“Estimation of Dosage Reveived by Personnel of USS PATAPSCO (A0G-1) following the BRAVO shot of Operation CASTLE. A. - Introduction Problem: In response to the Navy Nuclear Test Personnel Review office request (ref. 1) the following analysis of personnel exposures was undertaken. During a transit of the USS PATAPSCO from Eniwetok Atoll to Pear] Harbor Hawaii, the personnel of the PATAPSCO encountered an unknown amount of radioactive fallout that resulted from the Castle-Bravo shot (ref. 1). The captain of the ship had been alerted to the possibility of radioactive material contaminating the ship and so made attempts to measure the radioactivity but because of inadequate equipment only uncertain readings were obtained (ref. 2). When PATAPSCO arrived at Pearl Harbor the ship and personnel were monitored and the ship was found ‘ .o have been contaminated (ref. 2). The following analysis will provide esti- mates of the range of possible external gamma radiation doses received by the crew from this fallout. Approach: Two primary sources of radiation data for dose estimation are used in this analysis: (1) published unit reference (H+1) dose rate contours (ref. 3) and, (2) radiological survey data obtained on arrival at Pear? Harbor. Extrapolations of these data are then utilized to estimate the range of dose -variations caused by environmental conditions, exposures situations and times. Valuable information contained in the PATAPSCO captains recollections (ref. 2), the ship's logs (ref. 4) and notes describing the survey and decontamination ‘procedures employed at Pear] Harbor (ref. 4) was used in the preparation of this analysis. The time interval for the dose estimates undertaken here will 2 form fallout arrival at the ship to the time of crew evacuation as reported Enclosure (1)