in marked contrast to previous operations. The photo tower, to all intents and purposes, was of no use during the Hardtack events. The two underwater shots introduced complications in obtaining the desired contamination information. On the Wahoo shot the monitoring was done from a Navy seagoing tug (ATF). Surface contamination was somewhat high so the time delay in reaching the target ships was considerable. The tug was also used for obtaining a water sample for radiochemistry yield determination. . This operation proved quite successful in that a useful sample was obtained without contaminating the ship significantly and with no more than 1 r total dose received by anyone engaged in the sampling operation. For the Umbrella - event landing craft (LCM) from the H&N boat pool were used for the moni- toring operation with considerable success. Surface contamination was quite low (highest reading observed was 5 r/hr), and within 90 min following detonation all target ships had been monitored and recovery operations were proceeding. A Navy seagoing tug was once again used for water sampling without trouble. The tug obtained the water sample at approximately H+45 min. Monitoring operations on the underwater shots did not include an actual boarding of the target ships. Primary concern was to determine the general radiation intensities in the vicinity of the targets and immediately alongside the targets. Recovery parties were allowed to proceed, based on the TU-6 information, with the party monitor providing the necessary information concerning the situation aboard ship. The water-borne operations proved, in general, to be successful; operations were limited in some cases due to the effort made to prevent excessive contamination of participating Navy ships and boats, , The Quince and Fig shots produced contamination only on the shot island, Quince resulted in considerable alpha contamination. After Fig, heavy local contamination (fission products) existed as far as 200 feet-from the zero point. A combination of residual alpha contamination from .Quince and the high levels resulting from Fig required that a check point and a personnel decontamination station be set up on Runit. Approximately 1,600 people were processed through this check point during the Fig recovery operations. The water circulation patterns in the lagoon provided fairly rapid dissi~ pation of the contaminated water that remained after the barge shots, and almost all the water zero sites could be re-entered within 24 hr without hazard to the boat crews. Although water-borne recovery operations for Pinex and detector foils were held up after some events, no more than a 24 hr delay was ever experienced, Use of the barge zero points required that underwater radiation measuring instruments be available for use by divers working on signal cables and mooring devices, Six meters manufactured vy the Isotopes Specialties Co., Burbank, Calif., were used. The meters were designed to withstand pressures -14- - “ . | | | a! t . _