Cell-Wise Temperature and Deformation Reactivity Feedback Modeling in Heat Pipe-Cooled Microreactors

The compact design of microreactors can potentially lead to a strong interdependence between neutronics and thermo-mechanics, making the development of coupling methodologies essential to quantify the importance of such effects. This study introduces a high-fidelity thermo-mechanical-neutronics coupling approach, applied to a heat-pipe-cooled microreactor (HPM) inspired by the eVinci microreactor design. The methodology combines the OFFBEAT finite volume fuel perfor-mance code, based on OpenFOAM, with the Serpent2 Monte Carlo particle transport code. The primary objective is to validate the coupling approach and evaluate the impact of key such as the Doppler effect and thermal expansion, on the neutronics behavior of these systems. phenomena, High-fidelity results are achieved by exchanging critical fields-temperature, deformation, density, and power density-on a cell-by-cell basis within the unstructured mesh, allowing for an accurate representation of core heterogeneities. Additionally, the study incorporates a heat pipe model, which simulates heat transfer within the vapor core by approximating it as heat conduction, leveraging a correlation specifically developed for effective thermal conductivity. This integrated approach enables a detailed assessment of the thermo-mechanical and neutronics interactions, advancing the understanding of these complex systems.