Multiphysics and multiscale simulation for an experimental sodium-cooled fast reactor

This work aims to explore a new upscaling methodology to describe heat transfer simultaneously coupled with the neutronic process, in the core of a sodium-cooled reactor. The upscaling method, as demonstrated in this work, allows the development of models that describe reactor-scale phenomena, starting at the scale of a cell, composed of a nuclear fuel pin and liquid metal. In principle, this methodology allows high fidelity in the description of these multiphysics and multiscale phenomena. The main result is the two-upscaled energy no- equilibrium model to describe the temperature distribution of the fuel and coolant. These upscale models are described in terms of the upscaled heat transfer coefficient, which is presented and developed in this work, for the Experimental Sodium-cooled Fast Reactor. The use of the new proposed models/methodology leads good results within lower computational times compared with CFD codes, which is useful when computations have to be done a large number of times, for instance for sensitivity analyses to parameter choices in the conception phase of the reactor, and other applications such as plant analyzers, and for operator training in full-range simulators.