Education and Training Series #88: Multiphysics Depletion & Chemical Analyses of Molten Salt Reactors

These webinars, organised by the GIF Education and Training Working Group are streamed live monthly. The recordings and slide decks are accessible after the webinar on this website. These webinars cover a very broad range of technical and policy related topics. At the end of 2023 they have been viewed by more than 15000 people (approximately half of the views during the live streams and the other half views being of the archives on the public GIF website). In total, the GIF webinars have reached Generation IV enthusiasts, scientists, and engineers in more than 80 countries.

These webinars are organised and hosted by the GIF Education and Training Working Group (ETWG). 

Molten Salt Reactors (MSRs) are an innovative Generation-IV reactor concept which use nuclear fuel dissolved in a high temperature liquid salt and allow for enhanced safety and economic performance. The liquid fuel feature also entails several multiphysics effects that can complicate reactor design. One primary effect, coined here as depletion-driven thermochemistry, is the changing chemical redox potential of the fuel salt due to chemical composition changes driven by depletion. As the fuel is consumed and fission products are formed, the redox potential of the fuel salt shifts toward a more oxidizing state. Without active control, the changing chemistry can have multiple effects on the multiphysics behavior of the reactor that are important for both steady state operation and for accident scenario transients. A new multiphysics framework capability developed at Idaho National Laboratory can now simulate these coupled processes occurring in MSR systems during depletion including neutron transport, nuclide generation, thermal hydraulics, thermochemical equilibrium, chemical species transport, corrosion, and active chemistry control. The application of this work includes modeling source term, decay heat removal, reactivity transients, corrosion, chemistry control, and safeguards analyses. Future work focuses on validation efforts by defining a thermochemical benchmark against the Molten Salt Reactor Experiment (MSRE) and future digital twins of near-term experiments.