The Acheson-Lilienthal Report


"Safe" and "Dangerous" Activities

It is true that the internationalization of activities intrinsically dangerous to security reduces the hazards in the way of security and does bring into more manageable form the problems of enforcement and the suppression of atomic weapons. If it were necessary, in such a scheme of safeguards, to vest in an international agency a total monopoly as to all aspects of atomic energy, disadvantages would arise so great as conceivably to make the prospect of effective internationalization itself beyond realization. Such an overall grant of exclusive right to develop, operate, and utilize, conferred upon an international agency, would change many of the industrial and economic practices of this country, for example, and would change them quite disadvantageously.

Such a complete international monopoly would be hard to live under. Its restrictive limitations would chafe, and might in time cause serious loss of support to the security purposes that lay behind the proposal itself. Many of the considerations of complexity, irritation, the engendering of suspicion, the encouragement of deceit that we found militated against a system of safeguards based upon national operation and international inspection would to a lesser degree be repeated by such an all out proposal for centralization.

This problem need not arise. For there are important areas in the field of atomic energy where there is no need for an international monopoly, and where work may and should be open not exclusively to the international organization, but to private and to national institutions in a quite free manner. These fields are among those of the greatest immediate promise for the beneficial exploitation of atomic energy. They are technically complex and closely related to the central scientific problems. That open and, in some respects, competitive activity is possible in much of the field should go a long way toward insuring contact between the experts of the international organization and those outside it, in industry and in scientific and educational organizations. The same fact should help correct any tendencies that might otherwise develop toward bureaucratic inbreeding and over-centralization, and aid in providing healthy, expanding national and private developments in atomic energy.

The technical facts which underlie the possibility of regarding many developments in the field of atomic energy as safe for national and private exploitation are in themselves rather complex; to the discussion of these we must now turn. These are, of course, activities which without reliance on the conscious determination of the operators, and with a minimum of control and supervision, are physically incapable of contributing to the making of atomic weapons.

A word may be in order about our views on what constitute "dangerous activities"--those that, in our opinion, ought to be subject to an international monopoly. It will be appreciated at the outset that this distinction between the "safe" and the " dangerous" can be useful without being completely sharp or fixed for all time. In our view, any activity is dangerous which offers a solution either in the actual fact of its physical installation, or by subtle alterations thereof, to one of the three major problems of making atomic weapons:

  1. The provision of raw materials,
  2. The production in suitable quality and quantity of the fissionable materials plutonium and U 235, and
  3. The use of these materials for the making of atomic weapons.

Thus we regard the mining and processing of uranium as a dangerous activity even though it must be supplemented by plants and ordnance establishments if atomic weapons are to result. We regard the facilities for making atomic weapons as dangerous even though some control be exercised over the provision of the fissionable material; and we regard the operation of reactors or separation plants which make the material for bombs or which, by relatively minor operational changes, could make the material for bombs, as dangerous even though they in turn would have to be supplemented by supplies of raw material and by installations for assembling atomic weapons.

We need not regard as dangerous either amounts of material which are small in relation to those needed to make a weapon or installation whose rate of production is small in these terms. A further point which will prove important in establishing the criteria for the safety or danger of an operation is this: U 235 and plutonium can be denatured; such denatured materials do not readily lend themselves to the making of atomic explosives, but they can still be used with no essential loss of effcetiveness for the peaceful applications of atomic energy. They can be used in reactors for the generation of power or in reactors useful in research and in the production of radioactive tracers. It is important to understand the sense in which denaturing renders material safer. In the first place, it will make the material unusable by any methods we now know for effective atomic explosives unless steps are taken to remove the denaturants. In the second place, the development of more ingenious methods in the field of atomic explosives which make this material effectively useable is not only dubious, but is certainly not possible without a very major scientific and technical effort.

It is possible, both for U 235 and for plutonium, to remove the denaturant, but doing so calls for rather complex installations which, though not of the scale of those at Oak Ridge or Hanford, nevertheless will require a large effort and, above all, scientific and engineering skill of an appreciable order for their development. It is not without importance to bear in mind that, although as the art now stands denatured materials are unsuitable for bomb manufacture, developments which do not appear to be in principle impossible might alter the situation. This is a good example of the need for constant reconsideration of the dividing line between what is safe and what is dangerous.

We would, however, propose as criterion that installations using material both denatured and insufficient in quantity for the manufacture of bombs could be regarded as safe, provided the installations did not themselves make large quantities of suitable material. With some safeguards in the form of supervision, installations in which the amounts of material are small, or in which the material is denatured, might also be regarded as safe; but installations using or making large amounts of material not denatured, or not necessarily denatured, we would call dangerous.

Let us see now what we regard as safe activities in this field.

(1) Perhaps the clearest case is the application of radioactive material as tracers in scientific, medical, and technological studies. This is a field in which progress may be expected to be very rapid, and we can see no reason at all for limiting, on grounds of safety, the activities using such tracer materials.

(2) It is easy to design small nuclear reactors which use denatured U 235 or plutonium. These reactors can be operated at a power level low enough to be incapable of producing dangerous quantities of fissionable materials but high enough to provide neutron sources and gamma ray sources of unparalleled intensity. The material in these reactors is neither in quantity nor in quality significant for bomb production; even if one combined the material from many, no practical method of making weapons would be available. On the other hand, reactors of this kind can and almost inevitably will be designed to operate at so low a power level that they cannot be used to produce quantities of fissionable material which are of military significance. Reactors of this general kind have the following important applications:

(a) They may be used to make radioactive materials, and as such may be a supplement, and a valuable supplement, to the more dangerous reactors operating at higher power levels;

in particular, they can make useful radioactive materials that last too short a time to permit them to be provided from remote plants.

(b) As a source of radiation, primarily of neutron radiation, such reactors are research tools for physics, for chemistry, and for biology. This may, in fact, be one of the most important applications of the release of atomic energy.

(c) The high intensity of radiation from such reactors will bring about changes in chemical and biological systems which may be of immense practical value, once they have been understood.

(3) More marginal from the standpoint of safety, but nevertheless important, is another case of an operation which we would regard as safe. This is the development of power from the fission of denatured U 235 and plutonium in high power level reactors. Such power reactors might operate in the range from 100,000 to 1,000,000 kw. If these fissionable materials are used in installations where there is no additional uranium or thorium, they will not produce further fissionable material. The operation of the reactors will use up the material. If the reactors are suitably designed, a minimum of supervision should make it possible to prevent the substitution of uranium and thorium for the inert structure of the materials of the reactors. In order to convert the material invested in such reactors to atomic weapons, it would be necessary to close down the reactor; to decontaminate the fissionable material of its radioactive fission products; to separate it, in what is a fairly major technical undertaking, from its denaturant; and to establish plants for making atomic weapons. In view of the limited amount of material needed for such a power reactor, and of the spectacular character and difficulty of the steps necessary to divert it, we would regard such power reactors as safe provided there were a minimum of reasonable supervision of their design, construction, and operation. If the material from one such reactor (of a size of practical interest for power production) were diverted, it might be a matter of some two or three years before it could be used to make a small number of atomic weapons.

We attach some importance to reactors of this type because they make it possible in large measure to open up the field of atomic power production to private or national enterprise. It is; in this connection, important to note that the materials required to construct these reactors cannot themselves be produced in installations which we could regard as safe. It is, furthermore, important to note that for every kilowatt generated in safe reactors, about 1 kilowatt must be generated in dangerous ones in which the material was manufactured. Thus if atomic power is in fact developed on a large scale, about half of it will inevitably be an international monopoly, and about a half might be available for competitive exploitation. That is to say, the primary production plants necessary to produce the materials required to construct safe power plants will in that process of production produce large amounts of power as a by-product. It is, furthermore, clear that the stockpiling of appreciable quantities of fissionable material suitably denatured, must precede the development of these safe power reactors. We think it fortunate that the actual operation of such reactors will have to await the production of these essential materials, so that there will be time for further study of means by which they may be supervised and their safety insured.

All the above illustrations show that a great part of the field of atomic energy can be opened with relative safety to competitive activity. They also show that the safe operations are possible only because dangerous ones are being carried out concurrently. It is not possible to devise an atomic energy program in which safeguards independent of the motivation of the operators preclude the manufacture of material for atomic weapons. But it is possible, once such operations are undertaken on an international basis, to devise others of great value and of living interest in which safety is no longer dependent on the motivation of the operators.

We have enumerated elements of the large field of non-dangerous activities under (1), (2), and (3) above. Among the activities which we would at the present time classify as those dangerous for national exploitation are the following:

(4) Prospecting, mining, and refining of uranium, and, to a lesser extent, thorium.

(5) The enrichment of the isotope 235 by any methods now known to us.

(6) The operation of the various types of reactors for making plutonium, and of separation plants for extracting the plutonium.

(7) Research and development in atomic explosives.

Of these activities, (6), as have indicated, not only plays an essential part in providing active materials, but involves installations capable of generating power.

It should be added in conclusion that to exclude even safe activities from international operation seems unwise, but these should not be an international monopoly. It would equally be unwise to exclude from knowledge and participation in the dangerous activities experts who are not associated with the international authority. As the next section will show, there are practical means for making this collaboration possible in such a way that security will be promoted rather than impaired. Only a constant reexamination of what is sure to be a rapidly changing technical situation will give us confidence that the line between what is dangerous and what is safe has bees correctly drawn; it will not stay fixed. No international agency of control that is not qualified to make this reexamination can deserve confidence.

  1. If nations or their citizens carry on intrinsically dangerous activities it seems to us that the chances for safeguarding the future are hopeless.
  2. If an international agency is given responsibility for the dangerous activities, leaving the non-dangerous open to nations and their citizens and if the international agency is given and carries forward affirmative development responsibility, furthering among other things the beneficial uses of atomic energy and enabling itself to comprehend and therefore detect the misuse of atomic energy, there is good prospect of security.

* This panel included A. H. Compton, E. Fermi, E. O. Lawrence, and J. R. Oppenheimer. Their report was prepared in consultation with S. K. Allison, Zay Jeffries, C. C. Lauretsen, I. I. Rabi, C. A. Thomas, H. C. Urey, and with the further help of numerous specialists.

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