Preliminary study on physical characteristics of single‐pass super‐critical water‐cooled reactor core

Abstract

Summary The super‐critical water‐cooled reactor (SCWR) is one of six types of Gen‐IV reactors. Based on the current mature pressurized water reactor technology, it has several advantages, including high conversion ratio, high breeding of nuclear fuel, high thermal efficiency, and a simplified system. However, due to the combination of water coolant and fast neutron spectrum, there is a need to address safety problems caused by the positive void coefficient. The purpose of this paper is to give a study on physical characteristics for the reactor core. Herein, the core modeling of an SCWR with a single‐pass flow is that seed assemblies and blanket assemblies are arranged in a tornado manner, in which MCNP and SERPENT are used for critical calculation. The assembly design is discussed from the aspects of the thickness of the solid moderator layer and cladding material. Based on the optimized assembly design, UO2, PuO2‐ThO2, and PuO2‐UO2 are selected for the sensitivity analysis of fuel composition. In addition, sensitivity analysis for axial coolant density distribution, water‐to‐fuel volume ratio, reflector thickness and fuel arrangement are carried out. Several fundamental system characteristics are discussed in this paper, including keff, void coefficient, Doppler coefficient, neutron spectrum, power distribution, one‐cycle burnup and conversion ratio. The results help in understanding the design of the SCWR better and provide fundamental research data for further study.