CANDU6 LOCA Analysis With Three-Dimensional Multi-Physics Code System

Abstract

For an accurate analysis of LOCA scenario in the CANDU6 system, a 3-D neutronics code COREDAX-2 and a thermal-hydraulics system code MARS-KS has been coupled. Additionally, based on a review on exiting methodologies for estimating the fuel sheath failure, a function treating the fission gas release during a transient analysis has been added to COREDAX-2 to consider the potential impact of the fuel behavior during a LOCA scenario. Using this multi-physics code system, the CANDU6 LOCA scenarios with and without the actuation of SDS-1 (emergency shutoff rod insertion) have been analyzed. According to the results, the fuel melting can occur in 2.5 seconds in case of an unprotected LOCA scenario, while the xenon gas release does not give a noticeable amplification of the reactor power since it takes time to be released from the active core region.