Development of in-vessel source term analysis code, TRACER(II)

not registered; not registered  

The computer code TRACER has been developed to evaluate the species and quantities of fission products (FPs) released into the cover gas in an LMFBR during the fuel pin failure accidents (In-vessel source term). In this fiscal year, analytical models for the following key phenomena were developed and were coded in the code, which had been proposed from the results of sample calculations in last fiscal year. (a)Aerosol behavior in a bubble, (b)bubble behavior near the surface between cover gas and coolant, and (c)behavior of coolant temperature change. The fundamental functions of these models were validated by conducting sample calculations for the analyses of MOL7C/6 in-pile source term experiment and out-of-pile experiment for xenon-iodine mixed gas bubble behavior in liquid sodium. However, the calculational results by the above models could not reproduce the iodine decrease behavior within the bubble during the bubble rising in the out-of-pile experiment. Therefore, it is necessary to consider another mechanism in transport phenomena of iodine from the xenon-iodine mixed gas bubble into the sodium.