Demonstration of Cobalt-60 Heat Source Capsule Performance

Satisfactory performance of superalloy capsules at conditions typical of those expected in radioisotopic heat sources was demonstrated. Capsules of Hastelloy X, Hastelloy C, InconeI 600, and Haynes 25 were heated in air at 850 to 1000°C; those containing unirradiated cobalt metal were tested for up to 39 400 h (4.5 yr), and those containing irradiated cobalt metal for up to 19 500 h (2.2 yr). These tests indicated that Hastelloy X is the best encapsulating material for these applications , and Hastelloy C is a good alternative. General agreement of the data on inactive and active capsules indicates that the performance of active capsules is not significantly affected by the radiation field or the buildup of nickel from radioactive decay of the cobalt.