qau> Mr. Fine referred to the fact that deuterium, which is made from heavy water, is an essential ingredient of thermonuclear weapons and pointed out that when the U.S. sells heavy water to other countries, these countries agree to use it only for peaceful pruposes. He observed, however, that if U.S heavy water technology were declassified, the U.S. would have no control over the use of this information by other countries. N.r. Strauss said he believed that for this reason the technology of heavy water plants should remain classified. With regard to the declassification of zirconium-hafnium separation technology, the Commissioners indicated that they would consider favorably such &@ recommendation. The Commissioners then considered the possibility of downgrading the classification of gaseous diffusion plant technology. Mr. Libby said he did not believe that the downgrading of the classification of this information would make a substantial contribution to basic engineering knowledge in other fields. He also indicated that he believed private industry would find it too expensive to construct and operate a gaseous diffusion plant. For these reasons and because he considered gaseous diffusion technology related to weapons production, Mr. Libby said he could find no justification for downgrading the information. Mr. Marshall said that most of the gaseous diffusion plant technology, now recommended for downgrading, was already being treated as ‘‘Confidential’’ rather than ‘‘Secret’’ since the classi-~ fication guide in use at the time of the Paducah expansion had not distinguished between ‘*‘Secret’’ and **Confidential’*. However, according to the most recently approved classification guide, the same information should be classified ‘‘Secret'’. Therefore, N.r. Marshall, said, in order for diffusion plant operations to be brought into conformity with the new guide, it is necessary either to upgrade many of the documents concerning diffusion plant technology to *‘Secret** or formally downgrading the technology to ‘‘Confidential’® and thereby permit continued handling of the documents on a ‘'Confidential’* basis. Mr. N.arshall pointed out that upgrading this information to ‘Secret’ in accordance with the new guide would entail a large expenditure of time and money - 2360-

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