ratio, the current value will be maintained at 1.0 Sunshine Unit if the
environment allows strontium-90 to be incorporated at the same rate which
provided the current 1.0 Sunshine Unit.
If the amount of strontium-90
available decreases with time, then as a child grows it will lay dow
relatively more calcium than strontium-90, and the Sunshine Unit value
borne by the child will decrease.
Thus the uncertainty relative to
the continued availability for uptake of the strontium-90 created in
past detonations but not yet deposited is still an unsettled problem.
Evaluation of the SUNSHINE Model Hazard Calculations.
The
Sunshine model listed six parameters necessary for assessing the
strontium-90 hazard on a world-wide scale.
Since the time this model
was constructed, additional data have been collected so that it is
worth while to re-examine these factors in the light of more recent
knowledge.
thatdistribution
ofstrontium-90, requires drastic correction.
tion is as follows:
1.
In summary, the situa-
:
50-90% of gross fission product fall-out is accounted for
locally for land surface bursts.
of 60% appears reasonable.
For purposes of calculation, a figure
It will be recalled that the SUNSHINE model
assumed @ high air burst, which would involve a negligible local deposition of fall-out.
2.
Less than 2% of the gross fission products created in
detonations to date have been accounted for in world-wide fall-out.
3.
One-third of the expected amount of strontium-90 on the
basis of uniform distribution relative to other fission products was
observed 80 miles downwind after the first CASTLE shot.
4.
The world-wide gummed peper fall-out collections by the
Atomic Energy Commission are, on the average, three times enriched in
strontium-90 over the content in a normal gross sample of fission
products.
5.
A British calculation estimates 20 MI of gross fission
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