Modification and Verification of Discharge and CHF Model in LOCA Evaluation Program Development Based on RELAP5 Platform

In order to develop the licensing LOCA evaluation program,a discharge model and CHF model modification and verification to RELAP5/MOD3.3 in accordance with Appendix K of 10CFR 50.46 is carried out.With the accomplishment of typical separated tests modeling,namely,Marviken Test-22 and ORNL THTF,input modeling,comparative analysis for the modification are presented.Verification to the conservatism of the employed Moody two-phase critical flow model and CHF correlations,as per related Appendix K requirements,is demonstrated and discussed,which lays a preliminary foundation for further development of LOCA licensing safety evaluation program.