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AECR E S E A R C H R E P O R T S

AEC Category: H EALTH A ND SAFETY

ARIZONA LIBRADocum ents C ollectio

A U G 191964

IC HIBA N : T H E DOSIM ETRY P R O G R AM F O RNU CLEAR BOM B S U R V IVOR S O F HI R O S HIM AAND NAG AS AK I - STATU S R E P O R T AS O FAP R I LI, 1 9 6 4

J . A. Auxier

IssuanceDate: July 31, 1964

U .S . ATOM IC ENERGY CO M M ISSIO N

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NOTICEThis report is published in the interest of providing information which may prove of

value to the reader in his study of effects data derived principallyfrom nuclear weaponstests and from experiments designed to duplicate various characteristics of nuclearweapons.

This document is based on information available at the time of preparation whichmay have subsequently been expanded and re-evaluated. Also, in preparing this reportfor publication} some classified material may have been removed. Users are cautionedto avoid interpretations and conclusions based on unknown or incomplete data.

LEGAL NOTICEThl* report wa prepared us an account of Government sponsored work. Neither the UnitedStates, nor the Commission, nor an y person acting on behal* of the Commission:A. Makes any warranty or representation,expressed or implied, with respect to the accuracy, completeness, or usefulness of the Information contained In this report, or that the uae of any Information, apparatus, method, or process disclosed in this report mn y not Infringeprivately owned rights; or

B. Assume* any liabilities with respect to the use of, or for damages resulting from theuse of any Information, apparatus, me thod, or process disclosed In this report.As used In the above, "person acting on behalf of the Commission" Includes any em

ployee or contractor of the Commission, or employee of inch contractor, to the extent thatsuch employee or contractor of the Commission, or employee of such contractor prepares,disseminates, or provides access to , any Information pursuant to Ws employment or contractwith the Commission, or hie employment with such contractor.

PRINTED IN US APrice $0.50. Available from the Office of

Technical Services, Department of Commerce,Washington D. C. 20230

USAEC Division of Technical In for motion Extension, Oofc Ridge, Tennee

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ICHIBAN: TH E D O SIMETRY PROGRAM FO R NUCLEAR BOM B SURVIVORS OF HIRO SHIMAAND NAGASAKI - A STATUS R EP OR T AS O F

APRIL 1 , 1964

ByJ. A. Auxier

Approved b y : L . J . DEALChiefCivil Effects BranchU . S . Atomic Energy Commission

Oak Ridge National LaboratoryOak Ridge, TennesseeApril 1964

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ABSTRACT

I n 1 9 5 6 , t h e Health Physics Division o f the Oak Ridge Nationalc

Laboratory undertook t h e task of developing a method of evaluatingthe radiation doses received by the survivors of t h e nuclear bombingsof Hiroshima and Nagasaki, Japan, Data f o r this project, sponsoredby the Civil Effects Branch o f the Division of Biology and Medicineand d es i g n ated Ichiban, have been obtained i n nuclear weapons tests,Operation BREN, laboratory experiments, physical surveys i n Japan,and i n c alcu lati o n al studies. The approach t o the problem has beena s fundamental a s possible with emphasis on quantitative measurementsand calculations o f the energy, angular, and spatial distributions of

o

weapons radiations in an air-over-ground geometry. Spatial distributions of dose in various shields, including Japanese dwellings, havebeen measured. Techniques have been developed in Japan for verifyingthe location of survivors and accurately describing their shieldingenvironments. Simple empirical equations have been developed whichpermit the calculation of the shielding factors for Japanese residential-type structures with a probable error of approximately + 6f f> .

i i

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ILLUSTRATIONS

1 . Gamma Air Dose a s a Function of Slant Range f o r a TypicalNuclear Detonation ....................... 3

2 . Neutron Air Dose and Flux a s a Function of Slant Range for aTypical Nuclear Detonation ................... 4

3 . One of Two Japanese Houses Used During Dosimetry Studies DuringOperation Plumbbob ...................... 6

4 . Collimator Devices Used for Measuring the Angular Distributionof Radiation from Nuclear Weapons ...*,*......... 7

5 . Angular Distribution o f Neutron Dose at 1000 Yards from aTypical Nuclear Weapon of Nominal Size ............. 9

6 . Angular Distribution o f Gamma-Ray Dose at 1000 Yards from aTypica l Nuclear Weapon of Nominal Size ............. 1 0

7 . Radiation Dose a s a Function o f Horizontal Distance fromGround Zero i n Hiroshima .................... 1 1

8 . Radiation Dose a s a Function of Horizon tal Distance fromGround Zero i n Nagasaki .................... 1 2

9 . Typical Array o f Japanese Houses (Radiation Analogs) UsedDuring Operation Hardtack 1 1 .................. 1 4

1 0 . The Health Physics Research Reactor .............. 1 51 1 . The Health Physics Research Reactor Mounted on Hoist Car on

BREN Tower ........................... 6i i i

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ICHIBAN: THE DOSI METRY PROGRAM FOR NUCLEAR BOMBSURVI VORS OF H IROSHI MA A ND NAGASAKI: A STATUSREPORT AS OF APRIL 1 , 1964

Soon after the nuclear bombings o f Hiroshima and Nagasaki i nAugus t 1 9 4 5 , U . S . military medical t e a m s entered the cities. I n1947 a permanent medical survey-research organization, the A tomicBomb Casualty Commission (ABCC), was established. Since that t i m e ,a comprehensive program has been directed t o documenting and analyzing

the effects of nuclear weapons radiation on the survivors of thebombings and their offspring.

During "Operat ion Teapot" at the Nevada Test Site ( N T S ) i n 1 9 5 5 ,the Health Physics Division of the Oak Ridge National Laboratory, i ncollaboration with the L o s A lamos Scientific Laboratory, conducted aseries o f experiments w h i ch provided significantly increased under

s t a n d i n g o f w e a p o n s r a d i a t i o n f i e l d s . G a m m a r a d i a t i o n dosimetry> n

3,4utilized tetrachloroethylene chemical dosimeters, and t h e neutronflux and dose distributionswere measured with threshold detectors*The dose-distance relationship, D(R), for fastneutrons and gamma

*radiationwas shown to be

GD(R, -

for distances greater than about one relaxation length, w here G i s afunction o f the yield and design of the weapon and L i s the relaxationlength for the type radiation considered. For a particular detonation

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where p I s the air d en s i ty and p and L are the values for thes e' o ofactors at an air density o f 1.29 g/liter. Gamma radiation exposureand neutron flux and dose a s a function of di s t a nc e are shown for atypical de t ona t i on i n Figs. 1 and 2 , respectively. I t was also shown,for d i s tan c es g reater than L ~ 1 , that the neutron spectrum was, t o aclose approximation, constant; i . e . , an equilibrium spectrum wasobtained, F i g . 2 . These data have been discussed i n detail byRitchie and Hurst.

Th e data from Operation Teapot indicated the po s s ibili ty of ade f i ni t i ve de s c r i pt i on o f t h e radiation fields from t h e Hiro s hima andNagasaki bombs. Consequently, early i n 1 9 5 6 , a survey t e a m , includingmembers from the Los Alamos Scientific Laboratory, t h e Medical Collegeof Virginia, the Atomic Energy Commission (Division of Biology andMedicine), and the Oak Ridge National Laboratory, v i s i ted the ABCC i nHiro s hima and Nagasaki with the o bj ec ti v e of determining the feas ibili tyof a dosimetry study. After reviewing records and examining typicalshielding configurations, the survey group rec ommended that a dosimetryprogram be initiated. Emphasis was t o be placed on persons exposedi n Japanese dwelling-type buildings due t o the high structural uniformityand t h e large fraction of survivors exposed i n such buildings.

As a result of the recommendations of t h e survey group, a programwa s established i n t h e Health Physics D iv i s i o n of t h e O a k RidgeNational Laboratory (ORNL). The program i s sponsored by the CivilEffects Branch of the Division of Biology and Medicine, U.S.A.E.C., andi s designated as Ichiban*

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K > 6 8 10 1 2 14 16 1 8 20SLANT RANG E R IN HUNDREDS OF YARDS

22 24 26 28

GAMMA A I R DOSE v s SLANT RANGE

Fig. 1 - Gamma Ai r Dose as a Functi on of Slant Range for a TypicalNuclear Detonation

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1 0 '

10 1 7

, o ' 6OJe nQ

o c .10'

l o 1 '

I

L E G E N D ;0 Pu FLUX

Au FLUXx Np FLUXA U FLUXD S FLUXCOLLISIONDOSE -0 10

OJ

1 0 8

10'

0 10 20SLANT RANGE R IN HUNDREDS OF YARDS

NEUTRON AIR DOSE 8 FLUX vs SLANT RANGEFig. 2 - Neutron Air Dose and Flux as a Function of Slant Range

for a Typical Nuclear Detonation4

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The overall problem was divided i n t o three p a r t s : 1 ) t h e documentation o f the location o f t h e survivor a t the instant t h e bombexploded; 2 ) t h e es t ablishment o f t h e air-dose curves; 3 ) t h e shieldingfactors f o r t h e houses. B y working with the ABCC, t h e solution o f t h efirst p a r t o f t h e problem reduced t o a matt er o f time a n d requiredlittle research. The second part was further subdivided i n t o t w op a r t s , t h e determination of t h e shape o f t h e curves during weaponst e s t s , and normalization o f these curves t o t h e radiation yield o ft h e subject weapons. From t h e beginning o f t h i s investigation t h eproblem o f normalization was expected t o be the most difficult.

A pilot study o f neutron a n d gamma radiation dose distributionsi n Japanese houses was conducted during Operation Plumbbob a t N T S i n1 9 5 7 . A larger a n d more fundamental study o f t h e dose distributions

oi n air was carried out also f o r several weapons during t h i s operation.Two replicas o f a typical Japanese residence were constructed a t N T S ,F i g . 3 . The only variations from t h e detailed specifications w ereomissions o f t h i n glass a n d paper doors a n d windows; materials wereimported f r o m Japan. I n addition, 1 2 0 "collimation" devices wereconstructed t o permit measurement o f t h e angular distribut ion o f t h eradiation f i e l d incident o n a point detector i n a n open f i e l d , F i g . 4 .Seventy collimators were f o r gamma radiation measurements a n d fi fty f o rneutron measurements.

D a t a from Plumbbob indicated t h a t t h e radiation do se distributioni n Japanese houses might be r e l a t e d , i n general, t o a few identifiableparameters s u c h a s house s i z e , orientation, mutual shielding, proximity

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of walls and windows, etc. The basic program extended the air-dosedata and provided a description of the angular distribution ofradiation, Figs. 5 and 6, especially for fast neutrons. The greatestuncertainties in the air-dose distribution involved the gammaradiation.

Upon completion of the analysis of data from Plumbbob, a summaryof al dosimetry information applicable to the survivors was preparedand transmitted to the shielding group in ABCC. Designated T57D, thistentative dosimetry information served as a guide to establishment oftechniques for determining dose values from the shielding "histories"of the exposed individuals; italso provided an estimate of dose whichsupplanted the use of distance as the correlative factor for observedresponses. The "air-dose" curves, Figs. 7 and 8, were provided by

9York, based on all weapons data available to him. The largeuncertainties (probable error) in the curves are indicated by thedotted lines.

After Operation Plumbbob, laboratory studies of the shieldingcoefficients of Japanese and domestic building materials were conducted.Cement-asbestos board, commercially available in large sheets, was foundto be suitable as a substitute for the mixture of clay, oyster shells,and sea-weed wall plaster and for the mud and tileroofs of Japanesehouses for both neutrons and gamma rays* The wood framing used inJapan fitted well with the substitution of cement-asbestos board. Consequently, itwas planned to use radiation analogs of Japanese housesfor any further field experiments.

8

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20

50

6 0 '

F i g . 5 - Angular Distribution of Neutron D o s e a t 1 0 0 0 Yards froma Typical Nuclear Weapon o f Nominal Size9

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30< 20 < 1 0 C 1 0 ' 20* 30