Thermonuclear Reactions

THERE have been three historic developments during the short dozen years of our national atomic energy program. The A-bomb, of course, was one. We are just now attaining the second, the controlling of the A-bomb process by means of the fission reactor so as to yield power and peacetime products on a significant scale. The third was the success in making the H-bomb. Now we must consider a fourth step, which appears the next and best atomic bet--the mastering and controlling of thermonuclear, or fusion, reactions for man's benefit.

The process underlying this potential source of power and energy, however, must be distinguished from the fission chain reaction with which we have become familiar. Thermonuclear reactions produce energy through the combination of nuclei of appropriate light elements at the hydrogen end of the table of elements. If suitable light nuclei are weighed individually, and then fused together, the resulting weight of the fused nucleus is less than the original components. The difference in weight corresponds to an enormous conversion of matter into energy. However, accomplishing the fusion which releases this energy is most difficult, in part because nuclei are charged positively, and as the particles approach, their like positive charges repel each other. The nuclei must therefore be made to approach with the high energies necessary to overcome the repulsion, and for this purpose huge amounts of heat-energy are necessary. When fusion does occur, a great amount of energy is released, which can be utilized to help maintain the high energies of the material so as to contribute toward propagation of the reaction.

Heretofore the prospects for beneficent applications of atomic energy have been limited to the fission chain reaction. In the fission reaction, neutrons are used to bombard the nuclei of suitable heavy elements, such as uranium or plutonium. Because neutrons carry no electrical charge, they encounter no repulsion in approaching the nuclei. When fission occurs, energy is released, and the additional neutrons required for a self-sustaining chain reaction are also produced. A nuclear "reactor" therefore has two key functions. The first of these is to provide what scientists call a "neutron source." It is by means of neutron bombardment that radioisotopes useful in medicine, agriculture, industry and science can be created. So also entirely new materials can be made, just as uranium is transmuted into plutonium at Hanford. The second function of a reactor is to furnish a new and plentiful source of power. A nuclear reaction generates huge amounts of energy in the form of heat; for years we have looked forward to the time when this heat could be used economically to produce steam for the generation of electricity.

Fusion of the light elements, if controlled in a "thermonuclear reactor," would produce great quantities of neutrons and heat-energy, and the scale of production might be vastly beyond hopes which are confined to the fission reactor. The energy inherent in thermonuclear reactions is significantly greater than the fission chain reaction, just as an H-bomb is vastly more powerful than the A-bomb. Nor is there any theoretical limit to the amount of the fuel which might be "burned" in a thermonuclear reaction. The latter does not have a limiting "critical size," as does the fission chain reaction, beyond which the reaction would proceed out of control (i.e. explosively). Furthermore, thermonuclear materials appear more abundant and cheaper than the relatively expensive uranium and plutonium used in the fission chain reaction. Sir John Cockcroft, the eminent British expert, recently characterized the source of power which would be provided by light element fusion as "without limit."

An even more spectacular hope would be the direct production of power through controlled fusion reactions, a possibility raised a year ago by Senator Bourke Hickenlooper of the Joint Committee on Atomic Energy. Despite considerable improvement in our generating plants, the conversion of heat to steam and steam to electricity remains exceedingly wasteful. Efficiencies are on the order of 25-35 percent, and conversion losses are on the order of 65-75 percent. The direct generation of electricity would constitute a revolutionary advance in man's conquest of energy, because the steam cycle would be entirely bypassed.

Such prospects, if they can be realized, would presage a new competitor for our future source of power. At their most optimistic, they dwarf existing hopes for material benefit from atomic energy. By this means power might become available for the most ambitious of projects, even processing the waters of the oceans for their contents. The worth of our present achievements in atomic energy might then, from such a vantage point, be measured not in terms of what they now produce, but by the yardstick of what they contribute to helping achieve control of thermonuclear reactions.

II

How much work, if any, is the Atomic Energy Commission doing in this field? There is little clue. At no time has the Atomic Energy Commission referred in any way to beneficent thermonuclear possibilities or to the absence of them. Reports published by industrial participation groups studying atomic power are also strikingly silent on this subject. The realities of organizing and obtaining appropriations for major Federal projects suggest that if a substantial thermonuclear power program were under way, there would be a budgetary or other reference to it in the public domain. (The hydrogen bomb program, for example, was announced at the inception of active development in 1950. Quite recently the Air Force has confirmed interest in the development of an intercontinental ballistic missile.) Nor was any attention apparently accorded thermonuclear reactor possibilities during consideration of the Atomic Energy Act of 1954. While the record of inquiry into peacetime atomic uses was otherwise voluminous, only one reference to thermonuclear power appears in the hearings, and that reference was made by a public witness. The total silence emanating from the Commission and the relative silence of the law suggest that any such work is quite modest in scope.

There is some guidance, however, from other sources. As early as 1945 Dr. Hans Bethe, who had first explained the thermonuclear cycle of the sun's energy, told a Congressional Committee that light element reactions were of possible interest for the future development of atomic power, although the difficulties would undoubtedly be very great. His remark, made in passing, was unheard or unheeded. Seven years passed before the late Senator Brien McMahon, then Chairman of the Joint Committee on Atomic Energy, made the next square public reference to a hopeful prospect. In the last speech before his death, he held out the possibility of "important peacetime applications of hydrogen principles," and he noted also that this prospect might amount to a "basic change in the focus" of atomic energy control.

Later in 1952 the world's first full-scale hydrogen explosion, the "Mike" test at Eniwetok, in the Marshall Islands, fired the starter's gun of the thermonuclear age. As awesome reports of the bomb's power were carried on the first pages of our newspapers, Senator Bourke Hickenlooper of the Joint Committee on Atomic Energy announced "hope, in time" for peaceful and constructive applications of hydrogen energy. The Senator's statement was hailed in the Federation of American Scientists Newsletter as more startling to scientists outside the Atomic Energy Commission than accounts of the bomb. It was in comment upon this statement that Dr. George Gamow, who had been interested in thermonuclear energies since the 1920's, referred to "theoretically possible" techniques for "slowed-down" atomic reactions with hydrogen bomb materials.

Other encouraging comments have occurred recently. Among these is the passing but unmistakable reference made in February 1954 by Sterling Cole, then Chairman of the Joint Committee on Atomic Energy, to fateful consequences "for good as well as evil" from the fusion of nuclei. That April, Senator Hickenlooper reaffirmed his 1952 statement by noting "definite reason to hope that applications of new principles we are learning in the so-called fusion field can have great possibilities in the future for industrial and humanitarian uses." The Senator's reference to the possibility of generating power directly from thermonuclear reactions dates from a year ago, and Sir John Cockcroft's reference to thermonuclear power "without limit" was made last September.

Others have contended that such a development is impossible. Most of the contrary statements, however, occurred before and during the controversy over whether the hydrogen bomb should be built. Many who doubted the wisdom of proceeding with the hydrogen bomb expressed a one-dimensional moral view of thermonuclear work, arguing that it would be directed solely toward killing and destruction. The statements were made with surprising flatness; if it were true that thermonuclear reactions could have only destructive applications, the result would be unique in the history of science.

The technical difficulty of harnessing thermonuclear reactions represents a sounder basis for great pessimism. Every statement holding out hope has characterized any peacetime potential of the light elements as long range, or has in other ways underscored the magnitude of the scientific challenge. The difficulties of igniting a fusion reaction, and then of containing the extremely high temperatures which would be produced, are in all probability huge. Indeed, President Eisenhower in his April 7, 1954, press conference suggested that no direct application of the hydrogen bomb principle to peacetime power was known. The report of his statement is ambiguous; it probably is to be interpreted as saying merely that the H-bomb apparatus held no known promise for peacetime applications. Hopes for constructive uses, of course, might well not be limited to direct application (or any application) of the bomb principle. In any event, however, the President chose a comment which had a negative answer, and it was reported in the press as such.

III

Eventual success in harnessing the fusion reaction is not assured. Indeed, it could prove unattainable. Or, if attainable, fusion power might prove merely to be marginally competitive with other power sources. The statements on the subject suggest that technical prospects for controlling light element reactions approximate those for the hydrogen bomb in the mid-40's.

As against this, success would represent a "quantum jump" forward in nuclear technology. Nor can we easily gauge the difficulties before those difficulties have been subjected to prolonged attack. In the case of every major discovery since fire, the obstacles must have loomed dishearteningly large before solutions were found. How one assesses these difficulties may therefore reflect in large measure a deep-seated attitude toward discoveries in nuclear technology. Ultimately, in resolving supremely difficult questions of this nature, we perform an act of faith or, as has sometimes been the case, lack of faith.

Throughout the brief history of our atomic program, there have been the optimists and the pessimists. At the outset there was doubt about achieving the atom bomb; the Navy, to which development was first proposed in 1939, did not proceed to develop it because its representatives "weren't sure" of success. For more than a half decade after the Hiroshima bomb, it was taken for granted that both our bomb stockpile and our chances for atomic power would be severely limited by a scarcity of uranium ore. American pessimism concerning the early attainment of atomic power has contributed to the likelihood that the British will be the first to complete and operate a commercial-type atomic power plant. Only a few years ago doubts concerning the feasibility of the hydrogen bomb were widely expressed.

Hindsight may show that we have consistently exaggerated the difficulties of exploiting atomic energy. Morally as well as militarily, our nation might have benefited had the mysteries of the atom proved more impenetrable. The greater the difficulties, the greater the advantage to the United States as a morally responsible and scientifically superior nation. But there are signs that the book of nature was not so written. We may be forced to conclude that the whole business across the board is easier of exploitation than we first thought. And, although we cannot be sure, harnessing thermonuclear reactions may also prove less refractory than now appears.

There are persuasive nontechnical reasons for emphasizing fusion development. By an apparent lack of interest in developing beneficent hydrogen applications, we increase our vulnerability to foreign charges that the United States is preoccupied with the destructive aspects of atomic energy. From Japan to the British Isles, these charges have been focused upon H-bomb work. We had no alternative but to build the H-bomb and have no alternative now but to continue its development. So far as observers can tell, however, we act as though no other use of fusion energy were of interest. In this respect, the 1949 debate over the hydrogen bomb has left behind a scar: the later comments holding out hope for constructive applications, such as the Congressional statements, have been given little public consideration and have never caught up with the representations of the 1949-1950 period. As long as the earlier statements continue unchallenged, we can be pictured as the developers of a thermonuclear force which can only wipe out cities and crater battlefields but which has no place in peace. The most unfortunate consequence of such an attitude would be to obscure from us, ourselves, the nature of thermonuclear work as a major avenue of science--perhaps the major avenue of nuclear science--to be traveled by inquisitive men, unhampered by moral prejudgments.

Would work toward a thermonuclear reactor interfere with the atomic fission power program? It seems hardly possible that prospects for thermonuclear power are so immediate that the fission program would be disrupted in the short term (although, conceivably, breakthroughs could occur at any time). The longterm concern would undoubtedly be that fission reactors be rendered obsolete before they could earn back capital investment in the tens of millions of dollars for each facility. If there be any such problem, it should be met only one way: as squarely as possible and as soon as possible. It should be understood (to the extent that it can be) while fission reactor commitments are made. Far from arguing against thermonuclear effort, any possibility of technical obsolescence of fission facilities constitutes a major reason for going forward. If we fear technical progress toward the enormously beneficial results promised by the harnessing of thermonuclear reactions, we do not deserve the scientific supremacy upon which we predicate our defense and survival. Nor will we have it for long.

Would success in controlling fusion reactions lead to an increase in the destructive potential of nuclear energy? If a means could be achieved to control the interaction of light elements of a scale producing useful neutrons or commercial power, it seems likely that the reaction might be made to proceed out of control with the effect of a nuclear weapon explosion. The abundance of thermonuclear materials plus the apparently open-ended size of the fusion reaction conjures up the possibility of a genuinely huge reaction and an enormous explosive and radioactive force. Apart from cataclysmic conjectures, any advance in a peacetime thermonuclear program might have a secondary military consequence, even if only that the neutrons produced might be diverted to the manufactures of war.

If, however, we forgo technical progress because constructive goals in the art may also entail a military use, we will be the first Great Power to do so--and probably the last. There is considerable probability (and scant comfort) that by the time thermonuclear reactions could be harnessed, their mastery would not prove a radical addition to the science of destruction. But if thermonuclear work could significantly affect our future military posture, it is the ineluctable logic of the atomic arms race that we understand it first and that we attain the answers first. Control of thermonuclear reactions may thus provide the most recent example of the duality of atomic energy--but one in which both the constructive and military stakes are exponentially increased.

IV

What kind of program, then, is practical today? The following steps could be taken immediately.

Initially, a policy in favor of bold development could be crystallized and announced. In the past our major atomic energy programs have been preceded by firm decision and top-level directives. No less may be fitting in this case. The President would be the most suitable spokesman to declare American interest in any aspect of thermonuclear development which may lead to the betterment of man or industry. Indeed, there may be need for the peacetime counterpart of the historic White House statement of January 31, 1950, which launched our real assault on the hydrogen bomb.

Secondly, this policy should be implemented by having work proceed as publicly as is prudent. Urging lower security classifications on the Atomic Energy Commission has been a popular pastime. But there may be unusual reasons why the Commission should adopt the most liberal policy consistent with security in declassifying any data which would help develop peacetime applications of the light elements.

Such work, after all, would look toward humanitarian objectives: creating vast new sources of power and electricity, manufacturing radioisotopes for medicine, agriculture and industry. It is perhaps true that an apparatus performing these constructive tasks might be diverted to military use. However, with past developments we seem to have recognized a distinction between weapons, as such, and items designed for peacetime purposes but which could be adapted to war. The internal combustion engine and electronics have vital combat applications; yet, for classification purposes they are treated (and correctly so) quite differently from such an item as the long-range ballistic missile. If our intentions are realized, controlled fusion reactions would resemble the former rather than the latter.

The resolution of classification problems must be left to those officials who have before them the full range of considerations and who bear the responsibility of maintaining the most scrupulous attention to national security. The judgments are difficult and the considerations competing. How much concealment do we gain, and how much achievement do we lose? Among the considerations are two on the affirmative side of what might be achieved by recognizing a large area of low-security sensitivity. First, we would make manifest here and abroad our interest in the constructive side of fusion energy. More importantly, however, release of information may furnish the only feasible way of making rapid progress toward understanding this subject. To develop the A-bomb, the H-bomb, and much of the fission-power program, large numbers of scientists were assembled behind walls of secrecy to make an intensive effort at government expense. A repetition today of the H-bomb effort in order to develop its peacetime counterpart is quite unlikely, although the technical problems are at least as great, and perhaps greater. The alternative way to enlist new minds and more people in harnessing the light elements for constructive applications is to make as much information as prudent available to non-A.E.C. scientists and personnel.

The other side of the problem is what may be lost by making information public. It is striking that every public reference to beneficent thermonuclear possibilities has characterized them as long-range. Radically new ideas (and perhaps many of them) appear needed. It is at this stage that the risk of losing time is perhaps the greatest. In all these respects information policies seem different from those for the controlled fission reaction (which had been demonstrated as feasible) and the A-bomb and the H-bomb (which are useful solely as weapons).

As a third stimulus, the Atomic Energy Commission might urge as many companies as possible to undertake study and development contracts as soon as their interest warranted. Some industries might be willing to carry part of the financial and developmental burden at the present time. Other firms may feel encouraged to study thermonuclear possibilities because such research might contribute to the soundness of their atomic energy business. Furthermore, the knowledge that there was an opportunity to participate would bring the know-how of American industry to a challenging effort. It might also ease the way for integrating an eventual thermonuclear power industry (if there is to be one) into our economy.

A further step should be taken which would cost the government (or industry) a modest amount of money, but which would add greatly to the effectiveness of the effort and the rate of development. A laboratory should be established to pursue all avenues which might lead to constructive thermonuclear uses. A new site should be chosen for the work, possibly in conjunction with a university, but distinct from nuclear weapons work. Such a laboratory, in addition to providing a focal point of all effort in this field, could symbolize our intentions to give thermonuclear development every chance for realization. Particularly now, when our scientists have been divided by controversies concerning the history of the hydrogen bomb program, there might be advantages in offering them the challenge of working to control fusion reactions.

We cannot seek security by military supremacy alone: we must demonstrate our constructive intentions and capabilities with comparable emphasis. Scarcely 16 years have passed since the fission of uranium was discovered, and a bare two and one-half years since the first full-scale hydrogen test. In all likelihood, progress in nuclear energy has just begun.

A correct guess as to the future of controlled thermonuclear reactions could be of overriding importance. We may now be able to contemplate what may prove the biggest step of all: harnessing thermonuclear reactions would be a conquest equal to or greater than any other in our national effort. Again we cannot assume success; but we can recognize that if we were to succeed, all our present work could prove to have been merely preparatory. We have, then, every moral and practical incentive to develop what appears our leading chance for the next big step forward in atomic energy. The initial cost may be little more than a decision to proceed boldly. Failure to do so could lose for the United States the accelerating race for scientific discovery and the contest for the allegiance of men of good will.