Reduced order modeling for coupled thermal-hydraulics and reactor physics problems

The development of a new generation of reactor presents several modelling challenges that cannot be effectively addressed by traditional tools used for Light Water Reactors. Multi-physics approaches allow for a comprehensive modeling of reactor cores, as they intrinsically couple the involved physics (i.e. fluid-dynamics, heat transfer, neutronics, thermo-mechanics), but require intense computational efforts that preclude their use in reactor control applications. This work aims at applying a Reduced Order Model (ROM) technique to multi-physics modelling. Such objective is achieved through a ROM technique previously used for Navier-Stokes equations and thermal-hydraulics problems (POD-FV-ROM). The technique used in this article, is built on a modeling framework developed ad-hoc for the Finite Volume (FV) scheme and relies on the Proper Orthogonal Decomposition (POD) and the Method of Snapshots. The reduced order multi-physics approach outlined in this work has been tested with success on a Lid-Driven-Cavity-based homogeneous reactor model. Reduced-order simulations have reproduced accurately the full order velocity, temperature, neutron flux and precursor concentration fields, resulting in relative L2 norms of the differences between full order and reduced order simulations below 1 % for all the considered fields.