health and safety laboratory - Digital Collections

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For many years, gummed film sampling comprised the only widespread
m network for measuring fallout. This technique fulfilled its original pur-
, poses of delineating the geographic distribution, of fallout and indicating
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the time of arrival of radioactive material. While the test pattern remained
simple and included only fission devices, it was also possible to
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estimate individual long-lived nuclides such as Sr© and to estimate the
.fallout infinity gamma dose.
More complex test patterns and delayed fallout from thermonuclear
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devices made the Sr© and gamma dose estimates very difficult. Despite the
complexities, considerable effort has been devoted to testing various math
ematical models to allow computation of these two parameters arid thus to
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extract the utmost from the available data.
This report describes the model
adopted and gives the results of these computations in some detail.
In ad
^ had reported activity of unloiovm origin in paperboard in 1945* The Health
and Safety Laboratory was subsequently given the responsibility of deter
mining the relative fallout at distances beyond 200 miles from the Nevada
test site.
Later this responsibility was modified to delineating world-wide
fallout from the megaton weapons fired in the Pacific and elsewhere.
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dition, comparisons have been made with more direct measurements of
fallout where these are available.
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The data indicate that useful information on Sr©
obtained by the gummed film technique.
confirmed, but are the best available for any network.
Historical
deposition has .been
The gamma dose estimates cannot be
The first detection of radioactive fallout away from the site of the
explosion was in Rochester,, New Tori, in i?ebruary of 1951., although Webb
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