FF3/7.3/32:mf ee of their washdown systems, concentrations of up to several roentgens per hour built up on BATROKO and: PHILIP (plane guard for BAIROKO), with average readings’ sgaching 500 and 750 nillircentgens per hour, respectively, The fallout pattern : vas not symmetrical, since both DSTES and CURTISS, approximately the sane distance “von ground zero as BAINOKO but on opposite aides.of her, received less contam-. ‘ ination. Other ships, including these which had been moved southwardbefore the detonation, received none of this early fallout. 3. In addition to the early heavy fallout encountered by some chips during the moming, in the afternoon andearly evening of 1 March, light, invisible fallout was detected by all ships in the area, Again, damage control measures wore em~ ployed: byall ships, This fallout commenced about 1300M, reached a naximm about: 1800M and decreased to almost zero by 2400M, Average readings during thie period. - reached 300 mr per hour, with maximum concentration up to 475 mr per hour.. Ships experiencing this fallout were located in the general area between trus bearings oerTt to 155°T from ground zero, distances from n20 to 70 miles... ~ oo 4. Decontamination of the ships by the ships ow decontamination crews, plus natural radioactive decay, brought the radioactive intensity down rapidly. The following table shows average topside ‘intensities in milliroentgens in milli- roentgens per hour (gamma only) of three representative ships at various timeg: DATE TIME 1 MAR 0900 1000 1100 2200 1300 1400. 1500 1600 1700 1800 GYPSY - 750 265 19% | U5 U7: _ 138 134 * 180 225 262 — 0000 1,00 0800 160 U5 134, 188 156 ni, 1600 2000 36 30 60 4h? 1200 3 MAR PHILIP 500 500 500 350 300 240 200 170 140 200 1900 2000 2 MAR BATROKO 0000 04,00 0800 . 180 180 108 27 25 22 . - 194 199 . ~ m-= = ’ -<--. 22. -2; Bo mee 7. Dos, 30.. re “200 - 230° 250: 20 150 130 110 80 78 45 er 39 Al 3h 40 >) 35 35 25 - Ve aOEa ee LD