Analysis of KRUSTY reactor behaviour with OFELIA environment

Mathematical modeling plays a crucial role in designing and obtaining licenses for nuclear reactor cores, particularly when many physics are involved e.g. neutronics, thermomechanics, thermal hydraulics etc. This becomes even more significant for innovative reactors like KRUSTY, which uses unique heat-pipe cooling and Uranium-Molybdenum monolith blocks as fuel. KRUSTY serves as a testbed for future space reactors, where environmental conditions are harsh and human intervention is limited. The study analyzes the stationary behavior of the KRUSTY reactor considering the coupling between the neutronics and the thermal phenomena within the OFELIA environment. OFELIA is a Python-based open-source multi-physics environment based on OpenMC and FEniCSx codes. Despite its design simplicity, the analysis of the KRUSTY reactor requires an accurate evaluation of the temperature and power distribution inside the fuel structure in order to assess the reactivity feedback coefficient with high accuracy, allowing for the evaluation of passive safety and the autonomous load following capabilities of the reactor. In this regard, the coupling framework provided by OFELIA is essential. The results of the coupled model are evaluated and compared against the data obtained during the Kilopower project in order to verify the model and to assess the accuracy of the proposed simulation approach.