Sensitivity of Thermo-Physical Salt Property Changes on Reactor Equilibrium for Salt-Cooled Pebble Bed Reactors

The use of molten salt in high-temperature reactors enables better heat extraction while avoiding the need to pressurize the primary loop.However, impurities will accumulate in the molten salt during operation due to mechanism such as corrosion.These impurities affect the thermo-physical properties of the molten salt as density, heat capacity, thermal conductivity, and viscosity, which can yield drifts in the operational margins.Due to the multiphsyics coupling in the molten salt, quantifying the potential effect of thermo-physical property changes on the global reactor behavior is only possible using a baseline multiphysics model that couples the neutronics and thermal-hydraulics reactor response.Then, this model can be used for the prediction of the reactor response to salt property changes to adapt the operational conditions and the safety margins according to the evolution of the equilibrium state.This investigation is especially focusing on pebble bed reactor using molten salt as coolant.A baseline model for a Fluoride-Salt-Cooled High-Temperature Reactor has been previously developed using Idaho National Laboratory's Multiphysics Object-Oriented Simulation Environment (MOOSE).This model is then used to quantify the extent to which perturbations in the thermophysical properties will affect reactor operation.This work paves the way for a model including corrosion and its effect on reactor behavior.