Final Rad-Safe Report, Operation Castle

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MEMORAIDLJM THRU: CHIEF, WEAPONS EFFECTS DIVISION F FOR: DEPUTY CHIEF OF STAFF, TECHNICAL SERVICES SUBJECT: Final Rad-Safe Report, Operation CASTLE 1. This final report, consisting of two thick volumes, is broken It covers the overall CASTLE primarily into five parts as described on page 1, paragraph 1, Volume I. (References a r e tabbed with paper clips.) radiological safety program of direct concern t o Headquarters, Joint Task Force SEVEN. the rad-safe problems a t CASTLE, isto assist inthe development of future radiological safety plans by discussions of the problems and solutions that arose during this operation. The purpose of the report, i n addition t o docunenting 2. The basic maximum permissible exposure (WE) was the integrated exposure of 0.3r/week over thirteen weeks resulting in 3.91- total excefi inthe case of personnel remaining longer than the basic thirteen weeks. Members of air sampling aircraft were authorized a total WE of 20r for the operation. The Task Force Commander was authorized to revise the 309r MPE when circumstances indicated the need and justification there for. (Pages 25 and 26) Except for relatively high accidental exposure inthe case of 28 personnel in the Task Force Weather Station on Rongerik Atoll and a few other cases, none of the Task Force personnel received more two natives of Rongelap Atoll and 154 natives of Uterik were evacuated t o Kwajalein as the result of fall-out from the Bravo Shot, Rongelap natives received more than lOOr and the Uterik natives, approxiThe much publicized Japanese fishing vessel was i n an area 80 t o 90 miles East Northeast of aik in i (accordine tothe Japanese). This vessel was, not inthe expected direction of fall-out and was not noticed during the pre-shot warning surveys. After the shot, when the fall-out direction became apparent, planes were sent in this specific direction to warn ships that might have been missed earlier, but this vessel was not warned due t o severe aerial contamination of both the original search aircraft and a replacement search aircraft. No significant after cff ect s resulted from these exposures. 4. The IVY Mike early crosswind and upwind intensity lines were plotted as an overlay on Bikini Atoll as an approximation tothe close-in contamination that could be expected from high yield land surface shots, with allowances for differences in yields and shot conditions. I n addition,a new technique t c define close-in fall-out was developed by Declassified by DNA, Chief, ISTS

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SUBJECT: Final Rad-Safe Report, Operation CASTLE Dr. Thorns White, Los Alamos Scientific Laboratory, .ndis being further refined for future tests. generally speaking, wind conditions acceptable at Bikini Atoll were also acceptable a t Zniwetok, but that the converse isnot always true. (Page (Page 5 5 and Tab D, Incl3) It was found that 5. Though not too specific on this point,the report seem to indicate that the failure to prognosticate proper b the fall-out areas was due in large part to the lack of precise weather forecasting,specifically as regards the winds aloft. Specific recommendatiom as t o needed improvements in the solution of fall-out problems are given on page 70. 6. The significant fall - out area from the large yield shots (infinity dose greater than 50r) was a zone in the order of 100 miles wide and 300 miles long. (Page 87) 7.Specific recommendations based on the experience during this operation a r e given on pages 101-106. sented i n seven groups entitled general, weather, fall-out forecasting, dosimetry, rad-safe survey, personnel, and corinnunications. Chief, Radiation Branch

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Chief, ifeapons Zffects Division Deputy Chief of Staff, Technical Se rices SUBJECT: 3 r d Rad Safe Report, Operation CASTLE 1. With regard to the come nts al re aQ drafted,I offer the following: a. Para. (5) - The *report* i s not too specific on assigning " failure to prognosticate properly the fallout areas was due in large part t o the lack of' precise weather forecasting specifically as regards winds aloft." The reason for lack of speci€ic indication is the report cannot state boldly some operational considerations which cannot be admitted - i.e. the command personnel lmew that the weather situation was a deteriorating one. The decision was shaved too closely - note History o f Operation CASTLE, Vol. I Chart Page 176 - BRAVO time line. To say that the forecast of wind directions at critic zl lower levels changed about 10 degrees toward the inhabited islands after shot time is no revelation of poor €orecastinE. The state of the artof forecasting does not permit such refinement, a forecast of wind levels a11 the way from the surface to 70,000 feet is actually within the error of measurement itself or the wind parameter. Had ERAVO been fired on D-2 orD - 1 upper wind patterns which were known t o be favorable, Ithe native e qo sure episode would never have happened. 3ec is ions on &ether t o shoat ornot were shaved a t GR~NHOUSE- ITEFI, and the result was an exposure incident - but you can ' tfind it i n the BRAVO was better than Eood - and when tbinkinf; of wind one should think of direction and velocity - had the velocity of wind bet7deen 15-55OoU feet been 1s t o 20 hots less the problem again at thc native illhahited islands riould have been much less of an ernergencj' nature. Ten degrees plus o r minus for The weather forecasting for the degree required prior to 2. AltnouE;:i much is said 01 ne?$ dynanic ?all. out forecasting techniques, the fact still remains 'that the degree of precision in fallout forecasting required from the ueather rorecasting input must synoptic weather data-could be reconmended but t h e answer t o avoiding BPAVO episodes i s i n not shooting under margj.nal conditions. There are firm wind patterns favorable for even larger yields than CASTLE series, but. man must wait for them - they are randoin i n occurrence - !,re saw then about tvrice a month a t PFG area - but i f they are to be

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SUBJECT: Final Rad Safe Report, Operation CASTLE Et ili zed, JTF nust be ready for them on short. notice, i.e. 2atall capability and flexibility in "go" o r "no go" decisions at either atoll. 3. Testing o f Negaton range devices requires much radial space 9 hours duration i s considered areal problem, then future testing at PFG is rough business. If 50-100 mr/hr a t 500 miles plus from GZ for say 8or L. I consider t \ e CASTGT radsafe report the most comprehensive t o date from an operational standpoint. Weapons Test Division

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Effects Dir is i Memo t o DCS/TS thru EF, cy LI Cy8 2A & 3 A retained for f i l e in EF-1.