Status and trends of kinetic Monte Carlo simulation in reactor physics

Monte Carlo simulation is the reference method for reactor physics applications. Yet, the use of Monte Carlo for time-dependent problems (operational or accidental reactor transients) is still in its infancy, mainly due to the inherent challenges posed by the simultaneous presence of delayed neutron precursors and neutrons: the vast separation of their typical time scales, coupled to fission-induced correlations, leads to huge fluctuations and variance jumps. We will review the variance-reduction techniques recently developed in order to cope with these issues and enable the simulation of kinetic Monte Carlo in reactor physics and present a novel systematic approach possibly leading to considerable gains in computing time for a given target accuracy.