ot: 2-9 surface-sampler and animal data were obtcined, The failure of a project tin- ing circuit during shot Umbrella resulted in loss of time-dependent airsampler data, although total air samples were cbtainec, Estimates of the internal dose due to inhalation in the test compartments during ahoo indicated that the doses were below the threshold for acute exposure but that possible chronic effects might be produced. Similar estimates for Umbrella indicated the doses were below the threshold for chronic effects, with the possible exceptior :f the internal dose received in the engine roon. Umbrella estimtes of the external-des" rates in the test compartments due to ingress of contaminants showed ther “c be » srull fraction of the compartment's total dose rate, Radiological Environment. This study -7s t2 document the radiological en- vironment resulting from underweter nucl-ar cetonations. The gross garm:. fields from shots Wahoo and Umbrella were detined by means of GITA instrumen~ tation located on coracle plitforms, 23 /°ll as on the m jor target ships, These measurements were supplemented by those of total ganna dose made with floating film packs located throughout the target array. Incremental collec- tions of radioactive material denosited frim the resultant base surge and cloud permitted resolution of tne gross ganma fields .nto initial, freefield, and residual doses and dose rates, tUncerwater probes were used to obtain information on radiation from radioictive materials suspended in the water, During both ‘jahoo and Umbrella, it was found thet nearly all of the total gamma dose occurred within 15 minutes after zero time and was due to the passage of air-borne radioactive matericl, However, the records of gamma dose rate versus time obtained from the two shcts show pronounced and character= istic differences in the transiting panma fields. ben fo oe Gamma doses in excess of PAGE weet