Parametric effects on coupled neutronic-thermohydraulic stability characteristics of supercritical water cooled reactor

Supercritical Water-Cooled Reactor (SCWR) is one of the advanced reactor types under the Generation IV program. Similar to BWR, there are large changes in thermodynamic properties of the coolant in SCWR, but its dynamic characteristics are different from existing reactors due to the supercritical conditions of the coolant. This necessitates the study of the stability behaviour of SCWR, which requires a dynamic model of the reactor. A simple unsteady lumped parameter model (LPM) for coupled neutronic-thermohydraulic transients in SCWR has been developed in this paper. The LPM includes point reactor kinetics for neutron balance and a two-region model for fuel and coolant thermal hydraulics. The two regions considered in the model are separated from each other by a boundary that depends on the pseudocritical temperature of the coolant. The results of dynamic simulation and linear stability analysis are shown by plotting stability maps. These results show good agreement with each other. Furthermore, to study the effect of parameters on the stability of the system, variations of some geometric, control and neutronic parameters are studied. The stability maps predicted by the LPM are also compared with those obtained with RELAP5 code, and are found to show similar trends