Search

Abstract Driven by the huge advantage of Monte Carlo method, the application of assembly homogenization by continuous-energy Monte Carlo method draws more and more attention. This paper presents the theory and the verification results of few-group constants generation for a conventional two-step procedure by Monte Carlo code cosRMC. Currently in cosRMC, 69 WIMS fine group constants are tallied and then B1/P1 equations are solved to compute few-group constants with leakage correction. And diffusion coefficient can be obtained by the B1/P1 leakage term. In addition, diffusion coefficient calculation based on classic out-scatter approximation and in-scatter approximation using the B1/P1 current spectrum are included in cosRMC as well. For verification, the simulation results performed by the nodal diffusion code SIMULATE5 using group constants generated by cosRMC have been compared to cosRMC Monte Carlo solution. The k inf /k eff /power distribution (radial & axial) obtained by two schemes cosRMC-SIMULATE5 and cosRMC shows good agreement with each other regarding to single assembly/full core level benchmark. These positive outcomes indicate that the few-group constants generated by cosRMC are highly accurate. Highlights • Group constants generation by Monte Carlo method have been developed in cosRMC. • Quality of group constants generated by cosRMC is investigated. • Results of cosRMC-SIMULATE5 and cosRMC show good agreement with each other. • B1/P1 spectrum correction is important, P1 correction is recommend in this work. • Correcting DF is necessary and diffusion coefficient by P1 In method is recommend. [ABSTRACT FROM AUTHOR]

This paper describes the methods used in the Serpent 2 Monte Carlo code for producing homogenized group constants for nodal diffusion and other deterministic reactor simulator calculations. The methodology covers few-group reaction cross sections, scattering matrices, diffusion coefficients and poison cross sections condensed in infinite and B 1 leakage-corrected critical spectra, as well as the calculation of discontinuity factors, pin-power form factors, delayed neutron parameters and total and partial albedos. Also included is a description of an automated burnup sequence, which was recently implemented for the handling of restart calculations with branch variations. This capability enables covering the full range of local operating conditions required for the parameterization of group constants within a single run. The purpose of this paper is to bring the methodological description provided in earlier publications up to date, and provide insight into the developed methods and capabilities, including their limitations and known flaws. [ABSTRACT FROM AUTHOR]