Oxidation rate of K-Basin spent nuclear fuel in moist air

Experiments have been conducted by Pacific Northwest National Laboratory to determine the oxidation rate of damaged/corroded N-Reactor fuel material in moist air. Five SNF pieces (with regular geometrical shapes) sectioned from a damaged element stored in the K-West Basin were oxidized in flowing air containing moisture. The SNF oxidation behavior in moist air at a temperature of 198 C can best be fitted by parabolic oxidation kinetics. A linear rate equation gave the best fit to the oxidation data at 250 C and above. The results within the temperature range studied, therefore, show a transition from parabolic oxidation kinetics to linear oxidation kinetics. The transition temperature is somewhere between 198 C and 250 C. The tests at approximately 300 C gave results that were very different from the other tests at temperatures of 198 C, 250 C, and 349 C. The SNF sample weight change at this temperature showed erratic behavior. Visual examination indicated the sample fragmented into small pieces and powder as a result of rapid oxidation and hydration. Additional tests at temperatures close to 300 C (i.e., 300 {+-} 10 C) are recommended in order to fully understand the oxidation behavior of the damaged/corroded SNF samples in moist air at about 300 C