NEAMS Activities Supporting Mechanistic Source Term Model Development for Molten Salt Reactors

As vendors of MSR technology enter the reactor licensing process, the determination of an appropriate and accurate source term will be central to the approval of the design by the U.S. NRC. The Multiphysics Applications technical area under the NEAMS program within DOE-NE is supporting development of mechanistic source term (MST) modeling and simulation tools to assist in the licensing process for advanced (non-LWR) reactors. Additional activities such as assessing and demonstrating multiphysics coupling of NEAMS-developed tools for MSRs are also ongoing. Multiphysics simulations can directly support licensing activities such as with transient analyses or indirectly by providing initial or boundary conditions to radionuclide (RN) transport analyses. Such efforts under NEAMS are complementary to the development of the accident analysis tool MELCOR by Sandia National Laboratories as indicated in a DOE-NRC Memorandum of Understanding to jointly advance the state of MST modeling and simulation tools for advanced reactors. Four specific tasks supporting MST development are ongoing, including an uncertainty quantification and sensitivity analysis (UQSA) study on the MSTDB-TC thermochemical properties database for molten salt mixtures, the development of salt aerosol modeling correlations based on experimental data generated from salt spill experiments, (3) a UQSA study on tritium within the reactor systems, and (4) the calculation of the RN inventory in auxiliary (ex-core) systems transport such as the off-gas system. An overview is also provided of the types of multiphysics simulations that are being demonstrated within the NEAMS program, such as the coupling of neutronics tools with thermal hydraulics and chemistry modeling tools.