Neutronic Evaluation of a Liquid Salt–Cooled Reactor Assembly

Abstract

This study presents a thorough parametric neutronic analysis of a plate-based tristructual isotropic (TRISO) fuel particle bearing liquid salt–cooled reactor assembly. The analyses presented investigated the effects of altering fuel enrichment, packing fraction, plate region thicknesses, assembly structure thicknesses, assembly size, numbers of plates per assembly, use of burnable poison materials, replacement of assembly and plate carbon material with silicon carbide, and use of uranium nitride fuel kernels. The effects or trends observed included reactivity behavior, discharge burnup, cycle length, and other key design parameters such as moderator temperature coefficients, coolant density coefficients, control blade worth, and impacts upon power peaking (i.e., power and flux distributions).

This study is based upon two-dimensional lattice physics calculations involving the SERPENT 2 code and by using the nonlinear reactivity model as a reasonable tool for predicting discharge burnup. The reported results show that the system’s reactivity can be significantly altered by varying these design parameters, thus providing a starting point for future design optimization studies, and it is understood that future studies will need to be expanded to equilibrium full core analysis for more complete and accurate design and safety assessments, which is also a work in progress.

Keywords:

• TRISO particles
• FLiBe
• liquid salt–cooled reactor

Acknowledgments

This research is being performed using funding from the U.S. Department of Energy (DOE) Office of Nuclear Energy’s Nuclear Energy University Programs (NEUP) under grant NEUP 12-3870, SRC 00128483 under prime contract DE-AC07-05ID14517.

This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under contract DE-AC05-00OR22725.

We also acknowledge Jaakko Leppänen for his prompt and exemplary support with any SERPENT-related questions or issues.