3, 4, 5and6). Figure 1-4 depicts the steps taken in calculating personnel film badge doses. These steps are pursued to a level of detail governed by the availability of data. Sufficient data were recorded at the time and enough have survived to understand the ship and land operations and to characterize the radiation environment. Individual ship deck logs serve as an authoritative source of ship position and activity. Radiation intensity data and crew activity scenarios are applied to reconstruct the time-dependent radiation environment for an average crewman on each of the sixteen ships of interest. Characterization of the radiation environment starts with the determination of on-deck 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 topside 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 significant 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 shipdeck or soil, is taken to be the same. As ships operated in the contaminated waters of Bikini Lagoon, their hulls and salt water piping systems accumulated radioactive materials, thus increasing the radiation exposure to crew members while below deck. The radiation environment due to ship contamination is derived from a previously-developed ship contamination model (Reference 6). Specific data regarding the development of the time-dependent radiation environments are presented in Section 2. Shipboard radiation surveys indicated a considerable variation in topside inten- sities because of ship geometry, redistribution of fallout during washdown and decontamination, and non-uniform adherence of fallout particles to ship materials. only an average survey reading was reported, this value is used. If In those cases where readings were taken at many predetermined positions on the ship's exposed surfaces, they represent the topside radiation field. located at random positions when The ship's crew is presumed to have been on deck; thus, the mean survey readings, appropriately decayed, are used to determine the mean intensities encountered by the crew when on deck. The distribution of survey readings suggests a distribution in radiation exposure to the crew. Uncertainties associated with mean survey readings 13