“REGULATION OF ARMAMENTS 95.

ized by the international agency. The plan, to the extent that it has been
worked out in the various reports of the United Nations Atomic
Energy Commission, does not specifically consider the questions of
when or how stocks of fissionable material would be turned over to the.
international agency or what safeguards would apply to prevent or
detect the withholding of fissionable material, although it does deal
with safeguards against diversion of fissionable material after the
plan has gone into effect. Presumably, the transfer of fissionable ma-:
terial to the international agency was left to be considered under the
subject of “stages” of transition in putting the plan into operation.

Whether there exist safeguards against withholding of fissionable
material is a crucial matter for any control plan, as indicated in your
letter. One approach to this problem is to inquire whether methods are
available for the determination of the total past output of facilities
for the production of fissionable material, ,

With regard to reactors, waste material in the form of radioactive
fission products must necessarily be produced in the fuel elements
and must be disposed of after extraction of the fissionable material.:
These fission products would be subject to control by the international
agency because of their possible use in radiological warfare. In this
country, the fission products are stored in large underground tanks
and it would be possible by sampling and analyzing their contents
and estimating their volume, to get some idea of the amount of plu-
tonium produced to date and the time when production began. Repre-
sentative samples and accurate results might be difficult to obtain in
this way. In the case of the USSR, if the purpose were to deceive the
international agency, the liquid wastes containing fission products
might be allowed to run off into the ground without regard to health
hazards or, with considerable effort, might be reduced in bulk and
scattered, hid, or altered in such a way that significant measurements
could not be made, Some of the fission products are gases and escape -
into the atmosphere during chemical processing of the reactor fuel
elements, . . . Methods of sampling and analyzing the atmosphere
are being investigated.

In addition to the fission products, radioactive materials are formed
in the moderator, shielding, and structural elements of reactors. Some.
of those are so short-lived that they could not be used to obtain —
: information | on the past history of the reactor, but there are others
which may be suitable for that purpose. Where graphite is used as a
moderator as at Hanford, carbon-14 with a half-life of 5000 years is’
produced by absorption of neutrons in ordinary carbon. Measurement

of the specific activity of. samples of graphite taken from various
positions i in the reactor would ‘give ¢ an indication of the total number