An improved deterministic truncation of Monte Carlo solution for pin-resolved nuclear reactor analysis

Abstract

An improved deterministic truncation of Monte Carlo (iDTMC) solution method has been developed for acceleration and variance reduction of Monte Carlo (MC) neutronic analysis. A new calculational strategy has been applied by taking advantages of partial-current-based coarse mesh finite difference (p-CMFD) method with two different mesh sizes in a tactical way. Fast convergence of source distribution is attained by a coupled assembly-wise p-CMFD method in inactive cycles, and detailed deterministic solutions are obtained by a decoupled pin-wise p-CMFD method in active cycles. Assistant schemes are also devised to enhance efficiency of the iDTMC method, which include one-node p-CMFD acceleration, new inactive cycle strategy, and real variance estimation method for iDTMC solutions. The iDTMC method is evaluated in a small reactor and a big-size one. The iDTMC solutions are compared with those of the pCMFD accelerated MC calculation, and they are appraised in terms of source convergence, computing time, and figure-of-merit. (c) 2021 Elsevier Ltd. All rights reserved.