McCARD/MASTER Hanbit Unit 3 Multi-Cycle Analyses with Monte Carlo-Based Reflector Cross-Section Generation

In this study, we established a fully Monte Carlo (MC)-based McCARD/MASTER two-step core design analysis code procedure without relying on conventional deterministic code by incorporating a newly developed MC reflector cross-section generation code. For reflector cross-section generation, the MACAO code was developed and used to produce the discontinuity factors required for whole-core nodal analyses; these factors were generated via the source expansion nodal method. To examine the updated McCARD/MASTER two-step code system, multi-cycle core follow calculations were performed for cycles 1 and 2 of a commercial pressurized water reactor, namely, Hanbit Unit 3. The validity of the nuclear core design parameters, including the critical boron concentration, power distribution, pin power peaking factor, and moderator temperature coefficient, was assessed through comparison with conventional deterministic DeCART2D/MASTER two-step analysis results and the related nuclear design report. Overall, the McCARD/MASTER results were found to be in good agreement, with all the results meeting the design criteria, except for the critical boron concentration at the beginning of cycle 2. To fully exploit the strengths of the MC method, the McCARD few-group constant and reflector cross-section generation system will be extended to heterogeneous nuclear core systems requiring detailed resonance treatment. Furthermore, the newly developed MACAO is expected to facilitate efficient and accurate reflector cross-section generation for the various heterogeneous core systems.