Development of OpenMC/Trivac two-step scheme for fast reactor core neutronics analysis

Abstract

This research develops an open-source two-step scheme coupling the Monte-Carlo (MC) code OpenMC and the deterministic code Trivac for fast reactor neutronic modeling. The multigroup cross-sections are generated using OpenMC with a complete core model, continuous energy, and high-level heterogeneity. The core calculation is achieved with diffusion or simplified Pn (SPn) solvers in Trivac. The scheme is verified with a 1000 MWth metallic-fueled fast reactor. The MC/diffusion scheme in this work shows good performance in the prediction of core reactivity, sodium void worth, and Doppler constant. The overestimation of MC/SPn is discussed by combining a complete review of MC-based two-step schemes. The SPH correction in control rod assembly can improve significantly the prediction of control rod worth and power distribution. Based on the scheme developed in this research, the SPH correction at a full core level will be verified. The application in depletion, transient, and multiphysics analysis could be developed.