Chemical potential of carbon in the system U-Pu-C-O-N: measurements and calculation

The carbon potential of (U,Pu) mixed carbides with Pu/(U+Pu) ratios of 0.55 and 0.70 was measured in the temperature range 973 to 1173 K by employing a methane-hydrogen gas equilibration technique. The technique was validated by measuring the Gibbs energy of formation of WC. The compatibility of the mixed carbides with the stainless steel clad was analysed by using the measured carbon potentials. The carbon potentials of mixed carbides of other compositions were calculated theoretically in order to assess their compatibility. The calculations assume ideal solution behavior for all the solid solutions present in the U-Pu-C-O-N system. ((orig.))