i U. S. S. BAIROKO (CVE-115) Fleet Post Office wee: Franciscp, California ’ EO: TELM: rd CVEN15/M3-L Ser: 008 7 March 1954 From: To: Via: Commanding Officer | Chief of Naval Operations © (1) Commander Task Group 7.3 (2) Commander Joint Task Force SEVEN Subj: U.S.S. BAIROKO (CVE-115); radiological contamination of lL, 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 BALROKO was in the process of launching five (5) helicopters at the time the fall-out was received and the wash-down equipment was layed cut in the catwalks. One helicopter was in the air but was immediately recalled and lamied. The first warning of fall~out was the report of approx- imately one (1) roentgen per hour on the flight deck, The order to set Material: Condition ABLE was given at 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 prevented contamination of real ‘ consequence of any spaces below the hangar deck, the engineering spaces rising to only eight (8) milli roentgens per hour, gamma only. The wash-dewn equipment was turned on as soon as Condition ABLE had been set but proved to provide an in-= sufficient volume of water to handle the heavy fall-out of contaminated coral sand deposited on the flight deck, catwalks, island structure, forecastie and | 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 broken out 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 veryfine 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 1645-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 ~~ Ze. $ weretaken on 1 March 1954, ENCL (2) TO ENCL (4) S3°YIASAI