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 duction and use of nuclear fuels. It is to be expected that, in a peaceful state of the world, such activities will be carried on for beneficial purposes. Most of these same activities are also involved in the production of atomic weapons. Each of them involves an element of danger, since attempts may be made to divert materials or to seize materials or installations with the aim of using them for the production of atomic weapons. In the following discussion, the words "danger" and "dangerous" will always be used with this connotation. In this chapter we propose to analyze the relative importance of these dangers and to explore to some extent the problem of possible safeguards against them. As regards diversion it may be observed generally that the later the stage at which diversion occurs, the more immediate is the danger arising from it because fewer subsequent operations, less time, and fewer plants are then necessary to produce weapons. It should also be observed that attempts to divert materials at certain stages might be so planned as to take advantage of the fact that losses in processing are normal in metallurgical and chemical operations. The ease of diversion and the nature of necessary safeguards vary from stage to stage, and each will be considered in turn. It must be stressed, however, that all of the operations are interrelated, and the effectiveness of safeguards at any one stage depends in large measure on the safeguards erected at other stages. In addition to diversion there is the possibility of seizure either of the fuel materials themselves or of the facilities for producing them. This will be dealt with in the final section of the chapter. Uranium and thorium are, as far as can be foreseen, the only naturally occurring substances from which nuclear fuel in significant quantities can be produced. Hence, these substances play a fundamental and unique role in the control of atomic energy. Mining Operations Uranium and thorium are obtained from ores and deposits. It is clear that, unless appropriate safeguards are taken ensuring that material cannot be diverted from the mining operations, attempts may be made to use it for weapons. The consequences of diversion at this stage will not immediately be serious since it would require considerable time and industrial activity-how much precisely would depend on the facilities available-before weapons could be produced by clandestine operations. In considering safeguards over mining operations, the following circumstances will be helpful. The mining operations, al though widely different for the rich deposits and for the low grade deposits, would always be on a significant scale; they take place along conventional lines and involve the handling of large quantities of ore, concentrates, and tailings. It would hence appear feasible to keep track of the distribution of any significant quantities of material from the mines. A special significance must be attached to the devising of adequate safeguards against the diversion of raw materials, since none of the subsequent operations can proceed without uranium, or uranium and thorium. Extraction From Ore-Concentrates and Production of Uranium and Thorium Compounds Extraction and production of uranium and thorium compounds involve somewhat less bulk of material than has been considered in the previous section and may take place in plants far removed from the mines, as is the case in Canada. The processes involved are carried out in chemical plants of ordinary size and the products are still somewhat bulky. The processes normally involve losses comparable with those in other industrial chemical activities. These provide an opportunity to conceal diversion by making it appear that only process losses have occurred. Therefore, only the application of very close and careful safeguards would provide an adequate assurance against the diversion from those plants of purified chemical compounds of natural uranium or thorium for the surreptitious production of explosive material for atomic weapons. Production of Metal and Preparation for Insertion in Reactors Preparation of the metal from the uranium or thorium compounds also involves process losses which may be used to conceal diversion of material. The quantities of materials handled are less and the difficulties in detecting diversion are greater than those in the chemical plants discussed in the previous section. There is also the possibility of diversion during the machining and the mechanical preparation of the metal for its insertion in atomic reactors. Just as in the previous case, very careful safeguards will be needed to prevent the danger resulting from such diversion. Production of Nuclear Fuels Production of nuclear fuels is the crucial stage in the operations. Both separation plants for the production of uranium enriched in U-235 and the reactors and extraction plants for the production of plutonium or U-233 deliver nuclear fuel, which, under proper conditions, may be used directly for the manufacture of atomic weapons. According to the published statements available to us. the installations necessary for weapon manufacture are relatively small and the time required is relatively short if the necessary high-skilled personnel is available and the procedure is known. If therefore the strictest safeguards are not taken to prevent the material in the installations producing nuclear fuel from being diverted, the danger is extremely serious. The technical nature of the processes involved in the production of nuclear fuels is different for the different types of plants concerned. Very large installations are required, together with highly skilled personnel and methods differing widely from usual industrial methods. The final nuclear fuel product is very small in bulk compared with the quantities of material which are processed. It is possible that even those managing such plants will not find it easy to keep track in a quantitative way of the flow of materials, in much the same way as is the case in usual industrial refinery and extraction plants. These technical facts should be borne in mind when devising the safeguards against diversion mentioned above. It is clear that such safeguards should not only reckon with the materials in the installations themselves, but also with the stocks of purified product. Remarks on Operation of Secondary Reactors Secondary reactors, i. e. reactors which are fed with nuclear fuel especially prepared from the products of separation plants or of primary reactors, can be designed in various ways, depending on their purpose. Secondary reactors for research and medical purposes would be of low power and could be designed so as to contain insignificant quantities of nuclear fuel. These would be unimportant as possible sources of diversion, unless present in large numbers. Secondary reactors for the production of electric power or industrial heating would be comparable in fuel consumption to primary reactors, i. e. the reactors which are fed with natural uranium. If they regenerated fuel, they would afford opportunities for diversion similar to those afforded by large primary reactors, and in order to avoid this serious danger, the same strict safeguards would be required for both. If the secondary reactors were designed so as not to regenerate fuel, safeguards would still be required in relation to the fuel supply and to the circumstance that, by redesign and rebuilding, the reactor might be converted to other purposes. 8 It has been suggested that secondary reactors for electric power or industrial heating, designed so as not to regenerate explosive material, might operate on "denatured" fuel." If so, and to the extent that this proves to be technically feasible and effective, diverted material would not be usable for weapons without further processing, involving large plants and appreciable time. Seizure of Installations We have been discussing the possibilities of clandestine diversion of materials from the peaceful activities in the domain of atomic energy, but we must not overlook that with certain systems of control one would have to consider the possibility that plants or materials might be seized. This implies a danger, the seriousness of which would be greatest in the case of seizure of stocks of concentrated nuclear fuel, because from that stage weapons could be produced most quickly and in relatively small plants. Next in order of seriousness would be the seizure of plants producing nuclear fuels. A wide geographical dispersal of stocks and plants and the restriction of stocks to minimum operating levels would reduce the risk that a large quantity would be involved in a single seizure. Seizures of mines or of facilities at other early stages would only be of advantage to those desiring to make weapons if they had at their disposal a plant capable of producing nuclear fuel. Chapter 4: Clandestine Activities Clandestine manufacture of atomic weapons from nuclear fuels diverted from stocks or from the plants producing such fuels would be extremely difficult to discover because the operations involved can be carried out in comparatively small installations which could easily be concealed. This emphasizes again the importance of preventing the diversion of nuclear fuels which we have stressed in the previous chapter. If it were sought to divert materials from earlier stages of production, or from undisclosed mines, into the production of atomic weapons, large and complicated installations would have to be clandestinely operated in order to produce the nuclear fuels. 8 See press release of United States Department of State, Apr. 9, 1946, and A Report on the International Control of Atomic Energy by the Lilienthal Board, sec. II, chap. 5, par. 10. See chap. I. |