On the oxidation of (U,Pu)C fuel: Experimental and kinetic aspects, practical issues

The oxidation of mixed (U, Pu) carbide fuel was studied to meet some of the general requirements applicable to the back- and front-end of the nuclear fuel cycle. Data are unfortunately scarce in this field. Based on an experimental study and a kinetic treatment, it was proved that the oxidation of solid or powdered mixed carbide fuel does not involve any unwanted kinetic transition and does not have the intrinsic ability to self-sustain. We never observed the formation of a protective oxide layer on the samples. The oxidation products were always low-density, finely-divided oxide powder expanding and tending to slow down the process. The low thermal activation observed demonstrates the key role of gas transport when using powders. Practical solutions have been derived from this work.