FF3/7.3/32:mf J15-9 of their washdown systems, concentrations of up to seve roentgens per hour built up on BATROKO and PHILIP (plane guard for BAIROKO), with average readings’ ~gaching 500 and 750 nillircentgens per hour, respectively, The fallout pattern was not symmetrical, since both OSTES and CUNTISS, appreaximately the aane distance “von ground zgere as BALIOKO but on opposite sides. of her, reccived less contam-. ination, Other ships, including these which had been moved southward before the detonation, received none of this early fallout. 3. In addition to the early heavy fallout encountered by some ships during the moming, in the afternoon and: early evening of 1 March, light, invisible fallout was detected by all ships in the area, Again, damage control measures were em- ployed by all ships, This fallout commenced about 1300M, reached a maximum about 1800M and decreased to almost zero by 2400M, Average readings during this period reached 300 mr per hour, with maximm concentration up to 475 mr per hour, Ships experiencing this fallout were located in the general area between true bearings Llo*T to 155°T from ground zero, distances from 20 to 70 miles. . he Decontamination of the ships by the ships ow decontamination crews, Pine ie natural radioactive decay, brought the radioactive intensity down rapidly. following table shows average topside intensities in milliroentgens in wie roentgens per hour (gamma only) of three representative ships at various timep: DATE TIME BAIROKO PHILIP GYPsY 1 MAR 0900 1000 1100 500 500 500 750 265 196 -=---seo, 1200 350 5 1400 240 _ 138 2000 180 199 150 2 MAR 0000 01,00 0800 1200 1600 2000 160 145 134, 108 36 30 188 156 I, 78 60 La 130 110 so L5 10 35 3 MAR 0000 04,00 0800 39 41 34 35 35 25 1300 1500 1600 1700 1800 1900 300 200 170 140 200 180 ~—(t U7 134 180 225 262 194 --- - --- 7 30 200 230° 250 200