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Demands for cobalt-60 have been relatively small as long as the principal applications were for radiography and gaging. The accumulated production in the entire United States is less than ten megacuries, although the Hanford plant is capable of producing about 150 megacuries every year using uranium enriched to 0.95 percent, and greater amounts with higher enrichments. The new developments brighten the prospects for large-scale utilization of cobalt-60. First is the possible us of cobalt-60 as a heat-producing radioisotope. Although shielding weights make cobalt-60 unattractive for space applications, the general size of thermal applications can be appreciated by noting that 32 megacuries of cobalt-60 would be required to provide the 500 kw of isotope heat which NASA reports they will need by 1980; terrestrial applications may be an order of magnitude larger. This application of cobalt-60 has been promoted primarily by Savannah River and utilization of high activity cobalt-60 (200-500 curies/gram) as a heat source is being investigated by them under MFC 5.

This report puts under one cover numerous data which have been used and are used in health physics considerations of plutonium and americium.