b'Using CoupledMultiphysics-based modeling and simulation of molten salt reactors enable Multiphysics Tools toefficient design efforts and improved safety.Investigate Design- T he goals of this research were to: (1) perform first-of-a-kind, high-fidelity, transient modeling and simulation of molten salt reactors (MSRs); and limiting Criteria for(2) explore the impact of design choices on core behavior during an Molten Salt Reactors unprotected loss of forced cooling accident.The first phase of the project involved the direct coupling of the Griffin and Pronghorn codes. Griffin is the MOOSE-based reactor multiphysics code created by joining INL (Rattlesnake and MAMMOTH) and Argonne National Laboratory (Multigroup Cross section generation Code cross-sections and PROTEUS neutronics) capabilities. Pronghorn is a multi-dimensional, coarse-mesh, thermal-hydraulics TOTAL APPROVED AMOUNT:code for single-phase fluids. Both Griffin and Pronghorn are equipped to address the $111,723 over 1 year fundamental physics challenges posed by MSRs while keeping execution time below PROJECT NUMBER:an hour on a desktop computer. Coupling the two codes for multiphysics analysis of 20A1049-015 MSR concepts was demonstrated as part of this project.PRINCIPAL INVESTIGATOR:The second phase of the project involved testing the novel capabilities against an Sebastian Schunert open-source benchmark for MSR. The results agreed well with other solutions provided by alternative codes. The third phase of the project then implemented these capabilities CO-INVESTIGATORS: to a simplified MSR geometry and investigated the sensitivity of core design parameters Abdalla Abou-Jaoude, INL on the steady-state behavior of an MSR. The last phase of the project dealt with Nicolas Martin, INL design-limiting considerations for MSR, namely the impact of thermophysical property Paolo Balestra, INL uncertainties on safety performance issues. Due to the lack of existing capabilities to irradiate and conduct post-irradiation examination uncertainties on salt-based fuel and industry interest in high burnup salts, assessing allowable ranges in property uncertainties will be crucial to future MSR deployment. The project demonstrated a framework for evaluating the impact of thermophysical properties against multiphysics accident conditions in a MSR (e.g., unprotected loss of flow accident).Steady-state temperature (a) and velocity (b) distributions in a molten salt fast reactor obtained from the coupled multiphysics Griffin/Pronghorn 42 simulation with nominal material properties.'