DNA 1240H-2 2. Underwater Bursts " Operation Hardtack: At Operation Hardtack, three destroyers utilized as target ships during the two underwater shots were instrumented with film badges and GITR's in many compartments. In addition, ea CITR waa suspended from a boom over each ship's fantail, and was to drop into the water after the passage of the underwater shock wave. After Shot Umbrella, GITR and film-badge data were obtaired on all 3 ships, although not all GITR's operated. From gamma dose-histories tabulated in Appendix D of Ref. 33, it is possible to compare doses recorded by the GITR‘'s at several shipboard stations located 3 to 6 ft below the waterline of the DD-593 with the doses recorded by the GITR suspended in the water over the fantail at station 15. Stations 11 and 18 were at the lower level in the forward and aft firerooms, respectively, and station 8 was located in the magazine. At station 15, doses measured were 0.0) r by 18 min, 0.03 r by 81 min, and 0.367 r by 8.5 hr. At stations 1) and 18, doses measured about 2.8 r by 9 min. They were about 3.24 r at station 11 by 93 min and 2.91 r at station 18 by 92 min. At station 8, doses were 13.2 r by 9 min and 13.4 r by 90 min. These doses are listed in Table 17-7. Table 17-7. Station 15 Dose data from DD-593 for Shot Umbrella. Location Dose In water 0.0lr 0.03 r 0.367 r| ll 18 8 Lower level, fwd fireroom Lower level, aft fireroom Magazine 2.8r 3.24 r 2.85 r 2.91 r 13.2 r ar Time 18 min 81 min 8.5 hr 9 min 93 min 9 min {91 min 9 min 90 min Comparison of the doses recorded in the water with the doses recorded aboard ship indicates that the former were only about 1% of the latter even at shipboard locations only partially shielded from airborne activity. Thus the contribution of waterborne contamination to shipboard doses must have been very small. Although shipboard doses were recorded at Shot Wahoo, 17-102