CORRELATIONS ON DEBRIS FROM SILICATE BURSTS
73
INTRODUCTION
In the summer of 1962, the U. S. Naval Radiological Defense Laboratory (NRDL) collected fallout from three shots at the Nevada Test
Site (NTS)—Johnie Boy, Small Boy, and Sedan. Radiochemical studies
were made of the debris from these shots and were reported.-3 During the past several months, we have made log—log correlations of
these radiochemical results and have attempted some interpretation
of them.
Before the results are discussed, it seems appropriate to review
the shot conditions since important differences existed among the three
events. These differences undoubtedly had effects on the fractionation
behavior of the fallout.
SHOT CONDITIONS
Small Boy was a low-yield shot fired from atop a 10-ft-high
wooden tower above alluvial soil in Area 5 at NTS. NRDL collected
many fallout* samples of debris at 43 stations within 8.7 miles of
ground zero and took other samples on a line 15 miles from ground
zero. Further samples were supplied by the University of California
at Los Angeles sampling network at distances of 18, 27, 36, 52, and
70 miles. Four cloud samples were supplied by Los Alamos Scientific
Laboratory. The discussion in this report is mainly restricted to
samples from within 8.7 miles of ground zero and from the cloud
samples. The number of samples used from each station varied, and
many Samples were subdivided by sieving into seven fractions that
were analyzed individually. A total of about 187 samples is dealt with
here, all of which were analyzed for ™Sr, *°Sr, °!Y, and *Zr. In addi-
tion, about one-third of them were analyzed for *°Mo, !"Ru, !%Ru,
138cg '8lcs, M9Ba Mice, M4ce, *Np, and 738Pu. Some of this last
group of samples were also analyzed for I and ‘Te. The numbers
quoted do not include a fairly large number of radiochemical analyses
on samples used for solubility studies.
NRDL’s participation in the Johnie Boy and Sedan shots was ona
rather limited basis. Johnie Boy was a low-yield burst 23 in. below the
surface of basaltic
material in Area 18 at NTS. Forty-four fallout
samples from the area out to about 1, miles from ground zero and
two cloud samples were studied radiochemically. All of these were
analyzed for Sr, Sr, *!y, and ®Zr, and about one-third of them were
analyzed for the long list of nuclides previously given for the Small
Boy samples.
*As distinguished from cloud and air-filter samples.