Development Program of LOCA Licensing Calculation Capability with RELAP5-3D in Accordance with Appendix K of 10 CFR 50.46

Abstract

In light water reactors, particularly the pressurized water reactors, the severity of loss-of-coolant accidents (LOCAs) will limit how high the reactor power can extend. Although the best-estimate LOCA methodology can provide the greatest margin on the peak cladding temperature (PCT) evaluation during LOCA, it will take many more resources to develop and to get final approval from the licensing authority. Instead, implementation of evaluation models required by Appendix K of the Code of Federal Regulations, Title 10, Part 50 (10 CFR 50), upon an advanced thermal-hydraulic platform can also gain significant margin on the PCT calculation. A program to modify RELAP5-3D in accordance with Appendix K of 10 CFR 50 was launched by the Institute of Nuclear Energy Research, Taiwan, and it consists of six sequential phases of work. The compliance of the current RELAP5-3D with Appendix K of 10 CFR 50 has been evaluated, and it was found that there are 11 areas where the code modifications are required to satisfy the requirements set forth in Appendix K of 10 CFR 50. To verify and assess the development of the Appendix K version of RELAP5-3D, nine kinds of separate-effect experiments and six sets of integral-effect experiments will be adopted. Through the assessments program, all the model changes will be verified.