MODELING OF SHORT-LIVED FISSION-PRODUCT RELEASE BEHAVIOR DURING ANNEALING CONDITIONS

An analytical model has been developed to calculate the post-irradiati on release of short-lived fission gases during high-temperature reacto r accident conditions. The generalized treatment accounts for a time-d ependent diffusivity, and is shown to reduce to the standard Booth dif fusion model when the isotopic half-life is much longer than the annea l period. The present formalism is further extended to include the cas e where a steady-state fission product distribution has developed for the radioactive species in the fuel grain during an irradiation prior to the anneal. More tractable analytic formulas for analysis are also provided as short and long-time approximate solutions.