time of entry. This time delay was caused by the practice of issuing film badges at Eniwetok and developing the film at Bikini and by a lack of night transportation in the lagoon. The practice of entry control by film-badge exposures left much to be desired, but it was the only method avail- able in the absence of reliable self-reading dosimetric devices. The practice of issuance and development of film badges may have penalized many individuals because of inherent inaccuracies of the film badge in the presence of low-energy radiation and low dosages. PRE-EVENT SAFETY MEASURES Hazard Zones A security zone, 150 x 300 nmi (278 x 556 km), was established around Enewetak and Bikini prior to CASTLE (Reference 26),* and this also served as a radsafe precaution area. The area was patrolled by P2V aircraft and destroyers to assure that no unauthorized vessels were present. also diverted shipping from within a sector 500 nmi (926 km) The Navy from ground zero in an are extending from the southwest, clockwise to the east. volving primarily U.S. H+24, In- shipping, this was done on all shots from H-hour to ‘ After BRAVO, maximum cooperation with other nations was sought to control shipping in the hazard zone. The area was officially designated a danger zone and redefined as the sector centered on 12°N, 164°E, from 240° clockwise to 95°, with a radial distance 450 nmi (833 km). (designated Area Green) A subsector was defined as the region bounded by 10°15'N, 16°40'N, 160°10'E, and 170°20'E, which was subject to more intensive air and sea search prior to a shot than the rest of the danger zone. Addi- tionally, all U.S. shipping that passed within 600 nmi (1,111 km) of Bikini came under the operational control of CTG 7.3 (for radsafe diversion if necessary). * The area was bounded by 160935' to 166°16’E and 10°15' to 12°45'N. 107