Source extrapolation scheme for Monte Carlo fission source convergence based on RMC code

Abstract The source extrapolation method had been used to accelerate the convergence of fission sources in the deterministic methods. However, it has not been effectively used for the Monte Carlo criticality calculation. We apply the source extrapolation method to the Monte Carlo criticality calculation to accelerate the fission source convergence. An explicit and straightforward formula for determining the extrapolation factor is given based on the mathematical derivation and numerical calculations, and a new source extrapolation scheme for the Monte Carlo criticality calculation is proposed. This source extrapolation scheme is easily implemented and makes the fission sources converge twice as fast as the standard Monte Carlo criticality calculation. The validity and optimality of the source extrapolation scheme are tested by a single fuel rod model and the OECD source convergence benchmark. The results show that the new scheme can accelerate the fission source convergence.