Analysis of the Effect of Fuel Compressibility on Super-Prompt-Critical Dynamics of the Molten Salt Fast Reactor

The Molten Salt Fast Reactor (MSFR) is a next generation nuclear reactor in which a mixture of molten salts acts at the same time as fuel and as coolant. This reactor offers interesting characteristics of safety and sustainability, raising at the same time new technological challenges, that need to be addressed with suitable simulation tools, tailored on the specificities of this innovative system. In this work, an OpenFOAM solver for the MSFR developed in a previous work [1] is applied to the analysis of the MSFR dynamics, with a particular focus on super-prompt-critical transients. The results point out that the fuel mixture compressibility plays a crucial role in the time evolution of these transients, introducing delays in the expansion feedbacks that strongly affect the dynamics behavior of the system. The outcomes of this analysis represent a starting point for further research on the MSFR, with a particular focus on the reactor safety during accidental super-prompt-critical scenarios.