Models for Safety Analysis of the Generation IV Supercritical Water-cooled Reactor

Abstract

The nuclear performance analysis of the pressure tube version of the Supercritical Water-Cooled Reactor (SCWR) requires the study of the neutron population in its lattice cell. Studies involving assemblies of SCWR cells are also needed to take into account environmental effects. In this paper, we present the SCWR lattice cell model that has been developed using the DRAGON code. The radial and Cartesian mesh discretization as well as the tracking parameters have been optimized based on the study of the multiplication constant and two groups cell averaged cross sections.The assembly model we selected corresponds to a checkerboard pattern with two different cell types (different local properties such as coolant and fuel temperature) and periodic boundary conditions. Comparisons of the multiplication constant, neutron spectra and reaction rates obtained from the cell and assembly models indicate that a strong coupling exists between neighboring cells because the light water coolant has a significant effect on neutron slowing-down and neutron absorption.