Transient analysis of KRUSTY reactor system

<bold>Background</bold>The Kilopower Project is initiated by NASA (National Aeronautics and Space Administration) to demonstrate reactor of small space fission power. KRUSTY (Kilowatt Reactor Using Stirling TechnologY), as a prototypic nuclear-powered test of a 5-kWt Kilopower space reactor, is successfully operated in March of 2018. The testing, which operated the reactor at various temperatures and power levels, shows that the reactor is highly tolerant of possible failure conditions and transients.<bold>Purpose</bold>This study aims to further enhance the prediction ability for the transient operation of heat pipe cooled reactor (HPCR) and evaluate the behavior and safety performance of heat pipe cooled reactor under accident conditions.<bold>Methods</bold>Firstly, a multi-domain one-dimensional multiphysical field tool of MATLAB/Simulink platform named Simscape was introduced as the modelling environment. Then, related functions was extended to include point reactor module and heat transfer module for heat pipes, making Simscape preserving the ability to systematically analyze the heat pipe cooled reactor. Subsequently, taking KRUSTY as the target, the model was built and the key processes were simulated. Finally, the calculation results, including normal operation and accident conditions, were compared with the experimental data.<bold>Results</bold>The comparison results show that the average power error of each working condition is less than 10%. The temperature error is about 10% in the initial operation stage, but drops to less than 3% in thereafter stages.<bold>Conclusions</bold>The calculated results in this study are in good agreement with experimental data, proving the feasibility of the research method to a certain extent, hence lay a foundation for further safety analysis of heat pipe cooled reactor in the future.