Chapter 1
INTRODUCTION
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 af
locations of possible operational interest about the surface zeros of two underwater nuclear det-
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
gamma-radiation dose and dose-rate histories in the water adjacent to the ships; and (4) measurement of gamma-ionization decay of a fallout sample ccllected on one ship a few minutes after
each shot.
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 antisubmarine nuclear-weapon-delivery ships is determined by radiological 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 de-~liveries.
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
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