OFFICE WMORANILY TO: Ul Maren 1953 SUBJECT: Dunean Curry, Deputy for Administration Taaig Group 7.1, JTF 7 John 0. Servia, Coamander TU}7 Task Group 7.1 LAGOON CONTAMINATION DURING OPERATION CaSTLZ SYMBOL: J-14513 REF: 1) FROUs Digfusion ia Biicini Lagoen, W, H. Munk, GC. C. Deing and Re R. Bevelle. irepagtnions, American Geophysical Vation, Vol. 30 No. eo. 1949. 2) Prelininary Report on the Oceanography of Bikini Atoll. Operation Crossroads. 3) Radiological Decontamination of Target and Non-Target Vessels, Cirector of Ship saterial Technical Inspection Report, JTF1, Operation Crossroads. b) Hadlological Safety Regulations, Bureau of Liedicine 5) Radivisten memorandum, and Surgery, U. $. Mavy Departaent, “ashington, 0. ¢. @. . Health Hasards of Operation 1. [ntredection The eencept of Operation Castle has peinted out 3 requirement for ships to re-enter Bilcini scagoon following detonation of atanic devices on the surfaes or near the surface of the lagoon. These ships would be limited in number, but would be required for shop and laboratory work 4a preparation for susceeding shots. This study is therefore undertaker te evalunte the health hasards and sontagination probleas tnat caignt _ result from ship reeentry inte centamineted lagoons. Technical information was ebtained from Scri,pe Institute of Oceancgrapny, La Jolis, Califermia; Health Division, LASL, Los Alams, and the laboratory recor ef Task Unis 7. It is felt taat this study aay be of assistance in Ciejperetienal planning of Castle and therefore is presented at this time. It my be expected that less than LOZ of thu total quantity of fieeion preduets will de deposited in ths witers of the ligean. At Us i hour, the intensity <t the surface ia expucted to axseed 400 2h hye. Radioactivity will be present in the area from fission pro= dusts trepped in the Liquid fall-eu&. The neutron flux rvsulting fraa the bemb, especinily in thu barge shots, will induce activity in water and bottom sediments. The three iapertant neutron absorbers in sea water are hydregen, sodiua, and ehlorine, but the only alement of coneern is sodium 24, which is of Little concern after three days. eS rae. Inel 1 of Inel 2 to TAB “P¥