Development of an SP3 neutron transport solver for the analysis of the Molten Salt Reactor
The aim of this paper is the extension of a multiphysics OpenFOAM solver for the analysis of the Molten Salt Fast
Reactor (MSFR), developed in previous works (Cervi et al., 2017, 2018). In particular, the neutronics sub-solver
is improved by implementing a new module based on the SP3 approximation of the neutron transport equation.
The new module is successfully tested against a Monte Carlo model of the MSFR, in order to assess its correct
implementation. Then, a neutronics analysis of the MSFR is carried out on a simplified axial-symmetric model of
the reactor. Particular focus is devoted to the analysis of the MSFR helium bubbling system and its effect on
reactivity. The presence of bubbles inside the reactor is handled with a two-fluid thermal-hydraulics module,
previously implemented into the solver. The void reactivity coefficient is evaluated on the basis of the bubble
spatial distribution calculated by the multiphysics solver. Then, the results are compared to simulations carried
out with uniform bubble distributions, highlighting significant differences between the two approaches. The
outcomes of this work constitute a step forward in the multiphysics analysis of the Molten Salt Fast Reactor and
represent a useful starting point for the optimization of the MSFR helium bubbling system, as well as for the
development of appropriate control strategies.