Study on the load loss characteristics of a space nuclear power system with multi Brayton loops

Space nuclear power system (SNPS) is very attractive for the future civil and military space demands. SNPS with multi Brayton loops (SNPS-MBL) can achieve high-power output for space applications. The accident characteristics is the key to safe and efficient operation of SNPS-MBL. In this study, the dynamic model of the SNPS-MBL was established, the characteristics of SNPS with dual Brayton loops (SNPS-DBL) after single or dual Brayton loop (BL) load loss were studied. The results indicated that load loss was a serious accident. The positive torque on the turbine shaft after load loss increased the rotational speed rapidly to maximum value at 69.15 krpm exceeded the upper limit. Countermeasures should be taken after load loss. There was a coupling effect between the two BLs after load loss of single BL. load loss of the accident BL increased speed rapidly to 69.15 krpm, and decreased the BL power generation to 0 kW. The increase of inventory in normal operation BL increased power generation. Total power generation of SNPS-DBL decreased from rated value 150.8-81.8 kW. Furthermore, the influence of BL number on the safety of SNPS-MBL under accidents was analyzed. The results showed that increase of BL number improved the safety of SNPS-MBL in case of one BL load loss. The maximum speed of accident BL was not related to the number of BL. This study provides a reference for the design and operation of SNPS-MBL.