The International Control of Atomic Energy

Radioactive Isotopes

In addition to radiations, the operation of a reactor produces comparatively enormous quantities of radioactive materials, approximately a kilogram of fission products for each kilogram of nuclear fuel consumed. This material is equivalent in its effects to many thousand times the same amount of radium because of the more rapid rate at which many of its constituents disintegrate. Although the fission products consist of some thirty chemical elements of medium atomic weight, radioactive isotopes of most other elements can be produced as a result of neutron absorption. Since a great many neutrons exist inside and around an operating reactor, it is easy to use them in the preparation of substantial quantities of the desired isotopes. The availability of radioactive materials in adequate quantities should permit a renewed and very vigorous attack by tracer techniques on many research problems, notably in physiology, medicine, and the mechanism of chemical reactions. Some of the fission products may possibly replace radium in cancer treatment in the future. There is in addition the possibility of new techniques based on the selective localization in malignant tissues of chemical compounds containing radioactive elements.

Comparatively small reactors will usually be adequate, and in many cases most convenient, for applications requiring radiations and radioactive isotopes, although the latter may often be obtained as by-products from large reactors operated for other purposes.

Atomic Bomb

The atomic bomb constitutes a highly specialized type of reactor in which the principal design requirement is that as much as possible of the nuclear fuel in the bomb shall be consumed in the very short time before the bomb bursts apart. Clearly, highly concentrated fuels are required to permit the most rapid combustion. Such materials will explode spontaneously as soon as the quantity of material in a single piece becomes large enough that the neutrons are effectively confined and utilized. The detonation of the bomb is then a matter of bringing together rapidly two or more pieces of fuel material which together exceed this critical size. Little more information than this has been released about the construction of atomic bombs, except that the critical size was predicted in 1941, within very wide limits, as more than

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two and less than one hundred kilograms. In all probability, highly skilled personnel and specialized facilities are required for bomb production, but a large establishment does not appear to be

necessary.

Estimates of the Amount of Power or the Number of Bombs Available

An estimate of the total electric power, or alternatively, of the number of bombs, which might result from the utilization of the world's production of uranium can hardly be made with any reasonable accuracy. The present production of uranium, the amount of material required for a single bomb, and the fraction. of U-238 (or thorium) which can be utilized for power are all figures which are not available. However, the annual production of uranium in 1939 can be estimated at approximately one thousand tons (uranium content in ores) on the basis of data in the Engineering and Mining Journal for September 1945.

One might, as an example, assume that one thousand tons of uranium per year are available for the production of electric power. One thousand tons of natural uranium contain about seven thousand kilograms of U-235. This amount of U-235, used in power plants having an over-all efficiency of ten percent, could provide two million kilowatts of electric power for one year. If all of the uranium (and thorium) can be used, the amount of power available would be several hundred million kilowatts. In this connection, it may be of interest to quote a passage from the report of the Lilienthal Board: "We have examined in some detail the technical problems of making available heat and power on the scale of present world consumption from controlled nuclear reactors. We see no significant limitations on this development, either in the availability or in the cost of the fundamental active materials."

As an alternative example, if one were to assume that one thousand tons of natural uranium, containing approximately seven thousand kilograms of U-235, were available each year for the making of bombs, then using the limits on critical size given above as the amount of U-235 required for a bomb, the number of bombs which could be produced from all of the available uranium would be between 70 and 3,500 per year.

Report of the National Academy of Science, quoted in sec. 4.49 of “Atomic Energy for Military Purposes" by H. D. Smyth.

A Report on the International Control of Atomic Energy, sec. II, chap. 3, par. 10 Department of State publication 2498).

Summary

There are three neuclear fuels (U-235, Pu-239, and U-233) which can be used in a sustained chain reaction yielding enormous quantities of heat, radiations, and radioactive materials. The consumption of one kilogram per day of U-235 releases energy at the rate of approximately a million kilowatts, and produces nearly a kilogram of radioactive materials per day.

The large-scale production of electric power from atomic energy appears feasible, though still in the developmental stage.

The engineering design of a large-scale power plant will determine whether it requires concentrated nuclear fuels such as are used for bombs or can use dilute or denatured fuel unsuitable for bomb manufacture; also, whether or not further production of nuclear fuel (Pu-239 or U-233) accompanies power production.

Small installations for power production appear unlikely for several reasons, one of which is the thick shields required to provide protection from radiation.

The intense radiations and the substantial quantities of radioactive material available from a reactor may be expected to find important applications in medicine, industrial chemistry, and nuclear research. The availability of radioactive isotopes opens the way for the intensive use of tracer techniques in chemical, physiological, and medical research.

Comparatively small reactors will be adequate for most of these applications of radiations and radioactive isotopes.

The production of atomic bombs requires comparatively large quantities of concentrated nuclear fuels, and correspondingly large installations for the separation of U-235 or the production of Pu-239 or U-233. Bomb manufacture is a highly specialized, but hardly a large-scale, operation.

Examples based on published information suggest that raw materials are readily available for the production of from 70 to 3,500 bombs per year, or for the generation of electric power at a rate of two million kilowatts, and possibly many times this rate.

Chapter 3: Peaceful Uses of Atomic Energy and Their Bearing on Control

Introduction

In the foregoing chapters we have given a general description, based on published information which is limited but which we believe is reliable, of the various activities involved in the pro

two and less than one hundred kilograms. In all probability, highly skilled personnel and specialized facilities are required for bomb production, but a large establishment does not appear to be necessary.

Estimates of the Amount of Power or the Number of Bombs Available

An estimate of the total electric power, or alternatively, of the number of bombs, which might result from the utilization of the world's production of uranium can hardly be made with any reasonable accuracy. The present production of uranium, the amount of material required for a single bomb, and the fraction of U-238 (or thorium) which can be utilized for power are all figures which are not available. However, the annual production of uranium in 1939 can be estimated at approximately one thousand tons (uranium content in ores) on the basis of data in the Engineering and Mining Journal for September 1945.

One might, as an example, assume that one thousand tons of uranium per year are available for the production of electric power. One thousand tons of natural uranium contain about seven thousand kilograms of U-235. This amount of U-235, used in power plants having an over-all efficiency of ten percent, could provide two million kilowatts of electric power for one year. If all of the uranium (and thorium) can be used, the amount of power available would be several hundred million kilowatts. In this connection, it may be of interest to quote a passage from the report of the Lilienthal Board: "We have examined in some detail . . . the technical problems of making available heat and power on the scale of present world consumption from controlled nuclear reactors. We see no significant limitations on this development, either in the availability or in the cost of the fundamental active materials."

As an alternative example, if one were to assume that one thou sand tons of natural uranium, containing approximately seven thousand kilograms of U-235, were available each year for the making of bombs, then using the limits on critical size given above as the amount of U-235 required for a bomb, the number of bombs which could be produced from all of the available uranium would be between 70 and 3,500 per year.

"Report of the National Academy of Science, quoted in sec. 4.49 of "Atomic Energy for Military Purposes" by H. D. Smyth.

A Report on the International Control of Atomic Energy, sec. II, chap. 3. par. 10 [Department of State publication 24981.