Preliminary Analysis of Criticality Safety for a Space Heat Pipe Reactor in the Event of Impact

Compared with other energy sources in space, space nuclear reactors (SNRs) offer advantages such as independence from solar radiation, wide power output range, and strong environmental adaptability, making them one of the ideal power supplies for deep-space missions including lunar/planetary surface bases and solar system boundary exploration. However, complex mission profiles endow SNRs with characteristics such as high mobility throughout their lifecycle and non-repairability. Consequently, their safety issues—particularly criticality safety—have emerged as key evaluation metrics directly tied to mission success or failure. This paper focuses on the criticality safety analysis of space heat pipe reactors (SHPRs) under impact accidents, conducted using ABAQUS/Explicit and OpenMC. Taking the Kilopower design concept as a case study, the criticality safety assessment was performed. First, core deformation following impact was analyzed. Subsequently, the criticality safety of the deformed core was calculated, and the influence of different impact conditions on criticality safety was investigated. The findings can provide valuable references for the overall design of SHPR power systems and the planning of engineering mission implementation.