go 1-t2 The DO program particip-tion in HARDTACK was of greater magnitude than in any other Pacific Operation. Program 1. This program was designcted primarily to obtain data from under= water bursts, such as blast overpressure end ground motion records. This in- formation was necessary to ascertain the effects of underweter burst geometry and to understand the conditions which various structural objects, such as missiles and underground structures , are subjected at various locetions fron an underground detonation. Program 2. This program objectives were: 1. To determine the gross radiological hazards resulting from underwater bursts. Included were free-field measurements, deck and selected come partment contaminction measurements, and measurements of ingestion and inhalation of contamination entering the ship via ventilation and come bustion air systens. 2. To collect neutron energy spectrum data to supplement the prosently inadequate knowledge of neutron energy sp:ctrums from thermonuclear weapons. Prompt neutron measurements were to be determined from a ‘ small yield weapon. 3. To measure radiation in the muclear cloud which contributes to world wide contamination. Prosram 3. This program was designed for determination of the effects of underwater bursts on surface and sub-surface vessels, and for the study of various types of land structures under various loading conditions. The ine formation obtained by both programs 1 and 3 will be used to aid in formulae tion of operational doctrine, particularly insofar as delivery ranges and tactics for both surface and sub-surface vessels. The information obtained on the response of ship structures will be used to provide eriteria for future designs. Data obtained from various earth-covered flexible arches tested under both long and short duration eir blasts, and deep reinforced conerete slabs tested under blast loading, will be used to determine construction criteria for future underground structures. Procram 4. f. This program will perticipate only at Johnston Island. we | 5