Development and application of safety analysis code for He-Xe cooled space reactor

Abstract

Space nuclear reactor power system can offer high energy density and a wide power coverage, providing electric power for space exploration. The safety characteristics of space nuclear reactor during in-orbit operation accidents is key to evaluate its feasibility. In this paper, a safety analysis code is developed for He-Xe mixture cooled space reactor based on SCTRAN, which used to be applied for Supercritical water or CO₂ cooled reactor. A semi empirical formula is applied to develop a physical property calculation model of He–Xe. Flow resistance and heat transfer correlations as well as turbomachinery models for He-Xe are developed. A numerical model for S⁴-CBC space reactor power system is established by using the newly developed code. The calculation results of reactor and system model have the maximum relative errors of 3.43 % and 0.47 % compared to the reference design values, which proves the code is reliable to simulate the thermal–hydraulic behavior of the S⁴-CBC space reactor power system. The transient responses of the S⁴-CBC space reactor power system under the reactivity insertion accident and the mechanical failure of one and two Brayton loops are simulated and analyzed. The results of the accident analysis provide guidance for the core design, operation strategy, and safety system design of future He-Xe cooled space reactor system.