- i U. S. S. BAIROKO (CVE-115) Fleet Post Office wee: Franciscp, California ’ EO: TELM: rd CVELL5/M3-4, Ser: 008 7 March 1954, - From: Tos Via: (1) Commander Task Group 7.3 (2) Commander Joint Task Force SEVEN Subj: 1. Commanding Officer ‘ Chief of Naval Operations ~ U.5.S. BAIROKO (cvE-15); radiological contamination of About O800-M on 1 March 1954 this ship received a heavy fall-out of contam- inated coral particles following the detonation of an atomic device on. Bikini Atoll. At the time of the fall-outthe ship was thirty-one (31) miles bearing 133°T from the shot site, The BAJROKO was in the process of launching five (5) helicopters at the timé the fall-out was received and the wash-down equipment was layed out in the catwalks, One helicopter was in the air but was immediately. recalled and lanied, The first warning of fall-out was the report of approximately one (1) roentgen per. hour on the flight deck, The order to set Material Condition ABLE was givenat the first indication of fall-out and all ventilation, _ including ventilation to the engine room spaces was shut down and remained _ secured for approximately two (2) hours. This preventedcontamination of real. ° consequence of any spaces below the hangar deck, the engineering spaces rising to ~ only eight (8) milli reentgens per hour, gamma only. . The wash-dewn equipment was turned on as soon as Condition ABLE had been set but proved to provide an ine — sufficient volume of water to handle the heavy fall-out of contaminatedcoral sand deposited ‘on the flight deck, catwalks, island structure, forecastie arid fantail. Operation of the wash-down equipment. was continued for approximately. two (2) hours and then secured, Monitoring of the flight deck at this ‘time ‘gave-readings as high as five (5) roentgens per hour in many of the cross deck gutters and a high of twenty-five (25) roentgens per hour was recorded in the flight. deck drain on the starboard side aft, Fire hoses were then brokenout and used —— to washdown the exposed areas for the remainder of the day. The fire hoses proved to be much superior in washing away the comparatively large particles of coral sand which had been received and it was possible to reduce the flight deck count to approximitely two-hundred (200) milli roentgens per hour, gamm. only or less by 1600-M, 2. A second fall-out was received starting at about 1600-M, This fallout was composed of very fine particles and increased the count on the flight deck and bridge to between two-hundred (200) and four-hundred (400) milli roentgens per hour, gamma only. The fire hoses were again used on the flight deck, forecastle and fantail and bridge structure until about 1845-M when the Task Unit 7.1 radio- logical personnel recommended sending all personnel who could be spared below. © decks because of the possibility of inhaling the extremely fine particles into the lungs. No further decontamination measures weretaken on 1 March 195k. ENCL (2) TO ENCL (4) AVASAL