-u.
sampling of water at various depths, making tows to gather plankton -- the tiny marine organisms which tend to concentrate radioactive materials in their tissues -- and catching of fish for
analysis for radioactivity.
In addition to these investigations, land and marine
biological surveys again will be conducted at Eniwetok and Bikini
and other pntolls nearby.
Samples of water and of plants and
animals living in the lagoons and on the reefs and islands of
the atolls will be collected and analyzed for radioactivity.
Fallout Monitoring in United States
The heavier particles fall out of the radioactive cloud
at early times after a detonation, while their radioactivity is
still high.
Therefore,
the highest levels of radioactivity occur
over a local area downwind from the point of detonation,
The area
of significant fallout is expected to occur entirely within the
uninhabited danger area surrounding the Eniwetok Proving Ground.
As the radioactive cloud is transported away from the
point of detonation, it is widely dispersed by air currents and
diluted by normal air.
Its radioactivity also decreases rapidly
because of the normal process of radioactive decay.* By the time
the cloud from a detonation in the Eniwetok Proving Ground has
traveled across a vast expanse of ocean, it will have become
thoroughly dispersed into the air and will have lost most or its
Original radioactivity.
As a result,
the exposures to radioactivity in the
United States from the Eniwetok tests are expected to be low.
Although levels of many times the normal background may be reached
in some localities, these increases will be temporary and will
not greatly increase the total exposure to radiation.
Average
exposures of residents of the United States to radiation from
weapons tests during the past five years has been much less than
the average exposure to radiation from natural sources during the
same period,
Outside of the Pacific area monitoring and sampling
activities will be conducted in cooperation with the U. S.
Weather Bureau, the U. S. Public Health Service, and at Atomic
*Radloactive fallout consists of a mixture of radioisotopes, with
varying half-lives.
The mixture as a whole decreases in radioactivity in such a way that for every seven fold increase in age,
the total radioactivity is decreased 10-fold.
Thus, the radioactivity at seven hours after H+1 hour is only one-tenth that at
H +1 hour, and in 49 hours is one-hundredth, etc.
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