A sub-critical wait-time experiment to validate stochastic nuclear reactor kinetics models for low neutron source Nuclear Power Plant (NPP) start-up simulations

The aim of this paper is to present a theoretical sub -critical wait -time experiment that may be used to validate stochastic nuclear reactor kinetics models which compute the neutron population probability distribution. The regulation governing many zero -power reactors prohibits super -critical nuclear reactor operation. This paper shows that a desirable wait -time probability distribution can be computed by only modifying the neutron source strength. An analytical model, which ignores the contribution of delayed neutron precursors, is presented. Additionally, a six -delayed neutron precursor group model using the P & aacute;l-Bell equations is used to investigate the relationship between the nuclear reactor system parameters and the resulting wait -time probability distribution. Finally, this paper shows that two neutron energy group models can be collapsed down to an equivalent single (one speed or mono -energetic) neutron energy group model which accurately reproduce the same wait -time probability distribution.