The effect of insulation layer of KRUSTY on reactor power

[Background]: Small modular reactor has the characteristics of simple structure, convenient construction and easy deployment. As a type of small modular reactor, the heat pipe reactor operated in load following mode. Kilopower is a typical heat pipe reactor designed to provide 1 to 10 kilowatts of electricity in space or on the surface of a planet or moon. As the prototype of the heat pipe reactor Kilopower, The Kilowatt Reactor Using Stirling TechnologY (KRUSTY) has been tested and achieved satisfactory results. [Purpose]: This study aims to optimize the structure of KRUSTY, understand the influence of insulation layer on the reactor, and improve the efficiency of reactor output energy. [Methods]: Firstly, the multi-physics software Simscape is used as the system analysis tool, and the reactor power calculation module, heat pipe module and so on are added for the simulation of heat pipe reactor. Secondly, taking KURSTY as the object, the system model of different insulation thickness schemes ( Case1-Case6 ) is built. Finally, the reactor behavior under the conditions of 0.6 $ reactivity startup, ±40 pcm reactivity introduction and ±50 % load change is studied, and the calculation results under different schemes are compared. [Results]: Among them, the energy output efficiency of case 6 is the highest, reaching 79.71%. Moreover, the influence of each working condition on the energy output efficiency of case 6 is also minimal. [Conclusions]: The results show that the efficiency of the reactor's energy output is higher when the number of gaps is increased between the core, the vacuum tank, the neutron reflecter and other structures, and the vacuum tank contains a thick insulation layer.