Coupling of dynamic Monte Carlo with thermal-hydraulic feedback

•Development of a new technique to simulate transient behaviour of nuclear reactors.•A transient Monte Carlo neutronics code has been coupled to a thermal-hydraulics code.•This code system is able to simulate transients, including feedback mechanisms.•Investigation of the effect of variance in the Monte Carlo on the stability.•Method successfully tested on an international benchmark problem.

Transient analysis of nuclear reactors is traditionally the domain of deterministic methods, even tough these methods are known to have limitations. With the development of dynamic Monte Carlo and the development of coupled-steady state Monte Carlo calculations the road has been paved to perform transient analysis of high power reactors using Monte Carlo. By this way, it is possible to take into account the thermal-hydraulic feedback, while the neutron transport is modelled in full detail.In this paper a new method is described, which can perform such stochastic analysis of a transient scenario.