Diffusion coefficient of Xe-133 in a SIMFUEL with a low burnup

Abstract

Post irradiation annealing tests were performed to obtain the Xe-133 diffusion coefficients in a SIMFUEL which was a simulated irradiated UO2 fuel with a burnup of 27,300 MWd/t U. Specimens were fabricated as cubic polycrystals with the same composition for a given burnup. Each 300 mg specimen was irradiated in the HANARO research reactor for up to a 0.1 MWd/t U burnup. Post irradiation annealing tests were carried out at 1400 degrees C, 1500 degrees C and 1600 degrees C. The xenon diffusion coefficients for the SIMFUEL were lower than those for UO2 in near stoichiometric UO2 due to a relatively higher concentration of the tri-valent additives, which is related to the concentration of a cation vacancy. The activation energy in the SIMFUEL was also lower than that in UO2 due to the lower formation energy of a cation vacancy and the migration energy. The xenon diffusion coefficient for the SIMFUEL increased with an increasing oxygen potential of the ambient gas. (c) 2006 Published by Elsevier Ltd.