operated in series. To discover such clandestine plants during their construction stages would require inspection of building activities and investigation of possible sources of diffusion membranes, pumps, seals, leak detectors, and any other special materials or equipment required. Once these plants were built, their discovery might be more difficult. However, there would be problems connected with the shipment of processed material between plants, and this might lead to detection. The difficulty of obtaining secretly a supply of uranium feed material would depend on the effectiveness of the controls of uranium applied at the mines, mills, refineries, and chemical processing plants.

Seizure

The seizure of a gaseous diffusion plant would represent a hazard if large amounts of uranium were available. In isotope separation plants, as in certain common industrial processes, there is some latitude of operation between quantity produced and enrichment of product. Even a plant intended for the production of considerable quantities of material of low concentration might, if it were seized, be used to produce lesser amounts at higher concentrations. It is therefore important that stocks of uranium be kept small and widely dispersed and that plants be designed to operate with the minimum inventories.

also the operating agency must be approached from the viewpoint that any operating agency consisting of nationals of any country might at any time act as a group to effect diversion.

The term operating agency is here used to denote the organization that manages and operates the plant; it may or may not own the plant. The term inspection agency is used to denote a force of technical experts which is on duty twenty-four hours a day and which may equal the operating force in number. It is assumed that this inspection force would have the authority and responsibility to know at all times what was going on in the plant. A further point for clarification is that the present remarks are based on present-day design of the gaseous diffusion plant. Conceivably, future plants might be designed in such a way as to change greatly the problems of inspection and management.

Due to the size and complexity of the present plant, the withdrawal of material by the operating agency could be done with extreme ease from any number of places by any number of methods with little risk of immediate detection by any inspection agency. Such withdrawal could be made by taking oversize samples, by storing up material in equipment which was subsequently taken out during maintenance procedures, by not immediately discovered secret withdrawal connections, or by other more or less obvious methods. Diversion of material could be concealed by an unreported improvement in the process, since recovery and operating efficiency of any process plant are continually being improved by the operating organization. Diversion could also be covered up by very minor falsifications of isotopic analyses used in calculating material balances. The detection by an inspection agency of such deliberate diversions by an operating agency would take months to accomplish, since the accuracy of a plant material balance depends on the statistical study of a large amount of data. The operator could explain such diversions by stating that any discrepancies that might show up in the material balance were due to material remaining on the inner metal surfaces of the plant.

Real inspection and control can be exercised only by the operating agency and even here absolute assurance rests on the loyalty of the members of such an organization.

Clandestine Plants

In the case of clandestine plants of the gaseous diffusion type, the possibilities of detection would depend to some extent on the size of the installation. The construction and operation of a plant of the size of the present one at Oak Ridge would be difficult to conceal. However, it is conceivable that such a plant might be broken up into a number of smaller plants, hidden at different locations and normally

operated in series. To discover such clandestine plants during their construction stages would require inspection of building activities and investigation of possible sources of diffusion membranes, pumps, seals leak detectors, and any other special materials or equipment required. Once these plants were built, their discovery might be more difficult. However, there would be problems connected with the shipment of processed material between plants, and this might lead to detection. The difficulty of obtaining secretly a supply of uranium feed material would depend on the effectiveness of the controls of uranium applied at the mines, mills, refineries, and chemical processing plants.

Seizure

The seizure of a gaseous diffusion plant would represent a hazard if large amounts of uranium were available. In isotope separation plants, as in certain common industrial processes, there is some latitude of operation between quantity produced and enrichment of product. Even a plant intended for the production of considerable quantities of material of low concentration might, if it were seized, be used to produce lesser amounts at higher concentrations. It is therefore important that stocks of uranium be kept small and widely dispersed and that plants be designed to operate with the minimum inventories.

6. Control of Primary Reactors and
Associated Chemical Plants

by Harry A. Winne

Mr. Winne is vice president in charge of engineering policy
of the General Electric Company and is in administrative
charge of the primary reactors of the Manhattan District
at Hanford. He was a member of the Lilienthal board of
consultants of the State Department which prepared "A
Report on the International Control of Atomic Energy."
During the war, he was closely associated with the develop-
ment of equipment and the production of material for the
Manhattan District.

Introduction

6

The primary reactor produces "nuclear fuel." The following quotations from the published report of the Scientific and Technical Committee of the United Nations Atomic Energy Commission emphasize the extreme importance of absolute and unquestioned control of this operation.

"Production of nuclear fuels is the crucial stage in the operations.

...

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. the installations necessary for weapon manufacture are relatively small and the time required is relatively short if the necessary highskilled 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."

"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."

It is obvious from the foregoing quotations that, in the operation of the primary reactor and the chemical processing of its products,

"A First Report on the Scientific and Technical Aspects of the Problem of Control," September 27, 1946.

we have a stage in the development of atomic energy which requires the maximum of control.

Diversion of Materials

I think it will be well to review briefly the various steps in the processing through such an installation and to point out some of the opportunities for diversion. In this connection, it is well to remember, in considering the problem of preventing diversion of material in atomic energy installations, that we are dealing with a situation quite different from any which has ever existed before, quite different from diversion in diamond mining, gold mining and refining, alcohol manufacture, or any other operation with which the world has had experience. In these latter types of operations, industries and states have been fairly successful in preventing individuals, or at most small groups of people, from circumventing systems of inspection and checking. In the field of atomic energy, the type of diversion we have to fear is that instigated and implemented by a national government, with all the resources, facilities, and skills which a government could bring to bear on such a project. Consequently, we must be prepared to cope with extraordinarily clever, bizarre, complex, and intricate schemes. A nation bent on circumventing a system of inspection or control might, in the construction of an installation, incorporate very elaborate provisions to facilitate diversion.

The important raw material for the primary reactor installation is pure metallic natural uranium, and possibly thorium, in some form such as ingots or bars or rods. This incoming material must be accounted for very precisely, and stocks of it must be inventoried meticulously at intervals frequent enough to detect any theft or diversion. There is the possibility that attempts might be made to remove some of the raw stock and substitute for it bars or rods of other material of similar appearance and weight. This would be difficult and is rather unlikely, but cannot be discounted entirely.

This raw material must then be put in proper form for insertion in the nuclear reactors or piles. This may involve melting and casting, and in any case it will be necessary to machine the material to produce pieces or "slugs" of exact size and shape. Consequently there will be metal shavings, turnings, dust, and floor sweepings, which must be accounted for strictly. To do this requires accurate weighing and accounting of the rough rods or bars brought into the machine shop, of the finished slugs, and of the waste. There will be some unavoidable loss here, and consequently possibility for diversion of a small percentage of the material processed. To keep this possibility to a minimum will require a thorough daily inventory of all material in process in the shop.