milliliter. It is difficult to give a precise evaluation to these data
since the activity was a result of fallout from more than one detonation
and thus was representative of mixedfission products of different ages.
Prior to Hardtack-Phase if all the measurements of activity in water
supplies (including Reed, Nev.) were’ less than 1x J077 microcuries
per milliliter. The major portion of the highest activity measured
resulted from fallout produced during the fall 1958 tests.
Since this activity was the result of relatively fresh fission products
containing short-lived isotopes, the water was deemed safe for consumption for a hfetime.
Fe 9
'h
Cril Effects Test Operations
During Operation Hardtack, Phase IZ, conducted at the Nevada
Test Site, Civil Effects Test Operations were divided into two major
groups. Under the Cirl Effects Test Group (CETG) there were three
programs.
The first program continued enginecring studies on the effects of
blast on structures and measurements of radiation attenuation.
Existing structures were tested and actual performance data were
provided for design and construction of future structures.
Under the second program, aerial monitoring was used for measuring radioactive contamination around the site. Pre-series and postseries fallout data were collected to provide ® base line for measuring
contamination that might result should any other tests be held in the
future.
The third program conducted by Oak Ridge National Laboratory
continued measurements of the angulardistribution of prompt gamma
and neutron radiation and tested the shielding characteristics of light
frame houses. Seven houses were constructed and used in three
Shots. These data are expected to advance the combined Oak Ridge
National Laboratary-Atomic Bomb Casualty Commission program
for determining dose to populations exposed to atomic detonations.®
Underthe Office of Civil and Defense Mobilization—formerlyFederal
Civil Defense Administration and the Office of Defense Mobilization—
there were five projects: (a) testing pre-production models of anairborne radiation detector for civil defense developed by the Com-
Mission’s Health and Safety Laboratory; (6) obtaining data on effect
of blast on civil defenSe, shelters; (c) re-testing anti-blast valves
tested during Operation Plumdbod; (d) obtaining data on attenuation
of radiation by Nevada,soil; and (e) air blast phenomena in tunnels.
re
"See pp. 235-286, Twenty-third Sumlannual Report to Cuneress (July-December 1957).
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197
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JULY-DECEMBER 1958