fraction was higher than thet of the ionic fraction so that the average
energy for the solid fraction was higher than for the Shot 1 samples,,
The absorption curve of the colloidal fraction was again the highest of
the three resulting in a highest average energy for the colloidal frace
tions.
Gamma spectra were taken of samples for Shots 2,3, and 4, but
because of low resolution and other limitations, it was not possible to
use the gamma-spectra to obtain important information about the constitue
ents of the physical state fractions,
In general, the spectra only support what was already obvious,
suoh as the fact that Np239, which was the most important single contributor to the activity in the time range 2 to 10 days, became less
important at later times,
Figure 3.8 is a gamma analyzer plot for pure neptinium separated
after detonation,
from the fallout sample 3-251.02. It was taken 7 days
In the range 0 to 0.7 Mev, it shows the reported Np 9 peaks at 0.065,
0.105,
0.230,
and 0.295 Mev.
Figures 3.9 through 3.11 are gamma analyzer spectra (low energy
region) for the physical state fraction of the same sample at the same
time. The solid fraction spectrum, which contained 94 per cent of. the
activity was a fair reprodustion of the neptunium spectrum with an additional peak at 0.51 Mev due to an unknown constituent. The ultrafiltrate fraction, however, did not reproduce the neptunium spectrum; the
spectrum had peaks at 0.14, 0.39, and 0.49 Mev.
The peaks at about 0,5
Mev are undoubtedly due largely to annihilation gammas, indicating the
presence of gamma radiation with energies greater than 1 Mev. The colloidal fraction spectrum appeared to contain portions of the neptunim
spectrum, as well as peaks found in the other fractions. Spectra of
fractions taken at other times show other peaks, but it was not possible
to identify these in the absence of other information about important
species present,
3.2.2.4
Quantitative Analysis of Physica] State Fractions
The concentration analysis of the solid and ionic fractions
(as separated in the field) is given in Table 3.9. Aliquots of the solid
and the ionic fractions of samples 2-Ad, 3-Coca TC, 3251.02 and 4=¥39
were returned to the laboratory as liquids (the solid fraction had been
dissolved in HCl and made up to 100 ml). The concentrations are given
in micrograms per milliliter (ppm). The colloidal fraction was not
returned fér analysis because it was used in its entirety as a counting
sample and because of the difficulty of recovering the small quantities
from the ultrefilter membrane. There were no visible-deposits on the
membrane.
Table 3.10 gives the mass in milligrams of each element in the
liquid and solid fractions of the total sample recovered in the field.
It also gives the total mass of each element in the total original senple as well ac the percentage distributionofeach element between the
liquid and the solid fractions.
For sample 2-44, the liquid fraction
data are taken as the average of the supernatant and ultrafilter data.
For the other samples the ultrafiltrate represents the liquid; supernatant
was not returned for analysis.
48