Equilibrium core design methods for molten salt breeder reactor based on two-cell model

Abstract

Two unit-cell-based core design methods are presented for a molten salt breeder reactor (MSBR) equilibrium core with online reprocessing and refueling: a single-cell method and a two-cell method. The single-cell method adopts a representative single unit cell which has the same fuel-to-moderator volume ratio as the average value of an MSBR core which actually consists of two zones with different ratios. The two-cell method uses two representative unit cells, one for each zone, with each zone having the appropriate fuel-to-moderator ratio. It is demonstrated that the two-cell-based method is able to catch the neutron physics of spectral interaction of the two zones with different neutron energy spectra, whereas the single-cell method cannot accurately predict the breeding ratio nor the resonance escape probability of the MSBR core. A new code system was established using MCNP6/PYTHON script language for modeling of the online reprocessing of molten fuel, and the depletion and online refueling of the MSBR core.