On application of quasistatic and point-kinetics schemes for subcritical systems with external neutron source

Quasistatic and point-kinetics schemes provide an efficient way to simulate transients in conventional nuclear reactors. They imply utilization of a weighting function that is used to compute integral reactor parameters such as reactivity. Currently, the applicability of these schemes and the choice of the weighting function for modeling transients in subcritical systems with external neutron source are widely discussed. In the paper the direct, quasistatic, and point kinetics methods are compared for particular transients in subcritical systems. The applicability of the quasistatic scheme with a conventional weighting function is demonstrated. It is shown that the point-kinetics method can be extended to improve its accuracy and applied efficiently in the subcritical case with the conventional weighting function under certain conditions