248
SESSION I DISCUSSION
kilometers of air, I was wondering whether or not the natural aerosol
concentrations in these large volumes would be sufficient to add anything appreciable to the weight of the debris and tend to produce this
effect.
~
BENSON: I don’t think so. A high-energy thermonuclear device is
a fairly heavy weapon, and, at these fairly high altitudes, the natural
aerosol is small. The contribution of dust raised from the groundis
insignificant. Therefore the total mass engulfed at high altitudes would
be rather small.
I think the main reason, however, for this peculiarity les in the
fact that we are talking about large particles, in the neighborhood of
5 to 15u. With respect to the radiochemical analysis of these particles,
one of the facts we did not bring out in the paper was that the volatile
constituents had yields of less than the independent fission yield.
Values of barium were found, for example, which were 0.003 of what
they should have been in relation to what the zirconium was. This
implies that at the temperatures at which particles of this type are
formed (roughly the boiling point of aluminum oxide, which is rather
high)
elements
like
rubidium
and barium are volatile. The first
member of the *Zr fission chain is rubidium. think the effect is
caused by a volatilization of the early precursors within the fission-
product chains. Although we think of the refractory fission products
as being distributed evenly throughout the mass of the weapon, this
does not appear to be true. When we are talking about large particles,
the fission products are all potentially being reduced rather than
being enriched or evenly distributed throughout the volatilized mass.
FOOTE: I would like to know the approximate costof Dr. Nielsen’s
spectrometer.
,
NIELSEN: It cost us
than $50,000 today.
about $70,000. It can be obtained for less
BENSON: While we are talking about costs, I would like to ask
Mr. Foote how he gets the $0.15 per analysis that he mentioned.
FOOTE: That is the total cost of readin and readout.
MILLER(C, E., Jr.): I would like to point out that we have in
progress a program on the fractionation of fission products as part of
the Nuclear Safety Program at Oak Ridge National Laboratory. It is
sponsored by the AEC’s Division of Reactor Development and Tech-
nology rather than the Division of Biology and Medicine andis, therefore, not being reported here. However, I do feel that the work is
pertinent to the fallout program. We are interested in amounts of
fission products contained in transported materials in a reactor accident and in any information «> can extract concerning the mecha-