Capturing multiphysics effects in hydride moderated microreactors using MARM

•Hydride moderator multiphysics effects in microreactors.•3D finite element based steady state neutronics, heat transfer, and hydrogen diffusion analysis.•MCNP and Abaqus based Reactor Multiphysics (MARM) framework.•Additional R&D for steady-state and transient analysis needed for microreactor deployment. High temperature hydrides are being considered as neutron moderators for LEU microreactor systems due to their ability for creating a compact core with minimum loading of a fissile material. Under the influence of a temperature gradient, hydrogen in metal hydrides is prone to diffusion. This migration of hydrogen during the reactor operation results in local changes in moderator material properties; such as changes in neutron cross sections leading to changes in power and temperature distributions. High fidelity multiphysics modeling is required to properly understand the reactor dynamics during its operation. MCNP, a Monte-Carlo based particle transport code, and Abaqus, a finite-element engineering simulation software, are used to develop a multiphysics framework named MARM for high temperature reactor analysis. MARM is short for MCNP and Abaqus based Reactor Multiphysics software package being developed at the Los Alamos National Laboratory. This suite of codes is aimed to enable multiphysics analysis for full core applications by incorporating neutronics, heat transfer, and mass diffusion solutions. This paper demonstrates the significance of capturing multiphysics effects in a hydride-moderated reactor system. This paper also provides an outline of MARM multiphysics development and its future plans.