$3.10 RECOVERY OPERATIONS The problems involved in the recovery of experimenta! data following each shot were quite similar for all shots in the Bikini! area since the conditions established by@EEeld throughout the operation. Despite earlier qualms regarding the complexities of shipboard operation, most recoveries were effected as early 28 could have been expected, any real delay being for the most part due to radiological considerations. A certain amount of study of the recovery problem had preceded the overseas phase of the operation. Recovery methods were discussed, and the various support items were laid on. In the field further discussions of recovery methods resulted in a firm operating plan which was then in atull rehearsal with such vehicles, helicopters, or boats as the mission required. on ecovery plan was issued on February 22 as a result of these discussions. It detailed the movements of each project for the period from shot time through when it was felt that the majority of the recoveries would have been accomplished,The results ed this plan to be abandoned, and recovery of data went at a much slower rate than planned dueto the extensive fall-out in the islands. This experience led to the conclusion that detailed plans based on assumptions of yield and fall-out patterns were of little value except as they served to acquaint the operations people with the problems involved. @ubsequent plans were far less elaborate, allowing leeway for conditions which could not be predicted. Essentially these were lists of the participating projects, the locations of the instrument stations, and the types of vehicles and other support most likely required. Following each shot the CTG 7.1 left the USS Estes to make an initial survey of the atoll to determine the damage to the stations and the radiation levels in critical areas. Upon his return the approximate times for the recovery missions were decided upon, and the early missions were dispatched. Some of these were made while the vessels were at sea, but the majority of the recoveries waited for the reentry of the fleet into the lagoon, when the recovery teams could be collected and dispatched by helicopter or boat. In all cases the recovery missions were closely coordinated with the Rad-Safe Control] Officer, who determined that the personnel were properly badged and clothed, and accompanied by a qualified monitor before proceeding into a contaminated area. The J-3 representative aboard the USS Bairoko directed the helicopter missions and made certain that the crews and project personnel were properly briefed. It was found that confusion and misunderstanding could be avoided by requiring that all helicopter recovery missions originate on the carrier in order to bring the people together to talk over the missions. Of the total of 63 projects participating in Operation Castle roximately 75 per cent took 69 per cent Of these, about 30 per cent were able to make at least limited recovery on elicopters to get into the hot areas for short visits. Generally, the recovery time depended on the distance of the station from Ground Zero, but the majority of the recovery missions went out on the day following the shots when the radiation levels had fallen somewhat. The exceptions to th all recov: delayed due to extensive fall-out reentry into the islands, Precautionary measures were observed on those missions entering hot areas, where engine failure or other mishap could result in dangerous radiation overdose. Helicopters flew in pairs on such missions, passengers were provided with signal flares, battery-operated Motor- ola sets were established in isolated bunkers, and, of utmost importance, special attention esselé was given to the briefing of the crews and passengers on signals to be used, It was apparent that the simplest approach to the problem was the best and that the success of any system was entirely dependent upon the mutual understanding of that system by the pilot and passengers. 3.11 POSTSHOT REENTRY It became arrestIs the Bikini portion of Castle would be conducted from aboard ship. Ina way this simplified the operation because the evacuation and reentry problems 48 BEST AVAILABLE copy C