9 u s DEPARTMENT OF STATE $1 me Director of Intelligence mfg and esea RES-29 -- November 2 1961 1 ck To g he Secretary Through From DIR- Thomas L Hughes Wm M1691 Subject The Chinese Test Our pre October 16 estimates did not anticipate that the Chicoms had the capability of producing the isotope This paper canvasses current explanations for the use of U-235 in the Chicom nuclear device and examines the dif culties that prevent our achieving a firm estimate now It also touches on the problem of handling public discussion of Chicom nuclear capabilities Until the Chinese October test proved otherwise it had been expected that the first Chicom device would use plutonium rather than mainly because it was stron 51y felt that the Chinese did not have the facilities for production of weapons- at grade U-235 The most practicable way of getting is through the gaseous diffusion process which separates the rare isotope from the much more abundant U-Z 38 by ltering a gaseous uranium compound through an appropriate screen or barrier There are formidable engineering problems and high costs involved in building a gaseous diffusion plant However the alternatives such as the gas centrifuge and electromagnetic calutron process also involve difficult technical problems and the US UK USSR and French have all chosen the gaseous diffusion method Lanchou Gaseous Diffusion Plant A single large gaseous diffusion building unmistakably of Soviet design was 131 tographed at Lanchou in 1959 It could not have been operating at that time because it 1 3 0de electric power In September 1963 it was again photographed and different but equally reasonable arguments again led to the judgment that it was not operating All outward appearances however indicated that it was complete and ready to go From a purely technical standpoint it has been the opinion of most but not all -- experts who examined the problem before the blast that the single cascade building at Lanchou could not produce weapons-grade material that either a second til 01' I summary 03 00 LE9- g ggudsgifrom automatic 9 Lu 5 33 113 and Date cla lfiostion PRESERVATION COW m Ti L333 Waterman building would have to be built the photographs suggest that such a building was en- visioned at Lanchou or that an electromagnetic or gas centrifuge process either at Lanchou or elsewhere would have to be used to raise the enrichment No such facilities have been identi ed anywhere in China The experts made a reevaluation of Lanchou after the 16 October test and have put forward additional alternative explanations for the appearance of 35 All start with the assumption that Lanchou is the only facility available and that it did not start operating until about a year ago None of the explanations are very satis- factory either because of the 12 month time limit or because the available buildings do not seem to have space for the necessary equipment In short the alternative explanations are feasible but only just feasible and they by no means overcome satisfactorily the objections that can be raised against them Other Possibilities Other theories that look beyond the Lanchou establishment have also been considered For example prior to the 1959 split the Soviets might have supplied enou for a nuclear device However it is difficult to imagine that the Soviets would supply weapons grade furthermore it is dif cult to explain the Chinese public accusation that the Soviets refused to provide a sample of an atomic bomb and technical data concerning its manufacture if the Soviets had in fact given them its most important component - the ssionable core Another possibility would be that there exists elsewhere in China a second gaseous diffusion building an electromagnetic facility or a gas centrifuge The gas centrifuge has been generally ruled out on the basis that the technological problems involved are more difficult than those of either gaseous diffusion or electromagnetic separation A second diffusion building elsewhere in China cannot be completely ruled out on the basis of available photography but the large amounts of power IOOMW needed for this process are dif cult to reconcile with our knowledge of the Chinese power grid and cansumption An electromagnetic facility is a better possibility and could go undetected From a technological standpoint however it is an expensive and not very ef cient way of producing except in small quantities It is a process the US investigated but ultimately gave up in preference for the diffusion method Future Capabilities An estimate of what Chicom capabilities are and will be over the next few PRESERVATION COPY WNOFORN WNOFORN years depends to a large extent on which o the possible alternatives or combinations of them one chooses The estimates will range from very low if the came from the Soviets and they supplied only enou for one or two devices to very high if one credits the Chinese with another as yet unidenti ed cascade building To this must be coupled great uncertainties about Chinese missile development and somewhat lesser ones about plutonium production At one extreme it is quite feasible to postulate a variety of warheads and delivery systems which while limited in number would present a formidable military asset At the other it is equally possible to argue that the Chicoms have pulled o a tour-de force of more than military signi cance and that their actual capabilities to produce advanced weapons remain as we have previously estimated quite limited Resolution of these unanswered problems is not likely to come quickly since it depends in part on additional and time consuming technical analysis of data we already have and in part on the acquisition of new data that will be extremely dif cult to get Problems of Public Discussion The fact that was used in the first Chinese communist device is now a matter of public record In such technologically sophisticated countries as Japan there is a tendency to credit the Chinese with far greater capabilities than the evidence now at hand will support However premature such conclusions may be they cannot be rejected summarily given the uncertainties enumerated above On the other hand to emphasize heavily the unknowns and uncertainties could have undesirable results in countries like India In this situation meaningful public discussion of Chinese com - munist capabilities will be dif cult for some time to come 1 summon cow WNOFORN COPY LBJ 83 my This document is from the holdings of The National Security Archive Suite 701 Gelman Library The George Washington University 2130 H Street NW Washington D C 20037 Phone 202 994-7000 Fax 202 994-7005 nsarchiv@gwu edu