Application of CMFD with superhistory method on continuous energy Monte Carlo simulation for eigenvalue problems

Abstract

The Coarse Mesh Finite Difference Method (CMFD) has been widely used to accelerate the convergence of deterministic calculations. Recently, the application of CMFD for accelerating the Monte Carlo (MC) simulation is increasing. Unlike the deterministic method, MC has inactive cycle to make the fission source convergence, and active cycle to tally the results. The CMFD method can accelerate the fission source convergence of MC. The number of inactive cycles can be reduced. And, it was expected that the effect of CMFD on active cycle is also good if CMFD can cut the inter-cycle correlation. However, it turns out the CMFD also has inter-cycle correlation since the parameters for the CMFD calculation were generated by MC. To reduce the inter-cycle correlation of CMFD accelerated MC, superhistory method was adopted. In this paper, the intercycle correlation of CMFD, superhistory method, and CMFD with superhistory method was studied.