Development of in-vessel source term analysis code, TRACER

not registered; not registered  

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), the computer code TRACER (Transport phenomena of Radionuclides for Accident Consequence Evaluation of Reactor) has been developed. The code can analyze mechanistically the physical and chemical phenomena of FPs release and transport behavior from the failed fuel to the cover gas through sodium coolant. The code validation was performed through the sample calculations for the results of Mo17C/6 in-pile source term experiment. In the beginning of this study, the production and transport phenomena of bubbles of the noble gas and volatile FPs in the coolant, and mass transfer between the bubble and coolant were investigated, and the functions needed for the code were clarified. After that, several mechanistic models for the bubble behavior were developed, and the programs were coded. From the results of the sample calculations, it was confirmed that the code was capable of simulating the FP transport phenomena in the primary system.