Application of Coarse-Mesh Rebalance Acceleration to Monte Carlo Eigenvalue Problems

The coarse-mesh rebalance method is adopted in Monte Carlo schemes for aiming at accelerating the convergence of a source iteration process to obtain the eigenvalue of a nuclear reactor system. At every completion of the Monte Carlo game for one batch of neutron histories, the scaling factor for the neutron flux is calculated to achieve the neutron balance in each coarse-mesh zone. This rebalance factor is multiplied to the weight of each fission neutron in the coarse-mesh zone for playing the next Monte Carlo game. The numerical examples have shown that the present rebalance method gives a new usable sampling technique to get a better estimate of the number of neutrons lost or produced in each coarse-mesh zone by modifying the value obtained directly from the normal Monte Carlo calculation.