VERIFICATION & VALIDATION OF MCS MULTI-PHYSICS ANALYSIS CAPABILITY FOR OPR-1000 MULTI-CYCLE OPERATION

Abstract

This paper presents a verification and validation (V&V) study of the MCS code for the multiphysics simulation of pressurized water reactor (PWR) multi-cycle operation. MCS is a Monte Carlo (MC) neutron-photon transport code developed by the COmputational Reactor physics and Experiment (CORE) group of Ulsan National Institute of Science and Technology (UNIST). MCS features a three-dimensional (3D) whole-core depletion capability coupled with thermal-hydraulic (T/H) feedback and shuffling/refueling capability for the analysis of multi-cycle operations. In this work, the two-cycle operation of a commercial PWR of type OPR-1000 with 2815 MW thermal power is modeled and analyzed with MCS (the name of the PWR unit and the numbers of the analyzed cycles cannot be disclosed due to confidentiality agreements). The 3D whole-core pin-wise depletion calculation is performed with 1D closedchannel thermal-hydraulic feedback (TH1D), On-The-Fly Doppler broadening of ENDF/BVII.1 cross-sections based on the windowed multipole approach developed at MIT (Massachusetts, USA), equilibrium xenon (Eq-Xe) and Critical Boron Concentration (CBC) search. MCS simulation results are verified against calculations of the STREAM/RASK-K2.0 (ST/R2) two-step deterministic code developed at UNIST, against data from the OPR-1000 Nuclear Design Report (NDR) and are validated against measured plant data. The compared parameters include the quantities measured during the zero power physics testing and the boron letdown curves, the axial/radial power profiles, the axial profiles of fuel temperature and moderator temperature/density for two consecutive operation cycles. Excellent agreement between MCS and measurements is observed with a root mean square (RMS) error of CBC within 20 ppm and an RMS error of assembly power within 1.88%.