Transient analysis of KRUSTY reactor system

[Background]: The Kilopower Project is initiated by NASA to demonstrate reactor of small space fission power. KRUSTY, 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. [Purpose]: This study aims to further enhance the prediction ability for the transient operation of heat pipe cooled reactor and evaluate the behavior and safety performance of heat pipe cooled reactor under accident conditions. A system analysis tool was developed and validated. [Methods]: First, a multi-domain modelling environment named Simscape was introduced. And then, related functions was extended, including point reactor module and heat transfer module for heat pipes, to make Simscape have the ability to systematically analyze the heat pipe cooled reactor. Again, taking KRUSTY as the target, the model was built and the key processes were simulated. At last, the calculation results, including normal operation and accident conditions, were compared with the experimental data. [Results]: The results show that the average power error of each working condition is less than 10 %. In the initial operation stage, the temperature error is about 10 %, and in the other stages, the temperature error is less than 3 %. [Conclusions]: The calculated results are in good agreement with experimental data. To a certain extent, the feasibility of the research method is proved, which lays a foundation for further safety analysis of heat pipe cooled reactor in the future.