APPENDIX
Ideally, an abundance of shipboard radiation measurementsis available to define the
topside environment. Where such data are lacking, auxiliary information is used, through
appropriate conversions, to quantify topside intensities. The radioactive decay function described
in section 2 is an example. For those ships totally lacking intensity readings, the land-equivalent
radiation fields depicted in Reference 2 for fallout deposited on Bikini Lagoon provide readily
convertible substitutes. The intensity curves depicted for all ships in section 3 do not include the
transient contributions from shine. Aside from water shine, which is addressed in section 2,
exposures occurred from proximity to contaminated vessels. As those vessels were often of
unreported intensities, the foregoing approachis used for them as well.
Intensities on contaminated ships differ from land-equivalent intensities because of the

limited extent, flatness, and nonporosity of ship decks. Conversion from land to ship levels is
facilitated by a radiological quantity that is invariant to these differences, the surface activity per
unit area. That quantity has been related to land intensity in Reference 18, and is related herein to
all required ship intensities, through numerical methodsof radiation transport. These calculations
convert surface activity to intensity (peak or average) on a ship of specified dimensions, and to the
associated shine on a proximate ship of specified dimensions and separation. The calculated ratio
of shine to source vessel intensity, or shine factor, is confirmed for one ship configuration by the
available data.
The radiation transport calculations assumeideally flat, rectangular deck surfaces with a
uniform distribution of surface activity. Gammaintensity is calculated at points 3 feet above the
deck through a spatial discretization of the radiation source. While the peak intensity is found
through the summation of all contributions to the center point, the average intensity involves a
double summation. This amount of computationisfacilitated by applying radiation transport at a
level commensurate with the accuracyof the underlying parameters. The unscattered photon flux,
with a l/e attenuation length of 300 feet in air, is computed to a satisfactory resolution for the
geometry involved. This provides time- and cost-effective solutions that are reasonableforline-ofsight exposures for variously positioned ships.
Ship dimensions are based on information in Reference 17, which applies to the specific
ships in this report or to vessels related by type and class; however, estimates are required for the

barges. The approximated dimensions used in the calculations are: COCOPA, MOLALA,

111

Select target paragraph3