POTN... rn APAINee e 12 3.7 io Safety. of Operators Despite the nature of the work, no significant radioactive contamination of the personnel is reported to have occurred. & face masks and good personal hygiene procedures were required. operators wore dosimeters. Routine urine analyses and film-ba rezdings showed no significant exposure. I¢ should be noted over 5,000 filters from air samplers, over 50 percent showed nc contamination from transuranic elements, over 95 percent showe than 1 percent of tne maximum permissible concentration (MPC), ment"). 3.8 Cactus Crater The Cactus Crater, which received all the contaminated deb of Runit Island (Pigure 4). Most of the crater rim is on land before construction of the dome, about a quarter of the cir spit of coral. A surface shot in May 1958 produced the 350-fob and 30-foot-deep crater. About 200 feet to the northeast of G& Crater on the ocean side is a somewhat larger crater, LaCrosse waa produced by a surface shot in May 1956. The rim of LaCrog high tide appears only as a few isolated rocks above the water if there was more material than LaCrosse could hold. For logitical reasons, however, the order was reversed and Cactus alone prove sufficient size for the disposal operation. The Cactus Crater was not formed in undisturbed rock. Th@ Zebra two shots caused fracturing of the rock around the site of Cad (Defense Nuclear Agency 1981, p. 409). The Zebra Crater was and oiled to prevent dust while the Dog Tower was being worked fissured. When the Cactus device exploded, a large amount of rock, it pulverized into small particles, was thrown upwards. Muchfof this filled with debris. The true crater is therefore twice as de$p as it appears to be, and this was demonstrated several years ago : was drilled through the debris to a u.>th beyond the bottom of the true Crater. A gamma counter was lowered down the hole and activiky leveis were cecorded at different depths (Figure 5). about 4800 counts per second (cps). At the bottom bf the The counting rate then &