(u)
The underground structures afforded the greatest amount of
protection against neutrons and gamma radiation; the OCE concrete
shelter, UPSHOT-KNOTHOLE, Project 3.8c, with 8 ft of earth cover,
offering the greatest protection.
The attemuation factors were 107
and 10°” against neutrons and gamma radiation, respectively. (U)
The value of providing minimum earth cover for all structures to
(u)
The neutron measurements made at the bottom of foxholes showed
_,inerease gamma and neutron protection was demonstrated; 2-3 ft of earth
.cover reducing the gamma dose by a factor of 1,000 at close-in ground ranges.
that the protection was high, 96% to 98%, against fast neutrons and lower,
4O% to 75%, against thermal neutrons. Results of instrumenting foxholes
with sulfur, gold, and fission detectors in Shots 3, 11, and 12 indicated
conclusively that the angular distribution of the incident neutrons became
more isotropic as the distance from ground zero became greater.
Owing to
this increasing isotropic nature of the incident neutron flux with increasing
distance
roentgen
physical
(neutron
from ground zero, it was impossible to correlate the total neutronequivalent physical dose with the partial neutron-roentgen equivalent
dose as represented by the corresponding sulfur measurements
flux above energy of 2.5 Mev).
(U)
The studies on film-badge orientation in foxholes reveal that when
a line-of-sight or near line-of-sight condition exists, the variation in
dose due to orientation is relatively insignificant; on the order of 7% or
less.
However, at deeper positions in the foxhole, orientation variations
are more significant; on the order of 20% or less.
(U)
The preliminary report of this work was published as ITR-1121;
a special report, CRLR 597.
Wr-1144
-
PROTECTION AFFORDED BY OPERATIONAL SMOKE SCREENS AGAINST
THERMAL RADIATION.
Operation TEAPOT.
J. J. Mahoney and E. H. Engquist, August 1956.
SECRET-RESTRICTED DATA
(U)
The evaluation of oil fog smoke screens was conducted on Shot 5
with an operational smoke screen set up with smoke generators,
nt
WG
44 |
wale
Total radiant exposure measurements in the air-zero direction,
as received under the smoke screen on 2nx-steradian field of view calorimeters, indicate exposure ranged from 17 cal/sq em at 1,000-ft ground range
to 1.5 cal/sq ex at 2,400-ft ground range.
These values represent an
attenuation of 78% to 90% of the radiant exposure, which would have been.
received had no smoke screen been present.