fall-out commenced, average readings indicated 15 mr/hr with localized maximumsof 35 mr/hr. Washdown procedures and other necessary radiological-safety measures reduced the hazard to the point where it was no longer a health hazard aboard the craft. The Horizon was considered as “marking” theedge of the fall-out pattern in its direction. (c) Kwajalein Liaison and Control. The officer performing this function acted as the radiological-safety officer of TU 7 for TG 132.1 personnel at Kwajalein Atoll. In addition, monitoring was accomplished for Project 1.3. Further monitoring activities included checking of snap sample removal from F-84 aircraft for Project 5.4b and monitoring of sample removals for Project 7.3. This mission also supervised and controlled the use of dosimetry devices for the F-84 pilots. Instructions were passed to the monitors accompanying samples on courier planes to the ZI. Assistance was rendered to the AEC (New York Operations) in conducting its World-wide Fall-out Program. Water samples were obtained from Bikini, Ponape, Kusaie, Majuro, and Kwajalein. 3.14.3.2 Laboratory Group (a) Electronics Section, Maintenance was satisfactorily executed, and at no time did the demandfor instrumentation exceed the available supply. Component spare parts were obtained by cannibalization of excess instruments. Sufficient quantities of instruments were available, and the decision to cannibalize was made in orderto facilitate repair and maintenance without excess-storage problems of the delicate component parts. (0) Radiochemical Section. This section remained afloat aboard the uss Rendova during the entire operation. A Signal Corps Radiochemical Laboratory trailer was the base of operations and was located on the port side of the hangar deck. They received, prepared, and sayed all samples delivered. Desired data were reported to all interested personnel. Data obtained included discriminated activities and some beta and gammaenergy determinations. The majority of the samples assayed were the water samples from various locations in the lagoon. In general, the primary assays desired were the decay rates and specific activities per measure of sample submitted. Standard methods and procedures were used in the subsequent analysis of samples furnished. (c) Photodosimetry and Records Section. This section operated until M+2 days aboard the USS Rendova, using a photodosimetry laboratory trailer located adjacent to the Field Laboratory. Upon re-entry the section moved ashore and resumed its operations at the Radio‘logical Safety Center, Parry Island. Films were stored, handled, and issued in such a manner as to minimize any undesirable effects, such as humidity, loss of control, etc. Films and the self-reading pocket dosimeters were calibrated, using standard radium-source procedures. Calibration curves were obtained for the film, and the pocket dosimeters were marked with an appropriate correction factor. Film readings were the standard of record, whereas dosime- ters were used primarily to indicate a “running” exposure record by the monitor or user. Records were maintained to effect as complete a history as possible of the various exposures. Upon completion of the operation, a master list of all exposures was prepared. The final repository for film records will be the AEC Division of Biology and Medicine. The final repository for all films will be AFSWP. Reports of exposures will be forwarded to the homestation of each civilian who was film-badged. Exposure records of military personnel will be forwarded to the proper Surgeon General. 3.14.3.3 Decontamination Group During the operational phases afloat, it was the responsibility of the Commanding Oificer of the USS Rendova to decontaminate any contaminated aircraft and/or personnel boarding his ship. The USS Rendova was a part of TG 132.3, and, during the operational phases afloat, all flights made prior to re-entry originated and terminated at the USS Rendova, making decon- tamination procedures a TG 132.3 responsibility. Upon re-entry, TU 7 commenced operations at the Radiological Safety Center on Parry Island. Check control points were maintained at the 42