> u e 27 teEE Martaaae aPS Th lee 14 16 0 Chapter 1 16 INTRODUCTION 19 30 1.1 OBJECTIVES The principal objectives were: (1) the determination of total gamma-radiation dose and doserate histories aboard three moored ships (destroyers) exposed to radiological environments at locations of possible operational interest about the surface zeros of two underwater nuclear det- 121 122 onations, Shots Wahoo and Umbrella; (2) estimation of remote-source gamma-radiation dose and and dose-rate histories at exposed weather-deck locations aboard ship; (3) estimation of total 123 gamma-radiation dose and dose-rate histories in the water adjacent to the ships; and (4) meas- urement of gamma-ionization decay of a fallout sample collected on one ship a few minutes after 124 each shot. 125 An additional objective was the provision of preproduction evaluation, production liaison, instrument-maintenance consultation, and a field maintenance facility for all projects using GITR’s developed by the U.S. Naval Radiological Defense Laboratory (NRDL). } 1.2 TERMINOLOGY In this report, total gamma-radiation dose indicates the combined contributions of all radiation sources that affect the detectors. Doses and dose rates are specified to apply to air absorption only. 1.3 BACKGROUND AND THEORY It is of interest to the Navy to find out whether the minimum safe standoff distance for anti- submarine nuclear-weapon-delivery ships is determined by radiclogical effects or by physical damage. (Standoff distance is defined as the distance of surface zero from the ship at the time of detonation.) Each tactical maneuver by the ship, during and after delivery of the weapon, will have associated with it physical shock and radiation effects. For a given weapon detonated under a specific set of environmental conditions, the shock effects will be chiefly dependent upon the ship’s position and orientation with respect to surface zero at the time of shock arrival, whereas the radiation effects will be dependent upon integration (with respect to time) of the shipboard dose rates received at each position along the entire track of the ship. Because it was not feasible to have the test ships actually perform representative tactical maneuvers in the radiological environments, doses for such maneuvers were not measured directly. The alternative was to obtain data for specific locations, which would be useful for the calculation of dose rates aboard ships performing maneuvers in hypothetical weapon deliveries, Parameters of interest in determinations of shipboard dose rates include: (1) the magnitudes of radiation sources on the surfaces of the ship, in the surrounding and remote air, and in the Surrounding and remote water; (2) the ingress of contaminants into the interior of the ship; and (3) the attenuation afforded by the ship’s structures or machinery with respect to the several