radiation sources. Some of these parameters have been previously investigated, principally
for other than underwater-detonation conditions.
In past calculations of shipboard radiation attenuation, the major emphasis has been given
to residual contamination on ships’ weather surfaces (Reference 1}, with some work done for
a ship enveloped in a radioactive volume of air (Reference 2), assuming monoenergetic gamma
radiation and uniform contamination in an idealized geometry. (Shielding calculations are in
progress at NRDL, which for both residual contaminant and remote-source radiation take the
entire radiation-energy spectrum into account and which eliminate much of the need for idealized geometries in the case of remote-source radiation. )
Gamma radiation from sources outside a ship has been investigated during various phases
{ the fallout environment from land-surface and water-~surface megaton-range detonations
during Operations Castle (Reference 3) and Redwing (Reference 4) and, to a very-limited extent, during Operation Wigwam (Reference 5) for a deep-underwater detonation, using Liberty
ships (YAG’s 39 and 40) as the test vehicles.
The experimental results from Operations Castle, Redwing, and Wigwam indicated that attenuation factors inside ships were dependent not only upon the geometries of the ships’ structures but also upon: (1) the geometries and relative magnitudes of the various radiation sources.
which depend upon detonation conditions and also change with time; and (2) the gamma-energy
spectra, which are functions of time and weapon design.
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