Neutronics feasibility of an MIT Reactor-driven subcritical facility for the Fluoride-salt-cooled High-temperature Reactor

The current study explores an innovative option for demonstrating the Fluoride-salt-cooled High- temperature Reactor (FHR) technologies with a reactor-driven subcritical facility. The FHR uses clean salt coolants, carbon-matrix coated-particle fuel similar to that used in High-temperature Gas-cooled Reactors and can be coupled to a nuclear air-Brayton combined cycle. Recent assessments indicate favorable economics and safety characteristics, but no FHR has been built. The question is what experimental facilities should be constructed to reduce technical uncertainties before a decision to build a test or demonstration reactor? The MIT Reactor design and license would allow the construction and operation of a subcritical facility with 700 degrees C salt circulating through multiple full-width partial-height fuel assemblies operating with a power density up to 60% of a commercial FHR. This option would allow hot systems testing as a major step toward building the test or demonstration reactor. Preliminary system design, power control options, testing capabilities, and key nuclear characteristics of such a reactor-driven subcritical facility are described. A method of deriving subcritical multiplicity using surface source has been proposed and verified in this study. Finally, the neutronic impacts on the driver facility, ie, the MIT Reactor, have been evaluated.