Further Results of Irradiation of Uranium Carbide

The results of the postirradiation examinations on UC compounds having nominal compositions of 4.6, 4.8, and 5.0 w/o C continue to be encouraging after irradiation to approximate burnups of from 1000 to 15,000 MWD/Ton of U. Density changes were small varying from a minimum of 0.7% to a maximum of about 2.5%. Cracking has occurred in all specimens, however, it can probably be largely attributed to thermal stresses. Depletion of carbon is occurring in the specimens having the nominal 5 w/o C composition. Metallographic examination shows that these specimens appear to revert to the 4.8 w/o C stoichiometric composition. The fission gas retention properties of this material appear quite good. In all cases, the amount of fission gas released is comparable to the calculated amount released by recoil.