wee
CRLIR - 115
-
DECAY OF RADIOACTIVE MIXTURES.
Hugh R. Lehman and Robert H. Iynch, 8 April 1952.
UNCLASSIFIED
(U)
The fission of u23? by slow neutrons results in a fission-
product rixture that exhibits a distinctive radioactive decay curve, which,
short-
-
as derived by Way and Wigner, approximates a straight line when plotted on
log-log graph paper.
From curves derived by Hunter and Ballou, it appears
that during the decay of such a mixture, the fractional activity of every
participant nuclide passes through a maximum value of percentage activity.
The purpose of this report was to derive a function predicting the time at
which the various fission products "peak", and to explain the deviations
from the wWay-Wigner theoretical curve.
1as
ate
It was demonstrated that a nuclide exhibits a "peak" at a time
dependent only on its half-life and on the slope of the log-log relation-
ng
ship for a particular fission-product mixture.
For the cited fission-
product mixture, the slope constant is approximately -1.2. Thus, most
nuclides will exhibit their fractional activity "peaks" at approximately
1.7 half-lives from the time of formation of the mixture. Whether or not
33
ited
a particular nuclide or fission chain will become so prominent during its
"peak" thet the mixture will temporarily appear to be a single species
depends on several factors (1) possible reinforcement of the “peaking”
nuclide by competitors of similar half-lives, (2) the original fission
yield of that nuclide, and (3) parent-daughter doubling of the activity
when the daughter's half-life is shorter than that of the parent.
CRLIR - 126
and
-
STUDIES ON ARMORED VEHICLES AT OPERATION JANGLE.
(WT-402 )
Elmer H. Engquist, 21 April 1952.
a>
SECRET-RESTRICTED DATA
D
Tre studies reported here pertain to the protection provided
by various types of armored vehicles against airborne, radioactive,
particulate material; to the shielding afforded by such vehicles in traversing contaminated areas; to the effectiveness of field decontamination of
o
these vehicles; and to the protective efficiency of the E26 tank collective
protector.
Test vehicles were located 2,000 ft from ground zero of the
surface anc underground shots, variously positioned with respect to the
blasts.
To provide comparative data, hatches were closed or open, and the
engines were operating or stopped.
54
an
ee:
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oe
REST
ATO
1S