The Effect of Heating Rate on Fission-Product Release: The HRE1 Experiment

Abstract

Small samples of irradiated UO₂ were heated at controlled rates of 1, 5, 10, and 50 K/s to 1920 Kin a flow of Ar/2%H2, in order to investigate the effect of heating rate on fission-product release from CANDU fuel. Observed fractional releases of ⁸⁵Kr were higher than those of the ¹³³Xe generated by trace-reirradiation, indicating that the grain-boundary inventory contributed significantly to releases under the test conditions. At 5 K/s, the Kr, Xe and Cs releases for heating to 1920 K were significantly higher than for heating to 1620 K, indicating that a threshold temperature must also be exceeded.