Chapter 3
RESULTS AND DISCUSSION
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3.1 DISCUSSION AND INTERPRETATION OF THE DATA
Tt is noted that the achievement of Objectives 1,2, and 3 depended wholly or in part on the
proper functioning of the rocket samplers.. Because of their failure, there are no results to be
reported on the vertical and radial distribution of particies in the clouds, which was Objective
3.
However, Objectives 1 and 2 were partially met, and 4 was fully met by the aircraft samples.
Referring to the nuclides listed in Section 1.3.5, it is to be observed that a number of them
were included for the purpose of developing a general background of information on nuclide
fractionation.
Although this material could serve as the basis for a separate report, it is not
being considered here, because it was not a primary concern of Project 2.8.
Only the data
that has a bearing on the distribution of Sr™ and Cs‘*’ tn the fallout will be covered in this
chapter.
The radiochemical resuits for each of the different types of samples collected contri-
bute something to the overall evaluation.
3.1.1 Cloud Data. For the coincident samples from the light and variable wind layer, there
are two sets available for Shot Koa, five for Shot Walnut, and six for Shot Oak. The ratio of
total fissions, as calculated from the sample analytical data for Mo", Kr®® and Krare given
in Table 3.1. Also listed are the R-values for Sr™® and Cs'*" from the gross particulate samples collected from the cloud at the same time. The measured Sr™ and Cs'*’ R-values for the
devices are listed in Tables B.1, B.3, and B.5.
Subject to the assumptions inherent in the
method, which include among others that the ratio of Mo” to Kr*® in the sampled portion is
representative of the entire cloud, the ratio of Mo” fissions to Kr™ fissions gives directly that
fraction of the total Mo’ formed in the explosion which was left in the cloud at the time of sam-
pling (Appendix E). Multiplication of these ratios by the cloud R-values and division by the device R-values convert them to the fractions of the nuclides remaining in the clouds, e.g.,
( Mo”?
=z)
Kr™/ajoud
x R(Sr™)
cioud = fraction of Sr® remaining in cloud.
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RUST) device
The last step is necessary to correct for the difference in fission yields between device neutrons
and thermal neutrons (Section 1.2.1). The assumption is made here that the ratios of Mo’® to
Sr® and Cs‘5* are. constant throughout the cloud. The samples in the table are identified by
aircraft numbers, as in Appendix B to which reference should be made for further details.
The calculated fractions of Mo”, Sr™, and Cs*" in the cloud, based on the Kr®® fission prod-
uct ratios, are plotted-as a function of time in Figures 3.1 through 3.3. Kr*® was not determined
on the 27-hour samples from Walnut and Oak because of its low counting rate at that time.
The
points on the curves for these shots at 27 hours are based on the fission ratios of Mo" to Kr",
corrected by the ratio of Kr®® to Kr*® at 12 hours. On Koa the late-timefission ratio is extrap-
olated, and the Sr® and Cs!" fractions are calculated from R-values averaged from the partic-
ulate samples taken {n the main cloud on the same aircraft as the gas samples. The fractions
for Oak are also from averages, here in the light and variable stratum, whereas for Walnut
the stabilized condition shown in Figure 3.1 1s used. Sample 980L for Oak is not included
because of the poor sampling conditions.
The fractions of these nuclides remaining in the cloud after 1 day are given in Table 3.2.
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