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UNITED STATES
ATOMIC ENERGY COMMISSION
Washington 25, D. C.
Tel.
ST 3-8000
Ext. 307
FOR RELEASE AT 9:30 A.M. (EST)
FRIDAY, APRIL 26, 1957
Remarks Prepared by Dr. Willard F. Libby, Commissioner
United States Atomic Energy Commission
For Delivery before the Spring Meeting of
The American Physical Society, Washington, D.C.
April 26, 1957
RADICACTIVE FALLOUT
I.
INTRODUCTION
The radioactivity preduced by the fission reaction
changes its characteristics continuously and rapidly following the explosion of an atomic weapon and the conditions of . _.
firing are of extreme importance in determining the rate of
~*
which the radicactivity descends to earth.
As a result there
are in general three different kinds of radioactive fallout,
the relative importance of which is determined by the nature
of the weapon, principally its yield, and the conditions of
firing. These three types are: First, the local fallout,
which is insignificant unless the fireballtouches Or comes
close to the zround, but which in case the fireball does
touch the ground can amount to a major fraction, in scme
instances as ™ th as &0 percent of the total debris.
This
pa
be
ra
tyve of fallouz consists of radioactivity which is carried
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