The concentration of ginc in sea water is 7 X 10-8 gr/al.
Therefore, one mole of neutrons would yield 2.12 me of zn65,
0.58 curies of zr69m and 3.07 curies of 2n69 at zero time.
If the Zinc-65 is distributed in the water at a concentration
of 1 dfa/liter to a depth of 100 mters, then approximately
5 square miles would be contaminated per megaton of fission
yield. In these calculations the effect of resonance levels
has not been considered. This might increase the total activity
and the area contaminated.
Free neutrons will be produced in the fusion reaction and there-
. fore, there will be a proportionate increase in radionuclides
from this source. Under some conditions other nuclides might
be produced from higher order reactions involving protons, alpha
and (n, 2n) reactions.
.
It is interesting to note that cobalt-—60 is produced in sea water
also. The concentration is about 2/5 that of sinc~65. Therefore
it should be readily found associated with the zinc. Since the
chemistry and radiation of these two nuclides are similar, the
cobalt has not been detected. However, experiments are in progress to sepurate and identify it.
Since Zinc-65 may be produced in copper and gine in the test
device by (p, n) and (n,¥) reactions, it should be found in
fallout at least within the immediate area.
However, we have
not found zinc-65 in fallout, and Donaldson did not find it in
Rongelap or Kabelle soils, vegetation or rats. This nuclide has
been found by the Japanese, Donaldson and NYOO in fish only.
This evidence strongly points to the production of ginc-65 by
direct irradiation of sea water, but does not eliminate entirely,
the irradiation of zinc and copper metals in the test device.
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