HEAD.UARTERS TASK GROUP 7.1 JOINT TASK FORCE SEVEN Los Alamoe Scientific Laboratory - J Division, P. 0. Box 1443 : Los Alams, New Mexico - Jo1L696L 22 April 1953 TO: Commander Joint Task Force Seven “Nashington 25, D.<C. FROM: SeLentifis Deputy Joint Task Force Seven Yasningtoa 25, 0. C. SUBJECT: LAGOON CONTALINATION AND H&aLTH HaZARDS DURING OPERATICN CASTLE 1. Hecent studies of lagoon contemination snd health nazards frog radioactive fall-out of Castle have indicated that although tne lagoons of Bildini and Eniwetok will be contaminated no serious health hazards will be experienced at tine of re-entry. 2. (inclosures 1 and 2) In all provability, ships that re-enter the lagoon following detonation of atomic devices on the surface or near tha surface will become contaminated with radioactive materials. The problem that re sults from this action is the decontamination thet my be naccssiry at the end of the operation. ‘ater evaporators, wator distribution aines, and microorganisms adhuring to tho bottom of the snips wil. tend to concentrate the radioactive asteriale to a degroe tnat U. S. N-vy shipe my require ecae decontamination at tha complotion of oporations in order to aset the final clearance standards of 15 atliiroentgens per we day cs specified by the J. S. Nawal Radiological Safcty Regulaticns cof 1951. (Por. 8.3) 3. Pinal Clearance'" as defined in paragraph 25 of the Yandbook of atomie Voapons for Uediorl Officers (Nav Med Pe1330) “indicatos tnsat etips, aireraft, and other naterial require no furtner control fro the etandpoint of radiation." "'OCperational Clearance’ implies tnit con- tamination exists and special opemting procudures are requircd. “perm ational cloaranse for ships, aircraft, or heavy oquinmont aay be granted ty the eommanding officer wien he is assured by the Radiological Savety Staff that the personnel tolerance Limit will not be exmeeded Sy tneir ase," In the past no time limitation has been placed om tne rate of accumulation of the total dose (3900 millircentgens per operaticn, since under this concept, the Scientific Task Group was able to taxo advantage of tho time intensity factor of radioactive doeay of fission procucts and ainimisa the tins necessary for the preparation of succouding <coton= ations. Under sueh a concect, the Naval Task Group may anter ccntacin= ated lagoons of sevorel hundred mlilroentgens shortly after <stcnat. oA Inel 2 to TAB “FP” | . | |