1. Weapons Test Limitations
Mr. Graham reviewed with the representatives of the AEC weapons laboratories a number of events which had led the Commission to request a meeting with them to discuss the question of weapons test limitations. He pointed out that the subject of weapons tests had been considered both by the General Advisory Committee and the Advisory Committee on Biology and Medicine at their recent meetings. In addition, the current congressional authorization hearings were concerned, in part, with funds to be authorized for the weapons test program. Mr. Graham said that all of these events had made it evident that the question of future weapons testing was still far from being resolved, and therefore he and other Commissioners believed it would be helpful if a full discussion of the subject could be held with representatives from the weapons laboratories. General Starbird added that the Laboratory Directors had in particular been requested to consider what technical problems were involved and what limitations would result from a decision to test underground only.
Mr. Teller began the discussion by stating that scientists at Livermore Laboratory had concluded that nearly all the information needed by the U. S. about nuclear explosions could be obtained from underground tests, and that underground weapons testing is more easily carried out than testing above ground. He said that he would be in favor of conducting future weapons tests underground regardless of whether an international test limitation should be agreed upon. He added, however, that before it could be known with certainty that weapons in the megaton range could be successfully tested underground, there would have to be a series of tests gradually increasing in size to the megaton range. In addition, if all tests were conducted underground, there would be no opportunity to test weapons effects or to proof-test anti-ICBM missile systems. Therefore, he recommended that it would be desirable to have some above-ground testing each year but to limit each country to tests placing a maximum DELETED of fissionable material in the atmosphere per year. This amount of above-ground testing, he said, would permit all the diagnostic weapons experimentation necessary for the weapons program. If the maximum amount of fissionable material which could be put into the atmosphere each year by each country were limited DELETED it would still be possible to conduct valuable above-ground tests, although the amount of information gained would be less and the results would be limited.
Mr. Brown discussed with the Commissioners the three major types of measurements for a weapons test and how accurate these measurements would be if applied to an underground detonation. Yield measurement for the Rainier shot, he said, had a margin of error DELETED DELETED but with additional experimentation, this margin could be brought down DELETED. Mr. Teller remarked that weapons yields could not be quite as accurately determined underground as above-ground. However, diagnostic details from direct measurements can be obtained more easily and more accurately underground than above-ground, he said.
Mr. Brown said that, in his opinion, radio-chemistry measurement techniques for underground tests, although not as accurate as yield measurements, are adequate. Reaction history measurements, he said, can actually be more accurate underground than above-ground. Mr. Brown said he agreed with Mr. Teller that all necessary above-ground experiments could be conducted within the limitation DELETED DELETED. . . . to keep within this limitation, he said it would probably be necessary to substitute clean weapons for normal weapons shots. Mr. Brown said special weapons types would have to be developed for effects testing and for anti-missile missile warheads to be detonated underground.
Mr. Brown said the best information available to him indicated that weapons DELETED could be tested safely underground but, as Mr. Teller had stated, the size of the tests would have to be detonated deeper and in much harder rock, and there is uncertainty about the effect of such detonations since the transmission of shock would be more direct.
Mr. Sewell reviewed with the Commissioners the advantages of an underground test program over the present series of yearly above-ground test programs. Greater flexibility of scheduling tests and therefore more rapid progress in developing new weapons would be possible if the laboratories were not restricted to waiting for only one test series each year. With an underground test program, tests could be conducted periodically throughout the year whenever a weapon under development reached the point where certain test experiments needed to be conducted. More radical weapons designs could be tested because a laboratory would know that if a particular test failed, a year would not have to lapse before it could conduct another test experiment. This fact could also lead to more rapid progress in weapons development. Costly, full-scale test operations such as are conducted in alternate years at the Pacific Proving Grounds could be eliminated. Tests would no longer be dependent upon weather conditions, thus saving additional time and money now consumed in conducting above-ground tests. The cost of digging the tunnel for the Rainier shot cost no more than a five-hundred foot tower for a test device, and the cost of digging new tunnels out from a main one is about one-fourth the cost of the original tunnel Mr. Sewell said. In addition, public opposition to the tests because of the fallout danger could be eliminated by under-ground testing.
Mr. Teller stated that conducting all future U.S. weapons tests underground would interfere somewhat with Project PLOWSHARE, the program for developing peaceful uses of nuclear explosive devices.
In response to a question by Mr. Fields, Mr. Sewell said as many DELETED bombs could be detonated in a single mountain.
Mr. Bradbury commented that although the Livermore scientists may be correct in believing that nearly all necessary weapons information could be obtained from underground testing, if actual experience proves this to be incorrect, the U.S. would be placed in a very difficult position. He pointed out that much of this work on megaton weapons now involved detailed improvements of the weapons and that with only underground testing there would be a greater risk of being misled about what the tests actually demonstrated. Mr. Bradbury said he took the position that a diversified testing program using balloons, towers, and underground tunnels would be preferable to a complete underground test program.
Mr. Teller remarked that data on a weapons test is most needed when that device misfires, and that the diagnostics of such a test could be done as well or better if the shot were underground rather than above-ground.
General Starbird pointed out that estimates regarding a major underground test program are being based to a large extent upon extrapolations from the Rainier shot. He said he concurred with Messrs. Bradbury and Graves in their view that the U.S. would be faced with a serious military problem if it agreed to underground testing for all weapons, and then discovered that the larger weapons could not be satisfactorily tested underground. He added that the public could not be expected to raise questions about the safety of even underground weapons tests, and the danger that the radioactivity created by the detonation might sometime contaminate water and plant life.
Mr. Graves said he favored the use of balloons for testing weapons devices and that this valuable testing technique would be lost if all above-ground tests were halted.
Mr. Teller stated the belief that there would be no chance that radioactivity from underground tests could contaminate animals or humans, and said he believed one could be overly cautious about questioning the feasibility of underground testing.
Mr. Vance referred to a statement by the GAC at their 58th meeting to the effect that the Commission must not wait too long in proposing an intermediate position between unlimited testing and a ban on all weapons testing. Alternatives suggested by Mr. Vance included: (1) A limitation on the amount of radioactivity released into the atmosphere; (2) Supervision by the U.N. of all weapons tests; and (3) Complete underground testing of all weapons. Mr. Vance said he favored the underground testing position because it would be the simplest to establish and because it would end completely any radioactive contamination of the atmosphere from weapons detonations. He said he considered that public concern with the question makes it an important consideration, even though the Commission recognized that the danger at present is negligible. Mr. Vance said the question he wished the representatives of the laboratories to discuss is what intermediate position would enable the U. S. to continue its weapons development program with the greatest freedom. Mr. Bradbury said it would be difficult to select the best alternative since each one would interfere with the development which is possible under unlimited testing.
Mr. Teller said he believed the most desirable alternative would be to restrict above-ground testing by each country to DELETED fission products released into the atmosphere each year, and to require that all other tests be conducted underground. Such a position would have a number of advantages, he said. It would permit the development of anti-missile missiles, which probably would be impossible if all testing had to be conducted underground. It would also make it quite difficult for nations which do not now have weapons capability to develop weapons. They would be forced to develop both very small weapons for underground testing and clean devices for above-ground testing. Finally, an agreement to limit the amount of fissionable material released into the atmosphere would necessitate establishing a mutual inspection system, thus giving U.S. observers an opportunity to gain first-hand information about the Soviet weapons program.
Mr. Teller said he would be reluctant to have the U.S. accept more stringent test limitations that the DELETED fission yield per year above ground, and unlimited underground testing.
Mr. Vance observed that Mr. Teller's arguments were quite logical; however, the question of limiting nuclear tests would not necessarily be resolved on a logical or strictly scientific basis. He cited the instance of Mr. Hans Bethe's recent statements to the effect that all nuclear testing should be halted as a first step in ending the arms race and reducing world tensions. These, he said, are political judgments, not scientific ones, although they are made by a scientist.
Mr. Floberg asked Mr. Teller how possible violations of limitations such as he recommended would be handled. Mr. Teller replied that he would not be too concerned if the violation were in the range DELETED of fission yield put into the atmosphere in a single year, DELETED. Violations substantially greater than this, however, would be a cause for serious concern, he said. He pointed out that all countries carrying out an atmospheric sampling program would know when serious violations had occurred. General Starbird remarked that continued violations of such a limitation might cause neutralist countries to conclude that the limitation was not effective and to demand a complete cessation of all types of weapons testing.
Mr. Strauss raised the question of how complete weapons systems could be proof-tested underground. Mr. Bradbury said he was not convinced that a final proof-test of a missile and warhead was absolutely necessary if the two could be adequately tested separately. Mr. Teller said a great amount of experimentation was still required for an anti-ICBM missile warhead and that some above-ground testing would be necessary.
Mr. Strauss then inquired whether fallout measurement techniques are accurate enough to determine precisely whether DELETED DELETED fission yield had been placed in the atmosphere by a particular country. Mr. Teller replied that this would be possible only if there were mutual inspection within the countries where the tests occurred.
The question of identifying from which country particular fallout originated was then discussed by Mr. Strauss and Mr. Teller. Mr. Strauss postulated that a country might detonate a number of weapons at extremely high altitudes, with the fallout not being detected until a year or more later. He asked whether it would be possible then to accurately determine which country was responsible for those tests. Mr. Teller said that with satellite counters it would be possible to detect almost immediately when high altitude shots have been detonated, but that the country carrying out the test could not be positively identified in such cases. He added, however, that scientists could probably make an intelligent guess about the origin of the shots.
Mr. Vance left the meeting briefly during the above discussion. The Commissioners returned to the question of the necessity of proof-testing complete weapons systems, and Mr. Graham inquired whether it would be satisfactory to test missile systems using chemical rather than nuclear war-heads. Mr. Teller said it would be possible to test a missile system without the nuclear warhead and determining the performance of such things as the timing of the detonation device, but of course, such a test would not provide any information on the effects of a nuclear explosion. Mr. Floberg said he believed there have been many examples in the past of the importance of conducting tests of complete weapons systems, such as submarine torpedos. He said he was unconvinced that it would be unnecessary to carry out proof-tests of the complete missile system. The Psychological factor of working with missiles equipped with nuclear warheads was important in itself, he said.
Mr. Fields then discussed with Mr. Teller and Mr. Graves when it would be possible to carry out the first diagnostic tests of an anti-ICBM missile. Mr. Brown said the Air Force had mentioned 1960 as the date when such tests might be held; however, the weapons laboratories do not yet know what device might be used. Mr. Teller said the DELETED may be a basis for developing such a weapon but that much more experimentation is required before it could be perfected. Following the detonation DELETED at Operation HARDTACK, it might be possible to conduct further test of it in 1959. Mr. Graves said he believed that it probably would be 1960 before an anti-ICBM device would be ready for diagnostic testing.
Mr. Strauss concluded the discussion by expressing the Commissioners' appreciation to Messrs. Teller, Bradbury, Graves, Brown, and Sewell for an enlightening discussion of the test limitations questions.
W B. McCool