Conceptual Design of Temperature-Controlled Fueled-Salt Irradiation Experiment to Support Demonstration of Advanced Nuclear Reactors

Irradiation testing of fuel-bearing molten salts is critical for supporting the development and demonstration of molten salt reactors (MSRs). These experiments can inform several important reactor design and safety parameters, including source term modeling, the evolution of thermophysical properties with burnup, and the degradation of structural materials under reactor-relevant conditions. Idaho National Laboratory is designing an instrumented and heated high-temperature molten-salt-fueled irradiation capsule to study the behavior of the fuel salt during in-pile irradiation. This paper details the neutronics, thermal, and mechanical analyses performed to date. Parametric studies were performed to assess a range of materials, different experiment dimensions, two in-reactor positions, and the fuel enrichment used. The principal recommendations are to select a peripheral reactor position in order to alleviate neutronic constraints, a thin salt annulus to achieve thermal design objectives, and high-temperature alloys that provide additional safety margins.