Table 1.2. Operation CASTLE ships addressed in this report. Personnel Ship Assigned Task Unit 7.3.1 Surface Security Unit USS PC-1546 62 Task Unit 7.3.5 Utility Unit USS USS USS USS COCOPA(ATF- 101) MENDER(ARSD-?2) MOLALA(ATF-106) TAWAKONI (ATF-114) 82 72 88 80 Task Element 7.3.7.2 Mine Project Element USS SHEA (DM-30) USS RECLAIMER(ARS-42) 279 94 Task Unit 7.3.9 Transport Unit USS LST-1146 95 Characterization of the radiation environmentstarts with the determination of on-deck (topside) and surrounding water intensities from radiological survey data. The periodic shipboard surveys, in conjunction with fallout time-of-arrival data and nearby island surveys, serve to define the radiological intensity as a function of time. At times following the last reported shipboard survey, a power law function determined from Bikini Atoll radiological data is utilized. Despite differences in decay rate between ship and shore because of early-time washdown, decontamination, and weathering,late-time decay, mostly from insoluble particles adhering to shipdeckor soil, is taken to be the same. As ships operated in the contaminated waters of Bikini Lagoon, their hulls and saltwater piping systems accumulated radioactive materials, thus increasing the radiation exposure to crew members while below. The radiation environment due to ship contamination is derived from a previously-developed ship contamination model (Reference 4). When ships were in contaminated waters, the “shine” of radiation therefrom exposed topside personnel. Likewise, shine from contaminated vessels that were approached led to increased topside radiation levels. Both of these types of transient exposure are quantified to augment the meantopside intensities. Specific data and detailed methodology for the development of the time-dependent radiation environments are presented in section 2 of this report. Section 3 defines the radiation