs which should be considered in form ulating specific plans. It was p rep ared with the help of an international panel co m prising exp erts recom m ended by M ember States and rep resen tatives of o th er in tern atio n al o rg an iza tio n s. W hile the publication should be of in terest and use to all countries, it is hoped that it will be p articu larly helpful to the developing ones.


CONTENTS

1. INTRODUCTION ...................................................... ................................ 3

1 . 1 . A im s of the m anual .................................................................. 31 . 2 . S c o p e ................................................................................................... 3

2. O B JE C T IV E S OF EM ER G EN C Y ENVIRONMENTALMONITORING ........................................................................................... 5

2 . 1 . To determ ine whether an abnorm al re le a se ofrad ioactive m a te ria ls has o ccu rred ............................ 5

2 . 2 . To determ ine rapidly whether the re le a se of rad ioactive m a te ria ls is of such a type and extent that action m ust be taken to p ro tect thehealth and p rop erty of the public ................................... 5

2 . 3 . To provide inform ation on which subsequentrem ed ia l m e a su re s m ay be b a s e d ................................... 5

3. NATURE O F , AND HAZARDS RESULTING FROM,ACCIDENTAL R E L E A S E S O F RADIOACTIVE M ATERIALS TO THE ENVIRONS ............................................. 7

3 . 1 . Types of fa c ilitie s and th e ir in ven tories .................... 73 . 1 . 1 . T ypes of fa c ilitie s .................................................. 73 . 1 . 2 . In ven tories of rad io active m a te ria ls ......... 8

3 . 2 . Types of accid en ts and a sso cia ted re le a se ofrad io activ e m a te ria ls .......................................................... 113 . 2 . 1 . O verheating of irrad ia ted fuel elem ents . . 123. 2 . 2 . F i r e resu ltin g in d isp ersa l of the

radionuclides to the environm ent ............... 143 . 2 . 3 . R elease of radionuclides from

explosive accid en t .................................................. 143 . 2 . 4 . N aturally caused accid en ts .............................. 153 . 2 . 5 . N u clear excu rsio n .................................................. 153 . 2 . 6 . P h y sica l lo ss of a radiation sou rce ............ 163 . 2 . 7 . Rupture of con tain er ................................ ............ 16

LIST O F P A N E L M EM BERS .................................................................... 1


3 . 3 . D isp ersal of re leased m a te ria l in the environm entand possible m odes of exp osure of p erson s ............. 173 . 3 . 1 . D isp ersal in the atm osph ere ............ 173 . 3 . 2 . D isp ersa l in su rface w aters ............................ 193 . 3 . 3 . D isp ersa l in the sea ......................... .... 193 . 3 . 4 . D isp ersal in the soil .............................. 20

4 . THE EM ER G EN C Y MONITORING PROGRAMME ............ 22

4 . 1 . Form u lation of an ap propriate m onitoringp rogram m e ................................................................................... 224 . 1 . 1 . P re lim in a ry inform ation required .......... 224 . 1 . 2 . G eneral con sid erations ................................ 234 . 1 . 3 . The need fo r p re -e m e rg e n cy su rveys . . . . 264 . 1 . 4. Initial detection and assessm en t of

accid en tal re le a se ........................................... 274 . 2 . O rganization and staffing ....................................................... 28

4 . 2 . 1 . O rganization ....................................................... 284 . 2 . 2 . S ta ff in g ...................................................................... 30

5 . EM ER G EN C Y MONITORING PRO CEDURES ........................ 33

5 . 1 . E n viron m en tal m onitoring used as a detectionsy stem ...................................................................................... .. 33

5 . 2 . The in itial su rv ey ....................................................................... 345 . 2 . 1 . A ssessm en t of air-b orn e contam ination . . 345 . 2 . 2 . Rapid a sse ssm e n t of the a re a affected . . . 355 . 2. 3 . E xam in ation of w ater and food ................. 39

5 . 3 . Subsequent su rv ey s .................................................................... 405 . 3 . 1 . R e a sse ssm e n t of in itial m easu res ....... 415 . 3 . 2 . Follow ing the trend of contam ination . . . . 425 . 3 . 3 . M easu rem en t of in tern al doses ............... 425 . 3 . 4 . C ollection of scien tific data ...................... 43

6 . EM ER G EN C Y MONITORING EQ U IPM EN T .......................... 44

6 . 1 . In stru m en ts fo r detecting an abnorm al re le a seof rad io activ e m a te ria ls ..................................................... 44

6 . 2 . In stru m en ts for asse ss in g radiation andcontam ination levels in the field ................................... 456 . 2 . 1 . P o rtab le su rvey in strum ents .................... 456 . 2 . 2 . N on-portable survey instrum ents .......... 46


6 . 3 . Equipm ent fo r collectin g sam ples and instrum entsfo r a sse ss in g th eir rad ioactive contam ination . . . . 476 . 3 . 1 . Sampling ..................................................................... 476 . 3 . 2 . M easuring instrum ents ..................................... 48

6 . 4 . M iscellaneous equipment . s .............................................. 496 . 4 . 1 . T ran sp o rt equipment .......................................... 496 . 4 . 2 . Com m unications and warning equipment . , 516 . 4 . 3 . M eteorological equipment ............................... 526 . 4 . 4 . P ro te c tiv e equipment .......................................... 536 . 4 . 5 . W arning and con tro l equipment ................... 53

INTRODUCTION TO ANNEXES ........................................................... 54ANNEX I INVENTORIES OF FISSION-PRODUCTS AND

PO SSIBLE R EL EA S ES ................................................. 54ANNEX II AIR-BO RN E R EL E A S E S: DISPERSION,

DEPOSITION AND D O SE-EXPO SURERELATIONSHIPS ....................... ...................................... 59

ANNEX III A L P H A -, B E T A - AND GAMMA-RADIATIONSURVEYS .............................................................................. 69

ANNEX IV SA M PLE CO LLEC TIO N AND FIEL DEVALUATION ..................................................................... 80

ANNEX V SPE C IA L AN ALYTICAL CONSIDERATIONS . . 91ANNEX VI INSTRUMENTATION AND EQUIPM ENT . . . . . 97ANNEX VII ENVIRONMENTAL MONITORING

PRO CEDURES ADOPTED IN PREVIOUS EM ER G EN C Y SITUATIONS ....................................... 109

R E FE R E N C E S ................................................................................................. 118BIBLIOGRAPHY ............................................................................................ 119


L I S T OF P A N E L M E M B E R S

P ane l on E n v iro n m enta l M onitoring in E m ergency Situations

Chairm an

K. A. M ahmoud

M e m b e r s

A. A ark ro g

E . Fenyves

R .J . G a rn e r

A. R. Keene

D. M echali

H. W atanabe

P ro tec tio n D epartm ent,A tom ic E nergy E stab lish m en t, C a iro , United A rab Republic

D anish A tom ic E nergy C om m ission, R e se a rc h E stab lish m en t Ris0, R osk ilde, D enm ark

C en tra l R e se a rc h In stitu te fo r P h y sics ,

B udapest, H ungaryUnited Kingdom A tom ic E nergy

A uthority ,A uthority H ealth and Safety B ranch, Harwell^ B e rk s . ,United Kingdom

B ate lle -N o rthw est,R ichland, W ash .,United S ta tes of A m ericaC en tre d 'e tud es n u c le a ires de

F on tenay-aux-R os e s ,F ran ce

N ational In stitu te of Radiological Sciences,

Chiba, Japan

1


Observers

\S. H a lte r (Consultant)

E . Hampe

L .E . L a rs so n

E . W allauschek

G. W ortley

Scientific secretary

G .E . Swindell

W orld H ealth O rganization (P re se n t ad d ress :D ire c te u r g en era l de l 'a d m in is tra -

tion de l'hyg idne publique, M inistS re de la san te publique et

de la fam ille ,B ru s s e ls , Belgium )E uropean A tom ic E nergy

Com m unity (EURATOM),P a r is , F ran ceF o rm e rly R adiation and Iso topes, W orld H ealth O rganization (P re se n t ad d ress:In stitu te of R adiophysics, Stockholm , Sweden)

O rgan isation fo r Econom ic C o-opera tion and Developm ent/ E uropean N uclear E nergy Agency,

P a r is , F ran ceF o rm e rly A tom ic E nergy B ranch,

Food and A gricu ltu re O rganization (P re se n t ad d ress :Jo in t FAO/IAE A D ivision, Vienna)

D ivision of H ealth, Safety and W aste D isposal,

In te rn a tio n a l A tom ic E nergy Agency

2


1. INTRODUCTION

1 .1 .1 . The p u rp o se of th is m anual is to p rov ide advice and tec h n ic a l g u id an ce on m o n ito rin g in co n n ec tio n w ith e m e rg e n c y s i tu a tio n s re s u ltin g fro m ra d ia tio n a c c id e n ts involv ing the uncont r o l le d r e l e a s e of r a d io a c t iv e s u b s ta n c e s to th e n a tu r a l e n v ir o n m e n t1 . T h is g u id an ce i s p ro v id e d fo r th o s e p e r s o n s , w hethe r m e m b ers of the s ta ff of the e s tab lish m en t fro m which the r e le a s e o rig in a te d o r of o th e r o rg a n iz a tio n s , w hose ta s k i t i s to a s s e s s the s itu a t io n a r i s in g a s th e r e s u l t o f the a c c id e n t .

1. 1 .2 . The m anual does not se t out to provide an em ergency en v iron m e n ta l m o n ito rin g p lan a p p licab le to a l l s itu a tio n s . R a th e r , i t p ro v id e s g u id an ce on th e im p o r ta n t f a c to r s w hich shou ld be c o n s id e re d in fo rm u la tin g sp ec ific em e rg e n c y m o n ito rin g p la n s . F u r th e r m o r e , th e te c h n iq u e s and p ro c e d u r e s d e s c r ib e d in both the m a in te x t and the A nnexes shou ld be c o n s id e r e d a s e x a m p le s on ly . T h e ir a p p lic a b i l i ty to s p e c if ic c i r c u m s ta n c e s w ill v a r y w ide ly .

1 .1 .3 . W hile i t i s hoped th a t the m anual w ill be of help to c o u n tr ie s in a l l s ta g e s of developm en t, p a r t ic u la r a tten tio n i s g iven to the s p e c ia l n eed s of the develop ing c o u n tr ie s .

1 .2 . Scope

1. 2. 1. The em e rg e n c y en v iro n m en ta l m o n ito rin g r e f e r r e d to in th is m anual is concerned with the m easu rem en t of lev e ls of r a d ia t io n and le v e ls o f r a d io a c t iv e c o n ta m in a n ts in fo o d s tu ffs , w a te r , a i r and o th e r m e d ia of i n t e r e s t , to w h ich m e m b e rs o f th e p u b lic co u ld be e x p o se d a s th e r e s u l t o f an a c c id e n t o c c u r r in g d u r in g th e o p e ra t io n , h a n d lin g , o r t r a n s p o r t o f s o u r c e s of io n iz in g ra d ia t io n . I t i s n o t w ith in th e sco p e of the m a n u a l to a tte m p t to e s ta b lis h ra d ia t io n d o se s o r le v e ls

1. 1. A im s of the manual

1 T h e m onitoring o f persons is not d ealt with exten siv ely as that to p ic is considered in greater d e ta il in other p u b lication s, for e xa m p le : In ternational A tom ic Energy Agency, Assessment o f Radioa c tiv ity in M an, 2 vols, IAEA, Vienna (1 9 6 4 ).

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of co n ta m in a tio n in a i r , w a te r , e tc . w hich w ould be c o n s id e re d a c c e p ta b le to m e m b e rs of the public u n d e r e m e rg e n c y co n d itio n s .

1. 2. 2. C onsidera tion is given to the p o ssib le r e le a s e s and subsequent d is p e r s a l of r a d io a c t iv e co n ta m in a tio n re s u l t in g f ro m a c c i den ts to n u c le a r re a c to r s , p ro c e ss in g fa c ilit ie s , la b o ra to rie s , liq u id w a s te s to ra g e f a c i l i t ie s and sh ip p ing c o n ta in e rs , and to the fo re s e e a b le ra d ia t io n and co n ta m in a tio n le v e ls in the su rro u n d in g a r e a s .

1. 2. 3. An ou tline i s g iven of the re q u ire m e n ts of ad eq u ate e n v iro n m e n ta l m o n ito r in g fo r th e d e te c t io n of any e m e rg e n c y s i t uation , the d em a rca tio n of affected a re a s and the a s se s sm e n t of th e n a tu re , e x te n t and s ig n if ic a n c e of the c o n ta m in a tio n in o rd e r to p ro v id e t im e ly d a ta on w hich a p p ro p r ia te p ro te c tiv e and re m e d ia l a c tio n s could be b ased . P a r t ic u la r a t te n tion is given to the tim ing and re la tiv e p r io r it ie s of the actions to be taken .

1. 2. 4. It is an tic ipa ted tha t the period during which th is m anual would be m o s t u se fu l i s th e v i ta l p e r io d im m e d ia te ly fo llow ing an acc iden t when action needs to be rap id and dec is ive and th e re fo re , a s fa r a s possib le , planned in advance.

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2. OBJECTIV ES OF EM ERGENCY ENVIRONMENTAL MONITORING

2. 1. To d e te r m in e w h e th e r an a b n o rm a l r e l e a s e o f r a d io a c t iv e m a te r ia ls h a s o c c u r r e d

The d e tec tio n of an ab n o rm al re le a s e of rad io ac tiv e m a te r ia l by a sy s te m w hich w ill give e a r ly w arn ing i s a p re - r e q u is i te fo r the in itia tio n of a p p ro p ria te e m erg en cy ac tio n . It i s u s u a l ly m o re s a t i s f a c to r y to m ake p ro v is io n fo r th e d e te c t io n of the r e l e a s e a t the s o u rc e r a th e r th a n in the e n v iro n m e n t, but in s p e c ia l c i rc u m s ta n c e s p a r t of a con tinuously o p e ra tin g e n v iro n m e n ta l m o n ito r in g s y s te m m a y be u se d to d e te c t an a b n o rm a l r e le a s e . The in it ia l ind ica tions of the w arn ing s y s te m m u s t be fo llow ed ra p id ly by s p e c ia l e m e rg e n c y in v e s t i g a tio n s a im e d a t co n firm in g tha t an a b n o rm a l r e le a s e to the e n v iro n s h as in fa c t o c c u r re d .

2 . 2 . T o d e te r m in e r a p id ly w h e th e r th e r e l e a s e o f r a d io a c t i v e m a te r ia l s i s o f su ch a ty p e and e x te n t th a t a c tio n m u s t be ta k e n to p r o t e c t th e h e a lth and p r o p e r t y o f th e p u b lic

A rap id in i t ia l su rv ey of the a r e a s w hich m ay be contam inated is re q u ire d to a s s is t in deciding what action, if any, is n e c e s s a ry in o rd e r to sa feg u a rd the health of the public and to p ro te c t liv e s to c k , fo o d s to re s and o th e r p ro p e r ty . Such p ro te c t iv e a c tio n m ig h t in c lu d e th e im p o s it io n of r e s t r i c t i o n s on the consum ption of w a te r, spec ified c ro p s , inc lud ing c e re a ls , and o th e r fo o d stu ffs and m ilk p ro d uced w ith in d e s ig n a te d r e g io n s , the e v a c u a tio n of the p o pu la tio n in d e s ig n a te d a r e a s , th e t r a n s f e r of l iv e s to c k o r food to c o v e re d p r e m is e s , and the u se of a l te rn a tiv e food su p p lie s fo r liv e s to c k . A s fa r a s p o ss ib le the s u rv e y shou ld be p lanned to p ro v id e the n e c e s s a r y in fo rm a tio n w ith in a few h o u rs a f te r the a c c id e n t.

2. 3. To provide information on which subsequent r e m e d i a l m e a s u r e s m a y b e b a s e d

S urveys need to be continued to p rov ide adequate in fo rm atio n on the developm ent of the situ a tio n on which to b ase d ec is io n s co n ce rn in g the ex ten sio n o r re m o v a l of in it ia lly im p o sed r e -

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s t r ic t io n s and th e ap p lic a tio n of re m e d ia l m e a s u r e s . T hey sh ou ld be co n tin u ed u n til the e n v iro n m e n ta l s i tu a t io n i s s ta b le o r i ts changing s ta tu s is known and u n der c o n tro l. Such s u r v ey s a lso fo rm a b a s is fo r the a s s e s sm e n t of the d o se s w hich m ay be re c e iv e d by m e m b e rs of the public and m ay a lso p ro vide in fo rm ation of sc ien tific in te re s t on the p assag e of ra d io ac tiv e nuclides through the n a tu ra l env ironm ent.

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3. NATURE OF, AND HAZARDS RESULTING FROM, ACCIDENTAL RELEASES OF RADIOACTIVE MATERIALS

TO THE ENVIRONSIm p o rta n t c o n s id e ra tio n s w hich shou ld be ta k e n in to acc o u n t in

p lann ing an e n v iro n m e n ta l m o n ito rin g p ro g ra m m e th a t i s ad eq u a te u n d e r e m e rg e n c y c o n d itio n s in c lu d e :(a) T he ty p e s of ra d io n u c lid e s invo lved ;(b) T he q u a n ti t ie s of ra d io n u c lid e s p re s e n t;(c) The lo c a tio n of the fa c il ity in re la tio n to population c e n tre s and

th e ir com positions and d e n s itie s , su rface w a te rs , oceans, t r a n s p o rta tio n c e n tr e s and h ighw ays e t c . , tak in g in to accoun t m e te o ro lo g ic a l , h y d ro lo g ic a l and o th e r n a tu r a l c o n d itio n s w hich m ig h t in f lu e n c e the d is p e r s a l of r e le a s e d ra d io n u c lid e s ;

(d) T h e q u a n ti t ie s o f ra d io n u c l id e s w h ich m ig h t be r e l e a s e d and t h e i r p o s s ib le r a t e s o f r e l e a s e ;

(e) T he d is p e r s a l ro u te and su b se q u e n t p a thw ays th ro u g h the b io s p h e re le a d in g to hum an e x p o su re ;

(f) T he d is ta n c e s and a r e a s o v e r w hich th e ra d io n u c lid e s m ay be d is p e rs e d ;

(g) T he p e r s is te n c e of im p o rta n t q u a n ti t ie s of the r e le a s e d r a d io n u c lid e s in the e n v iro n m e n t.T he sp e c if ic m e c h a n ism by w hich an a c c id e n t i s b ro u gh t about

is of only in d ire c t im p o rtan ce in the planning of an adequate env iron m en ta l m on ito ring p ro g ram m e .3. 1. T yp es o f f a c i l i t ie s and th e ir in v e n to r ie s3. 1. 1. T ypes of fa c ilitie s

F a c i l i t i e s su ch a s th o se invo lv ing th e o p e ra tio n of r e a c to r s , the p ro c e s s in g of i r r a d ia te d fu e ls , the s to ra g e of ra d io a c tiv e w a s te s , th e p ro d u c tio n o f r a d io is o to p e s an d la b e l le d c o m pounds, the co n d uc t of la b o r a to ry r e s e a r c h , the u se of i s o to p e s ( e .g . in h o s p i ta ls ) , an d th e s h ip m e n t o f r a d io a c t iv e m a te r ia l s m ay have f e a tu re s w hich a r e su ffic ie n tly d if fe re n t to in f lu e n c e th e r e la t iv e im p o r ta n c e of th e f i r s t t h r e e c o n s id e r a t io n s l is te d in the p re v io u s s e c tio n . T h e se d if f e r e n c e s m u s t be re c o g n iz e d i f e m e rg e n c y m o n ito r in g p r o c e d u r e s a r e to be p r a c t i c a l and e f fe c tiv e .

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3. 1 .2 . Inventories of radioactive m aterials

T he q u a n tit ie s and ty p e s of ra d io n u c lid e s w hich a r e p r o c e s s e d , h an d led o r s to r e d in a f a c i l i ty , t h e i r p h y s ic a l and c h e m ic a l fo rm s and the n a tu re of th e i r co n ta in m e n t, a re of p r i m a ry im p o rtan ce in the p red ic tio n of the m agnitude and extent of an acc id en t involving the en v iro n s . The q u an titie s involved ra n g e fro m m ic ro c u r ie s to m e g a c u r ie s . The ty p es of ra d io n u c lid e s ra n g e fro m re la t iv e ly innocuous n u c lid e s w ith sh o r t h a lf - l iv e s and l i t t le o r no up take by the body to long h a lf - l ife b o n e -s e e k e rs . The d if fe re n c e s in the in v e n to r ie s of v a r io u s ty p e s o f f a c i l i t ie s a r e i l l u s t r a te d by th e fo llow ing re v ie w of s e v e r a l m a jo r c a te g o r ie s of f a c i l i t ie s :(a) R e a c to r s

W hile the ty p e s of r e a c to r s a r e f a r too v a r ie d to e n u m e ra te in th is m anual, i t can be s ta te d th a t a c h a ra c te r is t ic of m any r e a c to r s i s th a t th e y c o n ta in r e la t iv e ly l a r g e a m o u n ts of f i s s io n - p r o d u c ts . T he d e fin itiv e e s t im a t io n o f sp e c if ic in v e n to r ie s r e q u i r e s know ledge of su ch p a r a m e te r s a s :(i) T he typ e of r e a c to r ;(ii) T he p o w e r le v e l;(iii) T he fu e l u se d ;(iv) T he o p e ra t in g h is to ry of the fu e l in th e r e a c to r .S ince th e s e p a r a m e te r s v a r y w ide ly , and to a l a r g e e x te n t ind ep en d en tly , only ex a m p le s of q u a n tita tiv e d a ta can be in c lu d e d in th is m a n u a l2 . E x a m p le s of su ch q u a n ti t ie s of s e le c te d f i s s io n - p r o d u c ts fo r a u ra n iu m - fu e l le d r e a c to r a r e inc luded in T ab le I. 1 of Annex I. T h ese ta b le s obviously can o n ly s e rv e a s a g e n e ra l gu ide . W hile i t i s no t p a r t ic u la r ly ussetul to a tte m p t to ra n k the ty p e s of f a c i l i t ie s a c c o rd in g to p o te n tia l r is k , i t can be sa id tha t th e re a r e v e ry few, if any, r e a c to r s w hich w ould no t r e q u ir e an a s s o c ia te d e m e rg e n c y e n v iro n m e n ta l p lan .

2 For planning en v iro n m en ta l m o n ito rin g , it is only n ecessary to ap p roxim ate th e m agnitude

o f the inventory. The a ccu ra cy o f estim ates o f inventory which is required for th e planning o f em ergency m onitoring is not n ecessarily the sam e as that required in form al hazard analyses.


(b) P r o c e s s in g f a c i l i t ie s

F a c i l i t i e s p ro c e s s in g i r r a d ia te d o r sp en t fu e l e le m e n ts a lso co n s titu te , in g e n e ra l, a c a te g o ry of fa c i l i t ie s w hich re q u ire p lanning fo r e m erg en cy e n v iro n m en ta l s itu a tio n s in the event of an acc id en t. The q u an titie s of m a te r ia ls involved w ill u su a lly be s u b s ta n t ia l ly l e s s th a n the ra d io n u c lid e in v e n to ry in a la rg e r e a c to r . M oreo ver, the p ro p o r tio n s in w hich r a d io active nuclides a re p re se n t in p ro cess in g p lants a lso a re l ik e ly to be qu ite d if fe re n t fro m th o se in w hich they a r e p re s e n t in a r e a c to r s ince , a t the tim e of p ro cess in g o r re p ro c e ss in g , the inven to ry of sh o r t- liv e d nuclides w ill o rd in a r ily constitu te a m uch s m a l le r f ra c tio n of the to ta l inv en to ry . An add itiona l d if f e r e n c e w h ic h in f lu e n c e s th e e n v ir o n m e n ta l m o n i to r in g p la n n in g i s th e fa c t th a t a t s p e c if ic s te p s in th e p ro c e s s in g o p e ra t io n , th e n u c lid e c o m p o s itio n m a y be l im i te d to on ly a few ra d io n u c lid e s — w hich m ay be p a r t ic u la r ly h a z a rd o u s o n es su ch a s p lu to n iu m o r s tro n t iu m — and , th e r e f o r e , d e te c t io n in th e e n v iro n s m ay n o t be a s e a s i ly o r s im p ly a c co m p lish ed a s in the o rd in a ry m ixed f is s io n -p ro d u c t r e le a s e fro m a r e a c to r .

(c) Iso tope p roduction p lan tsIt i s n o t f ru i t f u l o r f e a s ib le to a t te m p t to g e n e r a l iz e on the n a tu re , m agnitude and sig n ifican ce of the inv en to ry of iso tope p ro d u c tio n p la n ts . It i s c l e a r th a t the p o te n tia l s e v e r i ty of a n a c c id e n ta l r e l e a s e f r o m a p la n t p ro d u c in g 32P , f o r e x am ple , i s su b s ta n tia lly d if fe re n t fro m th a t of a r e le a s e fro m a p lan t s e p a ra tin g and p roduc ing 89Sr, 90S r o r 238Pu.A few p o in ts a r e p e rh a p s w o rthy of b r ie f m e n tio n . U su a lly su c h p la n ts w ou ld h av e an in v e n to ry s u b s ta n t ia l ly s m a l l e r ( e .g . by a f a c to r o f 106 o r m o re ) th a n th a t of a p r o c e s s in g p lan t o r r e a c to r . E ven m o re so than in the ca se of a p ro c e s sing p lan t, the iso to p e p roducing p lan t is lik e ly to have w e ll- s e p a ra te d rad io n u c lid e s w hich could m a rk ed ly a ffec t the p ro c e d u re s and in s tru m e n ta t io n w hich would be em ployed in the e m e rg e n c y e n v iro n m e n ta l m o n ito rin g .

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(d) O th e r la b o r a to r ie sT h is c a te g o ry in c lu d e s a w ide v a r ie ty of f a c i l i t i e s ra n g in g f ro m v e ry s m a l l h ig h ly s p e c ia liz e d la b o r a to r ie s w ith r e l a t iv e ly s m a l l in v e n to r ie s of r a d io n u c l id e s to l a r g e m u l t i p u rp o se la b o r a to r ie s co n d uc tin g a w ide v a r ie ty of r e s e a r c h p r o je c ts an d w ith a r e la t iv e ly l a rg e in v e n to ry o f m a n y d if f e r e n t r a d io n u c l id e s . M any of th e f a c to r s w h ich in f lu e n c e e n v iro n m e n ta l m o n ito r in g u n d e r e m e rg e n c y c o n d itio n s fo r l a b o r a to r i e s a r e s im i l a r to th o s e in v o lv ed in iso to p e p r o ducing p la n ts . The sp ec ific q u an titie s and typ es of m a te r ia ls b e in g h a n d le d an d th e n a tu r e o f th e s i t e w i ll l a r g e ly sh a p e th e ty p e an d e x te n t of e m e rg e n c y p la n s .

(e) W a s te s to r a g e f a c i l i t i e sM any o f th e f a c i l i t i e s d e s c r ib e d ab o v e w ill have a s s o c ia te d f a c i l i t ie s fo r the s to ra g e of liqu id o r so lid rad io ac tiv e w as te s— u su a lly f is s io n -p ro d u c ts . L iqu id w a s te s to ra g e f a c i l i t ie s m ay ra n g e 'in s iz e and com plexity fro m m odest o rd in a ry s to r ag e ta n k s w ith re la t iv e ly sm a ll in v e n to r ie s to v e ry la rg e u n d e rg ro u n d v e s s e l s em p lo y in g co o lin g e q u ip m e n t to re m o v e e x c e s s iv e h ea t r e s u lt in g fro m ra d io a c tiv e d ecay . T he m o s t p ro b a b le m o d e o f r e l e a s e to th e e n v iro n m e n t f ro m liq u id w as te s to ra g e f a c i l i t ie s i s by lo s s of in te g r i ty of the s to ra g e v e s s e l p e rm it t in g som e lo s s of liq u id to the g round and p o s s ib ly g ro u n d -w a te r . L o ss of co o lin g cou ld c a u s e e x p lo s iv e b o iling in h ig h - le v e l w as te s to ra g e ta n k s and su b seq u en t r e l e a s e s to the a tm o s p h e re .W aste d is p o s a l f a c i l i t i e s w h ich a r e u se d fo r so lid c o n ta m in a te d i te m s , e . g . a n a ly t ic a l la b o r a to r y w a s te s , d e fe c t iv e s m a l l to o ls an d e q u ip m e n t an d r a g s , o f te n c o n s is t o f o pen t r e n c h e s in th e g ro u n d w hich a r e b a c k f ille d a f t e r d is p o s a l . T h is ty p e o f f a c i l i ty m ay o c c a s io n a lly a c c id e n ta l ly r e l e a s e s m a l l a m o u n ts o f r a d io n u c lid e s to th e e n v iro n s a s a r e s u l t of sp o n ta n e o u s c o m b u s tio n o r g ro u n d -w a te r le a c h in g of the t r e n c h . H ow ever, su ch d is p o s a l s i te s a r e u su a lly c o n s id e re d to be a v e r y m in o r s o u r c e of a c c id e n ta l r e l e a s e to th e e n v iro n m e n t.


( f) T ra n sp o rt co n ta in ers

T h ese s o u rc e s a r e m entioned b ecau se of the in c re a s in g sh ip -- m en ts of rad io ac tiv e m a te r ia ls betw een c e n tre s by a ir , w ater,

ro a d o r r a i l . A lthough the h a z a rd s f ro m a c c id e n ts invo lv ing th e se m odes of t r a n s p o r t m ay be v e ry d iffe ren t, the com m on c h a ra c te r is t ic i s the m obility of the source-. T h is c h a r a c te r is t ic n e c e s s i ta te s a high d eg ree of flex ib ility in en v ironm en ta l m o n ito rin g . F a c to rs w hich fa c ilita te e ffec tiv e en v iro n m en ta l m o n ito rin g in the event of an acc id en t inc lude:(i) A r e a s o n a b ly a c c u r a te know ledge of th e ty p e , q u a n tity

and p h y s ic a l s ta te of m a te r ia l s inv o lv ed ;(ii) Som e option w ith r e g a rd to the lo c a tio n of the c o n ta in e r

in re la tio n to i ts env ironm en t — in o th e r w ords, the ro u te and t im in g o f th e sh ip m e n t — w hich co u ld in f lu e n c e th e p o te n t ia l d e m a n d s on e n v iro n m e n ta l m o n ito r in g in th e e v e n t o f an a c c id e n t .

F a c to r s w hich h am p er the planning and c a r ry in g out of e m e r gency m o n ito rin g in the event of an acc id en t involv ing a sh ip ping c o n ta in e r inc lude:(i) T he h igh ly v a r ia b le lo c a tio n of the c o n ta in e r in re la t io n

to i t s e n v iro n m e n t w h ich cou ld n e c e s s i ta te g r e a t sp e e d an d l a s t m in u te c h a n g e s in th e e m e rg e n c y m o n ito r in g p r o c e d u r e s ;

(ii) The likelihood of the con tam inan ts fro m an acc iden t being f u r th e r d is p e r s e d s e c o n d a r i ly by t r a n s p o r ta t io n e q u ip m e n t b e fo re c o n t r o l a t th e s i t e o f th e a c c id e n t c a n be a c h ie v e d ;

(iii) L ack of e x p e r ie n c e d a id w ith in o p e ra tin g d is ta n c e of an a c c id e n t, w h ich co u ld th e o r e t ic a l ly o c c u r on h ighw ays, ra i lw a y s o r w a te r-w a y s o r a t any point on land u n d e r the w orld a i r ro u te s .

3 .2 . Types of accidents and associated release of radioactive

materials

A v e ry long l i s t of the ty p e s of ra d ia tio n a c c id e n ts w hich can o c c u r and w h ich c o u ld r e s u l t in r e l e a s e o f r a d io n u c l id e s to th e e n v iro n m e n t cou ld be fo rm u la te d . M any su ch a c c id e n ts w ould inv o lv e c lo s e ly r e la te d f a c to r s fo r th e p lann in g of e m e rg e n c y m o n ito r in g p r o g r a m m e s . T h e l i s t o f ty p e s of

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a c c id e n ts b r ie f ly d is c u s s e d in the n ex t few p a g e s i s n o t in ten d e d to be c o m p re h e n s iv e ; r a th e r , i t s u g g e s ts th e w ide ly d iffe rin g ty p es of ev en ts w hich can ca u se a c c id e n ta l r e le a s e s of ra d io n u c lid e s . A b r ie f d is c u s s io n of the m o re im p o r ta n t f a c to r s w h ich a r e p e r t in e n t to e n v iro n m e n ta l m o n ito r in g i s in c lu d e d fo r e a c h a c c id e n t typ e l is te d .

3. 2. 1. Overheating of irrad ia te d fuel elem ents

D u rin g o p e ra t io n o f a n u c le a r r e a c to r , l a r g e q u a n t i t ie s of r a d io a c t iv e m a te r ia l s a c c u m u la te w ith in th e fu e l. T he a b s o lu te and r e la t iv e q u a n ti t ie s o f th e s e r a d io n u c l id e s in th e c o re of the r e a c to r a r e d ep en d en t on s e v e r a l r e a c to r o p e r a tin g p a r a m e te r s in c lu d in g the typ e of r e a c to r , typ e of fuel, e x te n t of i r r a d ia t io n , p o w e r le v e l of th e r e a c to r , an d th e le n g th of t im e b e tw een r e a c to r sh u t-d o w n and th e a c c id e n t . The m o s t im p o rta n t f is s io n -p ro d u c t in the a c c id e n ta l r e le a s e f ro m a r e a c to r w ill v e r y l ik e ly be 131I. T he e f fe c ts of the r e l e a s e s of o th e r f is s io n -p ro d u c ts can n o t be ig n o re d , how e v e r . Inc luded am ong th e se o th e r n u c lid e s a r e : o th e r i s o to p e s of io d in e , iso to p e s of te l lu r iu m , s tro n tiu m , c a e s iu m , c e r iu m , ru th e n iu m , and the r a r e g a se s , k ry p to n and xenon.Two im p o rta n t fa c to rs affecting the en v iro n m en ta l m on ito ring fo llow ing a r e a c to r a c c id e n t a r e th e v o la ti li ty of the f is s io n - p ro d u c ts c o n c e rn e d , and the s ta tu s of the r e a c to r in re s p e c t of i t s s ta r t - u p tim e , o p e ra tin g h is to ry , and shu t-dow n tim e . An ac c id e n t o c c u rr in g a f te r a r e a c to r h as been o p e ra tin g fo r on ly a few h o u rs a t a s u b s ta n t ia l p o w er le v e l w ould inv o lv e only s h o r t- l iv e d iso to p e s in im p o rta n t am ou n ts . The q u an tit i e s of s tro n t iu m , c a e s iu m , ru th e n iu m , and c e r iu m w ould be n e g lig ib le .If an a c c id e n t w e re to o c c u r w ith in a few day s a f te r s ta r t in g th e o p e ra t io n o f a r e a c to r a t a s ig n if ic a n t p o w e r le v e l , th e iod ine iso to p e s w ould have la rg e ly a tta in ed e q u ilib r iu m w hile th e q u a n ti t ie s of lo n g -liv e d iso to p e s , su ch a s s tro n t iu m and c a e s iu m ,w o u ld s t i l l be n e g lig ib le . If th e r e a c to r h ad b e e n o p e ra tin g fo r a s u b s ta n tia l p e r io d of tim e and had b een shu t down fo r a p e rio d , fo r exam ple , of two m onths o r m o re , a l l of the s h o r t- l iv e d iso to p e s such a s iod ine would have decayed to n eg lig ib le q u a n titie s . A r e a c to r acc id en t u n d e r th e se c i r -

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cu m sta n c e s would have i ts m a jo r e ffec ts in the env iron s fro m the r e le a s e s of i37Cs and 90S r since th e se n u c lid es would not have decayed ap p re c ia b ly du ring the shut-dow n p e rio d .A u se fu l s im p lif ic a tio n in p lanning em e rg e n c y e n v iro n m en ta l m o n ito r in g in th e ev en t of a r e a c to r a c c id e n t i s to c o n s id e r 1311 a s the m ost dem anding rad ionuclide in re g a rd to the speed

w ith w hich m e a s u re m e n ts m u s t be m ade and s a m p le s m u s t be co llec ted . The p ro g ram m e, of c o u rse , m ust be su ffic ien tly c o m p re h e n s iv e to a s s e s s th e s ig n if ic a n c e of a l l th e i m p o rta n t co n ta m in an ts w hich m ay be r e le a s e d to the e n v iro n s . D ata a r e g iven in Annex I, T ab le s I. 2 and I. 3.In sp ite of the fa ir ly d e fin itive in fo rm a tio n w hich can be c o lle c te d re g a rd in g the in v e n to r ie s of r a d io a c t iv e m a te r ia l in r e a c to r c o r e s fo r d if fe re n t ty p e s of r e a c to r s in r e s p e c t of d if fe re n t o p e ra tin g h is to r ie s , th e re a r e m any im p o rta n t f a c t o r s w h ich in f lu e n c e th e q u a n ti t ie s and r a t io s of th o s e m a t e r i a l s w h ich m ay c o n ta m in a te th e e n v iro n s in th e ev en t of an a c c id e n t . In c lu d e d a r e su c h th in g s a s p r e f e r e n t i a l r e le a s e s of the m o re v o la tile com ponen ts and the e ffe c tiv e n e ss of build ing con ta inm en t and f ilte r in g s y s te m s . It should a lso be c le a r ly re c o g n iz e d th a t even in the c a s e of a r e a c to r fu e l a c c id e n t, w h ere a h a z a rd s a n a ly s is e s t im a tio n tra d it io n a lly h a s b een m o re th o ro u g h ly t r e a te d th a n h a z a rd s a n a ly s is in o th e r ty p e s of f a c i l i t i e s , th e p o s tu la te d r e l e a s e s a r e on ly e s t im a te s of th e c o n s e q u e n c e s of th e p o s tu la te d a c c id e n ts . At b es t, they p ro v id e an o rd e r of m agnitude in d ica tio n of the e x te n t of e m e rg e n c y e n v iro n m e n ta l m o n ito r in g w hich m igh t be r e q u ire d in the ev en t of an a c c id e n t.In th e c a s e of a r e a c t o r a c c id e n t , th e m o s t l ik e ly ro u te of d i s p e r s a l of im p o r ta n t a m o u n ts of ra d io n u c l id e s to th e e n v ir o n s i s th e r e l e a s e to th e a tm o s p h e re . E v en in th e c a s e of w a te r -c o o le d r e a c to r s , th e a tm o s p h e r ic d i s p e r s a l ro u te i s m uch m o re l ik e ly to c o n s titu te the m o s t dem and ing b a s is fo r planning, r a th e r than the re le a s e of rad io n u c lid es to s u r face w a te r-w a y s . A le s s lik e ly m ode of d is p e r s a l in the s t a t io n a ry r e a c to r , fu e l o v e rh e a tin g o r p a r t i a l m e lt-d o w n a c c id en t, i s th e r e l e a s e of ra d io n u c lid e s to th e g ro u nd .M ore c o m p re h e n s iv e p lann ing is re q u ire d fo r em e rg e n c y en v iro n m e n ta l m o n ito rin g follow ing a r e a c to r acc id en t than fo r

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the o th e r typ es of acc id en ts d isc u sse d below . T h is d ifference r e s u l t s f ro m the c o m b in a tio n of a la rg e f is s io n -p ro d u c t i n v en to ry in the r e a c to r and the high p ro b ab ility of a tm o sp h e ric d is p e r s a l . A s e r io u s r e a c to r a c c id e n t i s m o re lik e ly to r e s u lt in w id e sp re a d co n ta m in a tio n of th e e n v iro n s th a n m o s t o th e r ty p e s of n u c le a r a c c id e n ts . H ow ever, o th e r l e s s s e r io u s a c c id e n ts a r e m o re lik e ly to o c c u r .In s u m m a ry , th e l im itin g f a c to r s w h ich in f lu e n c e e n v ir o n m e n ta l m o n ito rin g fo r a r e a c to r a c c id e n t a r e th e d is p e r s a l ro u te to the a tm o s p h e re , and th e p re s e n c e of the r a d io is o to p e 1311. P lan n in g th a t i s b a se d , in g e n e ra l, on th e se two p a r a m e te r s sh ou ld p ro v id e a d e q u a te p r e p a r e d n e s s in the c a s e of o th e r d is p e r s a l ro u te s and in v o lv em en ts w ith o th e r ra d io n u c lid e s .The e n v iro n m e n ta l m o n ito rin g c a r r ie d out fo llow ing the r e le a s e of f i s s io n -p ro d u c ts to th e a tm o s p h e re f ro m th e W ind- s c a le No. 1 P ile in O ctober 1957 — an exam ple of an acc id en t in v o lv in g th e o v e rh e a tin g o f a r e a c to r c o re — i s d e s c r ib e d in A nnex VII.

3 .2 .2 . F i r e re su ltin g in d is p e r s a l of the rad io n u c lid es to the env ironm en tT he m a jo r and p robab ly the only im p o rta n t d is p e r s a l ro u te in the ev en t of f i r e in con ju n ction w ith an in v e n to ry of ra d io a c tiv e m a t e r i a l s i s th e r e l e a s e o f im p o r ta n t q u a n ti t ie s o f th e s e m a t e r i a ls to the a tm o sp h e re . It i s like ly tha t, except in the ca se of an e sp e c ia lly la rg e and c a ta s tro p h ic f ire , m o st of the co n ta m in a n ts r e le a s e d w ould be d e p o s ite d in th e v ic in ity o f the a c c id e n t s i t e . T he d e p o site d m a te r ia l m ay be m o re w ide ly d is p e r s e d a s d u st i f co n d ition s a r e fav o u rab le fo r r e s u s p e n s io n (heavy t r a f f i c , w in d s , e t c . ) o r m a y be w ash ed in to s e w e r s o r p u b lic w a te r -w a y s b y h e a v y r a in o r w a te r u s e d to c o n tr o l th e f i r e .

3 . 2 .3 . R e le a s e of ra d io n u c l id e s f ro m e x p lo s iv e a c c id e n tT he e n v iro n m e n ta l c o n seq u e n c es of an a c c id e n ta l r e le a s e of ra d io n u c lid e s fo llow ing v a r io u s ty p e s of e x p lo s io n s a r e no t su ffic ien tly d is tin c t fro m the consequences of a f ire to suggest the need fo r sp e c ia l planning fo r em erg en cy m on ito ring . F o r

14


a c c id e n ts in v o lv in g c o m p a ra b le in v e n to r ie s of m a te r ia l s i t i s l ik e ly th a t t h e r e w ould be l e s s c o n ta m in a tio n o f th e e n v ir o n s in th e c a s e o f an e x p lo s io n th a n in th e e v e n t o f f i r e b e c a u se of lo w e r t e m p e r a tu r e s in th e v ic in ity of the s o u rc e of r a d io a c t iv e m a te r ia l s .

3 .2 .4 . N a tu ra lly c a u se d a c c id e n ts

F a c il i t ie s which a re loca ted in g eo g rap h ica l a r e a s w here n a tu r a l phenom ena m ay d e s tro y the in te g r i ty of p ro te c tiv e c o n finem en t fa c i l it ie s should have en v ironm en ta l em erg en cy p ro g ra m m e s w hich a r e e s p e c ia l ly s u ita b le fo r d e a lin g w ith the co n seq u e n c es of such a c c id e n ts . E x am p les of su ch phenom en a a r e t id a l w av es and e a r th q u a k e s . T h is c a te g o ry of a c c id e n ts canno t be p r e c is e ly defined but u n u su a l o c c u r re n c e s s u c h a s r u p tu r e o f u n d e rg ro u n d s to r a g e ta n k s an d r e l e a s e o f t h e i r c o n te n ts in to th e g ro u n d , r u p tu re o f u n d e rg ro u n d t ra n s p o r t lin e s and s im ila r re le a s e of th e ir con tents, w ashing of ra d io a c tiv e m a te r ia l s f ro m s h o re - lo c a te d e s ta b lis h m e n ts in to the s e a and flooding of n u c le a r e s ta b lish m e n ts by in lan d w a te r-w a y s cou ld a l l r e s u l t in u n usu a l dem ands fo r e ffe c tiv e e m e rg e n c y m o n ito r in g . T h e m o s t u n u s u a l f e a tu r e o f 'th i s ty p e of a c c id e n t i s p ro b a b ly the r e l e a s e of r a d io a c t iv e m a t e r i a l in to w a te r , e i th e r d ir e c t ly , o r in d i r e c t ly by r e l e a s e in to the ground . W hile a l l m odes of d is p e rs a l to the en v iro n s a r e p o ss ib le follow ing a n a tu ra lly c a u se d a cc id en t, the m o s t lik e ly d is p e r s a l ro u te s in the c a se of an ea rth q u ak e w ould be in to the g round o r in to the g ro u n d -w a te r , and in th e c a s e of t id a l w aves, the s lu ic in g of rad io nu c lid es fro m s h o re - lo c a te d e s ta b lish m e n ts in to the s e a -w a te r .

3 .2 .5 . N u c lea r e x cu rs io n

W hile a n u c le a r e x cu rs io n m ay pose sev ere , o n -s ite p rob lem s, i t i s n o t l ik e ly th a t s u c h an a c c id e n t w ou ld g iv e r i s e to an u rg e n t s itu a t io n in the p u b lic e n v iro n m e n t. A ny r e l e a s e of ra d io n u c lid e s f ro m th e s i t e w ould m o s t l ik e ly be v ia the a tm o s p h e r e . T a b le 1 .4 , in A nnex I , l i s t s e x a m p le s o f r e le a s e s fro m p o stu la te d e x c u rs io n s of v a r io u s m a g n itu d e s .

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Tlie n a tu re and e x ten t of the e n v iro n m e n ta l m o n ito r in g p e r fo rm e d follow ing the n u c le a r e x c u rs io n a t the SL -1 R e a c to r , NRTS, Idaho, USA, a re d e s c r ib e d in A nnex VII.

3 .2 .6 . P h y s ic a l lo s s of a ra d ia tio n so u rc eT h is typ e of a c c id e n t i s no t lik e ly to in v o lv e m any p e r s o n s in th e p u b lic d o m a in , bu t b e c a u s e of th e u n c e r ta in ty of the c i rc u m s ta n c e s , th e re w ill be in te n se d em a n d s on the e m e r gency en v iro n m en ta l te am to lo ca te the so u rc e b efo re e x c e s s iv e hum an e x p o su re o c c u rs o r b e fo re the so u rc e i s in a d v e rten tly d es tro y ed o r d isp e rse d , fo r exam ple, by burn ing . The d u ra t io n of the e m e rg e n c y m o n ito r in g p ro g ra m m e i s l ik e ly to be re la t iv e ly s h o r t . S e a rch in g w ith su ita b le in s tru m e n ts , fo r p ra c t ic a l r e a s o n s , w ill g e n e ra lly be l im ite d to lik e ly lo c a tio n s w h ere the lo s s of c o n tro l could have o c c u r re d . The e x te n t of e n v iro n m e n ta l m o n ito rin g cou ld expand s h a rp ly if the so u rc e should lo se i t s p h y s ic a l in te g rity th e re b y p e rm it t ing re le a s e and d is p e r s a l of the co n tam in an ts .

3 .2 .7 . R up tu re of c o n ta in e r

The ru p tu re ,b y im pact, of a device o r v e s s e l containing ra d io ac tiv e m a te r ia ls would in s ta n tly change the n a tu re of c o n tro l and m o n ito rin g re q u ire m e n ts . The c o n tro l of se a le d o r co n ta ined s o u rc e s p rin c ip a lly invo lves co n tro llin g a c c e s s of p e r so n s to the s o u rc e and c o n tro l l in g m o v em en t of the s o u rc e . W hen the p h y s ic a l in te g r i ty of th e c o n ta in e r b a r r i e r i s im p a i r e d th e u n in te n tio n a l r e l e a s e o f r a d io n u c l id e s to p u b lic a r e a s i s p o s s ib le .Such s itu a t io n s in v o lv in g e n v iro n m e n ta l m o n ito r in g c a n be d e s c r ib e d in tw o e x a m p le s : C o llis io n o r im p a c t a c c id e n t a t s e a o r on lan d . Such a c c id e n ts a r e f re q u e n tly acc o m p an ied by f i r e s . A re le a s e of rad io n u c lid es fro m an im p ac t acc id en t on lan d co u ld ta k e m any f o rm s . R e le a s e of m a te r ia l s in to s u r fa c e w a te r , f o r ex am p le r i v e r s o r la k e s , w ould r e q u ir e know ledge, gained by en v iro n m en ta l m on ito ring , of the quant i ty and fa te of th e r e le a s e d m a te r ia l s . S am p lin g o f w a te r and aq u a tic fo rm s would be re q u ire d u n til the ex ten t and ra te o f m o v e m e n t o f r e l e a s e d m a te r i a l s th r o u g h th e b io s p h e r e w e re d e te r m in e d .

16


In th e c a s e w h e re im p a c t o f v e h ic le s o r t r a i n s r e s u l t e d in the ru p tu re of the s o u rc e c o n ta in e r , e n v iro n m e n ta l m o n ito ring would m o st p robab ly be re q u ire d in the im m ed ia te v ic in ity o f th e a c c id e n t . D is p e r s io n and r e d i s t r ib u t io n by w e a th e r in f lu e n c e s o r s c a t te r in g of any r e le a s e d co n ta m in an ts by h u m a n o r v e h ic u la r t r a c k in g c o u ld q u ic k ly an d s u b s ta n t ia l ly a f fe c t th e am o u n t, lo c a t io n and ty p e of e n v iro n m e n ta l m o n ito r in g r e q u i r e d .R a d io a c tiv e m a te r ia l s a r e u su a lly t r a n s p o r te d in tw o ty p e s of packag ing , one w hich w ould be d e s tro y e d in a s e v e re a c c id en t' and the o th e r so ro b u s t th a t i t would w ith stand se v e re im p a c t and f i r e . In the fo rm e r type the ra d io a c tiv e co n te n ts a r e so l im ite d in qu an tity th a t th e ir r e le a s e w ould no t c a u se sig n ifican t h a z a rd ; in the la t te r type the escap e of the ra d io a c tiv e c o n te n ts , ev en u n d e r s e v e re a c c id e n t c o n d itio n s , i s h ig h ly im p ro b a b le .

3. 3 . D i s p e r s a l o f r e l e a s e d m a te r ia l in th e e n v ir o n m e n t a n d p o s s i b l e m o d e s o f e x p o s u r e o f p e r s o n s

A know ledge of the lik e ly p a tte rn s of d is p e r s a l of ra d io a c tiv e m a te r ia l r e l e a s e d to th e v a r io u s e n v iro n m e n ta l m e d ia c a n be of help in the p re d ic tio n of the ensu ing m odes of e x p o su re of p e r s o n s and in d e c id in g on the n a tu re and u rg e n c y of th e e m e rg e n c y m o n ito r in g p r o c e d u re s w h ich sh o u ld be u n d e r ta k e n . F o r c o n v e n ie n c e th e s e m e d ia a r e d is c u s s e d s e p a r a te ly bu t, of c o u rs e , m o re than one cou ld be c o n ta m in a te d s im u ltan eo u sly . P a t te rn s of d is p e rs a l in the a tm o sp h e re and re la t io n s h ip s b etw een dose and le v e l of co n ta m in a tio n of e n v iro n m e n ta l m e d ia a r e fu r th e r d is c u s s e d in A nnex II.

3 .3 .1 . D is p e r s a l in the a tm o s p h e reR ad ioac tive m a te r ia ls could be re le a s e d to the a tm o sp h e re in the fo rm of g a se s , a e ro s o ls o r v a p o u rs and th e ir su bseq u en t d i s p e r s a l w ould be la rg e ly d e te rm in e d by th e p r o c e s s e s of tu rb u le n t d iffu sion in the a i r . The re le a s e d m a te r ia l , in the f o r m o f a c lo u d , w ill g e n e r a l ly m o v e d o w n -w in d f r o m th e p o in t of r e l e a s e . M a te r ia l in i t ia lly in the fo rm of a e r o s o ls o r v a p o u rs m ay be d ep o sited fro m the cloud on to the ground by s e d im e n ta tio n o r m a y be c a r r i e d dow n by r a in o r snow .

17


It i s fe a s ib le , by the a p p lic a tio n of th e o r ie s co n ce rn in g t u r b u le n t d if fu s io n and on th e b a s is o f a n u m b e r o f p la u s ib le assu m p tio n s , to p re d ic t the t im e - in te g ra l of the concen tra tion of a i r -b o rn e rad io ac tiv e m a te r ia l , in c u r ie -se c o n d s p e r cubic m e tr e , a t any po in t n e a r th e s u r fa c e of th e e a r th r e s u l t in g fro m the p a ss in g cloud, and the s u rfa c e co n c e n tra tio n of d e p o s i te d m a te r ia l a t p r e s c r ib e d d is ta n c e s f ro m th e p o in t of r e l e a s e . In A nnex II ty p ic a l c u rv e s a r e p re se n te d w hich in d ica te the p robable v a ria tio n with d is tance of the t im e -in te g ra l o f th e c o n c e n tra t io n fo r v a r io u s m e te o ro lo g ic a l c o n d itio n s . Such c u rv e s could be of a s s is ta n c e in the planning of the in it ia l e m e rg e n c y s u rv e y s and in the s e le c t io n of m e a s u r in g te c h n iq u e s of ad eq u a te s e n s it iv i ty .A v a r ie ty of m odes of ex p o su re of p e rso n s m ay be a s so c ia te d w ith a r e l e a s e of ra d io a c tiv e g a s e s o r a e r o s o ls to th e a tm o s p h e re . T hey in c lu d e :(a) W hole-body exposure to e x te rn a l rad ia tio n fro m the cloud;(b) W hole-body ex posu re to e x te rn a l rad ia tio n fro m m a te r ia l

d ep o sited on the ground o r o th e r su rfa c e s ;(c) W h o le- o r p a r t ia l - b o d y e x p o su re to e x te r n a l r a d ia t io n

f ro m m a te r ia l s d e p o s ite d on th e sk in o r c lo th e s ;(d) E x p o su re to in te rn a l ra d ia tio n follow ing inha la tion of a i r

bo rne m a te r ia l o r d is tu rb e d d eposited m a te r ia l;(e) E x p o su re to in te rn a l ra d ia tio n follow ing in g estion of con

tam in a te d food o r w a te r .Some typ es of exposure m ay begin v e ry soon a f te r the re le a se , fo r exam ple e x p o su re to e x te rn a l rad ia tio n fro m the cloud o r in h a la tio n of a i r - b o r n e m a te r ia l ; o th e r ty p e s m ay b eg in a t a l a t e r s ta g e an d co u ld p e r s i s t o v e r a long p e r io d o f t im e , fo r e x a m p le th e in g e s t io n o f d e p o s ite d m a te r ia l in i t s p r o g r e s s io n th ro u g h fo o d -c h a in p a th w a y s .Since ra d io a c tiv e m a te r ia ls in hazard&u& c o n c e n tra tio n s m aythe a tm o sp h e re , e m e rg e n c y m o n ito rin g m ay be u rg e n tly r e q u ire d to d e te rm in e the c o n c e n tra t io n of a i r - b o r n e and d e p o sited m a te r ia l o v e r a v e ry la rg e a r e a . It should be re c o g n ized , how ever, th a t the avoidance of hum an ex posu re during th e p e r io d im m e d ia te ly fo llo w in g a su d d e n r e l e a s e o v e r a s h o r t p e r io d of t im e i s n o t f e a s ib le by m e a s u r e s b a s e d on e n v iro n m e n ta l m o n ito r in g . M on ito rin g , h o w e v e r, m a y be

d is tan ces following a r e le a s e to


re q u ire d o v e r an ex tended p erio d of tim e to follow the m ovem en t of co n tam in an ts th rou g h food -chain pathw ays.

3. 3 .2 . D is p e rs a l in su rfa c e w a te rs

R a d io a c tiv e m a te r ia l cou ld e n te r la k e s and r i v e r s d ir e c t ly , fo r ex am p le a s liq u id w a s te s o r a s m a te r ia l d e p o site d f ro m th e a tm o s p h e re , o r in d i r e c t ly , f o r e x a m p le a s d e p o s i te d m a te r ia l c a r r ie d by r a in -w a te r . The d is p e r s a l p a t te rn s and m e c h a n ism s , fo r ex am p le , d iffu sio n of d is so lv e d m a te r ia ls , su sp e n s io n of so lid s and ion -exchang e w ith o th e r m ed ia , can in f lu e n c e th e su b se q u e n t p a thw ay o f e x p o su re to m a n f ro m m a te r ia l s r e le a s e d to s u r fa c e w a te r s . I t m ay be a d v is a b le to m a k e a p r i o r s tu d y of th o s e w a te r s in to w h ich l a r g e a c c id e n ta l r e l e a s e s m ig h t o c c u r .T h e m o d e s of e x p o su re co u ld in c lu d e :(a) E x p o su re to e x te rn a l ra d ia t io n fo llow ing im m e rs io n in ,

o r c lo se a p p ro a c h to , c o n ta m in a te d w a te r ;(b) E x p o su re to in te rn a l ra d ia tio n follow ing in g es tio n of co n

tam in a ted w a te r;(c) E x p o su re to in te rn a l ra d ia tio n fo llow ing the in g e s tio n of

con tam inated fish o r w a te r p lan ts o r the ingestion of food- c ro p s i r r ig a te d by con tam inated w ater;

(d) E x p o su re to in te rn a l ra d ia tio n follow ing the consum ption of m ilk p ro d u c ed by cow s fed on p a s tu re s i r r ig a te d w ith c o n ta m in a te d w a te r .

T he m o s t im p o rta n t m ode of ex p o su re in the p e rio d im m e d ia te ly fo llo w in g a r e l e a s e w ould be by th e in g e s t io n o f c o n tam in a ted w a te r . In an em erg en cy s itu a tio n it would be n e c e s s a r y to p ro v id e f o r v e r y e a r l y an d r a p id m o n i to r in g of p o s s ib ly c o n ta m in a te d s u r f a c e w a te r s w h ich m ig h t be u se d fo r h u m an c o n su m p tio n .

3 .3 .3 . D i s p e r s a l in th e s e a

R a d io a c tiv e m a te r i a l co u ld e n te r th e s e a d ir e c t ly , f o r e x a m p le , a s a r e s u l t of an a c c id e n ta l r e le a s e f ro m an i n s t a l la tio n lo c a te d a t th e edge of the se a , a s a r e s u l t of s e v e r e d am a g e to a n u c le a r sh ip o r to a s h ip c a r r y in g ra d io a c t iv e m a te r ia l s , o r by d ep o sitio n fro m the a tm o sp h e re . T he m a

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t e r i a l co u ld a ls o e n t e r th e s e a in d i r e c t ly th ro u g h a f r e s h w a te r p a th w a y . T h e o r e t ic a l ly , a p p lic a t io n of a p p ro p r ia te d iffu sion e q u a tio n s3 to g e th e r w ith p re l im in a ry s tu d ie s of the a r e a m a y p e r m i t p re d ic t io n o f th e g e n e r a l p a t te r n o f d i s p e r s a l . In p r a c t ic e , a s in the a tm o s p h e r ic c a s e , r e l ia n c e would have to be p laced on m e a su re m e n ts m ade subsequen tly to the acc id en t.

The p rin c ip a l m odes of ex p o su re inc lude:(a) E x p o su re to e x te rn a l r a d ia t io n by im m e rs io n in the s e a

o r by c lo se ap p ro ach to con tam inated beaches o r handling of a r t ic le s w hich have becom e contam inated w ith d e tritu s , s ilt , e tc . ;

(b) E x p o s u re to in t e r n a l r a d ia t io n by c o n su m p tio n o f c o n ta m in a te d s e a - fo o d .

T he m o s t im p o rta n t m ode of e x p o su re m ay be the co n su m p tio n of co n ta m in a te d se a -fo o d ; so m e m a r in e o rg a n is m s can c o n c e n t r a te c e r t a i n r a d io n u c l id e s by f a c to r s o f 1 0 4 -1 0 6 .The e n v iro n m en ta l m o n ito rin g re q u ire d follow ing c o n ta m in a tio n of s e a -w a te r i s u su a lly no t u rg e n t in n a tu re a s the co n su m p tio n of s e a -fo o d and e x p o su re to c o n ta m in a te d a r t i c le s c an be re la t iv e ly e a s i ly c o n tro lle d pending a d e ta ile d in v e s tig a tio n of the d is p e r s a l of the co n tam in an ts . P ro longed m o n ito r in g m a y , h o w e v e r, be r e q u i r e d in o r d e r to t r a c e th e p h y s ic a l loca tio n of re le a s e d lo n g -liv e d co n tam in an ts in s e a w a te r an d t h e i r s u b s e q u e n t u p ta k e in m a r in e o r g a n is m s . T h e re w ould be a g r e a t e r d em and fo r e n v iro n m e n ta l m o n ito r in g follow ing a r e le a s e to c o a s ta l w a te r in re g io n s w h ere c u r r e n t s flow to w a rd s the land o r in re g io n s w h ere se a -fo o d i s g a th e re d , fo r e x a m p le n e a r o y s t e r b e d s , th a n fo llow ing a r e l e a s e in to d eep w a te r .

3 . 3 .4 . D i s p e r s a l in th e s o i lR adioactive m a te r ia l could be d is p e rse d in the su rface la y e rs of the so il follow ing an a c c id e n ta l s p il l o r by d eposition fro m

3 S e e , for e x a m p le . In te rn a tio n a l A to m ic Energy A g e n c y , R a d io a c tiv e W a ste D isposal

in to th e S e a , A p p en d ix V I , S a fe ty S e r ie s N o. 5 , IA E A , V ie n n a (1 9 6 1 ) 1 7 4 pp.

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th e a tm o s p h e re . L iq u id ra d io a c t iv e m a te r ia l s r e le a s e d in the u p per la y e rs of p e rm eab le so il could p e n e tra te to the su b so il; p a r t ic u la te m a te r ia l d e p o site d on the su r fa c e cou ld be c a r r ie d to the su b so il by r a in . R ad io ac tive m a te r ia ls could a lso be re le a s e d d ire c t ly in the su bso il, fo r exam ple , follow ing the ru p tu re of underg round c o n ta in e rs o r p ip e - lin e s . The su b se q u e n t d i s p e r s a l w ill be d e te rm in e d by the n a tu re of the su b so il and the ex ten t and ra te of m ovem ent of the u n d e rg round w a te rs .The m odes of e x p o su re include:(a) E x p o s u re to e x te r n a l r a d ia t io n f ro m th e c o n ta m in a te d

s o il ;(b) E xposu re to in te rn a l rad ia tio n following inha la tion of con

tam in ated dust;(c) E x po su re to in te rn a l rad ia tio n follow ing in g estion of con

tam in a ted c ro p s o r w ater;(d) E x p o su re to in te rn a l ra d ia tio n follow ing the consum ption of

c o n ta m in a te d w a te r f r o m w e lls o r th e c o n su m p tio n o f c ro p s which have been ir r ig a te d w ith con tam inated g round w a te r.

T he e m e rg e n c y m o n ito rin g re q u ire d w ould inc lu d e the m e a su re m e n t of a i r and s u r fa c e co n ta m in a tio n o v e r a re la t iv e ly sh o r t p e rio d of tim e . The subsequen t m o n ito rin g of the s u r face la y e rs of the so il and of n earb y su rface w a te rs and v eg eta t io n o v e r an ex ten d e d p e r io d of t im e m ig h t be r e q u i r e d . Should p e n e tra t io n to th e s u b s o il be s u sp e c te d , e m e rg e n c y m onito ring should be concerned w ith the m e asu rem en t of conta m in a tio n in n e a rb y w e lls u sed fo r d rin k in g w a te r . Owing to the p o s s ib ly v e r y s lo w m o v em en t of u n d e rg ro u n d w a te r , lo c a l w a te r supp lies used fo r ir r ig a tio n p u rp oses o r consum ed by p e r s o n s o r d o m e s tic a n im a ls sh o u ld be m o n ito re d o v e r an ex ten d e d p e r io d of t im e .

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4. THE EM ERGENCY MONITORING PROGRAMME

A ction following an em ergency w ill need to be rap id and decisive . A s a m a t te r of p ru d e n c e , th e r e f o r e , the p ro c e d u re s to be adop ted shou ld , a s f a r a s p o ss ib le , be c o n s id e re d and d ec id ed upon by the a p p ro p r ia te a u th o r ity b e fo re an a c c id e n t r a th e r than im p ro v ise d a f te rw a rd s in an a tm o sp h ere of panic . T his sec tio n a ttem p ts to give guidance on fa c to rs which need to be taken into account when planning both the en v iron m en ta l m onito ring p ro g ram m e and the o v e ra ll e m e r gency sch em e . P lanning in the g re a te s t d e ta il i s obviously p o ssib le in re s p e c t of an acc iden t a t a fixed in s ta lla tio n and em phasis i s th e re fo re p la c e d on th is a s p e c t , bu t th e p r in c ip le s inv o lv ed a r e eq u a lly a p p lic a b le to m o n ito rin g p ro g ra m m e s and e m e rg e n c y sc h e m e s d e s ig n ed to c o v e r o th e r s itu a tio n s .

4. 1. Formulation of an appropriate monitoring p rogram m e

4. 1. 1. P r e l im in a ry in fo rm a tio n re q u ire dT he p r im a r y a im of any e m e rg e n c y e n v iro n m e n ta l m o n ito r in g p ro g ram m e is to supply the in fo rm ation needed to decide what ac tion , i f any, h as to be tak en to l im it the rad ia tio n ex posu re of m e m b e rs of the p u b lic . M o reo v e r, a t the p lann ing s ta g e , su ffic ien t in fo rm ation m u st be av a ilab le to p e rm it the a s s e s s m en t of the co n seq u e n c es of the ty p e s of a c c id e n ta l r e le a s e s to en v iron m en ta l m ed ia w hich can reaso n ab ly be fo re se e n and h en ce the ex ten t of the e m e rg e n c y su rv e y n eed ed . Such in fo rm a tio n , h o w ev er, i s v a lu e le s s u n le s s th e r e a r e c r i t e r i a by w hich i t s s ig n if ic a n c e c a n be ju d g ed . T he f i r s t r e q u i r e m e n t of th o se p lann in g the e m e rg e n c y e n v iro n m e n ta l m o n ito r in g p ro g ra m m e is , th e r e f o r e , g u id an ce on th e le v e ls of rad ia tio n and rad io ac tiv e con tam ination co n sid ered sign ifican t u n d e r e m erg en cy cond itions and, p a r t ic u la r ly , on the lev e ls a t w hich re m e d ia l ac tio n m u st be c o n s id e re d .T he typ e of a c tio n r e q u ir e d to m itig a te th e c o n se q u e n c e s of an a c c id e n ta l r e le a s e w ill depend upon the n a tu re of the p o s tu la ted acc iden t and the ro u te s th rough which people a re likely to be ex p o sed to ra d ia t io n . G e n e ra l g u idance on the m a g n itud e and n a tu re of p o ss ib le r e l e a s e s i s g iven in s e c tio n 3. 2.

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T he p o te n tia l ro u te s of e x p o su re f ro m ra d io a c t iv e m a te r ia l r e le a s e d in to the v a r io u s m e d ia have been d e s c r ib e d in s e c tio n 3 .3 . The s ig n ifican ce of th e se v a r io u s ro u te s should be d e te rm in e d fo r th e in s ta l la tio n in q u es tio n by ex am in in g the so c ia l , d ie ta ry , a g r ic u l tu r a l and o th e r p r a c t ic e s of the p o p u la tio ns lik e ly to be affected by a re le a s e of rad io ac tiv e m a t e r i a l . Such p o pu la tio n s w ill u su a lly be th o se in the v ic in ity of the in s ta l la tio n bu t the p o s s ib il i ty of e x p o su re of o th e r people e i th e r a s a r e s u l t of an o m alo u s m o v e m e n t of ra d io n u c lid e s in the a i r , o r in su rfa c e o r un derg ro un d w a te rs , o r a s a r e s u lt of c o n su m p tio n o f fo o d s tu ffs h a r v e s te d in th e a f fe c te d a r e a sh o u ld be b o rn e in m in d . F r o m th e s e s tu d ie s i t w ill beco m e c l e a r w h ich m a te r ia l s p ro v id e th e p r in c ip a l ro u te s o f e x p o su re and t h e r e f o r e sh o u ld r e c e iv e i n i t i a l a t te n tio n .L o c a l g e o g ra p h ic a l f e a tu r e s m a y b e su c h th a t so m e p eop le m ay be a t g r e a te r r i s k than o th e r s . P r e l im in a ry s tu d ie s of w ea th e r conditions — fo r exam ple v a ria tio n s in wind d irec tio n and veloc ity and o th e r fa c to rs which m ay affect the c o n cen tra tion of a ir-b o rn e m a te r ia l o r i ts deposition on the ground s u r fa c e — of m o v e m e n ts of b o d ie s of w a te r in to w hich a c tiv ity m ay be a c c id e n ta l ly d is c h a rg e d and, i f p o s s ib le , of th e d i re c t io n and sp e e d o f flow of u n d e rg ro u n d w a te r s in c a s e of p o s s ib le h e a v y c o n ta m in a tio n o f th e s o il , sh o u ld t h e r e f o r e be u n d e r ta k e n to e s t a b l i s h w h e re s a m p lin g w ou ld be m o s t e f fe c tiv e . W hen c a r r y in g out s i t e - s tu d ie s of th is ty p e i t i s a lw ays p ru d en t to c o n s id e r the adv ice of a p p ro p r ia te e x p e r ts know ing lo c a l c o n d itio n s . Som e d a ta m ay w e ll be a v a ila b le f ro m s tu d ie s c a r r ie d out fo r o th e r r e a s o n s .

4. 1 .2 . G e n e ra l c o n s id e ra tio n s

(a) When the re le v a n t in fo rm ation outlined in sec tio n 4. 1 .1 has b een c o lle c te d fo r the p a r t ic u la r in s ta l la t io n , a m o n ito r in g p ro g ram m e can be fo rm u la ted . The type of p ro g ram m e needed w ill v a ry a c c o rd in g to in d iv id u a l c i r c u m s ta n c e s and only th e m o s t g e n e ra l c o m m e n ts can be m a d e .On th e one hand, th e p re l im in a r y s tu d ie s m ay show th a t no acc id en t of su ffic ien t m agnitude to have an im p ac t ou tside the s i te i s fo re s e e a b le . In su ch a c a s e no e m e rg e n c y e n v ir o n m e n ta l m o n ito rin g p ro g ra m m e is n eed ed . T h is s itu a tio n is

2 3


l ik e ly to p r e v a i l a t in s ta l la t io n s p ro c e s s in g on ly r e la t iv e ly n o n - to x ic n u c lid e s , such a s n a tu r a l u ra n iu m . A t th e o th e r e x t r e m e , w id e s p re a d c o n s e q u e n c e s a r e l ik e ly to be found, and h en ce e x te n s iv e su rv e y s w ill be n eed ed , i f th e re i s any p o ss ib il i ty of a su b s ta n tia l r e le a s e of m ixed f is s io n -p ro d u c ts in to th e a tm o s p h e re in an a g r i c u l tu r a l a r e a , and , in p a r t ic u la r , of i s i j in to the a tm o sp h e re in a m ilk -p ro d u c in g a re a .R e le a s e s to th e a tm o s p h e re , b e c a u s e of th e r a p id i ty w ith w hich a c tiv ity can be d isp e rse d in th is m edium , w ill g e n e ra lly dem and m o re u rg en t ac tion and thus re q u ire m o re de ta iled p lann ing than r e le a s e s to bod ies of w a te r o r the g ro u nd . In deed , a t in s ta l la tio n s fro m w hich r e le a s e s in to a lak e o r the s e a c a n be p o s tu la te d , ro u tin e e n v ir o n m e n ta l s u r v e y s a r e o ften co n d uc ted and i t i s v e ry p ro b a b le th a t any e m e rg e n c y s itu a tio n can be adequate ly d ea lt w ith by in c re a s in g the f r e quency and sco p e of sa m p lin g u n d e rta k e n fo r ro u tin e p u rp o s e s .T he r e l e a s e to th e a tm o s p h e re of n u c lid e s w hich e n te r in to fo o d -ch a in s (in p a r t ic u la r , iso to p e s of iod ine , s tro n tiu m and c a e s iu m ) r e q u i r e m o re d e ta i le d and e x te n s iv e p lann in g fo r e n v iro n m e n ta l m o n ito rin g than a r e le a s e of th o se w hich p r e sen t p r im a r i ly an e x te rn a l ra d ia tio n h a z a rd (for exam ple the noble g a s e s ) .(b) U n le ss l a r g e r e s o u r c e s of m a n p o w e r and e q u ip m en t a r e a v a ila b le , i t i s s e n s ib le to r e s t r i c t p lann in g in d e ta i l to the "m ax im um fo re se e a b le a cc id en t" . At the sam e tim e the plan sh o u ld be k ep t s u f f ic ie n tly g e n e ra l and f le x ib le to d e a l w ith o th e r , l a r g e r o r s m a l le r , e m e rg e n c ie s s in c e the n a tu re of a c c id e n ts is such th a t it is n e v e r p o ss ib le to p re d ic t p re c ise ly w hat w ill o c c u r . Som e im p ro v is a t io n on the b a s ic p lan w ill a lm o s t inev itab ly be req u ired , p a r tic u la r ly in the la te r s tages a s m o n ito rin g is extended, but ev e ry endeavour m ust be m ade to e n s u r e th a t th e im m e d ia te s u rv e y , i . e . th a t p a r t of th e m o n ito r in g p ro g ra m m e d e s ig n e d to p ro v id e in fo rm a tio n on w hich im m e d ia te r e m e d ia l a c tio n can be b ased , can be c a r r ie d ou t w ithou t h e s i ta t io n . It i s t h e r e f o r e im p e ra t iv e th a t su ff ic ie n t v e h ic le s , m o n ito r in g e q u ip m en t and p e rs o n n e l be a v a ilab le a t a l l t im e s on an o p e ra tio n a l b a s is to m ake a rap id in i t ia l a s s e s sm e n t of the situ a tio n and tha t the co u rse of action of m o n ito rin g te a m s sen t out into the fie ld be c le a r ly defined. S ince, a s pointed out above, a r e le a s e of rad io n u c lid es to the


a tm o sp h e re i s m o re lik e ly to re q u ire ra p id ac tio n than a r e l e a s e to b o d ie s of w a te r o r to th e s o il , w ith th e e x c e p tio n p e rh a p s of t r a n s p o r t a c c id e n ts o r o th e r a c c id e n ts invo lv ing the re le a s e of ra d io n u c lid e s into w a te r in tended fo r consum ption , in the ensu ing d isc u ss io n em p h a s is is p laced on the r e q u ire m e n ts fo r dea ling w ith an a i r -b o rn e re le a s e .It is not u sua lly n e c e ssa ry , even if the "m axim um fo reseea b le a c c id e n t" could invo lve a r e la t iv e ly l a rg e r e l e a s e of r a d io ac tiv e m a te r ia ls , to have a la rg e r e s e r v e of v e h ic le s , equ ip m e n t an d m e n s e t a s id e s o le ly f o r e m e rg e n c y u s e . Som e in s ta lla tio n s w ill have ro u tin e e n v iro n m en ta l m o n ito rin g p ro g ra m m e s in o p era tio n . V eh ic les used in such rou tine su rv ey s can be equipped w ith su itab le em erg en cy in s tru m e n ta tio n , and p ro v is io n can be m ade in th is w ay fo r ra p id au g m en ta tio n of th e e m e rg e n c y s e r v i c e s w h ic h a r e im m e d ia te ly a v a i la b le . H ow ever, i t i s e s s e n t ia l th a t su ch f a c i l i t ie s should be a v a i l a b le a s w ill e n s u re th a t th e r e w ill be no d e la y in o b ta in in g m e a s u r e m e n ts v i ta l ly r e q u i r e d fo r ta k in g d e c is io n s on r e m e d ia l a c tio n .In the in te r e s t of ra p id ac tio n , i t i s ob v io u sly d e s ir a b le tha t th e te a m s r e s p o n s ib le f o r th e im m e d ia te s u rv e y sh o u ld be c e n tre d on the in s ta lla tio n . H ow ever, the ad d itio n a l su rv ey s w hich m ay su b se q u e n tly be n eed ed cou ld r e q u ir e m o re p e r so n n e l and equ ipm ent than a r e in i t ia lly a v a ila b le . P ro v is io n shou ld th e re fo re be m ade fo r invoking a s s is ta n c e fro m o th e r s o u rc e s if n e c e s s a ry .A n a ly t ic a l s e r v ic e s m u s t a l s o be a d e q u a te to p r o c e s s th e s a m p le s c o lle c te d by the m o n ito rin g te a m s and p la n s should be m ade to su p p lem en t th e se s e rv ic e s by help fro m o th e r s o u rc e s a s re q u ire d . P la n s shou ld a lso be d raw n up fo r the la b o r a to ry p ro c e d u re s to be ad o p ted fo r a n a ly se s of th e e n v iro n m e n ta l sa m p le s c o lle c te d by the m o n ito rin g te a m s . In g e n e ra l the a n a ly tic a l p ro c e d u re s should be s im p le , in o rd e r to avoid u n n e c e s s a ry o v erload in g of the la b o ra to ry fa c i l i t ie s , but capab le of y ie ld ing the re q u ire d in fo rm ation w ith adequate p re c is io n in a s sh o r t a tim e a s p o ss ib le . Some of th e se co n s id e ra tio n s a r e d isc u sse d in m o re d e ta il in Annex V.(c) T h e ro u te s to be ta k e n by m o n ito r in g v e h ic le s (o r th e flig h t p a th s in the c a s e of a i r c r a f t ) and the lo c a t io n s of

2 5


sa m p lin g p o in ts fo r p a r t i c u la r m a te r ia l s sh ou ld be c l e a r ly defined . T he ro u te s chosen should, a s fa r a s p o ss ib le , be tho se w hich would re m a in p a ssa b le u n d e r a d v e rse w ea th e r cond itions and sam p lin g p o in ts should be cap ab le of being re a d i ly lo c a te d . T h e o r d e r in w h ich s a m p lin g p o in ts a r e v is i t e d sh o u ld , in g e n e ra l, e n su re tha t m on ito ring te a m s w ork inw ard s to w a rd s th e a r e a s of h ig h es t con tam in atio n thu s avoiding u n n e c e ssa ry co n ta m in a tio n of in s tru m e n ts and p e rso n n e l. H ow ever, i t is im p o r ta n t th a t the o v e ra l l ex ten t of the c o n ta m in a tio n of the e n v iro n m e n t be a s c e r ta in e d qu ick ly .Som e g u id an ce of th e s e le c t io n of m o n ito r in g and s a m p lin g p o in ts i s g iven in s e c tio n s 4. 1. 1 and 5 .2 .2 . (a). T he adv ice o f e x p e r ts sh ou ld be so ug h t i f th e r e i s an y doub t r e g a rd in g th e a p p ro p r ia te n e s s o f the lo c a tio n of s a m p lin g s ta t io n s , m e th o d s of sa m p lin g and ty p e s of la b o r a to r y a n a ly s e s . In ad d ition to the above ite m s , in s tru c tio n s to the m onitoring team s should include a c le a r defin ition of the p ro c e d u re s to be u sed in m e asu rin g and sam pling, re lay ing in fo rm ation to the e m e r g ency c o n tro l c e n tre , t r a n s f e r r in g s a m p le s to the a n a ly tic a l la b o r a to r ie s and, m o s t p a r t ic u la r ly , in re c o rd in g a l l o b s e r v a tio n s and a c tio n s .

4 .1 .3 . The need fo r p re -e m e rg e n c y su rv e y s

The type of ac c id e n t en v isag ed m ay o r m ay no t c a l l fo r p r e e m e rg e n c y ra d ia tio n s u rv e y s . B ackground su rv e y s a r e e s s e n tia l , fo r ex am p le , i f the m ax im um u se i s to be m a d e of m e a su re m e n ts of gam m a d o s e - ra te s above the ground su rface to p re d ic t the le v e l of co n tam in a tio n l ik e ly to be found in food. T h e i r c o m p le x ity i s d e te rm in e d by th e m e th o d o f e m e rg e n c y s u rv e y s chosen : they should be c a r r ie d out o v e r the ro u te s o r a t the lo c a t io n s , and u s in g th e m e th o d s th a t w ould be u s e d in the e v e n t o f an e m e rg e n c y . T h e ir f re q u e n c y sh o u ld be d e t e r m in ed by th e v a r ia t io n in b ack g ro u n d m e a s u re m e n ts ,w h ic h c o n s id e ra t io n , f o r e x a m p le , of the c u r r e n t s i tu a t io n w ith r e g a r d to f a l l -o u t cou ld be e x p e c te d to r e v e a l .

P r e -a c c id e n t s u rv e y s have a s u b s id ia ry value a s a m e an s of t r a in in g p e rso n n e l. If they a r e not c a r r ie d out, it i s n e c e s s a r y tha t m on ito ring te a m s should be m ade fa m ilia r w ith p r e

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a r ra n g e d ro u te s , lo c a tio n s and p ro c e d u re s by freq u en t e x e r c is in g . S im ila r ly , la b o r a to ry p e rs o n n e l sh ou ld have e x p e r ie n c e in th e u s e of s ta n d a r d iz e d a n a ly t ic a l te c h n iq u e s .

4 . 1. 4 . I n i t ia l d e te c tio n and a s s e s s m e n t of a c c id e n ta l r e l e a s e

T he e v e n ts le a d in g up to in i t ia tio n of the im m e d ia te s u rv e y m a y b e s u m m a riz e d a s : (a) d e te c tio n of an a b n o rm a l co n d ition and (b) a s s e s s m e n t of the s ig n if ic a n c e of th e a b n o rm a l s i t u a tio n . T h e r e s u l t s o f th e s u rv e y a r e u s e d to c o n f i rm th e e s t im a te d s ig n if ic a n c e o f th e s i tu a t io n an d to d e c id e w hat a c tio n n eed s to be tak en to m in im ize the co n seq u e n c es of the in c id en t.(a) D e tec tio n of a b n o rm a l r e le a s e sIn m any c a s e s re lia n c e fo r d e tec tio n of an ab n o rm a l condition i s p laced on m on ito ring d ev ices in s ta lle d w ithin the e s ta b lish m e n t. T h e s e in c lu d e in s t r u m e n ts su c h a s c o n tin u o u s a i r s a m p le rs in la b o ra to r ie s , leakage d e te c to rs in r e a c to r co o ling s y s te m s , c r i t ic a l i ty a la r m s y s te m s , and con tinuous m o n ito rin g d ev ic es in s ta c k s o r on effluent l in e s . In such c a s e s the p r im a ry re s p o n s ib il i ty fo r in it ia tin g a c tio n m ay w ell fa ll upon the o p e ra to r who h ap p en s to be a le r te d by the in s ta lle d a la rm sy s te m . Standing in s tru c tio n s should th e re fo re specify w hat he is re q u ire d to do and, p a r t ic u la r ly , to whom he should r e p o r t . L e s s co m m o n ly , p a r t of an e m e rg e n c y m o n ito r in g p ro g ram m e m ay be o p era ted continuously a s p a r t of an o p e ra tio n a l d e tec tio n sy s te m . F u r th e r r e fe re n c e to su ch m ethods i s m ade in s e c tio n 5.(b) P r e l im in a ry a s s e s s m e n t of the s ig n ifican ce of a r e le a s eT he s ig n if ic a n c e of a r e le a s e can be a s s e s s e d only a f te r the event, but i t is p o ss ib le to m ake p ro v is io n s in the em erg en cy p lan to e a s e th e t a s k of the p e rs o n c a l le d upon to c a r r y out th is a s s e s s m e n t . S ince th is ta s k i s one w hich inv o lv es su b s ta n t i a l r e s p o n s ib i l i ty , a r r a n g e m e n t s sh o u ld be m a d e f o r s e v e r a l co m p eten t in d iv id u a ls to be av a ila b le a t s h o r t no tice a t a l l t im e s .

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(i) E s tim a tio n of the m agnitude of a r e l e a s e . An e s ta b lis h m e n t m ay be such th a t i t i s p o ss ib le to l i s t th o se b u ild in g s o r l a b o r a to r i e s in w h ich th e a m o u n ts o f n u c lid e s held a r e su ffic ien t, in th e o ry , to give r i s e to an o ff -s i te e m e rg e n c y shou ld th e y be in v o lv ed in an in c id e n t . In d raw in g up su ch a l i s t c o n s id e ra tio n shou ld be g iven to th e p h y s ic a l fo rm in w h ich th e n u c lid e s a r e h e ld and w h e th e r they a r e co n ta in ed , fo r su ch fa c to r s w ill in f lu en ce , fo r e x a m p le , th e p ro p o r tio n of th e m a te r ia l r e le a se d a s the re s u l t of a f i r e . In any c a se c le a r in s t ru c tio n s shou ld be la id down th a t a l l in fo rm a tio n a v a ila b le fro m the s ite of the acc id en t should be re la y e d to the r e sp on sib le p e rso n in ch a rg e a s soon a s p o ss ib le .

(ii) A cqu isition of m e te o ro lo g ica l and hy d ro lo g ica l d a ta . The p re v a ilin g w e a th e r co n d ition s m ay p ro found ly a ffe c t the s ig n if ic a n c e of an a b n o rm a l r e l e a s e to th e a i r . I t i s th e re fo re e s s e n t ia l th a t the p e rs o n re s p o n s ib le fo r the in i t ia l a s s e s sm e n t should have im m ed ia te a c c e s s to m e te o ro lo g ic a l in fo rm a tio n . S u ff ic ien t e q u ip m e n t sh ou ld be in s ta lle d on the s ite a t le a s t to p ro v id e an in d ica tion of wind d ire c tio n and speed , and standing a rra n g e m e n ts fo r obtaining su pp lem en tary in fo rm ation fro m o th e r m e te o ro lo g ic a l s ta tio n s sh ou ld be d e ta i le d in th e o v e ra l l e m e rg e n c y p lan .M eteoro log ical data and, in the case of re le a s e to a r iv e r , in fo rm a tio n on i ts r a te of flow a re a lso e s s e n tia l to en s u r e th a t the m o n ito r in g te a m s im m e d ia te ly a v a ila b le a re deployed a s e ffec tive ly a s p o ssib le a f te r an acc iden t.T h e re w ill be le s s need fo r u rg en cy in the c a se of a r e le a se to o th e r bodies of w a te r but in fo rm ation of the p r e v a ilin g w inds and d ir e c t io n of w a te r m o v em en t m ay be re q u ire d a t a l a te r s ta g e .

4. 2 . O rg a n iza tio n and s ta ff in g4 .2 .1 . O rg an iza tio n

C o n tro l of e m e rg e n c y a r ra n g e m e n ts w ill be e x e rc is e d by an e m e rg e n c y c o n tro l o rg a n iz a tio n lo c a te d in an a d e q u a te ly

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equipped c e n tre so situ ated that it w ill re m a in ten ab le under the con d ition s of a postu lated e m e rg en cy .

T he m o n ito rin g o rg a n iz a tio n fo rm s a com ponent p a rt o f the em erg en cy co n tro l organization . It w ill co n sis t e sse n tia lly of:

(a) M onitoring co n tro l cen tre

It i s th e ta s k o f the m o n ito rin g c o n tr o l c e n tr e to d ir e c t the m o n ito rin g te a m s , to c o l le c t and a s s e s s th e d ata p rov id ed by th e se te a m s , and to p re d ic t fu ture tre n d s . The in fo r m a tion assem b led by the m onitoring co n tro l cen tre w ill be t r a n s m itted to the em erg en cy co n tro l ce n tre . The use of a co n tro l ce n tre in a p ra c tice e x e r c is e i s illu stra te d in F ig . 1.

FIG . 1 . Em ergency con tro l ce n tre being used for a p ra ctic e e x ercise (Hanford P ro ject - USA)

(b) M onitoring team s

It i s the ta s k of the m o n ito rin g te a m s to p e r fo rm th e m o n ito rin g o p eration s and to tra n sm it the re s u lts of the m e a s u re m e n ts to the m o n ito rin g c o n tro l c e n tr e . T h e s e m o n ito rin g

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o p e ra t io n s w ill in c lu d e th e in i t ia l su rv e y and any su b se q u e n t s u rv e y s re q u ire d .In te rp re ta tio n of the r e s u l ts ob tained by the m o n ito rin g team s w ill r e q u ir e e x p e r t is e w hile ex ecu tio n of th e m e a s u r e s p lanned to m in im iz e th e c o n s e q u e n c e s of th e a c c id e n t w ill a lm o s t c e r ta in ly re q u ire the c o -o p e ra tiv e e ffo r ts of a n u m b e r 'o f o r g a n iz a tio n s . It i s th e r e f o r e d e s i r a b le th a t l ia is o n b e tw een the m a n a g e m en t of the e s ta b lis h m e n t and o u ts id e a u th o r i t ie s be m a in ta in e d , and i t i s e s s e n t i a l th a t th e e m e rg e n c y p la n in c lu d e a r r a n g e m e n t s f o r n o tify in g n o t o n ly k ey p e r s o n n e l b u t a l s o o th e r o r g a n iz a t io n s w h ic h m a y b e c o m e in v o lv e d .

. S ta ff in g

An a p p ro p r ia te n u m b er of te c h n ic a l and su pp o rting s ta ff m u st be av a ilab le to m an the m on ito ring c o n tro l c e n tre and to fo rm the m on ito ring te a m s .

(a) M onitoring c o n tro l c e n tre

The m on ito ring c o n tro l c e n tre should o p e ra te under the d ir e c tion of an ex p e rt in the fie ld of rad ia tio n p ro te c tio n who would d i r e c t th e m o n ito r in g te a m s , c h a r t th e r a d ia t io n an d c o n ta m in a tio n le v e ls and p ro v id e the te c h n ic a l in fo rm a tio n , in c lu d in g p re d ic te d fu tu re t r e n d s , r e q u ire d by the e m e rg e n c y c o n tro l c e n tre . He should be a s s is te d by an adequate num ber of tech n o lo g ica l and o th e r supporting sta ff. F o r m a jo r e m e r g e n c ie s it m ay be n e c e s s a r y to r e c r u i t a d d it io n a l s ta f f fo r c o n tro l l in g th e su b se q u e n t s u rv e y s .

(b) M o n ito r in g te a m s and a n a ly t ic a l s e r v ic e s

The m o n ito rin g te a m s w ill be c a lle d upon to p e rfo rm the in i t ia l su rv e y and any su bseq u en t su rv e y s re q u ire d .

(i) T he in i t i a l s u r v e y . A s u f f ic ie n t n u m b e r of te c h n ic a l p e rso n n e l m u s t be a v a ilab le a t v e ry sh o r t no tice to fo rm te a m s to m an the su rv ey v eh ic le s and to prov ide the a n a ly t ic a l s e r v ic e s . In g e n e ra l, e ac h v e h ic le te a m shou ld c o m p r is e a t l e a s t one te c h n o lo g ic a l s ta f f m e m b e r , who w ould d i r e c t th e p ro c e d u re s and c o m m u n ic a te w ith th e


m o n ito rin g c o n tro l c e n tre , to g e th e r w ith su ppo rting s ta ff who w ould m o n ito r r a d ia t io n and c o n ta m in a tio n le v e ls , c o lle c t s a m p le s and p e r fo rm s im p le g ro s s ac tiv ity m e a s u r e m e n ts . In a d d it io n a s s i s t a n t s w ould be r e q u i r e d to d r iv e the v eh ic le and to pack, la b e l and s to re the c o lle c te d s a m p le s . T he n u m b e r of te a m s w ould depend on the f a c i l i t ie s av a ila b le and the m agn itude of the r e le a s e . Suitably tra in e d tech n o lo g ic a l s ta ff a r e a lso re q u ire d fo r the ra d io c h e m ic a l a n d /o r s p e c tro m e tr ic a n a ly s is of the s a m p le s c o lle c te d by the su rv e y te a m s . F o r an a e r i a l su rv e y a tech n o lo g ic a l s ta ff m e m b e r should be av a ilab le to d ire c t the p ilo t, to re c o rd rad ia tio n lev e ls and to co m m unicate w ith the m on ito ring c o n tro l c e n tre .

(ii) Subsequent s u rv e y s . The m ain re q u ire m e n t is fo r a p o ss ib ly s u b s ta n t ia l i n c r e a s e in th e n u m b e r of m o n ito rin g te a m s and in th e n u m b e r of p e rs o n n e l a v a ila b le fo r the hand ling of s a m p le s and fo r the p e rfo rm a n c e of the a n a ly t ic a l s e rv ic e s . In g e n e ra l i t w ill be n e i th e r n e c e s s a ry n o r d e s ira b le to have av a ilab le on the s ite a l l the p e rso n n e l r e q u i r e d to p e r f o r m th e su b s e q u e n t s u r v e y s , bu t p r io r a r ra n g e m e n ts should be m ade to s e c u re th e ir s e r v ic e s ra p id ly w hen re q u ire d .

(c) C om m unication s ta ffThe m o n ito rin g te a m s should be ab le to t ra n s m it in fo rm atio n to , an d r e c e iv e in s t r u c t io n s f ro m , th e m o n ito r in g c o n tr o l c e n t r e in th e s h o r te s t p o s s ib le t im e . T he e m e rg e n c y c o n t r o l c e n tre shou ld a ls o be ab le to c o m m u n ica te ra p id ly w ith the m o n ito rin g c o n tro l c e n tre and w ith the v a rio u s in te re s te d a u th o r i t ie s . T he u se of te le x and sh o r t-w a v e ra d io co m m u n ic a tio n s y s te m s in ad d itio n to the n o rm a l te lephone s y s te m and th e p r e p a ra t io n in a d v an ce of a s e t of c o d e s co u ld m a te r ia l ly a s s is t in the tra n s m is s io n of in fo rm ation and in s t ru c tio n s . It w ill be n e c e s s a ry to e n su re th a t com peten t p e rso n s a r e a v a ila b le to o p e ra te s u c h s p e c ia l iz e d c o m m u n ic a tio n s y s te m s .(d) A v a ila b il i ty of a d d it io n a l s ta f fA rra n g e m e n ts shou ld be m ade in ad v an ce fo r the r e s o u r c e s to be in c re a s e d ra p id ly fo r the su b se q u e n t su rv e y s . It m ay

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a ls o be n e c e s s a r y to a r r a n g e fo r th e r a p id r e c r u i tm e n t of s k i l le d p e r s o n n e l to d e a l w ith s p e c ia l p ro b le m s a r i s in g in the su rv e y s and fo r the se c u rin g of add itiona l a s s is ta n c e fro m o th e r e s ta b lish m e n ts , fro m o th e r c o u n tr ie s and possib ly fro m a p p r o p r ia te r e g io n a l o r in te r n a t io n a l o rg a n iz a t io n s . T h e p ro c e d u r e s and a u th o r iz a t io n r e q u i r e d fo r a u g m e n tin g th e re s o u rc e s and fo r en lis tin g such add itiona l a s s is ta n c e a s m ay be r e q u i r e d sh o u ld be c l e a r l y la id dow n in th e e m e rg e n c y p la n s .


5. EMERGENCY MONITORING PROCEDURES

T he p ro c e d u re s u se d in e n v iro n m e n ta l m o n ito rin g can co n v e n ie n tly be g ro u ped in to th r e e p h a se s : d e te c tio n , in i t ia l su rv e y and su bseq u en t su rv e y s . O ccasio n a lly , a s ou tlined in se c tio n 4, m o n ito r in g m ay be conducted co n tin u o usly in o rd e r to s e rv e a s a d e te c tio n sy s te m . The in itia l, im m ed ia te su rv e y i s of p rim e im p o rtan ce fo r it i s on the r e s u l ts ob tained by m o n ito rin g te a m s w ithin the f i r s t few h o u rs fo llow ing an a c c id e n t th a t d e c is io n s on re m e d ia l a c tio n s m u s t be b a se d . S ubsequen t s u rv e y s d e s ig n ed to ex ten d m e a s u r e m e n ts to m a te r ia l s w hich r e q u i r e l e s s u rg e n t a tte n tio n , to o b ta in m o re a c c u ra te in fo rm ation on the s itu a tio n and to follow i ts developm ent, and to ob ta in sc ie n tif ic in fo rm a tio n on, fo r exam ple , the b e h av io u r of the r e le a s e d ra d io a c tiv e m a te r ia l , can be c a r r ie d out a t $ s lig h tly m o re le isu re ly pace s ince th e re w ill be tim e fo r each s tep to be co n sid e re d .5. 1. E n viro n m en ta l m o n ito rin g u sed a s a d e tec tio n s y s te m

It is u su a lly m o re s a t is fa c to ry to m ake p ro v is io n fo r d e te c ting th e e m e rg e n c y a t i t s s o u rc e r a th e r th a n in the e n v iro n m e n t but d e te c tio n by e n v iro n m e n ta l m o n ito r in g m ay be r e q u ire d in som e s itu a tio n s , p o ssib ly , fo r exam ple , n e a r i n t e r n a tio n a l f ro n t ie r s .O ff-s ite sy s te m s m ay inc lude such d ev ic es a s continuous a i r - s a m p l e r s o r w a t e r - s a m p l e r s o r d e v ic e s f o r c o n tin u o u s ly s c a n n in g th e sk y o r b o d ie s o f w a te r f o r r a d ia t io n , in e a c h c a se the re a d in g s being te le m e te re d back to a c o n tro l c e n tre . T hey a l l have the d isa d v a n ta g e th a t the d e te c to r s n eed to be c o n s id e ra b ly m o re se n s itiv e than if s ite d n e a r to the p o ss ib le p o in t o f r e l e a s e and a ls o n e e d to be e x t r e m e ly r e l i a b le i f d u p lica tio n is to be avo ided . S y stem s in tended to d e te c t a i r b o rn e r e l e a s e r e q u i r e th e d e te c to r s to be c lo s e ly sp a c e d , p o s s ib ly a t 10° in te r v a l s , i f a n a r ro w p lu m e of a c t iv e m a t e r i a l i s n o t to be m is s e d , and , s in c e th e y sh ou ld be f a r en o u g h f r o m th e p o s s ib le p o in ts o f r e l e a s e to m a k e i t u n lik e ly tha t they w ill be w ithin the "sk ip d is tan ce" of a re le a se , and should a lso c o v e r a l l popu la ted b e a rin g s fro m the in s ta l la tion , such s y s te m s can be v e ry exp en siv e . The u se of a i r - s a m p le r s in tro d u c e s c o m p lex te c h n iq u e s , i f e a r ly w a rn in g

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i s r e q u i r e d , b e c a u s e o f th e p r e s e n c e o f th e n a t u r a l d e c a y p ro d u c ts of ra d o n and th o ro n . H ow ever, i f t im e can be a l low ed f o r th e s e to d e c a y , a s im p le m e a s u r e m e n t o f g r o s s a lp h a - o r g ro s s b e ta -a c t iv i ty wiU in d ic a te w h e th e r cond itions a r e s e r io u s ly ab n o rm a l, a lthough i t m u s t a lw ays be re m e m b e red tha t the r e s u l ts cannot be in te rp re te d in te rm s of h azard to m an.C o n tin u o u sly o p e ra te d o f f - s i te s y s te m s h av e th e ad v a n ta g e th a t th e y can p ro v id e a ra p id in d ic a tio n , no t only th a t a r e le a s e to the en v iro n m en t h as tak en p la ce , but a lso of the d ire c t io n in w hich the r e le a s e d m a te r ia l i s m oving.

5. 2 . The in it ia l s u r v e yThe o v e rr id in g co n s id e ra tio n in the e a r ly p h ases of the m onito r in g p ro g ra m m e m u s t be sp e e d . M e a s u re m e n ts sh o u ld th e re fo re be l im ite d to th o se n e c e s s a ry to e s ta b lis h w h e th e r im m e d ia te r e m e d ia l a c tio n i s n eed ed , and th e a c c u ra c y of th e s e m e a s u re m e n ts shou ld be su b o rd in a te d to th e need fo r m aking them in tim e fo r the r e s u l ts to be u se fu l. N on-spec ific m e a su re m e n ts ,, such a s the d e te rm in a tio n of to ta l b e ta -a c tiv ity o r of g a m m a -ra d ia t io n le v e ls in the e n v iro n m e n t, w h ich a r e n o rm a lly d e p re c a te d in su rv e y s c a r r ie d out fo r p u rp o se s of rad io lo g ica l p ro tection , m ay th e re fo re becom e the m ethods of cho ice in the in i t ia l e m erg en cy su rv e y . The cho ice of the a p p ro p ria te m ethods depends upon the com position of the m at e r i a l r e le a s e d and upon the m ed iu m (a ir , w a te r o r ground) into which the m a te r ia l has been p redom inan tly re le a se d . The m o s t u rg e n t a c tio n w ill a lm o s t c e r ta in ly be c a lle d .for in the c a s e of a r e l e a s e to th e a tm o s p h e re b e c a u se of the ra p id ity of d is p e r s io n of a c t iv ity in th is m e d iu m .The v a r io u s p ro c e d u re s w hich m ay have to be u sed in the in i t i a l p h a se a r e d is c u s s e d in th e a p p ro x im a te o r d e r o f th e i r p r io r i ty .

5 .2 . 1. A s s e s s m e n t of a i r - b o r n e c o n ta m in a tio nIn th e c a s e of a r e l e a s e to th e a tm o s p h e re th e m o s t u rg e n t p ro b le m w ill be a s s e s s m e n t of the h a z a rd fro m in h a la tion o r, in the c a s e of noble g a s e s , f ro m e x te rn a l ex p o su re f ro m the

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c lo ud . If the a c c id e n t h a s g iven r i s e to a sudden r e l e a s e of s h o r t d u ra t io n , no a c t io n to l im it e x p o su re i s l ik e ly to be f e a s ib le bu t i f th e r e l e a s e i s d e la y e d o r p ro lo n g e d , a c t io n su ch a s te m p o ra ry ev acu a tio n m ay be p o ss ib le and a i r s a m p lin g sh ou ld th e r e f o r e be s ta r te d a s r a p id ly a s p o s s ib le in a d ir e c t io n d ow n-w ind f ro m th e p o in t o f r e l e a s e .M easu rem e n ts m ay be m ade e i th e r by m ean s of fixed d ev ices (see se c tio n 5 .1 ) o r by m o b ile equ ipm en t. In the l a t t e r c a se i t is , of c o u rse , im p o rta n t th a t som e co m m u n ica tio n sy s te m be av a ilab le to p e rm it r e s u l ts to be tra n s m itte d to the co n tro l c e n tre a s soon a s they a re obtained.I t i s d if f ic u lt to o b ta in a r e p r e s e n ta t iv e s a m p le o f a f a s t - m ov ing c loud and , in d ee d , the n e e d fo r sp e e d w ill p ro b a b ly be so o v e r r id in g th a t th e r e w ill be t im e on ly fo r v e r y r u d i m e n ta ry m e a su re m e n ts . Any a i r m on ito ring tha t can be done in the in i t ia l p h ase should th e re fo re p ro b ab ly be re g a rd e d a s su pp lem en tin g the In fo rm a tio n ob tained fro m the p re l im in a ry a s s e s s m e n t o f th e m a g n itu d e of th e a c c id e n t an d f r o m an y a i r - m o n i to r in g e q u ip m e n t in s ta l le d o n - s i t e .

5. 2 . 2 . R a p id a s s e s s m e n t of th e a r e a a f fe c te d

T h e m o s t r a p id a s s e s s m e n t of th e e x te n t o f e n v iro n m e n ta l co n tam in a tio n can be m ade by m e a su re m e n t of g ro s s ac tiv ity . The a r e a affected m ay be anything fro m a few sq u a re m e tre s , in th e c a s e of a s p i l l in to th e g ro u nd , to m any th o u sa n d s of sq u a re m e tre s , in the c a se of a la rg e a ir -b o rn e re le a s e . Under the l a t t e r c i rc u m s ta n c e s only a rough e s t im a te of the e x te n t of c o n ta m in a tio n c a n be m a d e in th e i n i t i a l s ta g e s an d a c c u r a te d e l in e a t io n o f th e a ffe c te d a r e a m u s t be le f t u n t i l t im e and a u g m e n te d f a c i l i t i e s p e r m it .M ost r e l e a s e s of im p o r ta n c e a r e l ik e ly to in c lu d e m ix ed f i s s io n - p r o d u c ts o r b e ta -g a m m a e m i t t e r s . Such n u c lid e s a r e r e la t iv e ly e a s i ly d e te c te d on th e g ro u n d o r in w a te r by g a m m a - ra d ia t io n s u rv e y s .A lthough the p re se n c e of a lp h a -e m ittin g o r b e ta -e m itt in g n u c l id e s can be d e te c te d w ithout sam p ling , fo r any q u an tita tiv e a s s e s s m e n t of th e a m o u n ts p r e s e n t sa m p lin g i s n e c e s s a r y . I t i s u n lik e ly th a t im m e d ia te s u rv e y s f o r a lp h a -a c t iv i ty on

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th e g ro u n d w ill be c a l le d fo r e x c e p t in th e v ic in i ty o f a r e l e a s e in v o lv in g a s ig n if ic a n t q u a n ti ty o f an a l p h a - e m i t t e r .(a) G a m m a - r a d ia t io n s u rv e y sM e a su re m e n t of g a m m a -ra d ia t io n le v e ls in the e n v iro n m en t i s of p a r t ic u la r value in the ca se of w idesp read d issem in a tio n of a c tiv ity due to a r e le a s e to the a tm o s p h e re . The r e s u l ts o b ta ined not only in d ica te the ex ten t of co n tam in a tio n but can a lso be u sed to e s tim a te the to ta l g a m m a -ra y dose to exposed p e r s o n s and to p re d ic t the le v e ls of c o n ta m in a tio n l ik e ly to be found in som e foods. T h is cap ab ility of p re d ic tio n is p a r t ic u la r ly v a lu a b le in th e c a s e of 131I r e l e a s e s to the a tm o sp h e re in a d a iry -fa rm in g a re a . If the affected a re a is la rg e , i t m ay take som e tim e to apply r e s t r ic t io n s to the consum ption o r s a le of m ilk , the p re d o m in a n t s o u rc e of e x p o su re u n d e r su c h c i r c u m s ta n c e s , and i t i s th e r e f o r e n e c e s s a r y to have an e s t im a te of the p o ss ib le le v e l of 131I in m ilk w ith in a few h o u rs .H ow ever, s in ce a n im a ls a re m ilked a t d is c re te in te rv a ls , no s ig n if ic a n t a c t iv ity m ay be found in m ilk fo r up to 24 h o u rs a f t e r d e p o s i t io n on h e rb a g e h a s o c c u r r e d , and a n a ly s is of m ilk i t s e l f d u rin g the e a r ly s ta g e s m ay th e re fo re g ive m is le a d in g r e s u l t s . P ro v id e d the co m p o s itio n of the d e p o s ite d m a te r ia l i s known, i t i s p o ss ib le to e s t im a te th e am ou n t of 1311 p re s e n t fro m g am m a e x p o s u r e - r a te m e a s u re m e n ts and

so to p r e d ic t w h at th e m a x im u m le v e l of c o n ta m in a tio n of m ilk i s l ik e ly to b e . T he v a lu e of g a m m a -s u rv e y s fo r th is p u rpose i s g re a tly enhanced if background lev e ls a re availab le fro m p re -e m e rg e n c y su rv e y s (see se c tio n 4 .2 ) . E x p o su re - r a t e s su ffic ie n tly h igh to w a r ra n t ev acu a tion of the c o n ta m in a te d a r e a in o r d e r to c o n tro l e x te rn a l ly re c e iv e d ra d ia t io n dose a re e a s ily d e tec tab le when o rd in a ry ion ization ch am b e rs o r s c in t i l l a t io n - c o u n te r in s t r u m e n ts a r e u s e d . E x p o s u re - r a t e s c o rre sp o n d in g to s ig n ific a n t le v e ls of co n ta m in a tio n in fo o d stu ffs a r e n o rm a lly d e te c ta b le only w ith m o re s e n s it iv e eq u ip m en t (see se c tio n 6).S ince e m e rg e n c y f a c i l i t i e s a r e l ik e ly to be l im ite d a s w e ll a s o v e r lo a d e d in th e in i t i a l s ta g e s , i t i s p ru d e n t to co n fine th e s u rv e y to th o s e a r e a s w h e re c o n ta m in a tio n c a n be e x


p e c te d , h av in g r e g a r d to th e w e a th e r c o n d itio n s p re v a i lin g a t th e t im e of r e l e a s e . In so m e c o u n tr ie s , p r e - s e l e c t e d ro u te s fo r v e h ic le s a r e c h o sen , a s f a r a s p o ss ib le , so a s to fo rm a p o la r g r id a ro u n d th e in s ta l la t io n , i . e . so a s to l ie on c o n c e n tr ic c i r c le s su rro u n d in g the in s ta lla tio n o r on ra d i i o f th e s e c i r c l e s . B e c a u se i t i s b e lie v e d th a t, u n d e r m o s t acc id en t conditions likely to be encoun tered , the la te r a l sp read of a p lum e of a c tiv ity would not exceed 30°, the ra d ia l ro a d s a r e ch o se n a t ro u g h ly 30° in t e r v a l s . T h u s , in th e o ry , th e im m e d ia te su rv e y would need to c o v e r only two 30° s e c to rs .G a m m a -ra d ia t io n m e a s u r e m e n ts c a n be m a d e in a n u m b e r o f w ay s and th e m e th o d d e c id e d upon w ill d e p e n d upon th e a r e a th a t the p re l im in a ry s tu d ie s o u tlined in s e c t io n 4 have show n to n eed c o v e r in g and upon th e n a tu r e o f th e t e r r a i n a ro u n d th e e s ta b l is h m e n t .The s im p le s t m ethod is to use po rtab le b a tte ry -o p e ra te d b e ta / g a m m a s u r v e y - m e te r s of th e ty p e s d e s c r ib e d in s e c t io n 6. T h e s e c a n be c a r r i e d in th e hand . If th e r e s u l t s a r e to be q u a n tita tiv e , m e a s u r e m e n ts shou ld be m ade a t a n u m b e r of p re -d e te rm in e d p o sitio n s w ith the d e te c to r held a t a s tand ard h e ig h t (u su a lly 1 m ) above th e g ro u n d s u r f a c e . U n le ss the m e a s u r e m e n ts a r e r e q u i r e d fo r a s p e c if ic p u rp o s e , th e s e p o s itio n s should be aw ay fro m ro a d s u r fa c e s , t r e e s , hedges o r bu ild ings, -all of w hich m ay d is to r t the d is tr ib u tio n . G rea t c a r e sh o u ld be ta k e n to a v o id c o n ta m in a tio n o f th e i n s t r u m e n ts . To in c r e a s e m o b ility , m en and in s tru m e n ts can , of c o u rse , be tr a n s p o r te d in ro ad v e h ic le s , b o a ts o r a i r c r a f t s . T h is typ e of s u rv e y i s c a p a b le of p ro v id in g a ra p id a s s e s s m e n t of the e x te n t of the c o n ta m in a te d zone.Som e c a re h as to be tak en tha t, a s f a r a s p o ss ib le , ro ad v e h ic le s w ork in tow ard s a r e a s of h ig h er con tam ination in o rd e r to av o id in v a l id a tio n of m e a s u r e m e n ts ow ing to g r o s s c o n ta m in a t io n of th e v e h ic le s th e m s e lv e s . T he e f fe c t of c o n ta m in a tio n can be m in im iz e d by m o u n tin g th e d e te c to r on a p o le above th e v e h ic le . T he g a in o b ta in e d by v ir tu e of th e d e te c to r " s e e in g " a g r e a t e r a r e a of th e g ro u nd p a r t ly c o m p e n s a te s f o r th e lo s s r e s u l t in g f ro m th e in s t r u m e n t b e in g f a r t h e r f ro m th e c o n ta m in a te d s u r f a c e .U ndoubted ly the m o s t ra p id g a m m a -s u rv e y can be ach iev ed by u s in g in s t ru m e n ts m o u n ted in a i r c r a f t . A e r ia l s u rv e y s

37


a ls o have the ad v an ta g e th a t m o v e m e n ts of a i r c r a f t a r e no t r e s t r i c t e d by g ro u n d c o n d itio n s . H e l ic o p te r s have p ro v e d to be v a lu a b le fo r th is p u rp o se . No s p e c ia l in s t ru m e n ts o r t ra in e d p e rso n n e l, o th e r th a n the p ilo t, a r e re q u ire d ; s ta n d a rd p o r ta b le equ ipm en t o p e ra te d by the n o rm a l m o n ito r in g s ta f f w ill su ff ic e . H e lic o p te rs m ay o p e ra te f ro m an y open sp a c e and in w e a th e r c o n d itio n s th a t w ould p ro h ib i t th e u se of fixed -w ing a i r c r a f t . T hey have the fu r th e r advan tage th a t th e y can be u se d to c o lle c t s a m p le s of, f o r ex a m p le , v e g e ta t io n f ro m a r e a s of h igh c o n ta m in a tio n . T he u se o f f ix e d - w ing a i r c r a f t h a s th e s e r io u s d is a d v a n ta g e th a t a v a i la b i l i ty m a y be r e s t r i c t e d ow ing to bad w e a th e r c o n d itio n s . In a d d itio n , s in c e th e a i r c r a f t h a s to be' s p e c ia l ly eq u ip p ed fo r th e p u rp o s e , th e c o s t of m a in ta in in g a s p e c ia l a i r c r a f t and a t r a in e d c re w i s h igh .E x am p les of m ethods in c u r re n t u se fo r c a rry in g out gam m a- s u rv e y s fo r p re d ic tio n p u rp o s e s a r e g iven in A nnex III.If s im p le g a m m a -d e te c t in g in s t r u m e n ts a r e e m p lo y e d and it i s d e s ire d to u se the r e s u l ts of the g a m m a -su rv e y fo r e s t i m a tin g le v e ls o f in d iv id u a l n u c lid e s , s a m p le s f ro m the g round s u rfa c e m u s t be exam ined in o rd e r th a t the co m p o s itio n of the d ep o sited m a te r ia l can be a s c e r ta in e d . An a l t e r n a tiv e i s to em ploy p o r ta b le g a m m a -s p e c t ro m e te r s . T h e se can e i th e r be re la t iv e ly s im p le in s tru m e n ts ch an n e lled on to one p a r t ic u l a r n u c lid e , e . g . 131I, o r th e y m a y be m u l t i channel in s tru m e n ts . Since in te rp re ta tio n of g a m m a -sp e c tra i s l ik e ly to be d if f ic u l t u n d e r f ie ld c o n d it io n s , i t h a s b e e n su g g e s te d th a t, i f su ita b le eq u ip m en t i s a v a ila b le , re a d in g s shou ld be te le m e te re d to th e c o n tro l c e n t r e w h e re th e y m ay be fed in to a c o m p u te r o r o th e rw is e p ro c e s s e d a s d e s i r e d .

(b) C o n ta m in a tio n s u rv e y s

T h e e x te n t of c o n ta m in a tio n w ith a lp h a -e m i t t in g o r b e ta - em ittin g n u c lid es is best d e te rm in ed by sam pling . The am ount of a c t iv ity d e p o s ite d on th e g ro u n d s u r fa c e a s th e r e s u l t of an a i r - b o r n e r e l e a s e c a n be e s t im a te d e i th e r by s a m p lin g th e v e g e ta tio n c o v e r a lo ne o r to g e th e r w ith th e u p p e r l a y e r of the s o i l . M e a su re m e n t of g r o s s a c t iv ity i s p ro b a b ly a c cep ta b le in the e a r ly p h ase of m o n ito rin g u n le s s an e s t im a te


i s r e q u i r e d of th e am ou n t of in d iv id u a l n u c lid e s p r e s e n t fo r p u rp o s e s of p re d ic tio n .S a m p le s o f h e rb a g e , e t c . , o b ta in e d to a s s i s t in th e i n t e r p re ta t io n of g a m m a -m o n ito r in g r e s u l t s , m u s t be c o l le c te d and exam ined v e ry ra p id ly if re m e d ia l ac tion i s co n tem p la ted on th e b a s is o f th e g a m m a -s u rv e y . T he s a m p le s a r e p r e fe ra b ly ob ta ined fro m p o in ts in the v ic in ity of the in s ta lla tio n s e le c te d on th e a d v ic e of a p p ro p r ia te e x p e r t s . K now ledge of the fo o d -ch a in b eh av io u r of the re le a s e d ra d io a c t iv i ty can be com bined w ith the e s tim a tio n of d ep o sitio n to in d ica te the p robab le con tam ination of a g r ic u ltu ra l and b io log ica l sam p les . On the o th e r hand, i f p re l im in a ry a s s e s m e n ts of the m a g n itude of the r e le a s e su g g es t th a t i t s s ig n ifican ce in re s p e c t of ex p o su re of the g e n e ra l public i s m arg in a l, i t m ay be prudent to w ait u n til sa m p le s of foodstu ffs have been exam ined befo re in itia tin g re m e d ia l ac tio n .E x am p les of m ethods in c u r re n t u se fo r sam ple co llec tion and fie ld evaluation a re given in Annex IV.

5. 2. 3. E xam ination of w a te r and foodSam pling and ex am in a tio n of w a te r and food w ill not re q u ire th e sa m e u rg e n c y a s th e p ro c e d u re s d e s c r ib e d ab o v e . T he e ffe c t of a i r - b o r n e r e l e a s e s on w a te r su p p lie s i s un lik e ly to be s ig n ifican t a s co m p ared w ith the in h a la tio n h a z a rd and the in g es tio n h a z a rd fro m co n tam in a ted food. On the o th e r hand, a r e le a s e to a r iv e r , to a lak e o r to the g ro u nd m ay lead to ra p id and s e r io u s c o n ta m in a tio n of w a te r s u p p lie s . A d e c is io n to p ro h ib it te m p o ra r i ly the u se of w a te r fo r hum an consu m p tio n o r fo r in d u s t r ia l p u rp o s e s c an n o t o r d in a r i ly w a it upon the r e s u l ts of sam pling and an a ly s is if p re lim in a ry m e a s u re m e n ts of g r o s s a c t iv ity have in d ic a te d th a t th e r e l e a s e m ay have s ig n if ic a n t c o n se q u e n c e s .A m ain a im of em erg en cy en v ironm en ta l m onitoring is to p ro v ide t im e ly in fo rm a tio n on w hich m e a s u re s can be b ased fo r p rev en tin g , to the ex ten t p ra c tic a b le , e x c e s s iv e ex p o su re of m e m b e rs of the public . Such m e a su re s include the avoidance of in take by in g estion of re le a s e d rad io n u c lid es by e a r ly co n tro l , w here w a rra n te d , of fo o d -p rod u c ts w hich w ill be p ro m p tly c o n su m e d by m a n . T he fo o d -p ro d u c ts r e q u i r in g th e m o s t

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im m ed ia te a tten tio n a re th e re fo re those which w ill be rap id ly c o n ta m in a te d an d w h ich a r e l ik e ly to be c o n su m e d s h o r t ly a f te rw a rd s . T h ese w ill include m ilk (see se c tio n 5. 2. 2. (a)), f r e s h g ra in , v e g e ta b le s , r ip e n in g f ru i t , and c e r e a l s re a d y fo r h a rv e s t in g in th o se p a r t s of the w o rld w h e re f r e s h ly - h a rv e s te d g ra in i s ea ten a t once. The te m p o ra ry c o n tro l of m ilk i s r e f e r r e d to a t s e v e r a l p o in ts of th is m a n u a l; i t i s a c o n tro l m e a su re w hich h as been in troduced in the p as t follow ing r e le a s e of ra d io n u c lid e s to the en v iro n m en t. It i s e s p e c ia lly im p o rtan t, how ever, to b e a r in m ind tha t it is r e f e r r e d to only a s an e x am p le and th a t the g e n e ra l co n cep t w ould be eq u a lly a p p licab le to o th e r fo o d -p ro d u c ts w hich a r e in tended fo r im m e d ia te h a rv e s tin g and co n sum p tio n .It i s e v id e n t th a t, once ag a in , a r e l e a s e to th e a tm o s p h e re d em a n d s the m o s t ra p id a c tio n s in c e co n ta m in a tio n of fo o d s tu f f s f ro m w a te r - b o r n e a c t iv i ty i s l ik e ly to be d e la y e d in c o m p a r is o n w ith th a t f ro m a i r - b o r n e a c t iv i ty .In g e n e ra l , m o n ito r in g of w a te r and of fo o d stu ffs o th e r th a n th o s e m e n tio n e d can th u s be c a r r i e d out a t a s lig h tly m o re le isu re ly pace and can be re g a rd e d a s fo rm ing p a r t of a phase o f e m e rg e n c y m o n ito r in g s u b se q u e n t to th e i n i t i a l s u rv e y .

5. 3 . S u b se q u e n t s u r v e y sO nce d e c is io n s on u rg e n t r e m e d ia l a c tio n have b e e n ta k e n m o r e t im e c a n be g iv e n to c o n s id e r in g s u b s e q u e n t s te p s . The ra p id ity w ith which th is subsequen t ac tion can be c a r r ie d out w ill depend, to a la rg e d eg ree , on the ex ten t to w hich the f a c i l i t ie s o r ig in a lly av a ilab le to d ea l w ith the e m erg en cy can be au g m en ted . The a im s of the m e a s u re m e n ts m ade a t th is s ta g e shou ld be fourfo ld :(a) To re -e x a m in e the m e a su re s taken during the in itia l phase

an d to d e c id e w h e th e r th e y sh o u ld be m a in ta in e d , e x ten d e d o r c o n tr a c te d in th e l ig h t of m o re a c c u r a te i n fo rm a tio n on the zo n es a ffe c te d and on the le v e ls of c o n ta m in a ti on ;

(b) To fo llow th e tr e n d of c o n ta m in a tio n on the g ro u nd , in w a te r and in foodstuffs and to d e te rm in e when re s tr ic tio n s can be rem oved and con tam inated a re a s re tu rn e d to n o r m a l u se ;

4 0


(c) T o e v a lu a te th e c o n se q u e n c e s of th e a c c id e n t in t e r m s of r a d ia t io n d o se s to p eop le and, to a l e s s e r e x ten t, to liv e s to c k ;

(d) To o b ta in sc ie n tif ic in fo rm a tio n on the b e h a v io u r in the en v iro n m en t of the r e le a s e d ra d io a c tiv e m a te r ia l in o r d e r to p rov ide data , fo r exam ple, to allow m o re a c c u ra te th e o re tic a l a s s e s s m e n ts of p o ten tia l h a z a rd s to be m ade.

5 .3 . 1. R e a s se ssm e n t of in i t ia l m e a su re sG a m m a -s u rv e y s , su p p lem en ted if n e c e s s a r y by sam p lin g of m a te r ia l s su c h a s h e rb a g e and w a te r , sh o u ld be u s e d a s a f i r s t ch eck th a t ra d io a c tiv e m a te r ia ls have no t been d is s e m in a te d in u n e x p e c te d d ir e c t io n s due, fo r e x a m p le , to ra p id f lu c tu a t io n s in w ind d ir e c t io n .A c c u ra te d e lin ea tio n of the a r e a s in w hich ac tio n to l im it e x p o su re of the public is re q u ire d m ust then r e s t on exam ination of a l l m a te r ia ls w hich can be re g a rd e d a s co n tr ib u tin g a s ig n ifican t ra d ia tio n d o se . T h ese m a te r ia ls w ill v a ry acco rd in g to the type of a c tiv ity p re s e n t and to the m e d iu m in w hich i t h a s been d is p e r s e d . G uidance on the p o ss ib le ro u te s of e x p o s u re i s g iv en in s e c t io n 3 .3 . W h ere th e a p p e a ra n c e of a s ig n if ic a n t am oun t of a c tiv ity in fo o d stu ffs , e tc . i s l ik e ly to be delayed , a s in the c a se of a re le a s e to the sea , delinea tion of the a ffe c te d a r e a m ay w ell r e q u ire only a s lig h t expansion of any ro u tin e su rv e y p ro g ra m m e w hich m ay be in o p e ra tio n . In o th e r c a s e s , s p e c ia l s a m p lin g m a y h a v e to be s t a r t e d .M ilk m ay be s ing led out fo r sp e c ia l m ention s in ce u n der many c i rc u m s ta n c e s i t i s the foodstu ff lik e ly to be m o s t w idely a f fe c te d . Som e m ilk s a m p le s m ay w e ll have been tak en in the in i t ia l p h ase of the m o n ito rin g p ro g ra m m e but, a s exp la ined in s e c t io n 5. 2. 2. (a), r e l ia b le e s t im a te s of th e h a z a rd f ro m th is so u rc e can be ob ta ined only by w aiting fo r up to 24 h o u rs a f t e r th e r e l e a s e . M ilk s a m p le s m a y n e e d to be c o l le c te d o v e r a wide a re a but sp e c ia l a tten tio n should be given to fringe a r e a s w ith a v iew to ex ten d in g o r c o n tr a c t in g the a r e a o v e r w h ic h r e s t r i c t i o n s m a y h av e b e e n im p o s e d on th e b a s is of g a m m a - s u r v e y r e s u l t s .In g e n e ra l, the su b seq u en t su rv e y shou ld p ro v id e d a ta on in d iv idual n u c lid es r a th e r than on g ro s s ac tiv ity , although rap id

41


sc re e n in g m ethods have th e ir value in the fie ld , fo r exam ple, fo r d e te rm in in g w hether the 131I co n cen tra tio n in a m ilk s a m ple is su ffic ien t to w a rra n t i ts condem nation .

5 .3 .2 . Follow ing the tre n d of con tam inationThe p re d o m in a n t h a z a rd in the e a r ly s ta g e s follow ing an a c c id en t m ay be fro m re la t iv e ly s h o r t- l iv e d n u c lid e s , su ch a s 1311, and em p h as is w ill th e re fo re be p laced on the d e te rm in a

t io n o f su c h n u c lid e s . A s r e s t r i c t i o n s o r ig in a l ly im p o s e d b e c a u se of the p re s e n c e of s h o r t- l iv e d a c tiv ity a r e re m o v e d a s a re s u l t of the decay of th is ac tiv ity , m e a su re m e n ts should e n s u re th a t r e s t r i c t io n s a r e no t s t i l l n e c e s s a r y in the m o re h ig h ly c o n ta m in a te d a r e a s b e c a u se of the p re s e n c e of lon g - liv e d n u c lid e s .The su rv e y m ay have to be continued o v er an extended p erio d of tim e if a l l consequences of the acc iden t a re to be tho roughly in v es tig a ted . Thus, i f a g r ic u ltu ra l land h as been co n ta m in a ted w ith lo n g -liv e d n u c lid es , c ro p s su bseq u en tly grow n on th is land w ould re q u ire to be ex am in ed to e n su re th a t up take o f a c t iv ity f ro m the s o il i s no t s ig n if ic a n t. F u r th e r m o r e , s in c e m o v em en t of ra d io n u c lid e s th ro u g h th e s o i l i s s o m e t im e s v e ry slow , i t m ay be n e c e s s a ry to m o n ito r fo r s e v e ra l y e a r s w a te r s u p p lie s em a n a tin g f ro m u n d e rg ro u n d s o u r c e s if la rg e am ounts of ac tiv ity have been re le a se d into the ground.

5 .3 .3 . M easu rem en t of in te rn a l d o sesA lthough the ra d ia tio n d o se s re c e iv e d by p e rso n s a s a re s u l t o f in h a la tio n o r in g e s tio n of a c t iv ity c a n be e s t im a te d f ro m m e a su re m e n ts of co n cen tra tio n s of rad io n u c lid es in a i r , food and w a te r , a m o re a c c u ra te a s s e s s m e n t can be o b ta in ed by m o n ito rin g re p re s e n ta t iv e m e m b e rs of the p u b lic . M ethods in c lu d e w h o le -b o d y m o n ito rin g , m o n ito rin g of th e th y ro id g la n d fo llow ing r e l e a s e of r a d io - io d in e and a n a ly s is of e x c r e ta . T h ese p ro c e d u re s should be im p lem en ted , to the ex te n t p ra c t ic a b le , i f th e r e i s an y r e a s o n a b le u n c e r ta in ty on th e e x p o su re r e c e iv e d by m e m b e rs o f th e p u b lic .

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5 .3 .4 . C ollection of sc ie n tif ic data

V e ry l i t t le in fo rm a tio n i s a v a i la b le on th e b e h a v io u r o f n u c lid e s in the en v iron m en t o r of the co n seq uences of th e ir r e l e a s e . T h e r e f o r e e v e r y r e a s o n a b le o p p o rtu n ity sh o u ld be taken to m ake u se of an acc id e n ta l re le a s e a s a so u rce of m a t e r i a l fo r sc ie n tif ic s tu d ie s . E x p e r t ad v ice should be sought on th e w ay in w h ich m e a s u r e m e n ts c a n be m a d e to p ro v id e th e m o s t u s e fu l in fo rm a tio n . M e a s u re m e n ts m a d e fo r th is p u rp o se a r e of c o u rs e su b o rd in a te to th o se m ade in o rd e r to a s s i s t in p ro te c tin g peop le fro m undue e x p o su re .

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6. EMERGENCY MONITORING EQUIPMENT*

T he typ e and am o u n t of m o n ito r in g e q u ip m e n t w hich sh ou ld be held in re a d in e s s , o r w hich should be a v a ilab le a t sh o r t n o tice , fo r u se in e m e rg e n c y s i tu a t io n s , w ill d epend on th e ty p e of a c c id e n ts w hich can be fo re s e e n and fo r w hich i t i s re a so n a b le to p lan in a d vance . Many of the m e a su re m e n ts re q u ire d in an em ergency su rvey can be p e r fo rm e d u s in g in s t ru m e n ts w hich a r e n o rm a lly a v a ila b le fo r ro u tin e w o rk w ith in an in s ta l la t io n . A ll in s t r u m e n ts in ten d ed fo r e m erg en cy u se should be ro b u st, re lia b le and s im p le to o p era te , and i t is m ost im p o rtan t tha t they should be p e rio d ica lly checked and kep t in good w ork ing o r d e r . W hen d ec id in g on the n u m b e r of e ac h type of in s tru m e n t to be held in re a d in e s s fo r em erg en cy m onito ring c o n s id e ra tio n shou ld be g iven to the p o ss ib il i ty of lo s s of u se of in s tr u m e n ts ow ing to d am age o r c o n ta m in a tio n d u rin g u s e . T he in s tru m e n ts and equipm ent re q u ire d m ay be c la s s if ie d in the following b ro ad c a te g o r ie s :(a) In s tru m e n ts fo r d e te c tin g an a b n o rm a l r e l e a s e of r a d io a c t iv e

m a te r ia l s ;(b) In s tr u m e n ts fo r a s s e s s in g ra d ia t io n and c o n ta m in a tio n le v e ls

in the fie ld ;(c) E quipm ent fo r co llec tin g sam p les and in s tru m e n ts fo r a s se s s in g

th e ir rad io ac tiv e content;(d) M isc e lla n e o u s i te m s , inc lud ing eq u ip m en t fo r t r a n s p o r t , c o m

m u n ica tio n s , m e te o ro lo g ic a l m e a su re m e n ts , p ro te c tio n of p e r so nn el and c o n tro l of a c c e s s .

6. 1. I n s tru m e n ts f o r d e te c tin g an a b n o rm a l r e le a s e o f r a d io a c tiv e m a te r ia ls ,An a b n o rm a l r e le a s e of ra d io a c tiv e m a te r ia l m ay be detected by co n tin u o u sly o p e ra tin g m o n ito r in g d e v ic e s in s ta l le d a t the p o in ts of d is c h a rg e of g a se o u s o r liq u id e ff lu e n ts . Owing to the re la tiv e ly high co n cen tra tio n of rad io ac tiv e m a te r ia l which m a y be f o re s e e n a t th e s e p o in ts s im p le r a d ia t io n d e te c to r s c an be u se d . T he d e te c to r s shou ld , w h en ev e r p o ss ib le , be coup led to c h a r t r e c o r d e r s in o rd e r to p ro v id e an in d ica tio n of the ra te of re le a s e , and should be fitted with d ev ices which a c t iv a te an a la r m w hen the r a t e of r e le a s e e x c e e d s p r e -

# In fo rm a tio n on som e e x a m p le s o f m o n ito rin g e q u ip m e n t is g iv en in A n n ex V I.

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d e te rm in e d v a lu e s . It i s im p o r ta n t th a t th e e q u ip m e n t sh ou ld be e x c e e d in g ly r e l i a b le in o p e ra t io n . M o n ito r in g d e v ic e s of th is type u su a lly fo rm a p a r t of the ro u tin e m o n ito r in g s y s te m s p ro v id ed fo r an in s ta l la t io n .

6. 2. In stru m en ts to r a s s e s s in g radiation and contam ination l e v e ls in the fie ldIn s tr u m e n ts of th is ty p e a r e u su a lly r e f e r r e d to a s s u rv e y - m e te r s . T hey a r e u sed fo r m e a su r in g ra d ia t io n f ie ld s p r o duced by d is ta n t so u rc e s o r fo r m e asu rin g the ra d ia tio n e m itted by a i r -b o rn e o r d ep o sited con tam ination . S u rv e y -m e te rs a r e d es ig n ed e i th e r to m e a s u re e x p o s u r e - r a te s o r to r e c o rd the n u m b er of im p u lse s p e r unit tim e produced in the d e te c to r . In s tru m e n ts in tended to m e a su re g a m m a -ra d ia tio n e x p o su re - r a t e s u su a lly u se an io n iza tio n c h a m b e r o r o rg an ic s c in t i l la t o r a s d e te c to r ; th e re s p o n s e m ay be in d ep en d en t of the gam m a photon en e rg y o v e r a wide ran g e , and hence they m ay be u se d fo r m e a s u r in g the to ta l g a m m a - ra y e x p o s u r e - r a te . The s e n s it iv ity m ay, how ever, no t be su ffic ie n t to allow a s s e s s m e n t of th e s ig n if ic a n c e of th e g ro u n d d e p o s it io n of g a m m a -ra y em ittin g m a te r ia l . In s tru m e n ts in tended to m e a s u re the im p u lse r a te u su a lly em ploy a GM c o u n te r o r in o r ganic s c in ti lla to r a s d e te c to r . The re sp o n se m ay be m arked ly e n e rg y -d e p e n d e n t, bu t a v e ry h igh s e n s i t iv i ty i s a t ta in a b le .

6 .2 .1 . P o r ta b le su rv e y in s t ru m e n tsP o r ta b le s u rv e y in s t r u m e n ts a r e d e s ig n e d to be c a r r i e d by hand and a re b a tte ry o p e ra ted . The sen s itiv e e lem ent m ay be an io n iza tio n c h am b e r, a GM tube o r a sc in ti lla t io n d e te c to r . C o u n te r- ty p e in s t ru m e n ts p ro v id e q u a n tita tiv e a s s e s s m e n ts of g a m m a -ra y e x p o s u r e - r a te s only w hen th e y have been c a l ib ra te d fo r sp e c if ic g a m m a -e m itt in g ra d io n u c lid e s . In g e n e ra l a ran g e of p o rta b le su rv ey in s tru m e n ts should be a v a ilab le fo r th e m e a s u r e m e n t of e x p o s u r e - r a t e s f ro m ab o u t 0. 01 m R /h up to a few R /h . I n s t r u m e n ts u s in g io n iz a t io n c h a m b e rs a r e u s u a lly d e s ig n e d to m e a s u r e e x p o s u r e - r a te s o v e r th e ra n g e f ro m ab o u t 1 m R /h to abou t 5 R /h o r m o re , bu t w ith s im p le m o d if ic a tio n s the ra n g e c a n be ex te n d e d to m u ch h ig h e r e x p o s u r e - r a t e s . I n s tr u m e n ts u s in g GM tu b e s a re u sua lly designed to co v e r the range fro m about 0. 0 2 m R /h

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to a b o u t 20 m R /h , o r f r o m a b o u t 1 0 2 c o u n ts /m in to ab o u t 105 c o u n ts /m in . In s tru m en ts em ploying sc in tilla tio n co u n ters a s d e te c to r s u su a lly have s e n s i t iv i t ie s w hich a r e one o rd e r of m agn itude o r m o re g r e a te r than tho se of in s tru m e n ts e m ploying GM co u n te r tu b es .G re a t c a r e sh ou ld be ta k e n to p re v e n t th e c o n ta m in a tio n of p o r ta b le su rv e y in s t ru m e n ts d u rin g u se . If the le v e l of a i r b o rn e con tam ina tion i s high, i t i s ad v isab le to o p e ra te the in s tru m e n ts in s id e d isp o sab le th in p la s tic c o v e rs .

6 .2 .2 . N o n -po rtab le su rv e y in s tru m e n ts

(a) V eh ic le -b o rn e in s tru m e n tsT h ese in s tru m e n ts a r e b a s ic a lly s im ila r to the c o rre sp o n d in g p o rta b le in s tru m e n ts ; they m ay, how ever, be pow ered by c a r b a t te r ie s o r by m o b ile g e n e ra to r s . T he se n s it iv ity re q u ire d i s s im i la r to th a t r e q u i r e d fo r p o r ta b le in s t r u m e n ts . T he d e te c to r i s o ften co n n ec ted to a c h a r t r e c o r d e r and o p e ra te d c o n tin u o u s ly . A s c in t i l l a t io n d e te c to r c o u p le d to a t r a n s p o r ta b le p u ls e -h e ig h t a n a ly s e r p ro v id e s a ra p id m e th o d fo r id e n tify in g g a m m a -e m itt in g ra d io n u c lid e s . It m ay be d e s i ra b le to m oun t th e d e te c to r on th e end o f a f a i r ly long po le fix ed o u ts id e th e v e h ic le a s the d e p o sitio n on ro a d s u r f a c e s m ay no t be ty p ic a l of th e g e n e ra l g ro u n d d e p o s it io n and th e v e h ic le i t s e l f m a y be s ig n if ic a n tly c o n ta m in a te d .(b) In s tr u m e n ts fo r a e r i a l s u rv e y sS u rv e y in s t r u m e n ts , p e rh a p s c o u p led to a c h a r t r e c o r d e r , m a y be m o u n ted in a f ix e d -w in g a i r c r a f t o r h e l ic o p te r fo r th e p u rp o se of p e r fo rm in g a ra p id co n tin u o u s s u rv e y of the le v e l s o f r a d ia t io n e m it te d by a i r - b o r n e o r d e p o s i te d m a t e r i a l . A f ix e d -w in g a i r c r a f t s u rv e y i s u s u a lly p e r fo rm e d a t a h e igh t of abou t 200 m e tr e s . At th is heigh t the ra d ia tio n le v e l f ro m g ro u n d -d e p o s ite d m a te r ia l m ay be v e ry low ; fo r ex am ple , the in c re a s e d c o u n t- ra te p ro d uced by a g round d e p o s it io n of 0 .4 /j Ci / m2 of 131I m a y be of th e sa m e o r d e r of m agn itude a s the v a r ia t io n s in c o u n t- ra te a ttr ib u ta b le to d iffe re n t g eo lo g ica l fo rm a tio n s . It i s n e c e s s a ry , th e re fo re , to u se a d e te c to r of the h ig h e s t s e n s it iv ity , such a s a la rg e in -

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o rg an ic c ry s ta l s c in t i l la to r capab le of m e asu rin g g a m m a -ra y le v e ls of the o rd e r of 0. 01 m R /h . Since h e lic o p te rs can ope r a t e a t low sp e e d s and c lo se to the g ro u nd , s ta n d a rd p o r ta b le s u r v e y - m e te r s m ay be u se d .(c) F ix e d m o n ito rin g in s t ru m e n ts

T he fixed m o n ito rin g in s tru m e n ts w hich a r e so m e tim e s u sed fo r co n tinuous ro u tin e m o n ito rin g in the neighbourhood of an in s ta l la t io n c a n p ro v id e a d d itio n a l in fo rm a tio n on ra d ia t io n and co n tam in a tio n le v e ls o c c u rr in g in e m e rg e n c y c o n d itio n s . F o r th is p u rp o se fixed m o n ito rin g in s t ru m e n ts m u s t be c a p ab le of m e a s u r in g the h igh le v e ls e x p e c te d in e m e rg e n c y s itu a t io n s .

(d) O th e r in s t ru m e n tsP o rta b le and tra n s p o r ta b le , s in g le -c h a n n e l and m u lti-c h a n n e l g a m m a - s p e c t r o m e te r s (se e s e c t io n 6 .3 .2 ) c a n p ro v id e i n fo rm a tio n v e ry ra p id ly on the co m position of m a te r ia l d ep o si te d on th e g ro u n d w ith o u t th e n e c e s s i ty of ta k in g s a m p le s . T h e m o re c o m p lic a te d in s t r u m e n ts r e q u i r e to be o p e ra te d by p e rs o n n e l w ith ad e q u a te know ledge and th e r e f o r e can n o t e n t i r e ly r e p la c e th e s im p le in s t r u m e n t s d e s c r ib e d a b o v e .

6. 3. E qu ipm en t fo r c o lle c tin g s a m p le s and in s tru m e n ts fo r a s s e s s in g th e ir ra d io a c tiv e con tam ination

6 .3 .1 . Sam pling

B a tte ry -o p e ra te d p o rta b le a i r s a m p le rs m ay be u sed fo r a s s e s s in g the co n ta m in a tio n of the a i r a t s e le c te d p o in ts . F o r p a rtic u la te m a te r ia ls a known volum e of a i r i s d raw n through a f i l te r p a p e r on w hich the p a r t ic u la te m a te r ia l i s d ep o sited . F o r g aseo u s m a te r ia ls , c a rb o n c a r t r id g e s o r o th e r sp ec ia lly desig n ed p lugs of a b so rb e n t m a te r ia l m ay be u sed to t r a p the c o n ta m in a tin g m a te r ia l . S p e c ia l d e v ic e s m a y be u s e d fo r t r a p p in g io d in e and th u s a r a p id a s s e s s m e n t m ay be m a d e o f th e c o n c e n tra t io n of 131I in th e a tm o s p h e re .

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S a m p le s o f w a te r , m ilk and o th e r liq u id s m ay be c o lle c te d by s im p le dipping d e v ic e s . T h e s a m p le s should be p laced in con tam in atio n -free , w ell-stoppered g la ss o r p lastic b ottles. It may be n e c e s s a ry to add sm a ll quantities of a p reserv a tiv e such a s F o rm a lin , to m ilk .

If s tra tific a tio n i s to be studied it w ill be n e c e s s a ry to obtain sa m p le s of s o i l by using a con v en tio n al c o r e cu ttin g d e v ice .

G r a s s and o th e r s im ila r ty p e s of v e g e ta tio n m ay be cu t by hand c l ip p e r s . The g r a s s should be held w hile b eing cu t in o r d e r to p rev en t i t s b eing con tam in ated by the s o il .

It m ay be n e c e s s a r y to sam ple o th er m a te r ia ls , fo r exam ple fish , sea-w eed and o y s te rs , and sin ce the value of the re su lts o b tained depends en o rm o u sly on the c a r e w ith w hich the sa m p les a re co lle c te d , the ad vice of e x p e rts should be obtained on sp e c ia liz e d sam pling tech n iq u es.

Solid sam p les should be placed in c lean paper o r p la s tic bags w hich should then be sealed with adhesive tape.

A ll sa m p le s should be c le a r ly la b e lle d a s to d ate , and tim e and lo catio n of co lle c tio n . G reat c a re should be taken at a ll t im e s to prevent cro ss -co n ta m in a tio n of sam p les during c o l lec tio n , packaging and tra n sp o rt.

A dditional equipm ent m ay be re q u ired fo r the tre a tm e n t and c h e m ic a l a n a ly s is o f s a m p le s p r io r to the m e a s u re m e n t of th e ir ra d io a c tiv e co n ten t. In fo rm a tio n on the equ ip m ent needed and on the ap p ro p ria te m ethods of c h e m ic a l a n a ly s is is av a ila b le in a nu m ber of r e p o r ts 4.

6 . 3 . 2 . M easu rin g in stru m en ts

The ra d io a c tiv e content of the c o lle c te d sa m p les m ay be a s s e s s e d by using stand ard counting equipm ent.

4 S e e in p a r tic u la r :

[ 1 ] W orld H ea lth O rg a n iz a tio n , M ethods o f ra d io c h e m ic a l a n a ly s is , T e c h n ic a l Reports

S e r ie s No. 1 7 3 , Report o f a Jo in t W HO/FAO Expert C o m m itte e . (A rev ised e d itio n

o f th is d o cu m en t in th e form o f a Jo in t WHO/FAO/IAEA S c ie n t i f ic C o m m itte e w ill

b e issued in 1 9 6 5 ) .

[ 2 ] U n ited S ta te s A to m ic Energy C o m m iss io n , M an u al o f S tand ard P ro ced u res, N Y O -

4 7 0 0 ( R e v .) , H ea lth and S a fe ty Laboratory .

4 8


T he id e n tif ic a tio n and a s s a y of in d iv id u a l a lp h a -e m ittin g and b e ta -e m it t in g ra d io n u c lid e s in a sam p le u su a lly r e q u i r e s the p re l im in a r y c h e m ic a l s e p a ra t io n of the s u b s ta n c e s p re s e n t . S pec ia l ra p id p ro c e d u re s have been developed fo r som e of the ra d io n u c lid e s of p a r t ic u la r in te r e s t in an e m e rg e n c y su rv e y . C e r ta in g a m m a -e m ittin g ra d io n u c lid e s su ch a s i31I and 131Cs m ay be ra p id ly id e n tif ied and a s sa y e d by u s in g a g a m m a -ra y s p e c t r o m e te r c o n s is t in g of a s c in t i l la t io n d e te c to r c o u p led to a m u l t i- c h a n n e l p u ls e -h e ig h t a n a ly s e r s .S am p le m e a s u r in g in s t r u m e n ts m ay be o p e ra te d in a la b o r a to r y in c o n ta m in a tio n - f re e re g io n o r in a m o n ito r in g v e h ic le . If th e y a r e m oun ted in a v e h ic le i t m ay be n e c e s s a r y to p ro v id e th e m w ith b a c k g ro u n d c o m p e n s a t in g d e v ic e s and to a v o id c o n ta m in a tio n of the e q u ip m e n t by k e e p in g the a i r - p r e s s u r e w ith in the v e h ic le s lig h tly ab o v e a tm o s p h e r ic p r e s s u r e and by f i l te r in g in c o m in g a i r .

6. 4 . M is c e l la n e o u s e q u ip m e n t6. 4 . 1. T r a n s p o r t eq u ip m en t

A n u m b e r of s u rv e y v e h ic le s sh o u ld be a v a i la b le in w h ich ra d ia tio n m e a su r in g in s tru m e n ts and sam p le co llec tin g equipm ent m ay be c a r r ie d . It i s adv an tageou s fo r the v e h ic le s to be p re p a re d fo r the in s ta lla tio n of ad d itio n a l equ ipm ent, such a s d e v ic e s fo r th e e s t im a tio n of g r o s s b e ta -a c t iv i ty of s a m p le s and p o s s ib ly a m o b ile g a m m a - s p e c t r o m e te r . T hey should a lso c a r r y pow er su p p lie s fo r any equ ipm en t th a t c a n not be o p e ra te d on b a t te r ie s . The v e h ic le s should be re a s o n ab ly sm a ll and should be cap ab le of t r a v e r s in g c o m p ara tiv e ly rough g ro u nd . F o u r-w h e e l d r iv e i s reco m m en d ed .E m e rg e n c y e n v iro n m e n ta l c o n d itio n s c a n c r e a te a n e e d fo r e x t r a v e h ic le s s u b s ta n t ia l ly in e x c e s s o f th e n o r m a l c o m p le m e n t. P r i o r a r r a n g e m e n ts sh ou ld be m a d e w ith o u ts id e s o u rc e s w h ere su ch v e h ic le s could be m ade re a d ily a v a ilab le . O r d in a r y v e h ic le s m a y be u s e d to s u p p le m e n t th o s e m a in ta in e d s p e c ia lly fo r s u rv e y w o rk by a r r a n g in g th a t, fo r ex -

5 S e e A n n ex V fo r a d iscu ssion o f so m e s p e c ia l a n a ly t ic a l co n s id e ra tio n s w ith re g a rd to e m e r g e n c y e n v iro n m e n ta l m o n ito r in g .

49


am ple , m o n ito rin g equ ipm en t can e a s i ly be in s ta lle d a t sh o r t n o tic e . A n e m e rg e n c y k it s u ita b le f o r t r a n s p o r t in an o r d in a ry v eh ic le and a ty p ic a l, sp e c ia lly equipped, su rv e y v e h ic le a r e show n in F ig s . 2 -4 .

FIG . 2 . Contents o f em ergen cy environm ental m onitoring k it (Hanford Pro ject - USA)

A s s ta te d in sec tio n 6 .2 .2 the u se of a i r c r a f t o r boats m ay be in d ica ted u n de r sp e c ia l co n d ition s. It i s p ro b ab ly b e s t to a r ra n g e fo r b o a ts o r h e l ic o p te r s to be m ade a v a ila b le a t s h o r t

5 0


FIG . 3 . Layout o f instrum ents w ithin em ergen cy m onitoring v eh ic le

(A to m ic Energy Com m ission - Denm ark)

no tice u n de r c o n tra c t w ith o u ts id e so u rc e s . Such an a r r a n g e m ent i s l e s s p ra c t ic a b le w ith fixed -w ing a i r c r a f t , in to w hich sp e c ia l equ ipm en t m ay have to be in s ta lle d .

6 ,4 . 2. C om m u n ica tio n s and w arn in g equ ipm entThe ra p id t r a n s m is s io n of in fo rm a tio n o r in s t ru c t io n s i s of g re a t im p o r ta n c e .The em e rg e n c y c o n tro l c e n tre should have p r io r i ty te lephone l in e s a t i t s d is p o s a l fo r th e t r a n s m is s io n of m o n ito r in g and o th e r in fo rm a tio n . Owing to the fac t, how ever, th a t the m o n ito r in g te a m s m a y be d is p e r s e d on th e g ro u n d o r m a y be o p e ra tin g in a i r c r a f t , s h o r t-w a v e ra d io -c o m m u n ic a t io n h a s m any a d v a n ta g e s and shou ld be a v a ila b le fo r c o n ta c t betw een te a m s o r ind iv iduals engaged in m on ito ring ta s k s and the con t r o l c e n t r e . It i s a d v is a b le th a t m o s t , i f n o t a l l , r a d i o c o m m u n ic a tio n s e t s sh o u ld be p o w e re d by b a t t e r i e s o r by ind ep en d en t v e h ic le -b o rn e p o w er su p p lie s . "W a lk ie - ta lk ie " type s e ts can co n v en ien tly be u se d .

51


FIG . 4 . Layout o f instrum ents w ithin em ergen cy m onitoring v eh ic le

(A tom ic Energy C o m m i s s i o n - Denm ark)

If p o ss ib le , it i s ad visab le to a rra n g e fo r the ta p e -re co rd in g of telephone com m u n ication s. In any event, m e ssa g es should be "logg ed " in som e sy stem a tic fashion .

6. 4. 3 . M eteo ro lo g ica l equipm ent

The standard equipm ent of a cu sto m ary s m a ll m e te o ro lo g ica l sta tion (b a ro m ete r, th e rm o m e te r , h y g ro m eter, and, in p a r

5 2


t ic u la r , w in d -sp eed m e te r) i s r e q u ire d in o rd e r to g e t lo c a l in fo rm a tio n a t p o in ts re m o te fro m fixed m e te o ro lo g ic a l s t a t io n s . In th e c a s e of l a r g e r e s ta b li s h m e n ts , fo r e x a m p le th o se con ta in in g pow er r e a c to r s and re p ro c e s s in g p la n ts , it i s a d v isa b le to in s ta l l a s m a l l m e te o ro lo g ic a l s ta t io n ort the s ite fo r the p r in c ip a l p u rp o se of d e te rm in in g w here and when s a m p le s sh o u ld be c o l le c te d an d m e a s u r e m e n ts sh o u ld be m a d e .

6 . 4 .4 . P r o te c t iv e e q u ip m e n t

M on ito rin g te a m s shou ld be p ro v id e d w ith a p p ro p r ia te p r o te c tiv e equ ipm ent to e n su re th e ir s a fe ty , fo r exam ple m a sk s , hoods, o v e ra l ls , sh oes, g loves, e tc . and a lso p e rso n n e l m o n ito rin g dev ices (d o s im e te rs , film badges, a la rm d o sim e te rs ) .

6. 4. 5. W arning and co n tro l equipm ent

S tan d a rd i te m s such a s w arn in g s ig n s , te m p o ra ry b a r r i e r s , r o p e s , e tc . w h ich a r e n e e d e d fo r th e d e m a rc a t io n o f th e b o u n d a r ie s of c o n ta m in a te d a r e a s , sh o u ld be k ep t in s to c k and e a s i ly a v a i la b le .

5 3


INTRODUCTION TO ANNEXEST he follow ing an n ex es a r e in tended to be of help in the deve lop

m e n t and a p p lic a tio n of th e e n v iro n m e n ta l m o n ito r in g p r o c e d u r e s d e s c r ib e d in th e m a in te x t. I t i s e m p h a s iz e d once a g a in th a t th e techn iques and p ro c e d u re s outlined should be co n sid ered a s exam ples on ly and th a t t h e i r a p p lic a b il i ty m u s t be ju d g ed in th e lig h t o f the p re v a ilin g c i r c u m s ta n c e s .

T he co n ten t of the an n ex es h as been co m p iled o r d e riv e d fro m p u b lish e d m a te r ia l o r f ro m m a te r ia l p ro v id e d by in d iv id u a l p a n e l m e m b e rs and re p re s e n ta t iv e s of the o th e r p a rtic ip a tin g in te rn a tio n a l o rg an iz a tio n s .

The annexes have not been rev iew ed by the com plete panel and it should th e re fo re not be a ssu m e d th a t the ind iv id u al m e m b e rs of the p a n e l n e c e s s a r i ly a g re e w ith , o r c a r r y any re s p o n s ib i l i ty fo r the in c lu s io n of, a l l th e m a te r ia l w hich i s p re s e n te d .

A N NEX IIN V EN TO R IES O F FISS IO N -PR O D U C T S AND

P O SSIB L E R E L E A SE S

(T a b le s I. 1-1. 4)

5 4


TABLE I. 1

C A L C U L A T E D A C T IV IT IE S O F SO M E IM P O R T A N T F IS S IO N -P R O D U C T S IN URANIUM * R E A C T O R F U E L

(D e r iv e d f ro m d a ta p r e s e n te d in R e fs , [ l , 3])

F is s io n -p ro d u c tA c t iv i t ie s a t th e en d o f

o p e ra tin g p eriod s

(k C i/ M W (t))

O p e ra tin g p erio d

1 0 0 d 1 yr

various

5 yr

A c t iv i t ie s a t th e end o f v ario u s sh ut-d ow n

p erio d s fo llo w in g o p e ra tio n fo r 1 yr

(k C i/ M W (t))

Sh u t-d o w n p eriod

7 d 3 0 d 1 0 0 d

85K r 0 . 0 5 0 . 19 0 . 82 0 . 1 9 0 . 1 9 0 . 19

88K r 2 3 2 3 2 3 - -

89Sr 28 38 39 3 5 2 6 10

90S r 0 . 4 1 . 4 6 . 7 1 . 4 1 . 4 1 . 4

106R u + 106Rh 1 . 5 4 . 4 8 . 4 4 . 3 4 3 . 6131j 2 5 2 5 2 5 13 1 . 9 0 . 0 0 4

13zT e 37 37 37 8 . 3 0 . 06 -13 3j 54 5 4 54 0 . 2 -

133X e 55 55 55 2 2 1. 2 -

137C s 0 . 3 1 . 1 5 . 2 1 . 1 1 . 1 1 . 1

140Ba 52 52 52 3 6 10 0 . 2 3

144C e + 144Pr 2 0 53 88 52 50 4 2

v T h is ta b le a p p lie s to n a tu ra l u ra n iu m , b u t fo r th e purpose o f e s t im a t in g th e a c t iv i t ie s o f f iss io n -p ro d u c ts w h ic h m ig h t b e

re le a se d in a n a c c id e n t i t c a n b e a p p lie d to e n r ic h e d u ran iu m .


O l05

TABLE 1 .2

VOLATILE RELEASE OF FISSION-PRODUCTS FROM URANIUM* REACTOR FUEL CALCULATED ACTIVITIES OF SOME IMPORTANT FISSION-PRODUCTS RELEASED

(Derived from data p resen ted in Refs. [2, 3])

Fission-product

Percentage of

fission-product

in fuel

assumed to be

released

Activities released at the end of various

operating periods

(kCi/MW(t))

Operating period

100 d 1 yr 5 yr

Activities released at the end of various

shut-down periods

following operation

at full power for 1 yr

(kCi/MW(t))

Shut-down period

7 d 30 d 100 d

85 Kr 60 0.030 0 .11 0 .49 0.11 0 .11 0 .11

88 Kr 60 14 14 14 - - -

85 S r 0.1 0.028 0.038 0.039 0 .035 0 .026 0 .01

90 S r 0 .1 0.0004 0 .0014 0.0067 0.0014 0 .0014 0 .0014

losRu+ I06Rh 4 0.06 0.18 0 .34 0.17 0 .16 0 .14131 j

25 6 .3 . 6 .3 6 .3 3 .3 0.47 0 .001

132 Te 15 5 .6 5 .6 5 .6 1.2 0 .009 -133 j

25 14 14 14 0.05 - -

133 Xe 60 33 33 33 13 0.72 -

131 Cs 15 0.045 0.17 0 .78 0.17 0 .17 0.17

140Ba 0 .2 0 .10 0.10 0 .10 0.072 0 .02 0.0005

144C e + 144Pr 0.15 0. 03 0 .08 0 .13 0.078 0 .075 0 .064

* This table applies to natural uranium, but for the purpose of estimating the activities of fission-products which might be released in an

accident it can be applied to enriched uranium.

Note: This table indicates the approximate activities of fission-products released from the fuel. The interplay of many factors, for ex

ample plating-out and containment, would undoubtedly reduce the activities of the fission-products actually released to the environment.


TABLE I. 3

V O L A T IL E R E L E A S E O F F IS S IO N -P R O D U C T S F R O M U R A N IU M * R E A C T O R F U E L C A L C U L A T E D A C T IV IT IE S O F SO M E IM P O R T A N T F IS S IO N -P R O D U C T S

R E L E A S E D AS P E R C E N T A G E S O F T H E A C T IV IT Y O F T H E 131I R E L E A S E D

Fission-product

Percentage of

fission-product

in fuel assumed

to be released

Activities released as percentage of

released at the end of various

operating periods

Operating period

100 d 1 yr

ill!

5 yr

Activities released

as percentage of

released at the end of

various shut-down

periods following

operation at full power

for 1 yr

Shut-down period

7 d 30 d

85 Kr 60 0.5 2 8 3.5 26

“ Kr 60 220 220 220 -

“ Sr 0.1 0.5 0.6 0.6 1 5

“ Sr 0.1 0.006 0.02 0.1 0.04 0 .3

1MRu+1MRh 4 1 3 5 5 34191 j

25 100 100 100 100 100

132 Te 15 90 90 90 36 2133 j

25 210 210 210 1.5

133 Xe 60 520 520 520 400 150

131 Cs 15 0.7 2.5 13 5 35

141 Ba 0.2 2 2 2 2 4

14*C e + 1MPr 0.15 0.5 1.3 2 2 15

$ This cable applies to natural uranium, but for the purpose of estimating the activities of fission-products which might be released in an accident

it can be applied to enriched uranium.

Note: This table refers to the activities of fission-products released from the fuel. The interplay of many factors, for example plating-out and

containment, would undoubtedly alter the relative activities of the fission-products actually released to the environment.


TABLE I. 4

CALCULATED MEAN ACTIVITIES OF SELECTED RADIONUCLIDES RELEASED FROM PREVIOUSLY UNIRRADIATED URANIUM M ETA L FOLLOWING;

(a) a c r i t ic a l i ty e x c u rs io n w ith a to ta l en erg y r e le a s e of 100 MWs (3 XlO18 fis s io n s ) w ith im m e d ia te p re fe re n tia l r e le a s e of v o la tile f is s io n -p ro d u c ts (a ssu m ed tim e of r e le a s e 4 .6 2 m in*)

(b) an e x c u rs io n w ith a to ta l e n e rg y r e le a s e of 300 MWs (1019 f i s sio n s) w ith m elt-d ow n , ox idation and slow p re fe re n tia l r e le a s e of v o la tile f is s io n -p ro d u c ts (a ssu m ed m ean tim e of r e le a s e 2 .4 h*)

(c) a sp ike e x c u rs io n of to ta l m agnitude 1020 f is s io n s re su lt in g in com p le te v a p o r iz a tio n of the sy s te m and im m e d ia te r e le a s e of a l l f is s io n -p ro d u c ts (a ssum ed m ean tim e of r e le a s e 4. 62 m in*)

N uclide H a lf- lifeAssumed

percen tage release ((a ) and (b ) only)

(a)

A ctiv ity released(C i)

(b) (c )

« B r 2 . 4 h 60 1. I X 10 3 . 5 x 1 0 6 . 3 x 1 0 *t tm Kr 1 .9 h 60 2 . 3 X l O '1 2 . 5 x 1 0 1 .3 X 1 0

w Kr 3 . 2 m in 60 2 .3 X 1 0 * - 1 .3 x lO 4« K r 33 s 60 1. 3 x l 0 ! - 7 . 0 x 1 0 s®Rb IS m in 15 2 . 2 x 1 0 * 2 . 3 4 . 9 x 1 0 4•°Rb 2 . 9 m in 15 9 . 9 x 1 0 * - 2 . 2 x 1 0 s#,Rb 100 s 15 3 .3 X 1 0 * - 7. 4 x 1 0 4

* lm Rb 14 m in 15 2 . 0 x 1 0 * 6 .9 x 10“1 4 . 5 X 1 0 *" R b 5 .3 s 15 3 . 6 X l O '1 - 8. 1 x 10" S r 53 d 0. 1 3 . 9 x l 0 ' s 1 .7 x lO " 3 1. 3" S r 2 8 yr 0 . 1 2 . 9 X 10 -• 1. 5 X 1 0 'S 9 . 6 x 1 0 - *“ Sr 9 . 7 h 0 .1 4 . 8 x 1 0 - * 2 . 4 X 1 0 '1 1. 6 X 1 0 s

“ Sr 2 . 7 h 0 .1 3 . 3 X 1 0 " 1 6 . Ox 1 0 "1 1 .1 X lO 410<Ru i v 4 3 . 6 x 1 0 "* 1 .2 x lO * 4 3 . 0 X 1 0 * 1lOTRu 4 m in 4 8 . 5 - 7 .1 X lO 3

i 3 i m je 3 0 h 15 1. 8 X 1 0 - 1 8 . 2 x 1 0 ’ * 3 . 9 X 1 0m T e 2 5 min 15 2 .1 X 1 0 3 . 4 X 1 0 6 .1 x 10 s“ *T e 7 7 . 7 h 15 9 . 9 x 1 0 - ' 3 . 8 2 . 2 x 10 *

u s m je 6 3 min 15 6 .3 X 1 0 7 . 5 X 1 0 1. 4 x 1 0 4u iT e 2 min 15 2 . 1 X 1 0 * 7 . 7 x 1 0 4 . 7 x lO 4m T e 4 2 min 15 1 . 8 x 1 0 * 6 . 5 x 1 0 3. 9 X 1 0 4m i 8 . 1 d 2 5 1 . 2 x 1 0 - * 1 . 7 1 . 6u s , 2 . 3 h 25 1 .4 5 .5 1 . 9 x 1 0 *lss. 2 2 . 4 h 25 2 . 5 3. Ox 10 3 . 3 X 1 0 *l « i 53 m in 25 7 .5 X 1 0 2 . 8 x 1 0 * 1 . 0 X 1 0 4135, 6 . 7 h 25 3 .3 X 1 0 8 . 7 x 1 0 4 . 4 X 1 0 3IWj 86 s 25 9 . 8 x 1 0 * - 1 . 3 x 1 0 sU7X e 3 . 9 m in 60 3 .8 X 1 0 * - 2 .1 x l O 5140X e 16 s 60 2 . 0 x 1 0 - 1 .1 x l O 3w C s 30 yr 15 2 . 3 X 1 0 - * 1 . 4 x 1 0 ' * 5 . 0 x 1 0 ' *M«CS 66 s 15 4 . 5 X 1 0 * - 1 .0 x 1 0 s^ B a 1 2 .8 d 0 .2

oX00 2 . 1 x 1 0 "* 9 . 7 x 1 0

M1Ba 18 m in 0 .2 5 .2 8 .2 x 1 0 "* 8. 7 x lO 4

MIBa 6 m in 0 .2 1 . 0 x 1 0 - 1 .7 x 1 0 s

“ ‘ C e 2 9 0 d 0 .1 5 1 . 7 x 1 0 '< 5 . 5 x l O " 4 3 .7

“ ‘ C e 1 4 .6 m in 0 .1 5 2 .9 1 . 2 x 1 0 " * 6 . 4 X lO 4

* The times chosen are for convenience in using the published data of Glendenin cited in Bolles, Ballou [4].

Note: The interplay of many factors, for example plating-out and containment, would undoubtedly reduce the activities

of die radionuclides actually released to the environment

58


ANNEX II

AIR-BORNE RELEASES:DISPERSION, DEPOSITION AND

DOSE-EXPOSURE RELATIONSHIPS*

B e cau se of the im p o rta n c e of the a tm o sp h e r ic ro u te of re le a s e to th e e n v iro n m e n t c o n s id e ra b le e f fo r t h a s b een g iv en to the stu d y of the d isp e rs io n of a ir -b o rn e m a te r ia l . S evera l th e o re tica l diffusion m o d e ls h av e b e e n d e v e lo p e d and d is p e r s io n p a t te r n s in sp e c if ie d w e a th e r co n d itio n s , b a se d on th e s e m o d e ls , have b een p u b lish e d (R e fs . [2, 5 -7 ]) . F r o m th e se p a t te r n s i t m a y be p o ss ib le to ob ta in e a r ly e s t im a te s o f the co n ta m in a tio n p a t te rn fo llow ing a r e le a s e of f i s s io n -p ro d u c ts to the a tm o s p h e re and to u se th e se e s t im a te s a s a b a s is fo r th e s e le c t io n of im p o rta n t sa m p lin g lo c a tio n s .

E s t im a te s of th e t im e - in te g r a l of c o n c e n tra t io n of a i r - b o r n e m a te r ia l a t g round lev e l, b ased on one of the th e o re tic a l m odels [7], a r e p re s e n te d in F ig s . II. 1 (a -d ). E s t im a te s of the g round d e p o s it io n m a y be d e r iv e d r e la t iv e ly s im p ly f ro m th e s e c u r v e s . T h e se d ia g ra m s a r e in ten d ed only to i l lu s t r a te som e of the p o ss ib le types of d is p e r s io n . P a t te r n s a p p lic a b le to the lo c a l w e a th e r cond itions a t the t im e of r e le a s e should be d e riv e d a s a b a s is fo r re a l is t ic e s t im a te s . M ethods of doing so a r e d e sc r ib e d in R e fs . [2, 5-7] and in o th e r p u b lica tio n s l is te d in the b ib liog raph y .

It m u s t be e m p h a s iz e d th a t e s t im a te s of c o n c e n tra tio n and d e p o sition d eriv ed fro m th e o re tic a l diffusion m odels a re not in any way a su b s ti tu te fo r e ffe c tiv e e n v iro n m e n ta l sam p ling and m e asu rem en t te c h n iq u e s .

* S o m e in fo rm a tio n o f th e se and o th e r re la te d to p ic s w ill be found in T a b le s I I . 1 - 6 and F ig s . I I . 1 - 4 .

59


TABLE II. 1 [8]

E S T IM A T E D A C T IV IT Y IN M IL K (mC i / l i t r e ) FO L L O W IN G AN IN IT IA L T O T A L D E P O S IT IO N O F 1 M C i/m 2 O F TH E

IN D IC A T E D N U C L ID E S (A llow ing f o r d e c a y of h e rb a g e w ith h a l f - t im e of 14 d)

D ays a f te r

d e p o sitio n1 3 1 1 133 I 132 X e 8SSr 30 Sr 140 Ba i ” C sa

1 0 . 1 1 0 .0 6 0 0 . 0 0 2 8 0 . 0 0 6 0 .0 0 6 0 .0 0 2 7 0 . 0 7

2 0 . 15 0 . 0 3 4 0 .0 0 6 5 0 . 0 1 3 0 . 0 1 4 0 .0 0 5 3 0 . 1 5

3 0 . 1 4 0 .0 1 6 0 .0 0 7 7 0 .0 1 7 0 .0 1 8 0 .0 0 6 4 0 . 1 9

4 0 . 1 2 0 .0 0 7 0 . 0 0 7 4 0 . 0 1 9 0 .0 2 0 0 .0 0 7 0 0 .2 0

5 0 . 1 2 0 .0 0 3 0 .0 0 6 4 0 .0 2 0 0 . 0 2 1 0 .0 0 7 0 0 . 2 2

6 0 . 1 0 0 .0 0 1 0 .0 0 5 3 0 . 0 1 9 0 .0 2 1 0 .0 0 6 8 0 .2 2

7 0 . 0 9 0 . 0 0 1 0 .0 0 4 2 0 . 0 1 9 0 .0 2 1 0 .0 0 6 5 0 . 2 1

8 0 . 0 8 - 0 .0 0 3 3 0 . 0 1 8 0 .0 2 0 0 .0 0 6 1 0 . 2 1

9 0 . 0 7 - 0 .0 0 2 6 0 . 0 1 7 0 .0 1 9 0 .0 0 5 7 0 . 2 0

10 0 . 0 6 - 0 .0 2 0 0 0 . 0 1 6 0 . 0 1 8 0 .0 0 5 2 0 . 2 0

2 1 0 . 0 1 - - 0 .0 0 8 0 .0 1 1 0 .0 0 1 7 0 . 1 3

a U sin g un p u blish ed in fo rm a tio n fro m D r. B .F . S a n so m .

N o te : T h e e s t im a tio n s in c lu d e th e assu m p tio n s th a t 2 5 % o f a c t iv i ty is re ta in e d on

e d ib le h e rb a g e an d th a t th e co w g ra z e s an a re a o f 16 0 m 2 a d ay .

60


TABLE II. 2 [8 ]

E S T IM A T E D A C T IV IT Y IN EG G S FR O M F R E E -R A N G E HENS (IN n C i/E G G ) FO L L O W IN G AN IN IT IA L

T O T A L D E P O S IT IO N O F 1 ju C i/m 2 O F TH E IN D IC A T E D N U C L ID E S

D ays a f te r

d e p o sitio n

131 [ a

W h o le eggd

89 S r'3

W h o le eg g E d ib le p art

90S rb

W h o le e g g E d ib le part

137 C s °

W h o le e g g

1 0 .0 0 0 2 0 .0 2 8 0 .0 0 0 0 6 0 . 0 2 8 0 . 0 0 0 0 6 0 .0 0 1 2

2 0 .0 0 0 5 0 .0 3 3 0 .0 0 0 1 6 0 . 0 3 4 0 .0 0 0 1 6 0 .0 0 1 6

3 0 .0 0 1 0 0 .0 3 5 0 .0 0 0 3 0 0 . 0 3 6 0 .0 0 0 3 0 0 .0 0 1 8

4 0 .0 0 2 0 0 .0 3 7 0 . 0 0 0 4 5 0 . 0 3 8 0 .0 0 0 4 5 0 . 0 0 2 0

5 0 . 0 0 3 4 0 .0 3 8 0 . 0 0 0 5 5 0 . 0 3 9 0 . 0 0 0 5 5 0 .0 0 2 1

6 0 .0 0 5 0 0 .0 3 8 0 .0 0 0 6 1 0 . 0 4 0 0 .0 0 0 6 2 0 . 0 0 2 2

7 0 .0 0 5 7 0 .0 3 8 0 . 0 0 0 6 1 0 . 0 4 0 0 .0 0 0 6 5 0 . 0 0 2 3

8 0 .0 0 5 7 0 . 0 3 8 0 .0 0 0 6 2 0 . 0 4 1 0 .0 0 0 6 9 0 .0 0 2 3

9 0 . 0 0 5 3 0 .0 3 8 0 . 0 0 0 6 4 0 .0 4 1 0 .0 0 0 7 1 0 .0 0 2 4

10 0 .0 0 4 9 0 .0 3 8 0 .0 0 0 6 5 0 .0 4 1 0 .0 0 0 7 1 0 .0 0 2 4

a D eriv ed by G arn er fro m d a ta g iv e n b y O k o n sk i, L e n g e m a n n , C o m a r [ 9 ] ,

b D e riv e d b y G a rn e r fro m d a ta g iv e n by C o m a r , D rig g ers [ 1 0 ] ,

c D eriv ed b y G arn er fro m d a ta g iv e n by E k m an [ 1 1 ] .

d S h e l l c o n ta in s in s ig n if ic a n t am o u n ts o f n u c lid e .

61


TABLE I I . 3

DOSE-RATE IN AIR AT A HEIGHT OF 1 m ABOVE UNIFORMLY DISTRIBUTED GAMMA-EMITTING

FISSION-PRODUCTS ON THE GROUND*Gamma-emitting nuclide Dose-rate for 1 Ci/m2

(rad/h)

9sZr + 9smNb 9.34

95 Nb 9.69

103 Ru 6.27

106 Ru + 106 Rh 2,05131 j 5.02

137 Cs 6.84

141 Ce 0.91

144 Ce 0.34

# Derived from data presented by Mahmoud [ 12].

TABLE II. 4

DOSE-EXPOSURE RELATIONSHIP EXTERNAL GAMMA-RADIATION FROM

AIR-BORNE MATERIAL*

Material Whole-body doseTime-integral of

concentration in air (Ci-sec/m3)

Total gaseous and volatile 1 rad (gamma) 3.8 (related to time of release) or

fission-products 0.8 (measured at one days decay)

* Derived from data given by Beattie [2],Note: The derived provisional relationships between radiation dose and time-integral of con

centration in air, concentration in milk, deposition on pasture and on green vegetables presented in Tables II. 4, II. 5 and II. 6 are intended merely to be of help in selecting monitoring techniques of adequate sensitivity for the measurement of contamination levels corresponding to the applicable emergency dose limits. The appropriate publications should be consulted for more precise and possibly more up-to-date information on those'relationships.

62


TABLE II. 5

DOSE-EXPOSURE RELATIONSHIPS INHALATION OF RADIOACTIVE MATERIAL

Nuclide C riticalorgan

Age Dose or dose-rate to critica l organ

Correspondingintake(MCi)

Corresponding tim e-integral of

concentration in air (Ci*sec/m8)a

isijb Thyroid 0 1 rad 0.035 1 .3 X 1 0 * 56 months 1 rad 0.035 5 .2 x 1 0 '*1 yr 1 rad 0 .0 4 4 4 .8 X 1 0 '*Adult 1 rad 0 .8 0 3 .4 X 1 0 ‘ 8

.9Srb Bone (at site of 0 1 rad 0 .187 6 .7 X 1 0 "3maximum 6 months 1 rad 0 .366 5 .4 X 1 0 ~3concentration) l y r 1 rad 0.553 6 .0 x 10 "s

Adult 1 rad 5 .5 3 2 .4 X 1 0 ~2

» Srb Bone (at site of 0 1 rad/yr 0 .0 1 9 6 .7 x l O '4maximum 6 months 1 rad/yr 0 .0 3 8 5 .5 X 1 0 ' 4concentration) 1 yr 1 rad/yr 0.057 6 .2 x 1 0 *4

Adult 1 rad/yr 0 .5 7 2 .4 X 1 0 '*

“ 'Csb Whole body 0 1 rad 0 .8 2 . 9 x 10 ~z6 months 1 rad 1 .9 2 .7 x l O '21 yr 1 rad 2 .2 2 .4 X 1 0 *2Adult 1 rad 15 ,0 6 .5 X 1 0 ' 2

Fission-product Thyroid 3 yr or less 1 rad 2 .8 X 1 0 ’*iodine + 182 Tec Adult 1 rad 1 .2 x 1 0 ' 3

(in terms of 131I at one day)

106Ruc G. I. tract 1 rad 3 .2 X 1 0 * 2

148 Ba (sol. ) c Bone Adult 1 rad 2 .1 X 1 0w0Ba (insol. )d Lungs Adult 1 rad 2 .9 x 1 0 *2

144 Ce (sol. )c Liver Adult 1 rad 1 .7 x 1 0 *3l44Ce (insol. )d Lungs Adult 1 rad 4 .2 X 1 0 *3

226 Ra (so l.)d Bone Adult 1 rem/yr 5 .0 x 1 0 ' 4

239Pu (sol.)^ Bone Adult 1 rem/yr 2 .9 x 1 0 *s

a To obtain the permissible emergency "lim its" recommended by the Medical Research Council, applicable to members of the general public, the figures given in column 6 above should be multiplied by the recommended maximum permissible doses or dose-rates to the critica l organs, which are: thyroid ( 1SII) - 25 rads, bone (**Sr) - 15 rads, bone ( 90Sr) - 1 .5 rad/yr, whole body ( l37Cs) - 10 rads.

b Data derived from report to the Medical Research Council by its Com m ittee on Protection Against Ionising Radiations [1 5 ] .

c Derived from data presented by Beattie [2 ] , d Derived from data presented by Cook [1 4 ] .

63


TIM

E-IN

TEG

RA

L Of

CON

CEN

TRAT

ION

AT

GR

OUND

LE

VEL

IN

Ci-s

ec/m

3 PE

R CU

RIE

RE

LEA

SE

D

FIGjJI. 1. Atmospheric dispersion from a point source (Redrawn from curves presented in Ref. [7]) v^/uo = deposition coefficient u0/ujj = wind speed shear

(a) Release height: (b) Release height:

...........ground level ...........ground level--------- 70 m --------- 70 m

Wind speed at release height: 1 m/s Wind speed at release height; 1 m/sAtmospheric condition: moderately stable Atmospheric condition: very stable

64


TIM

EHN

TEG

RA

L OF

CON

CEN

TRAT

ION

AT

GR

OUND

LE

VEL

IN C

i-se

c/m

J PE

R CU

RIE

RE

LEA

SE

D

FIG. II. 1. Atmospheric dispersion from a point source (Redrawn from curves presented in Ref. P]) v^/Uj = deposition coefficient uj/ujj = wind speed shear

(c) Release height: (d) Release height:

ground level -------- ground level■ 70 m --------- 70 m

Wind speed at release height: 10 m/s Wind speed at relase height: 10 m/sAtmospheric condition: moderately stable Atmospheric condition: very stable

65


TABLE II . 6

D O S E -E X P O S U R E R E L A T IO N S H IP IN G E S T IO N O F R A D IO A C T IV E M A T E R IA L

(a) I n g e s t i o n in m i l k

Nuclide C ritical organ Dose or dose-rateAgeto critical organ

Corresponding concentration

in milk (peak levels)3

Corresponding initial deposition

on pasture (see Table II. 1)

(Ci/mz)

lsijb Thyroid 0 -6 months 1 rad 3 yr

2 .6 x lO '1 iiCi/litre1 .2 x i o '1

1 .7 x lO "8

MSrb ' Bone(at site of maximum concentration)

All ages 1 rad 1.3X10"* jiCi/g Ca 8 x l 0 ‘ 7

s0Srb Bone(at site of maximum concentration)

All ages 1 rad/yr 1.3X10"’ liCi/g Ca 8X 10"*

' ” Csb Whole body

r-'

0 1 rad 6 months 1 rad

.Adult

1 .5 x 1 0 " ' (JCi/lilre 1 .5X10"’

7 x lO *8 7 x lO "8

(b) I n g e s t i o n i n g r e e n v e g e t a b l e s

Nuclide C ritical organ Dose or dose-rate to critical organ

Corresponding deposition on green vegetables (tentative estimates)

(C i/m l)

131jC Thyroid 1 rad 2 X 10"6

90Sr° Bone 1 rad/yr 2X 10"'

137Cs° Whole body 1 rad 1 x 10”5

a To obtain the permissible emergency "lim its" recommended by the Medical Research Council, applicable to members of the general public, the figures given in column 5 for concentrations in milk should be multiplied by the recommended maximum permissible doses or dose-rates to the critical organs, which are: thyroid ( IS1I) - 25 rads, bone (^ Sr) - 15 rads, bone <»<>Sr) - 1 .5 rad/yr,. whole body P 81Cs) -1 0 rads.

b Data (excluding that given in the last column) derived from report by the Medical Research Council by its Committee of Protection Against Ionizing Radiations [1 6 ] .

c Derived from data provided by Beattie [2 ] .


FIG. II. 2. Estimated activity in milk following an os initial deposition on herbage of 1 jiCi/m2 of the

indicated nuclides

u p ___ i___ i___ i___ i___ i___ i— i— i— i— i-------------0 1 2 3 4 5 6 7 8 9 10TIME AFTER DEPOSITION (d j

FIG. II. 3. Estimated activity in eggs from free-range hens following an initial deposition of 1 j iCi/m2


FIG. II. 4. Exposure-rate in air above infinite plane source of gamma-emitters [13]

6 8


A N N E X I I I

Radiation surveys, particularly gam m a-radiation surveys, are of value for the rapid determ ination of the extent of d isp ersa l of radioactive contam ination on the ground or in surface w ater. Although the presence of alpha- and beta-em itting nuclides can be detected without sampling, for any quantitative assessm ent of the amounts presen t sampling is necessary . Suitable methods are described in Annex IV.1. A lp h a -ra d ia tio n s u r v e y s

The detection lim it for a lpha-em itte rs on the ground using the A m erican "Scintillation Portable Poppy" or s im ila r instrum ents such as the B ritish Type 1320 alpha-probe (see Annex VI) is about 10'2 ^C i/m 2. This corresponds to an a ir exposure of approximately 2X10"5 C i-sec /m 3 or an average one-hour a ir concentration of the order of 10'9 /uCi/cm3 . Air concentrations of alpha-em itters of this magnitude a re difficult to generate and in a ll probability there will not be sufficient alpha-contam ination on the ground to warrant su rveys except in the im m ediate vicinity of an accident involving large quantities of an alpha-em itter.2. B e ta -ra d ia tio n s u r v e y s

Depending on the radionuclides involved, a direct ground survey may p resen t a m ore sensitive m easure of the probable vegetation contamination level than analysis of samples removed from the field as described in Annex IV. Conversion of ground survey readings to vegetation contam ination levels can be accom plished by use of the following equations and facto rs:(a) A portable GM su rv ey -m e te r ca lib ra ted to yield 3000 to

4000 counts/min per mR/h of Ray is used. Suitable instruments are described in Annex VI.

(b) The probe is held at not m ore than 5 cm above the ground with the beta-shield open.

(c) 100 coun ts/m in can be detected above a norm al 50 to 100 coun ts/m in background.

A L P H A - , B E T A - A N D G A M M A -R A D IA T IO N S U R V E Y S

69


(d) Readings are taken in open terra in not in close proximity to heavy vegetation cover or buildings.(1) D = RXF

where D= ground deposition in ;uCi/m2,R = GM m eter reading in units of 102 counts/min (back

ground corrected),F = factor from Table III. 1.

TABLE III. 1

GROUND SURFACE CONTAMINATION L E V E L S*OF VARIOUS NUCLIDES REQUIRED TO YIELD

100 counts/min (NET) ON A GM M ETER (OPEN WINDOW)

Nuclide F((iCi/m2 per 100 counts/min)

95Z r+ 95Nb 6

141Ce 2i03mRUj mixed Ru Rh (100 d old)a 1

60Co, ®Sr, 9»Sr, 90Y, S1Y . “ Cs, “ °Ba, 14«La

144Ce + 144 Pr, 106Ru+ 106Rh,0 .3

mixed radioiodines (1 h to 1 week old).

mixed fission-products (100 d old) >

* Level varies with background readings, ground roughness and vegetation cover. a Age refers to time since irradiation of the fuel from which the FP's were released.

(2) C=(DXf)/dwhere C = vegetation concentration in n Ci/kg,

D = ground deposition in /uCi/m2.d = density of vegetation cover in kg/m2,f = fraction of deposited nuclide which is on the

vegetation.f ranges from 0.1 to 1 and is usually taken to be 0. 25 for131I in the United Kingdom.

70


3. G a m m a -r a d ia tio n s u r v e y s

3. 1. G round su rv e y sAlthough gamma-radiation surveys may be needed to define con

taminated areas from which evacuation of people may be demanded, perhaps their most important role is the prediction of levels of contamination likely to be found in some foods. This is particularly so in the case of a possible re lease of 131I. Suitable instruments for the former purpose are described in Annex VI; for the latter purpose, more exact techniques may be required.

3. 2. The use of gamma-radiation surveys to predict i3iI levelsin milk

A release of1311, either alone or as one component of a mixture of radionuclides, to atmosphere in a dairy farming area will ca ll for the rapid provision of information on which to base decisions re garding any restrictions on the consumption of locally produced milk. If the composition of m aterial deposited on to pasture land is known, measurement of gamma exposure-rate over the ground surface can be used to estim ate the quantity of 131I deposited per unit area of ground and hence to predict future levels of 131I in m ilk.

It is necessary that gamma exposure-rate measuring instruments used for this purpose should be capable of detecting an increase in exposure-rate over the ground surface equivalent to that amount of 131I per unit area of ground which could lead to the emergency perm issible level in the milk of cows grazing the affected area. In the United Kingdom the emergency permissible peak activity of milk set by the Medical R esearch Council [16] is currently 0. 065 MCi/litre. From Table II. 6 of Annex II it can be deduced that the corresponding deposition is approximately 0 .4 /uCi/m2.

(a) Surveys using simple portable instruments

The exposure-rate at 1 m above a plane surface contaminated with 0. 4 MCi/m2 of 1S1I is 3. 3 AiR/h [13]. The natural background varies according to locality; in the United Kingdom it ranges typically from 6 to 15 juR/h. It is evident that the sensitivity range of any instrument must be better than 0 to 100 /jR/h and that, for any accurate

71


l -ENERSf (MevJ

FIG. III. 1. Energy sensitivity of British ratemeters Type 1368A and Type 1413A [17]

assessm ent of the contribution to the gamma exposure-rate from an accident, frequent background surveys are necessary.

The sensitivity requirements are met by many of the beta/gamma monitoring instruments described in Annex VI. Instruments using scintillation counters are, in general, markedly energy-dependent, having a greater response per roentgen per hour for low- rather than high-energy gammas. The United Kingdom beta/gamma monitor Type 1413A and the Type 1597A which is replacing it, for example, have a factor of overestim ation for 131I gammas of 3 .1 (Fig. III. 1). These instruments held at 1 m above a plane surface contaminated with 0 .4 MCi/m2 of 131I, with no nuclide other than 13ll present, would thus read 10 nR/h.

72


In using portable instruments for environmental monitoring, the following procedures should be adopted:

(i) M easurements should be made at a standard height (1 m) over short grass on undisturbed land (common grazing, heath, permanent pasture) to avoid changes which occur when vegetation contaminated by fall-out is either harvested or ploughed under, and at least 20 m from any building, barns, roads, drives, railways, bridges, or any heaps of m aterial such as gravel, rubble or road-grit. These a ll contain varying amounts of natural activity, mainly uranium or thorium products. Haystacks or silos should be avoided since they may have contained, in a concentrated form, the total fall-out deposited on grass which originally covered a large area. T rees and hedges also act as co llectors of fall-out which is washed out to a variable extent by rain. In an emergency they may trap large amounts of air-borne particulate matter and give a high gamma-radiation reading which is not representative of the average value of that area.

(ii) Precautions should be taken against contamination of the instrument. The best way of checking the datum level (cosmic background plus inherent count-rate of the instrument) is to read the instrument over a stretch of water.

(iii) Representative samples of grass and soil, from measured areas of ground, should be taken at reference stations where repeated gamma-measurements are made.

(iv) Comparisons should be made between the reading of scintillation instruments and the exposure-rate measured by an ionization chamber or GM-counter. The latter instruments are le ss energy-dependent than scintillation counters and the comparison will therefore give some indication of the nature of the deposited m aterial.

(b) Surveys using car-borne instruments

If an instrument is mounted in a car and its output is connected to a chart recorder, a rapid and continuous survey can be made and the results recorded for future referen ce . The disadvantages are that the vehicle may become contaminated and that the exposure-rate over the road will not be the same as over pasture. In addition, there are anomalies in the background gamma exposure-rate over roads

73


and near buildings, caused by the use of granite and similar materials. These difficulties can be reduced by mounting the instrument on a pole extending above or to one side of the vehicle, so that the detector receives a greater proportion of gam m a-rays from activity on the adjacent fields.

FIG. III. 2. Landrover as used in the United Kingdom with ratemeter Type 1413A on pole [17]

Figure III. 2 shows a Landrover vehicle with a ratemeter, Type 1413A, mounted on the top of a vertical 3. 3-m pole, as used by the United Kingdom Atomic Energy Authority. The output of the ra te meter is fed to a chart recorder while a push button operated by the driver actuates a marker working in the margin of the recorder chart. If the vehicle is driven round a predetermined route, the chart can

74


be marked as land-marks are passed and the position of the marks correlated with a large scale map at the end of the run. By driving at a steady speed, about 30 km/h, the charts can easily be compared one against another.

It has been shown that, under favourable conditions, a deposition of 131I equivalent to about one tenth of the British Medical Research Council emergency perm issible level in milk can be detected using such a system [17].

(c) Surveys using fixed-wing a ircraft

An aeria l survey is a rapid method of establishing the pattern of fall-out. Such surveys are usually carried out at a nominal height of 170 m. The true exposure-rate at this height is about one tenth of that at 1 m above the contaminated ground surface, this factor being approximately independent of the initial gamma-energy in the range 0 .4 -1 . 5 MeV [13].

The count-rate at 170 m corresponding to 0.4M Ci/m 2 of i31I, with no other radionuclides present, is about 130 counts/s on both the British Type 1531 aerial survey instrument [13] (this uses three Nal(Tl) crystals, 12 cm diam ., 2. 5 cm thick) and the American 53N equipment (see Annex VI). The total contribution from the instrument, cosm ic rays and natural activity in air (i.e . the reading over water) is approximately 170-190 counts/s; this remains fairly constant with tim e and position. The contribution to the count-rate at 170 m from natural activity in the ground varies from about 250 counts/s over chalk to 670 over granite. This response is also dependent on the height of the aircraft. It follows that the count-rate due to 0 .4 idCi/m2 of 131I would be of the same order as the variation associated with different geological strata.

If background surveys are made along known flight lines over the district around the nuclear facility, and the same flight lines are followed in any subsequent operational survey, it should be possible to detect the presence of 0 .4 mCi/m2 of 13il with reasonable accuracy.

(d) Surveys using helicopters

Helicopters have the advantage that the air speed is much lower and that measurements may be made clo ser to the ground surface. A less sensitive detector may therefore be used and standard portable gamma survey-meters coupled to chart recorders have performed satisfactorily.

75


The B ritish Type 1413A or 1597A ratem eter gives an increase in response equal to background for a level of 0 .4 nCi/m2 of 131I on the ground at 17 m and for a level of 1 /uCi/m2 at 35 m [18]. Similar results have been obtained with survey equipment developed by the Centre d'etude de l'energie nucleaire, Mol [19]. Figure III. 3 shows the response of the latter instrument, used either for measuring total gam m a-radiation or as a single-channel spectrom eter channelled on the 131I peak (see below) at various altitudes over an area of 7000 m2 artificially contaminated at a level of 1 /^Ci/m2 of 131I. The response over a larger, uniformly contaminated area would be expected to be about the same.

(e) T h e u s e of a n c i l l a r y m e a s u r e m e n ts a n d / o r m o re r e f in e din s t r u m e n ta t io nThe above considerations have referred to situations in which

131I alone is present on the ground surface; in practice other isotopes will usually be present. The possible variations in composition of deposited m aterial are infinite but four general situations can be re cognized for the purpose of comparison [13]:

(i) Mixed fission-products released in a very short time from a criticality excursion in a previously zero energy system; these can be term ed "instantaneous fissio n-p rod u cts";

(ii) Mixed fission-products in the proportions found in fuel after long irradiation (300 days may be taken as a standard period);

(iii) Volatile fission-products (iodine, tellurium, caesium) in the proportions found in fuel irradiated for 300 days;

(iv) 131I only (perhaps from a mishap in a chemical separation plant).

Figure III. 4 shows that the exposure-rate at 1 m associated with a deposition of 0. 4 /^Ci/rn2 of 131I, measured at one day afterwards, may be anything between 400 and 3 nR/h depending on which type of release has occurred. Moreover a release could be intermediate in nature between two of the cases (i) to (iv).

Although, given some knowledge of the nature of the m aterial released gamma readings obtained using simple instruments can be used for rapid delineation of areas in which milk consumption needs to be initially prohibited; it is evident that for a proper appreciation of the situation they must be interpreted by reference to m easurements of 131I and other nuclides in grass and milk. Suitable sampling and analytical methods are described in Annexes IV and V.

76


HEIG

HT

(m)

COUNTING-RATE (counts/s)

FIG. III. 3. Measurements from helicopter above an area of 7000 m* contaminated to a level of 1 jiCi/m* with oil [ig j


sooo

TIME SINCE RELEASE (d)

FIG. III.4. True gamma exposure-rates from fission-products associated with 0.4 jiCi/m2 of 131I on the ground [13, 21]

Alternatively instruments must be used which permit selective measurement of the 131I deposition.

The most direct method of identification of many nuclides, including 131I, is by gamma-spectrometry. The introduction of transistorized equipment has allowed the development of both portable and transportable gamma-spectrometers. The simplest instruments make use of energy discrimination by providing pre-set channels in a simple gamma-monitor. The monitors can then be set up by skilled personnel for a specific purpose (e.g. channelled on the 364 keVpeak of 131I for m easurem ent of 131I on the ground or in milk) and subsequently used in the field by le ss skilled personnel. Completely portable radiation spectrom eters are also available. The use of selective instruments in a moving vehicle (with the detector mounted on a pole in a sim ilar fashion to the ratem eter shown in Fig . III. 2) and in a helicopter have recently been described [19, 20].

78


TA BLE I I I . 2

RESPONSE OF INSTRUMENTS VERSUS CONCENTRATION IN W ATER

Water concentration(jiCi/cm3)

Instrument Reading

10 "3 "Cutie-pie” ionization chamber instrument at 1 m

2 mR/h

10 "4 GM counter instrument at 1 m 400 counts/min

10 -s 53N scintillation detector instrument at 170 m

8000 counts/min

10 "6 53N scintillation detector instrument at 1 m

8000 counts/min

5 X 10 ' 6 53N scintillation detector instrument on bottom of boata

8000 counts/min

2 X 10 ”6 53N scintillation detector instrument (collimator off) on bottom of boat

8000 counts/min

a Double-hulled, outboard motor boat.

3 .3 . W ater surveys

Instrument surveys can be used to estimate quickly the concentrations of fission-products and other beta-gamma emitters in rivers, lakes and oceans. Readings can be taken from a boat using portable survey-m eters or using aeria l survey equipment provided the body of contaminated water is reasonably large compared to the effective size of the infinite plane source for the instrument in use. Table III. 2 indicates the approximate response of the instruments described in Annex VI versus concentration in water, based on Hanford experience and calculations.

If a reservoir or river which is used as a water source is located within an area contaminated following an accident the contamination should be assessed by a water survey as soon as possible. Because of the large dilution in the sea it is extremely difficult to make direct measurements of the contamination and it is usually necessary to re sort to sampling techniques.

79


A N N E X IV

1. A i r sa m p le s

1.1. Particulate materials

1 .1 .1 . Collection

Particulate m aterials may be collected by fixed atmospheric monitoring equipment or portable equipment operated in the field during the passing of the cloud. Portable battery- operated a ir samplers having a capacity of 10 litres per minute (1/3 to 1/2 ft3 per minute) are often used for filter sampling. F ilte r papers employed for a ir sampling include a s bestos fibre mat (CWS-6, H-70inUSA), fibreglass, and c e llulose e s te r membrane paper (M illipore, Polypore). Any of these can be employed for a ir filte r sampling, although the high pressure drop of some membrane filte rs may preclude operation at the high flow-rates required for rapid field detection of abnormally high air-borne concentrations during an emergency. The paper chosen should have been evaluated in the routine environmental surveillance programme to provide information on collection efficiency, and pressure-drop versus flow-rate characteristics.

Charcoal impregnated filter paper may be used where collection of radioiodine is desired. Pre-em ergency evaluation of the paper will determine its collection efficiency. Although different grades of paper having different collection efficienc ies are available, a reasonable assumption in the absence of experim ental data would be 80% for radioiodine.

1 .1 .2 . Field evaluation of beta-emitters

The air concentrations leading to lung or critica l organ doses comparable to the British Medical Research Council "lim its"1 are easily measurable in the field via survey-meter readings obtained on exposed air filter papers. Using reasonable a s sumptions as to filter collection efficiency (80%) and GM

S A M P L E C O L L E C T IO N AND F IE L D E V A L U A T IO N

1 S e e A nnex I I , T a b le I I . 5 .

80


su rv e y -m e te r counting efficiency (2 %), one can derive Table IV. 1 of detection lim its versu s operating tim e for a 1 0 litre per minute sampler.

TABLE IV . 1

M E T E R READINGS ON A IR F IL T E R SA M P L E S VERSUS A IR CO N CEN TR ATIO N S OF B E T A -E M IT T E R S

A ir concentration ((jC i/ cm 3 )

O perating tim e at 10 litres/m in

GM m eter reading at surface o f filter

(counts/m in)

10 ' 6 1 min 400

1 0 ' 7 5 m in 200

10 ' 8 30 min 100

10 ' 9 4 h 100

It is possible to define the time-integrated air exposure during cloud passage and predict the resulting ground contamination from survey-m eter readings on filters rem oved from fixed atmospheric monitoring stations after the cloud has passed. The same assumptions as to collection efficiency and instrument efficiency apply as for the portable air sampler calculations. In addition it must be assum ed that a ll m easuredradioactivity cam e from the accident.

(1) M C i/filter = R /(5 0 000) = R '/(5 0 )where R = background corrected (net) counts/m in ob

tained on a portable GM su rv e y -m e te r with beta shield open (W . O. ) held at su rface of filte r paper,

R 1 = ionization cham ber (cutie pie (CP) or Juno type with ~ 7 m g /cm 2 window) surface reading in m rads/h .

(2) E= (juCi/filter)/(sample flow in cm 3 /s )where E = time integrated air exposure in units of

MCi-sec/cm 3 or C i-sec /m 3,-

81


(3) C = E / Twhere T = total time of cloud passage in seconds,

C = average air concentration at sam pler during cloud passage in f.iCi/cm 3*

(4) D = E X V g X l O 6where D = ground deposition in units of ^C i/m 2,

Vg = average deposition velocity for particulates in m /s . (At Hanford a suitable average Vg is taken to be 5 XlO ' 4 m /s ) .

1. 1 .3 . Field evaluation of alpha-emitters

The sam e considerations apply to a lph a-em itters collected on a filter paper sam ple as apply to b eta -em itters . The principal difference is the type and efficiency of the survey instrument used to m easure the collected m aterial. Either an air proportional ionization chamber or a ZnS scintillation probe may be employed in a portable battery-operated survey- meter. The sensitive window of these instruments is normally about 1 0 0 cm 2.

The background of the instrument is nearly zero and the minimum detectable quantity of an alpha-em itter is about 2. 3 X lO ' 4 /uCi per probe area. The instrument read-out is through "poppin g" sounds in a headphone set and thus the m easurem ents are only qualitative. D ifferent strength sources can be carried into the field to use for comparison with the m easured activity to quantitize m easurem ent. Table IV . 2 . su m m arizes the detection lim its for alpha- em itters in air when sampling at 1 0 litres per minute.

Exposure predictions can be made as follow s:

(1) M C i/filter = m eter reading in ju C iX r

where r = a correction for filter paper size,r = 1 (if the area of the filter is § the probe area),

filter arear = ------ ------------- (if filter area > probe area),probe area r '

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TA BL E IV . 2

M ETER READINGS ON AIR F IL T E R SAM PLES VERSUS AIR CONCENTRATIONS OF A LPH A -EM ITTERS

A ir co n cen tration (/iCi/cm 3)

Operating tim e at 10 litres/ min

Portable poppy m eter reading

0*C i)

10 ~8 2 m in 2 . 3 X 1 0 '4

1 0 ' 9 22 m in 2 .3 X 1 0 " *

1 0 - 10 4 h ■ 2 .3 X 1 0 " 4

10 40 h '2 .3 X 1 0 "4

(2) the tim e-integral of concentration in air (E), the average air-concentration at the sam pler during the passage of the cloud (C), and the ground deposition (D) may be derived fro m /u C i/filter according to the procedure d escribed in section 1 . 1 . 2 for b e ta -e m itte rs .

1.2. Radioiodine

1 .2 .1 . Collection and field evaluation

Field estimates of radioiodine concentrations may be obtained in the same way that other beta-em itters are estimated provided that the collection efficiency of the paper for iodine is known, or the radioiodine is present in an estim atable ratio to other particulate m aterials efficiently collected on the fil ter . If charcoal-im pregnated filter paper is used for sa m pling, then iodine may be assumed to be collected with about 80% efficiency. Sm all ch arcoal-filled cartridges may also be used for radioiodine collection and field estim ations can be made using portable GM or scintillation instrum ents, provided p re-em ergen cy calibration factors have been d e rived. The calculation of air-concentrations, integrated ex posure and ground deposition follow the steps outlined above. The one exception is the use of a deposition velocity (Vg ) for halogens (normally taken to be about 5 X IO " 3 at Hanford) in place of that for particulates.

83


Accurate spot field sam ples are best collected by operating a sm all caustic scrubber with the 1 0 litres per minute portable air pump. A sm all plastic test tube holding 50 cm3 of0. I N NaOH is sufficient to determine l31I concentrations as low as 10 ‘ 9 juCi/cm 3 in a 5-minute sample, provided laboratory analysis by chem ical separation and beta-counting is employed. The resulting laboratory analysis yields a sample which should count about 2 0 counts/min above a 2 0 counts/min background on a thin m ica-w indow GM counter having 20% geom etry.

2. W ater sam ples

N orm ally the procedures described in Annex III for water survey w ill be sufficiently sensitive to supply inform ation upon which decisions to restrict the use of the water can be based. If a lph a-em itters without accom panying gam m a- em ission are present then m easurem ents of water concentrations must be made by collecting sam ples for evaporation and measurement of the residue in the field or in the laboratory.

2.1. Field evaluation

Concentration of radionuclides in water samples can be m easured in the field by im m ersing the probe of a beta-gam m a survey instrument in the centre of the sample container. Care should be taken to securely wrap the probe in a thin w aterproof covering to protect it against water damage and contamination. Various types of probes can be used both inside and outside the water container. Table IV. 3 sum m arizes the approxim ate readings obtainable with a portable GM survey-m eter probe immersed in solutions of certain nuclides.

2.2. Collection of samples for laboratory analysis

2 .2 .1 . Gross measurements

Pre-accident plans should be available to define the probable nuclide(s) present so that rapid gross activity measurements

1 ,2 .2 , Collection of sam ples for laboratory analysis

84


TA BLE I V . 3 [ 2 2 ]

GM SU R V EY -M ETER OPEN WINDOW READINGS (counts/min per juCi/litre)

(Probe im m ersed in contaminated w ater)

N uclide1 litre

S iz e o f sam ple con tain er

5 litres —10 litres

89Sr 200 0 2000 2 000

90Sr + 9°Y 2000 2000 2 000

106Ru + 106 Rh 6000 8000 10 000

131j 500 800 1 0 0 0

137Cs 400 600 800

140B a + 14°La 1000 1500 2 000

are sufficient to determ ine the n ecessity for restriction of water use. Detailed isotopic analysis can be deferred until m ore tim e is available. F o r g ro ss alpha- or g ro ss beta- analysis 50 -cm 3 samples are sufficient. Larger sample containers can be used if necessary, but since the samples must be evaporated before counting, valuable tim e w ill be saved by instructing the laboratory to use the sm allest practical sam ple volum e. The estim ated counting-rates obtainable from various water contamination levels are illustrated in Table IV . 4.

Certain nuclides m ay yield rates much below those listed , especially if their radiations are of low energy or if the particle being counted is emitted in only a sm all fraction of the disintegrations. Counting effic ien cies for the nuclides of concern should be established before the accident. Consideration should be given to bulking water sam ples collected over large areas prior to analysis in order to reduce the laboratory work load. A n alysis of individual sam ples can be delayed until m ore tim e is available or until a significantly high concentration has been found in a bulked sam ple.

85


T A B L E IV . 4

TYPICA L COUNTING-RATES ON LABORATORY INSTRUMENTS VERSUS W ATER CONTAMINATION LE V E L S

Radiationemitted

Water concentration (MCi/cm3)

Sample size (cm3)

Conting-rate (net) (counts/min)

Beta 10 "« 50 20a

- 10‘ 5 5 20a

10 *4 1 40a

10 "3 1 400a

Alpha 10 "6 50 40b

10' 5 5 40b

© 1 1 80b

a On a thin-window beta-counter with 20% counting efficiency. b On a ZnS scintillation counter with 40% counting efficiency.

3. M ilk sa m p le s

3.1. Field evaluation of 131I using portable survey-meters

Portable survey-m eters of various types can also be used to estimate concentrations of 131I in milk at or above the British M edical R esearch Council " l im it " of 0. 065 /uCi 1 3 1 I / l i t r e . Readings can be taken inside a 40 -litre milk can if the meter is wrapped in waterproof plastic, A faster, less sensitive,method is to take readings outside the milk can at the surfaceof the m etal w all. A sum m ary of typical readings obtained with three different portable su rvey -m eters and with the transportable scintillation equipment is given in Table IV. 5.

3.2 . Field evaluation of 131I using transportable scintillation gamma-energy analyser

Milk concentrations corresponding to about one-tenth of the British Medical Research Council "lim it" of 0. 065/uCi 1 3 3 /litre

86


TA BLE I V . 5 [ 2 3 , 2 4 ]

SU R V EY -M ETER READINGS VERSUS CONCENTRATION OF 131I IN A 4 0 - litr e MILK CAN

Meter ( jC i131 I/litreNet counts/min

used milkInside can Outside can

Al-walled 0.9 1500 300GM probe 0 .5 500 200

0 .1 100 50

0.05 50 50

Background 50 50

Mica-window 0 .9 600 250GM probe

0 .5 400 150

0 .1 100 50

0.05 50 50

Background 50 50

a , fl, f 0 .9 5500 3000scintillation survey-meter3

0 .5 3000 1500

0 .1 600 300

0.05 250 150

Background 100 100

Transportable 0.10 1200single-channel analyser system

0.05 650 -

0.01 140 -

0.005 80 -

Background 30 -

a Crystal is 3-mm thick disc of "Bioplastic" scintillator sprayed with 10 mg/cm2 of ZnS. Effective area is 6 .4 cm 2.

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are detectable in the field with a transportable single-channel analyser system . Field determinations should be practicable for several hundred 40-litre milk cans per day using this type of equipment. A N al scintillation cry sta l of about 4 cm diameter by 2. 5 cm height is the preferred detector, although larger crystals may be used. If the single-channel analyser is operated with a 0. 01 -M eV window then the counting-rate obtained at a setting of 0. 365 M eV is about 80 cou n ts/m in above a 30 counts/m in background when the crystal is inserted in a 40-litre can of milk containing 0. 005 juCi 131l /litr e .

3 .3 . Field evaluation of radionuclides other than 1311

Nuclides, other than 1 3 1I, of possible interest in milk are 89Sr, 9 0 Sr, 137Cs and 1 4 9Ba. Usually these will be associated with 131I which should be the limiting nuclide. In instances where 131I is not present, monitoring for these others may be necessary. The field evaluation techniques described for l3iI are applicable to these other nuclides. The same counting-rates perjuCi/litre should be obtained on a GM meter for these nuclides in m ilk as in water (see Table IV. 3). The B ritish M edical Research Council "lim it" for 90Sr in milk (2. 2 X 10 ' 3 (uCi/litre) is only about 3% of that for isil (6 .5 X 10 ~2 ^C i/litre) and the 9t>Sr' w ill therefore be undetectable in the intact field sam ples at this level. The "lim its " for 9 0 Sr, i37Cs and 1 4 0B a+ 140La are sufficiently high to make field evaluation with a GM m eter practical. The i37Cs and 140Ba can also be measured at their respective gam m a-energies with the transportable equipment.

4. Sampling o f cereals, fru its and vegetablesIn certain countries of the Eastern Hem isphere as much as 50% of the dietary calcium may be derived from cereal grains, while fruits and vegetables m ay add another 25%. In such countries field evaluation on vegetation samples might provide usefu l inform ation on the need for crop confiscation or d iversion from human consumption. No special techniques are required for the sampling of cereals, fruits and vegetables. Before analysis, however, they should be treated in the same way as if being prepared for human consumption. Samples collected for analysis should weigh approxim ately 500 g.

88


5. Vegetation sam plingSampling of the herbage eaten by grazing animals allows prediction of the subsequent levels of radionuclides in their milk.

5 .1 . Collection

The vegetation cover from at least 1 m2 of ground should be collected — the aim should be to obtain at least half a kilog ram m e. The vegetation should be cut at the appropriate height (1 - 2 cm ) in order to obtain an estim ate of what a grazing animal would consume by simulating its grazing behaviour. Care must be taken to prevent the cut material from being contaminated with soil. It must be recognized that sam ples of vegetation cut in this way w ill not represent exactly what the grazing animal consumes particularly when the pasture is very varied in composition. Vegetation samples can, therefore, give only a rough indication of the intake of the anim al.

5 .2 . Field evaluation [22, 25]

A method of estim ating vegetation contamination le v e ls is described in the following stepw ise procedure:(a) Cut enough vegetation as described above to fill a

3 0 c m X 4 0 c m p la stic bagabouthalf full. This represents about one-half of a kilogram m e.

(b) Com press the air out of the bag and seal the end.(c) Move to a low background area.(d) Flatten the plastic bag and lay the probe of a portable

GM su rvey -m e te r on the centre of the bag.(e) Fold the bag over the GM probe and note the reading

(window open and background corrected).( f ) Calculate the vegetation contamination level from the

following equation:

C= R /k

where C = vegetation concentration in /uCi/kg,R = GM meter reading in units of 102 Xcounts/min

(background corrected), k = 102 Xcounts/m in per /uCi/kg as given in

Table IV. 6 .

89


TA BL E IV . 6

TYPIC A L GM SU R V EY -M ETER READINGS PRO BE INSERTED IN THE CENTRE OF A LARGE

SAM PLE OF VEGETATION

Nuclidek

(102 x counts/min per (jCi/kg)

89Sr, *9Sr + 90Y 20

106 Ru+ I06Rh 50

i40B a+ no La 10

1SII , 137 Cs 4

6. Marine productsThe monitoring of marine products is not dealt with here in detail since it form s the subject of a separate IAEA publication2.

2 INTERNATIONAL ATOMIC ENERGY AGENCY, Methods of Surveying and Monitoring Marine Radioactivity, Safety Series No. 11,IAEA, Vienna (1965) 95 pp.

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A N N E X V

1. Speed v e r s u s s e n s i t iv i ty

In the first few days following an accident, where information is required with as little delay as p ossib le , rapid and r e latively simple, albeit crude, analytical methods may be preferred in order that the analytical facilities available should not be overloaded.

As an example of the loss in sensitivity to be expected if rapid answers are required, the analysis of water may be considered. The detection level of counting methods used at Hanford for various radionuclides are listed along with the method used in Table V. 1. If a quick approximate answer is desired, the detection level will be about 1 0 0 0 tim es higher than those listed . An estim ate of the number of hours required to get such em ergency answ ers is also included.

2. Techniques

In m ost cases the radionuclides of importance will prove to be 1 3 1 I, is^Cs, 89Sr and 90Sr, 1 3 1 I, l37Cs (and many other fission-products) are capable of rapid determination, after suitable treatment of the sam ple, if n ecessary, by gam m a- spectrom etry. Radiochem ical analysis will, however, be r e quired for the strontium isotopes. An example fast method, adequate for use in the early stages of an em ergency, and applicable to a number of m aterials, is described below. Full information on routine methods of analysis is given in a number of publications [27, 2 8 ].

2 .1 . Ashing of samples

Conventional dry-ashing techniques can be used for most m ate r ia ls . Methods applicable to biological sam ples are d escribed in detail elsew here1. Milk presents a special problem . A suitable procedure is as follows.

1 See: Food and Agriculture Organization. "Report on the Organization of Surveys forRadionuclides in Food and Agriculture" Annex C (1961).

S P E C IA L A N A L Y T IC A L C O N SID E R A T IO N S

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TABLE V .I [2 6 ]

D E T E C T IO N L E V E L F O R VARIOUS RADIONUCLIDESIN W A TE R SAM PLES

Radionuclide Counting method Detection level ((jCi/ml)

Tim e required for emergency

answers (h)

?sAs Beta proportional counter 1 .5 x l O '8 1 .5131 j Beta proportional counter

and decay1 .5 x 1 0 '® 1 .0

48 Sc Gamma-gamma coincidence counts 2 .4 X 1 0 '* 2 .0

**Na Gamma-spectrometry 1. 5 x 1 0 "7 0 .5

65 Zn Gamma-spectrometry (assumes no interference

6 .5 X 1 0 '*

“ Np Gamma-spectrometry (assumes no interference)

4 .0 X 1 0 '* 2 .0

“ cu Gamma-gamma coincidence counts 8 .0 X 1 0 '* 1 .5

7*Ga Gamma-spectrometry 1 .4 X 1 0 ' '

SICI Gamma-spectrometry (assumes no interference)

1 .1 X 1 0 '7 2 .0

Th (n at.) Gam ma-scintillation with 234 Th reference standard and neutron activation

- 1 . 4 X 1 0 '9

90Sr+ 90Y Low background beta proportional counter

2 .0 X 1 0 ' 9

*9S r + 9"Sr Low background beta proportional counter

1 .2 X lO '9 4 .0

32 p Beta proportional counter 6 .4 X 1 0 " ' 1 .5

45 Ca Beta proportional counter 1. 8 x 10"*

RE + Y Beta proportional counter and decay

5 .6 x 1 0 "* 1 .5

59 Fe. Beta proportional counter and gamma-spectrometry

1 .5 X 1 0 '7 2 -3

91 Si Beta proportional counter and decay

6 .0 X 1 0 '7

“ Mn ■ Gamma - spectrometry 5 .8 X 1 0 '? 1 .0

‘" B a Beta proportional counter and decay (checked by gamma-spectrometry)

5 .7 X 1 0 '9 4

100 ml milk are shaken with S r-ca rrier (50 mg Sr) and after that transferred into a separatory funnel placed over a 1 -litre beaker containing 300 m l boiling concentrated HNO 3 . The m ilk is added dropwise to the boiling acid in approxim ately1 hour (1 -2 drops per second) under constant stirring. The

92


boiling and stirring are continued after a ll m ilk has been added until the solution begins to spatter. The solution is then quantitatively transferred into a silica tray and the evaporation is com pleted under an in fra -re d lam p. The black residue in the tray is ashed over a bunsen burner until the ash is grey. The total ashing p rocess w ill last approxim ately 3 hours.

2 .2 . Radiochemical separations [29]

2 .2 . 1. Rapid assessment of 89Sr and 90Sr

(a) Procedures

(i) The ashed sample (approximately 1 g ash) is treated with 15 m l water and approxim ately 5 m l HNO3 ; the insoluble residue (carbon) is removed by filtration and the clear solution is collected in a 1 0 0 -m l beaker. The solution is evaporated to 15 m l and tran sferred to a 5 0 -m l centrifuge tube.

(ii) 30 m l fuming HNO3 is added under stirring and cooling. The stirring and cooling are continued for 15 m inutes.

(iii) The sample is centrifuged and the super-natant liquid is discarded. The residue is dissolved in 10 ml water, and 22 m l fuming nitric acid is added. Stir and cool for 15 m inutes.

(iv) Centrifuge and b le e d -o ff the super-natant liquid.(v) The Sr(NC>3 )2 -precipitate is dissolved in a few drops of

water. 1 m l Y -c a r r ie r (10 mg Y /m l) , and 2 m l 6 N am monia water are added under stirring in a water bath. Cool and centrifuge. The precipitate is discarded. The analysis after this step has to be completed and the sam ple counted within 4 -5 hours (otherwise 90Y will disturb the counting and yield an over-estim ate of 8 9 Sr).

(vi) 1 drop methyl red solution is added and the solution is neutralized with 6 N HNO 3 . 1 m l 6 N CH 3 COOH and 2 m l 6 N CH 3 COONH 4 is added (pH = 5. 5). This is heated nearly to boiling then 2 m l B a -c a r r ie r (10 m g B a /m l) and 1 m l N a 2 CrC>4 are added dropwise under stirring . The BaCrC>4 is rem oved by centrifugation. If 140Ba is believed to be present in large quantity repeat this step(vi). If no 140Ba is present this step can be om itted .

93


(vii)Add a drop of 30% H 2 O 2 to the super-natant liquid and 2 m l ammonia water (pH= 10). Heat to boiling until all H 2 C>2 is destroyed and add during boiling and stirring 6 m l saturated (COO ) 2 (NH.j) 2 solution dropwise, cool and filter the strontium -oxalate through a tarred filter. Dry at 110°C for 1 /2 hour. Cool, weigh as (COO ) 2 Sr H2 O and mount the sam ple. Count with, and later without, 1 mm A l-absorber.

(b) Calculations

Activity of 89Sr - Tgg XHggt x 2 . 22 X U X E 8 9 pCl

C - -2—1 QQ

activity of 9°Sr = e ^ o Tx ! ^ pCi

whereC in counts/m in is the counting-rate for the strontium oxalate sample without the A l-ab so rb er,Ca in counts/m in is the counting-rate for the strontium oxalate sample with the A l-absorber,T 89 is the fractional transm ission of the radiation from 89Sr through the absorber2,U is the fractional yield of the strontium oxalate,Egg is the counting-efficiency for 89Sr in the sam ple, Ego is the countirfjg-efficiency for 90Sr in the sam ple, Hggt is the fractional decay of 89Sr for the time t in days which has elapsed between sampling and counting.

Note:(1) T 8 g, Egg and E 9 0 are determined by counting pure sam

ples of 89Sr and 9 0 Sr.(2) The 1 m m A l absorbs effectively a ll the beta-radiation

from 9 0 Sr.

_ counting-rate with absorber present 89 counting-rate without absorber

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2 .2 ,2 , Rapid assessment of 131I and/or 90Sr in water [30]

The iodine can either be distilled or extracted into carbon tetrachloride and the strontium can be precipitated as the carbonate.

(a) Iodine is distilled into ic e -c o ld carbon tetrachloride from an acid solution to which sodium nitrate has been added. An aliquot of the carbon tetrachloride solution is then counted in a w e ll-c ry sta l. R esults can be r e ported in le s s than 1 hour.

(b) Iodine can be extracted from up to 500 m l of acid-nitrate solution into 100-200 m l of carbon tetrachloride. The extracted iodine is reduced with bisulphite and back ex tracted into approxim ately 500 m l of w ater which can then be counted in a large w ell-crystal. Results can be reported within 1 1 / 4 hours.

(c) The strontium content of the carbonate precipitate can be estimated' by beta-counting. If the precipitate from about 50 m l of the sam ple is counted and it is assum ed that a ll the activity corresponds to 9 0 Sr, results can be reported within 1 hour, but the 90Sr content will be overestimated.

2. 2. 3. Rapid assessment of 131I and J37Cs in milk [29]

(a) 131I

The most rapid method to determine 131I in a milk sample is the direct gam m a-m easurem ent of the sample on a scintillation crystal in conjunction with a pulse-height analyser. If however it is desirable to obtain a greater accuracy it is advisable to separate the iodine from other activities, e . g . 140Ba and i3 7 Gs.

The milk could then be treated as follows: 1 mg Nal carrier is added to 100 m l milk and thoroughly stirred in. The milk is centrifuged and the cream removed.

The skim m ed m ilk is fo r about 1 hour passed through an approxim ately 3 - c m high colum n con sisting of 5 m l wet settled Dowex 1 X 2 (2 0 0 /4 0 0 m esh) resin .

95


The resin is transferred to a measuring cylinder, which fits into a sodium iodide w ell-crystal in conjunction with a pulse- height analyser and is measured for 131I.

(b) 137 Cs

137Cs (y: 0 .6 6 MeV) is most conveniently determined by gamma-spectroscopy directly on the milk. If, however, 132I (y: 0.67 MeV), the daughter product of 77 h I32xe, is present in the milk in larger quantities, it is necessary to measure 137Cs on the anion-exchanged milk obtained from the 131I procedure described in (a) above.


A N N E X V I

1, In s tru m e n ts and equ ipm en t in com m on use in the United Kingdom

1.1. Equipment carried by a typical vehicle intended for emergency environmental monitoring

IN S T R U M E N T A T IO N AND E Q U IP M E N T

1 12-volt battery1 12-voltdust-sampling pump12 Compressed air samplers1 Portable dual-phosphor air-sample probe21 Portable contamination monitor Type 1320 with alpha

and beta probes, alpha and beta castles and registerunit

1 Type 1368 field gam m a-ratem eter1 Type 1413 field gam m a-ratem eter31 Type 1349 beta-gamma dose-rate monitor6 Q uartz-fibre electroscopes, range 0-0 . 5 R1 Charging unit for quartz-fibre electroscopes2 Lamps2 Hand torches6 sets Protective clothing

1.2. Dust sampling unit, Type 1651 A. The unit is designed tocollect air-borne dust from a known volume of air. The alpha- or beta-activity is then measured with an alpha-scintillation counter or beta end-window counter. A dual-phosphor probe for this purpose is com m ercially available. The air-borne dust is drawn by a positive displacem ent pump driven by a 12-V DC electric motor through a standard filter paper set in a detachable supporting fram e. The throughput is m easured internally by means of an anemometer, the time being measured by means of a stop watch. The sampling rate is

1 Sim ilar to Type 1651A described in section 1 .2 .2 EMI Type PCM 1 monitor with a Type DP2 alpha-beta probe. This is a commercial

instrument.3 The Type 1413 is now being replaced by the similar Type 1597A described in section 1 .5 .

97


50 litres/min. The unit has an estimated service life of three years when operated for a period of 8 hours a day.

(Self-powered sets driven by sm all com p ressed -air containers are also in use, e .g . Type W. A. S. 1).

Alpha, beta/gamma radiation monitor, Type 1320. A portable, battery-operated instrument used for the detection and m easurem ent of alpha-, beta- and gam m a-contam ination. Two probes are included, a 1320 alpha-probe and a 1257 beta/gamma probe. The instrum ent covers three ranges of count-rate:

0-10 counts/s

0-100 counts/s

0-1000 counts/s

Headphones plug into a socket for aural indication of count- rate . Total weight (including probes, haversack and headphones) 9 kg. Weight of instrument only 6 kg.

Power is derived from six Mallory ce lls — the battery life being approximately 60 hours.

Beta/gamma monitor, Type 1368. A portable, battery- operated instrument, primarily designed for geological survey purposes but now adopted as a health physics instrument for environmental survey. A robust, sealed design. The instrument m easures gamma exposure-rate over five ranges:

0- 0. 05 mR/h

0- 0. 25 mR/h

0- 1 mR/h

0- 5 mR/h

0-25 mR/h

A separate probe is available for the measurement of beta- activity. Headphones are available for aural indication of count-rate. Total weight, with accessories, 13 kg. Weight of instrument alone 4^ kg.


The energy dependence is enhanced at low gam m a-energies,i .e . by a factor of 2 at 0.15 MeV. The response time varies from 0 .2 s to 25 s depending on the range in use and the m eter time constant chosen.

This is a GM counter instrument with a fully transistorized circuit. The first four ranges operate with three GM counte rs Type CV 2147, the fifth range uses an MG 10H counter. The batteries have a useful life of approximately 500 hours.

1 .5 . Gamma monitor, Type 1597A. A portable, battery-operated instrument intended to replace the more fam iliar Type 1413, this monitor covers three ranges of exposure-rate measurement:

0- 30/uR/h

0- 300 z R/h

0-3000 nR/h

The instrument was prim arily designed for geological survey work but has been adopted as a health physics instrument for environm ental survey. The ra tem eter is fully sealed and desiccated and can be used under water to a depth of 1. 5 m.

A socket is available for headphones for aural indication of count-rate. Weight, 2 kg.

The energy dependence is enhanced at low gam m a-energies, e .g . at 0. 6 MeV the reading is approximately 1. 5 tim es the actual exposure-rate, at 0. 15 MeV the reading is approxim ately 15 tim es the actual exp o su re-rate . The response tim e depends on the range in use with a maximum of 2. 0 s on the most sensitive range.

The detecting element is a sodium iodide cry sta l and photom ultiplier tube. The c ircu its a re entirely tran sisto rized . The batteries have a useful life of approximately 500 hours.

99


1 .6 . Beta/gamma survey-m eter, Type 1349. A portable, battery- operated instrument covering three ranges of exposure-rate measurement:

0- 15 mR/h

0-150 mR/h

0- 1. 5 R/h

A fully sealed, robust instrument. Weight, 3 kg.

The energy dependence of the instrument is within ±20% for energies above 65 keV. The response time is approximately 6 s on the most sensitive range and le ss than 1 s on other ranges.

The instrument uses a parallel plate ionization cham ber of total volume 380 cm 3. The battery life varies from approximately 120 hours (low tension supply) to several months (high tension supply).

2. Instrum en ta tion in com m on use a t the Hanford P ro jec t, USA2.1. Detection type survey-meters

2. 1 . 1 . GM survey-meters

The GM survey-meter is a portable battery-operated Geiger- Miiller instrument used for the detection of low intensity beta- and gamma-radiations. Nearly all GM m eters are basically the same in construction and operation, although different - style probes may be connected through a one-m etre cable to the m eter. The most common probe in use at Hanford is the thin aluminium-walled (Thyac 1-B85) GM tube. Another probe used for measuring very low energy beta-radiation is a thin mica-window GM tube.

Each instrument has three ranges: X I, XlO and X100; full sca le m eter readings are either 800 counts/min or 1000 counts/min. GM su rvey-m eters are calibrated at Hanford to yield readings of 650 counts/min, 6500 counts/min and 65 000 counts/min in fields of 0. 2 mR/h, 2 mR/h and

100


20 mR/h, respectively of radium gamma-radiation. Allowable erro r is ± 15%.

2.1. 2. Scintillation Portable Poppy (SPP)

The scintillation portable poppy (SPP) is a portable battery- operated scintillation instrum ent developed at Hanford for the detection and qualitative measurement of sm all amounts of alpha-em itter s. The detector has an alpha-particle sensitive ZnS coating painted on a p lastic light pipe. The in strum ent "read -ou t" is through headphones which em it a popping sound for each count m easured. Instrument range is 500 dis/min to 25 000 dis/min.

Calibration is accom plished at Hanford with distributed sources of plutonium and a geometry of not le ss than 5% is required. Background is adjusted by a bias control to be S4 counts/min. Care must be exercised during use not to puncture the thin light-proof covering over the ZnS.

2. 1 . 3 . Alpha, beta, gamma survey-meter

The a , /3, y survey-m eter is a Hanford prototype portable battery-operated scintillation instrument. The detector is a 3-m m disc of "B io p la stic " scin tilla tor coated with a 10 mg/cm2 layer of ZnS. The effective detector area is6 .4 cm 2. The "Bioplastic" is coupled to an RCA 6199 phototube through a plastic light pipe. The meter has three ranges — 103, 104 and 105 counts/min. It is described here principally because of its increased sensitivity over a GM survey- m eter for field m onitoring of m I concentrations in m ilk.

2.2. Ionization chamber instruments

2. 2. 1. Cutie Pie (CP)

The CP meter is a portable, battery-operated, a ir ionization chamber instrument used to detect and m easure beta- and gamma-radiations. The instrument measures radiation exposure-rates on three ranges of 0-50 mR/h, 0-500 mR/h

101


and 0-5000 mR/h, The beta to gamma response ratio is about 1:4. That is, one dial division on the Or50 mR/h scale is 1 mR/h if the radiation is gamma only, and one dial division is about 4 mrad/h if the radiation is beta only.

The ionization cham ber of the CP is 7. 6 cm diam eter by14.4 cm long and has a volume of660cm3. The end window of the cham ber is 6 m g / c m 2 cellophane and the walls are 440 mg/cm2 phenolic. A removable 440 mg/cm2 phenolic beta shield is attached to the end window to aid in determining the proportions of beta- and gam m a-radiations present in m ixed fie ld s. •

The CP m eter is calibrated for gamma response with a ra dium source to within -5%, +10% of the true exposure-rate. Spot checks are made with a natural uranium source to confirm the beta response.

2. 2. 2. Juno

The Juno meter is a portable, battery-operated, air ionization chamber instrument used to detect and measure alpha-, beta- and gam m a-radiations. The instrum ent is basically the same as the CP m eter except for the chamber shape and its ability to measure alpha-particles. Chamber dimensions are 4. 4 cm deep by 13. 3 cm wide by 8. 3 cm long. It has a total volume of 440 cm 3. The aluminium chamber walls are 700 mg/cm2 thick. The flat bottom of the instrument has a window made of rubber hydrochloride only 0 .7 mg/cm2 thick which will admit alpha particles to the chamber. This window can be covered by a beta window (alpha shield) of 6 mg/cm2 and a gamma window (beta shield) of 700 mg/cm2.

The gamma calibration of the Juno is accomplished the same way as for the CP m eter. Beta calibration is performed with a slab of natural uranium and a beta d ose-rate versus dial reading calibration curve is placed on the side of the m eter. Alpha calibration is performed with a plutonium source, and a graph of disintegrations per minute versus dial reading is also attached to the m eter. The average alpha sensitivity of the Juno is about 5X 106 dis/min full-scale on the X100 range.

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2.3. Aerial survey equipment

A erial survey equipment normally employs one or more scintillation crystal detectors coupled to suitable phototubes, amp lifiers, count-rate m eters and recording charts. Most in strum ents use tran sisto rized c ircu itry to save weight and space. Some employ automatic altitude recording devices and even automatic altitude correction circu its in the count- rate m eter. At Hanford a single scintillation crystal is employed and no altitude recorder or automatic altitude co rre c tion is used.

An early model of a eria l survey equipment (55B) employed a "B iop lastic" crysta l, 13 cm X l3 cm in size. This equipment is now maintained for r iv er survey work from a 19-ft outboard boat. The present aerial survey equipment employs two interchangeable N alcrystals, one is 13 cm diam. X 7 .6cm high (53N), the other less sensitive one is 5cm X 5cm (22N)4.

The calibration of the most sensitive 53N equipment for the three ranges of 104, 105 and 106 counts/min is 2, 30 and 400 MR/h of radium gamma resp ectively . One /uCi of 131I per square meter of ground will read about 8000 counts/min at a 170-m altitude on this equipment.

The calibration of the 22N detector connected to the 53N electronic equipment is 27, 350 and 4500 nR per hour of radium gamma for the three m eter ranges of 104 , 105 and 106counts/min respectively . The calibration for the 55B detecto r and associated equipment is 22, 110 and 1000 nR/h of radium gamma for the three ranges of 104, 105 and 106 counts/min respectively .

A ll three detectors are surrounded by a lead collim ator to lim it the response cone (50%) angle to 120 degrees which amounts to a viewed source diam eter of 600 m at 170-m altitude.

The a irc ra ft used for a e ria l survey at Hanford is a twin- engine Beechcraft D185 owned and operated by the local office of the Atomic Energy Com m ission. Available on contract is a four-place Cessna a irc ra ft also piloted by AEC per-

4 S e e F ig . V I. 1.

103


FIG. VI, 1. A erial survey instruments including three sizes o f scintillation crystals, transistorized ratem eters and battery-operated chart recorders (Hanford Project - USA)Crystal sizes: 55-B 1 2 .7 cm x 1 2 .7 cm - Bioplastic

5 3 -N 12 . 7 cffix 7 . 6 c m - N a I 22-N 5. l c m x 5 . 1 c m - N a I

sonnel. Background surveys are flown frequently over the project environs to assimilate information on normal readings. E stablished flight patterns and a e r ia l check points are mapped in detail for reference during routine and emergency surveys.

2 .4 . Wind-speed meter

Each Em ergency Environm ental Monitoring Kit includes a wind m eter (F .W . Dwyer Manufacturing Company). This m eter is a sm all hand-held, pitot-tube device calibrated in m iles per hour. It has two ranges of 2 to 10 mile/h and 2 to 65 mile/h. The m eter may provide useful wind speed inform ation in locations rem ote from fixed m eteorological stations.

3. M o b ile a i r m o n ito r in g u n it — C e n tre d 'e tu d e s n u c le a ir e s deS a c la y , C o m m is s a r ia t a l 'e n e r g ie a to m iq u e , F r a n c e [31]

The unit consists of a Legueu a Meaux, type TF 4 10F, truck which can carry two passengers in addition to the driver, as well as the necessary instruments. The a ir pressure inside


the truck is maintained at a level slightly above the norm al atmospheric value and can be heated or cooled for the benefit of the passengers and equipment. A ir is drawn in through a f ilte r by a pump capable of delivering 60 m 3 p er hour.

The e lectr ic supply is provided by a Leroy, type MDA 150, alternator, suspended in such a way that vibrations are not transm itted to the m easuring instrum ents. An em ergency supply is provided to perm it m easurem ents of beta- and gam m a-radiation to be continued, and rad io-contact to be maintained with the control cen tre .

Aerosols may be sampled by drawing a ir through a MECI M4 filte r paper using a Lecomble and Schmitt pump capable of passing 15 m3 per hour. The air can also be passed through a specific absorbent cartridge for trapping radioactive gases.

Gamma-radiation levels are measured using two Radiotechnique, type 18529 and 18552, GM counters, covering a range of 10 juR/h to 50 R/h.

Beta-radiation levels are assessed by subtracting the readings given by a detector sensitive to gamma-radiation only from the readings given by a probe sensitive to both beta- and gamma - radiation.

A Radiotechnique, type 18546, GM counter placed above the filter paper during collection of a ir samples provides a measurement of the instantaneous gross beta-activity of the deposited aerosols.

F o r measurement of the alpha- and beta-activity of the deposited aerosols the filte r paper is placed between a Radiotechnique alpha-scintillation detector and a Radiotechnique, type 18546, GM counter.

The gamma-ray activity of the samples collected (either aerosols deposited on filter papers or gases trapped in charcoal cartridges) may be assessed using a gamma scintillation detector, MESCOLEP/T, coupled to a MESCO ECS T8 transistorized analyser. Arrangements are available for determining the energy spectrum of the radiation and for determining the variation of activity within an energy band.

105


The levels of external beta- and gam m a-radiation and the readings of the gam m a-spectrom eter can be recorded on a Compagnie des Compteurs, type E P R 3, chart reco rd er .

The truck is equipped with a Chauvin Arnoux, type televent, wind-speed and direction indicator.

A Telecom m unications Radioelectriques et Telephoniques, type 313/20, transm itter-receiver is used for communication with the control centre and with other light veh icles. The unit operates on the frequencies allotted to the Commissariat k l'energie atomique.

4. Compensated ionization cham ber5 - R istf ResearchEstablishm ent, A tom ic Energy Commission, Denmark [29]The instrument is designed for food monitoring in emergency situations, where a cheap, sturdy and simple device — needing a minimum of maintenance and being easy to operate by relatively unskilled personnel — is required.

It consists of two cylindrical ionization cham bers, namely a measuring chamber and a compensating chamber mounted on top of it. They are charged at opposite polarity with r e spect to a common central electrode suspended by polystyrene insulators mounted on guard plates. The volume ratio of the two cham bers can be adjusted to com plete com pensation.

The potential difference is maintained by a transistorized DC converter. The prim ary power source is two 1. 5-V flashlight dry ce lls having a lifetim e of about 500 hours of continuous operation.

The rate of discharge, when a sample is placed in a sample tray (of capacity 1 litre) under the end wall (1 mg/cm2 metallized polyester foil) of the measuring chamber, is counted by means of a direct-reading pocket dosimeter of the usual type.

The sensitive volume of the two cham bers is very large (10 litres each). The count-rate will therefore be large, and the relative standard deviation small. For this reason it is possible to use the instrum ent without shielding in relatively

5 S e e F ig s. V I . 2 and 3.

106


FIG. VI. 2 . Compensated ionization cham ber for em ergency food monitoring (A tom ic energy Commission - Denmark)

large external gamma fields such as must be expected in a serious fall-out situation.

A check source of 0. 25 MCi 36C1 is used for demonstration purposes. It gives the sam e deflection as a liquid sample of about 15 000 pCi/tnl, corresponding to half the usuallyac- cepted concentration for a 30-d emergency period.

The maximum sensitivity is about 200 pCi/ml (corresponding to 1/20 full scale deflection per hour).

107


FIG. V I. 3 . Compensated ionization cham ber for em ergency food monitoring (A tom ic Energy Commission - Denmark)

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A N N E X V II

ENVIRONMENTAL MONITORING PROCEDURES ADOPTED IN PREVIOUS EMERGENCY SITUATIONS

1. A c c id e n t a t W indsca le No. 1 P ile , U nited K ingdom ,10th O ctober, 1957 [32-34]

The two original reactors at W indscale, known as No. 1 and No. 2 P ile s , were essentially graphite-m oderated, natural uranium fuelled reactors, cooled by a forced a ir draft. The coolant was exhausted through a filte r bank fitted at the top of a 125-m stack. During a routine operation begun on 7th October, 1957, to release Wigner energy from the graphite, excess nuclear heating was wrongly applied causing the failure of a number of fuel cartridges. The uranium caught fire and the fire spread until it involved about 150 channels. Fission- products were released to the atm osphere from the stack . From measurements of air-borne activity and of activity deposited ujson the ground it has since been estim ated that approximately 20 000 Ci 1311, 12 000 Ci 132Te, 600 Ci 137C S, 80 Ci 89Sr and 2 Ci 90Sr were released. Some of this activity reached the continent of Europe.

The firs t indication of an abnormal release of activity came through routine air-sam pling on the s ite . The a ir sample collected between 11.00 a .m . and 2.00 p.m . on 10thOctober at a point about 800 m from the stack indicated a contamination level of 3000 |3-dis/min per cubic m etre, about 10 times that normally resulting from the decay products of radon and thoron. The situation was confirmed by further a ir samples taken at other points on the site . The state of affairs in the reactor was discovered by visual inspection.

The f ir s t requirem ent was to determ ine gam m a-radiation levels in the d istrict around the W orks. A survey vehicle was therefore sent out at 3. 00 p .m . to make ground and air m easurem ents in the down-wind direction (south-east). A second vehicle le ft at 5 p. m. to explore the area north of the site .

The radiation levels due to deposited activity were generally about 0. 15-0. 20 mR/h in the area 3-5 km south of the Works

109


and much low er in other d irections. There then appeared to be no significant external radiation hazard. Measurements continued during the period of re lease and it has been e s timated that the integrated exposure to any member of the public did not exceed 7 5 mR.

Throughout the period of re lease some thousands of a ir samples were taken both on the site and in the nearby district. Although the a ir contamination rose on occasion to worrying, but not dangerous levels on the site, dilution resulting from wind variation considerably reduced the hazard in the district. A fter midday on 11th October a ir contamination levels both on and off site fell rapidly to well below the ICRP values for continuous exposure.

By the evening of 11th October it was clear that there was no significant external radiation or inhalation hazard. Further planning was based on tne assumption that the re lease contained a normal distribution of mixed fission-products. The gamma-radiation survey results were therefore interpreted as indicating that there might be a marginal risk from contam ination of m ilk with isotopes of iodine and strontium .

Milk sam ples were collected from lo cal farm s during the evening milking on 10th October and the morning and evening milkings on 11th October. However, the analytical results were not available until noon 12th October. The milk collected on the evening of the 10th and morning of the 11th, in fact, contained only traces of radioiodine but that obtained on the afternoon of 11th October contained 0. 4-0 . 8 /uCi/litre. The analyses revealed a higher proportion of radioiodine than would be present in a norm al reacto r fission-product mixture. It was evident that iodine vapour had passed through the stack filter but that the major part of the particulate materia l had been retained.

No perm issible level for 1311 in milk existed at that time. A group of experts was convened in the afternoon of 11th October and by 9. 00 p. m. the decision had been reached that distribution of milk should be prohibited if the 1311 concentration exceeded 0. 1 MCi/litre. Arrangem ents were made to prevent milk deliveries that night from 12 milk producers within a 3-km radius of Windscale.

110


On Sunday, 13th October, a widespread monitoring programme was initiated to delineate the areas over which an embargo on the consumption and sale of milk would be necessary. By 14th October, this restriction finally covered a coastal strip about 50 km long and about 500 km2 in area.

It was soon found that considerable use could be made of the gamma-survey as a guide to the area from which milk samples were required. The bulk of the survey work was done with portable scintillation gamma-monitors designed for geological prospecting. These were found to have many advantages over the conventional ionization cham bers previously used for district surveys. Ground measurements, coupled with simple direct measurement of the 131I level in milk made by placing the detector head of the instrum ent in contact with the side of a milk churn, provided a screening technique for deciding the farm s or collecting centres from which milk should be sampled for more p recise laboratory analyses.

Fifteen vehicles, each with,a team of two men, were used to delineate the restric te d a rea s and subsequently follow the trends of m ilk contamination until the restric tio n could be lifted. Altogether these team s collected over 2000 litres of milk, mainly in 250-m l sam ples. The analytical team s handled over 3000 sam ples.

In addition to milk, other foodstuffs were monitored and during the occurrence of the survey over 1 tonne of vegetables, about 700 eggs and about 50 kg of meat were handled. Drinking water supplies in Cumberland, Lancashire and North Wales were also analysed. In a ll cases it was found that the level of contamination was well below that which would constitute a hazard. In vivo monitoring of the thyroid glands of selected adults and children demonstrated the efficacy of the remedial measures; the highest dose to a child's thyroid was estimated as 16 rads and to an adult's thyroid, 4 rads. Thyroid glands from sheep, cows and pigs were also examined, the maximum dose to an anim al's thyroid being estim ated to be le ss than 1000 rads (incurred by grazing sheep).

By 4th November the only restricted area remaining was a coastal strip extending about 20 km southwards from Windscale.

I l l


This area remained under restriction until 23rd November, by which tim e sufficient analyses of strontium in m ilk had been made for it to be certain that no restriction was necessary on account of 90Sr.

In view of the possibility that some 90Sr might reside in the root mat and soil and find its way to grass and thence to milk at some later time, it was decided to examine grass and milk for this nuclide for an extended period and measurements went on, in fact, until late 1958. The early fears were not realized and by the late summer of 1958 there was no evidence of any contribution to radiostrontium contamination of m ilk from the accident.

Twenty persons were employed in handling and recording the sam ples obtained during the period of intensive monitoring and assisting in the operation of a control centre where a ll information was recorded and displayed on maps. Some 150 radiochemists, distributed between the various U. K. A .E . A. establishments, contributed to the analytical effort.

Several valuable lessons were learned from the accident which served to highlight the need for (a) authoritative and agreed exposure criteria for use in emergency situations, (b) portable, self-contained instrum ents of the required sensitivity for gamma-survey work, (c) means of obtaining assistance from outside sources to cope with the increased load on monitoring and, particularly, analytical fa c ilities , and (d) a prepared plan of action with both local and cen tral government organizations.

2. F ailure o f the A E R E effluent disposal pipe line,United Kingdom , 1st August 1961 [35]A burst occurred four feet below ground in the 18-inch cast- iron pipeline used to carry liquid effluent of low activity from the Atomic Energy Research Establishment, Harwell, to the Tham es. Inactive trade waste was being discharged at the time but the resulting flood carried a small quantity of active sediment from the pipe over a road and into a nearby private house and some garages. The activity was established to be almost entirely 137Cs and it was estimated that le ss than 1 mCi had been distributed over an area of roughly 200 m2 .

112


A monitoring team of three men reached the contaminated area within 30 minutes of the occurrence being reported to the health physicists. A rapid estim ate of the level of contamination was made using a standard portable contamination monitor (AERE Type 1320 fitted with a B. 12 /3-counter) and it was quickly established that there was no hazard from radioactivity. Sam ples of soil, s ilt and water were taken fo r rad io chem ical an aly sis and g am m a-sp ectro m etry .

A more detailed survey was made the next day to identify any isolated areas of contamination. Instruments used included an AERE Type 1320 contamination monitor, Type 1368 and Type 1413 geological survey-m eters, and a prototype sensitive ionization chamber.

Rem edial action consisted of decontamination of a ll a rea s showing more than 10 counts/s on a standard (3-probe (roughly equivalent to 2 XlO"4 MCi/cm2).

3. Nuclear excursion at SL-1 reactor, National Reactor Testing Station (NRTS), Idaho Falls, Idaho, USA

The m aterial which follows is summarized from the United States Atomic Energy Commission document IDO-19302 [36]. References to page, table, and figure numbers from that document are given in parentheses in this Annex.

3.1, Description of reactor

The SL-1 was a direct cycle, boiling-water reactor of 3000 kW gross heat capacity with enriched uranium fuel, clad in aluminium, and moderated and cooled by light water in natural circu lation. The reacto r was a prototype of a facility that could be operated at remote sites for three years without re fuelling. The reactor was located within the National Reactor Testing Station (NRTS) near Idaho F a lls , Idaho, USA (Fig. 1.1, page 13).

3 .2 . Description of accident

A nuclear excursion occurred within the reacto r v esse l at 9. 01 p. m ., January 3, 1961, resulting in the death of three persons, extensive damage to the reactor core and room, and

113


in high radiation levels (approximately 500 to 1000 R/h) within the reactor room. At the time of the explosion, which resulted from the nuclear excursion, the reactor was loaded with 40 fuel elements and 5 control-rod blades of cadmium. A three-man crew was on the top of the reactor reassembling the control-rod drive mechanisms and housing. The accident was caused by manual withdrawal, by one or more of the maintenance crew, of the central control-rod blade from the core, conside rably beyond the lim it specified in the maintenance procedure.

Some gaseous fission-products, including radioactive iodine, escaped to the atmosphere outside the building and were ca rried down-wind in a narrow plume. Particulate fission- product m aterial was largely confined to the reactor building, with slight radioactivity in the immediate vicinity of the building.

3. 3. Environmental measurements

Initial prediction of the trajectory of the plume from the accident site was based on winds m easured at the 250-ft leve l at the Central F acilities Area six m iles west of S L - l . The predicted tra jectory was nearly straight southwest, passing over nearly inaccessible territory (Fig. 4. 2, page 73). Aerial survey techniques did not detect any activity above background radiation except in the immediate vicinity of the S L -1 s ite . Measurements made on sagebrush samples indicated that the plume had firs t travelled toward the south southeast for approxim ately 20 m iles before shifting toward the southwest (F ig s. A -3 and A -4 , pages 134 and 135).

The quantity of 131I released from SL.-1 was estim ated from measurements obtained on sagebrush samples and on appropriate m eteorological assumptions (Table A - l , page 131). On this b a sis , 10 Ci of 131I had becom e air-borne by m id - morning of January 4, 1961, 20 Ci had become air-borne 24 hours la te r , and at le a st another 50 Ci of 131I had been released between January 6 and 30, 1961.

3 .3 . 1. Aerial survey

The aerial survey equipment included a battery-operated Nal scintillation detector, a logarithm ic count-rate m eter, and

114


a recording chart. The firs t post-incident flight was made at 6.35 a .m . January 4, 1961. Subsequent flights were made on January 7, 8, and 12, 1961 (Figs. 4. 1 through 4 .5 , pages 72 through 76). Only m inor activity peaks (approximately 100 counts/s above a 200 counts/s background) were detected outside of the immediate area of the SL-1 on January 7, 1961. Only one spot of ground contamination, approximately three m iles south of S L -1 , was found on successive flights, while the location of other peaks was dependent upon the prevailing wind at the time of the survey.

3 .3 .2 . Vegetation sampling

Starting on January 4 , samples of sagebrush were collected along roadways in the region south of the SL-1 site. Sampling was then extended in directions determined by the results of the in itial sam ples. Sagebrush sam ples were analysed by gross gamma-counting of a 100-200 g portion in a Nal well- c ry sta l. G am m a-activity on sagebrush sam ples had been about 1 - 3 counts/min per gram in D ecem ber, 1960. The post-incident measurements ranged from 104 counts/min per gram directly south of SL-1 to approximately 102 counts/min per gram in the region between Atomic City and Taber (F igs. 4. 7 and 4 .8 , pages 78 and 79).

G am m a-spectra from representative sam ples indicated the majority of the activity on sagebrush was due to 131I. Specific analyses for 13? indicated a maximum concentration of 105 pCi/g approximately 100 yards south of S L -1 , and a general level of 102 pCi/g between Atomic City and approximately 40 miles south of Atomic City (Table 4. 1, page 62).

The area of effluent deposition, approximated from the r e sults of sagebrush sampling through January 7, 1961, is given in Table VII. 1 (page 56 and Figs. A-5 through A-7, pages 136 through 138).

3 .3 .3 . Milk sampling

Twenty-eight milk samples were collected from the region 20 miles south of the SL- 1 site , which contained the closest dairy farms lying in the path of the plume (Fig. 4. 8, page 79).

115


Only six of the samples contained 131J significantly above the detection level (Table 4 .5 , page 67). These sam ples were collected between January 8 and 11, 1961 and ranged from 160 to 280 pCi of 131I per litre of m ilk.

TABLE VII. 1

EFFLUENT DEPOSITION

Distance from SL-1 area (m iles)

Width of deposition pattern (miles)

1 3

4 9

5 (NRTS boundary) 10

10 15

20 20

3 .3 .4 . Air sampling

Air-borne concentrations of radioactive m aterials were measured at numerous locations using sam plers consisting of a sm all cartridge of activated carbon for i31I collection plus a p re -filte r for particulate collection. The resu lts of the samples collected at Atomic City, the clo sest off-site community to the SL -1 site , indicated a maximum of 40 pCi 131I per m 3 a ir during the period from January 3 to 9, 1961 (Table 4 .7 , page 69 and Fig. 4. 14, page 85). Potential thyroid doses received by residents of Atomic City were calculated from the measured a ir concentrations of 1311 and "standard man" parameters to be less than 35 mrad. 13il concentrations in the immediate vicinity of SL-1 reached 102 pCi/m3 on typica l days during the second week after the accident (T ab le4 .8 , page 70 and F ig . 4. 15, page 86).

3. 3. 5. Gamma-radiation measurements

Film badge dosim eters are routinely placed at 313 locations throughout the NRTS to record gamma-radiation doses. Four-

116


teen d osim eters in the v ic in ity of SL -1 w ere changed on D ecem ber 1, 1960 and again at various tim es after the in c ident. E ight of th ese located approxim ately one m ile south and sou thw est of SL -1 had record ed gam m a-rad ia tio n e x p osu res of 40 to 50 m R when changed on January 4 , 1961. Four dosim eters, located at each corner of the SL-1 fenced a rea , w ere changed three to four w eeks after the incident. These four had recorded exposures of 420 to 580 R (Fig. 4.13, page 84).On January 5, 1961, 28 stations w ere estab lish ed around the SL-1 area fence where repetitive gam m a exposure-rate m easu rem en ts could be m ade at varying d ista n ces arid d irections from the reactor (Fig. 4. 17, page 88). The resu lts of these m easurem ents indicated that gamma exposure-rates consistently decreased with about a one month h alf-life . Typic a l readings are given in Table VII. 2 (F ig. 4. 18, page 89).

TABLE VII. 2

GAMMA EXPOSURE-RATES

Distance NE o f SL-1 reactor building

(ft)

DateGamma exposure-rate

(mR/h)

200 1 -5 -6 1 700

200 2 -8 -6 1 350

200 3 -8 -6 1 200

500 1 -5 -6 1 50

500 2 -8 -6 1 30

500 3 -8 -6 1 15

1300 1 -5 -6 1 2

1300 2 -8 -6 1 0 .9

1300 3 -8 -6 1 0 .5

1 1 7


R E F E R E N C E S

[1 ] RADIOLOGICAL HEALTH HANDBOOK, Rev. ed. , US Dept, of Health, Education and W elfare, Washington 25 D .C . (1960) 9798 pp.

[2 ] BEA TTIE, J . R. , An assessment of environm ental hazards from fission product re leases, U .K .A .E .A . rep. AHSB(S) R 64 (1963).

[3 ] BLOMKE, J .O . , TODD, M .F . , U ranium -235 fission product production as a function o f thermal neutron flux, irradiation tim e and decay tim e, Part I , 1 and 2 USAEC rep. TID-4500 (13th ed.) (1957).

[4 ] BOLLES, R .C . , BALLOU, N .E. , Calculated activities and abundance of UZ35 fission products, USNRDL-456 (1956).

[ 5 ] LA V IE, JrM . , DOURY, A . , « E v a lu a tio n des risques rad ioactifs lies au fon ction n em en t d’une installation n u cl6a ire» , CEA rep.No. 1724, Centre deludes nucl^aires de Saclay, France(1960).

[ 6 ] BRYANT, P .M . , Methods o f estim ation o f the dispersion o f windborne m aterial and data to assist in their ap p lica tio n , U .K .A .E .A . rep. AHSB (RP) R 42 (1964 ).

[7 ] WATSON, E .C . , GAMERTSFELDER, C .C . , "Environm ental rad ioactiv e contam ination as a factor in nuclear facility site selection” , Siting o f Reactors and N uclear Research Centres, IAEA, Vienna (1963).

[8 ] GARNER, R . J . , private com m unication.[9 ] OKONSKI, J . , LENGEiMANN, F. , COMAR, C .L . , Hlth Phys. 6 (1961) 27.

[1 0 ] COMAR, C. L. , DRIGGERS, J .C . , Science 109 (1949) 282.[1 1 ] EKMAN, L. , A cta vet. scand. 2 Suppl. 4 (1961).[1 2 ] MAHMOUD, K. A. , "An approach to relevant dose computations from environm ental con

tam in atio n ", Selected Topics in Radiation D osim etry, IAEA, Vienna (1961) 85.[1 3 ] CHAMBERLAIN, A .C . , GARNER, R .J. , WILLIAMS, D. , Environm ental m onitoring after

accid en ta l deposition of rad io activ ity , Reactor S c i. T ech n ol. 14 (1961) 155.[1 4 ] COOK, J . E. . Evaluation for emergency planning o f hazards from accidents involving stocks

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[1 8 ] LISTER, B. A .J . , The use o f helicopters for em ergency district survey after an accid en ta l release o f radioactive m ate ria ls , Hlth Phys. 9 (19t& ) 309.

[19 ] BOULENGER, R. , MAERE, X. de, OSIPENCO, A ., «Prospection radiologique par helicoptere applicable & un re jet atmosph£rique accid en tel de produits de fission dans la region de M o l» , Paper presented at Colloquium on Radioactive Pollution o f Gaseous M edia, S a c la y , France (1 2 -1 6 Nov. 1963).

[2 0 ] W ILUAM S, D. , DERRY, K .E .G . , "G am m a spectrom etry from a v e h ic le " . Proc. Sym p. Environm ental M onitoring, B erkeley, England (1 9 6 3 ) , Pergamon Press, London.

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[22] SOLDAT, S. K. , private com m unication.[2 3 ] RISING, F .L . , unpublished work.[24] McCONNON, D . , Calibration o f survey meters for field determ ination o f I131 in m ilk ,

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for environm ental m o n ito rin g ,. (McCONNON, D. , E d .) H W -75250.[26 ] HOLT. F. E. , Emergency radiological plans and procedures, (HEID, K .R ., Ed.) USAEC rep.

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(Rev.) (1964).[281 WORLD HEALTH ORGANIZATION, Methods o f rad iochem ical analysis; WHO T ech n ica l

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nucteaires de Saclay, France (1964).[3 2 ] "A ccident at Windscale No. 1 Pile on 10 October 1957" , Comnd. 3 02 , H .M .S . O . , London

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W indscale in c id e n t". Proc. 2nd UN Int. Conf. PUAE 18 (1958 ) 2 9 6 -3 0 8 .[3 4 ] LO UTIT, J .F . , MARLEY, W .G . , RUSSEL, R. S . , The nuclear accid en t at W indscale -

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A U S T R A L I AH u n ter P u b l ic a t io n s *2 3 M c K illo p S t r e e t M e lb o u rn e , C . l

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