ad
Shielding
_
-
Shielding by the ship's structure reduced gamma
radiation levels in below deck spaces to roughly 0.1 the
values on the weather deck.
Additional shielding by the
12" thich' concrete slab of the instrument recording room
gave a reduction to 0.001 the above deck value on the YAG-40.
Generally, shielding effectiveness increased somewhat with time.
Absorption data from detectors in a series
of steel pipes mounted on deck, with wall thickness varying
from 1/8 inch to 4 inches, clearly showed a decrease in effective radiation energy over the interval H+5 to H+ 7fShours.
Prior to, during, and after decontamination, a
complete radiological survey was made of both ships.
All
readings were taken ina prescribed inanner at measured
distances from previously marked stations.
The T1B gamma
survey meter and the USNRDL Beta Probe proved to be the most
useful instruments.
The USNRDL directional gamma instrument
was found to operate successfully, but its weight limits its
applicability.
The technical survey personnel supplied (imtrained)
by the Task Force have been used successfully to supplement
the small group regularly assigned to this duty.
On the whole,
the technical survey support hes been very satisfactory.
An attempt to photograph the fall-out with equipment
capable of recording all particles 2100 p was unsuccessful due
S=eRne
we a ERR Ate ee
.
7
Radiological Survey andPhotography