SBBRRSEE ho
72
RADIATION STANDARDS,
INCLUDING FALLOUT
Dr. Macuta. I would like to discuss with you three aspects: First,
the inventory of strontium 90 in the stratosphere and on the ground
before the Russians started their testing in 1961 and thelittle infor-
mation available concerning the Soviet 1961 test inventory; second,
the geographical and seasonal variation of the stratospheric fallout
on the ground; andfinally, a discussion of predictions of fallout from
areas of injection into the stratosphere which may be of current
interest.
Wewill start. with the first placard. The inventory as of May 1961,
SODSE DS sy
the last available one preceding September 1961, shows that the
Northern and Southern Hemisphere stratosphere and the troposphere
contained approximately 1 megacurie of strontium 90. The megacurie
is a unit which was not. introduced yesterday. Megacurie stands for
millions of curies. The large numbers result from radioactivity in
the entire atmosphere or deposition over the entire world. When we
deal with fallout in a specific area, we revert to the units of millicuries.
Onecan notice on thefirst placard that as of May 1961, about 4.2
megacuries of a total of 5.2 had already been deposited. This amounts
to 80 percent of that which was injected into the atmosphere still
available for worldwidefallout.
Mr. Ramey. How does that correspond to the amount of fission
products in the atmosphere?
Dr, Macuta. Thetotal fission products in the atmosphere? One
would have to go through an elaborate calculation in order to find
the fraction of the various lived activities as of this date. Most of
the shorter lived activities naturally have decayed away. So the bulk
of the activity will be in half-lives of greater than 1 or 2 years as
of this date.
Mr. Ramey. But as of the time of our last hearings, there was approximately 50 megatons of fission yield, or something like that?
_ Dr. Macura. Yes. Let me explain the fact that one megacurie of
stronium 90 corresponds to 10 megatonsof fission yield.
Mr. Ramey. That is what I was trying to getat.
Dr. Macuta. The total number of megatonsof fission yield which
have been detonated prior to the resumption of nuclear tests in 1961
was approximately 92 megatons or 9.2 megacuries of strontium 90.
The worldwide contribution appears to be 5.2 as of May 1961.
Representative Prick. When you say “total amount,” you include
all?
Dr. Macnra. Yes, sir.
Representative Price. United States, U.S.S.R., and even the
French ?
Dr. Macuta. Thatis correct.
Chairman Hou.trterp. Is it possible for us to put the amount of
radioactive material represented by a millionth of a curie in perspective to the amount of radiation in terms of curies which are used in
the laboratory experiments on mice in order to obtain observable or
detectable mutations in the genetic field or somatic damage in the
mouse that is being experimented upon? I knowthis is not in your
field. I know you are a meteorologist. But, in order to be meaningful to the layman, I think they have to recognize what we are talking
about when we are talking about a one-millionth of a curie and when
we talk about forty-five millionths of a curie.
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