CAPP/GAMMA+ code system for coupled neutronics and thermo-fluid simulation of a prismatic VHTR core

•A neutronics/thermo-fluid coupled code system was developed for prismatic VHTR.•The coupled code system developed was applied to a reference reactor, PMR-200.•Effect of bypass flow on the coupled analysis was analyzed.

There exists a large body of publications on neutronics or thermal-fluids analyses of a prismatic gas-cooled reactor core. They mainly focus on stand-alone analyses, although the neutronics and thermal-fluids behavior affect each other. In order to consider the interaction between the neutronics and thermal-fluids behavior, a coupled analysis is desirable. However, only a few studies are available in the open literature on the coupled analysis of a prismatic gas-cooled reactor core. In this work, a code system for a coupled neutronics and thermo-fluids simulation was developed using CAPP (reactor physics code) and GAMMA+ (thermo-fluid system code). Using the code system developed, coupled neutronics and thermo-fluid simulations were carried out for a prismatic very high temperature reactor (VHTR) core to extend the knowledge about the coupled behavior. In particular, the effect of the bypass flow modeling on the coupled behavior was analyzed.