Steady-state analyses of an smDFR with coupled Serpent-OpenFOAM calculation

Abstract

The small modular dual fluid reactor (smDFR) adopts a mixture of liquid uranium and plutonium chloride as fuel, with lead as a coolant. With its smaller size, lower weight, and inherent safety, the smDFR can be used as a mobile energy supply for vehicles or ships. Analyses of the smDFR are still in the early stage based on a single or separated physical field, which can hardly capture the impact of the flowing fuel on the neutron field. The coupled neutronic-fluid dynamic calculation is needed for reliable multidimensional, multi-field distribution of the steady-state smDFR core property. In this work, the Monte Carlo code Serpent 2 and the CFD code OpenFOAM are coupled via a Python interface, whereby the neutron field information can be exchanged with the fluid field in a region-average manner. The correctness and reliability of the coupled code are verified with two cases in the pressurized water reactor background, and the results show good agreement. The coupled code is applied to the steady-state analyses of an smDFR, a single-channel case, and a 1/6-core case. The results show that the temperature distribution of the fuel and coolant caused a lower drift of the axial power peak compared to the uncoupled cosine shape power distribution. The 1/6-core results show that the peak temperature of the fuel reaches 980 K at the top-center of the reactor core. Moreover, the influence of fuel thermal properties and inlet velocity are studied with rated power. Through the comparison of mapping schemes, the results can identify the dependence of specific parameters and help to reduce mapping errors. This work shows that through a coupled neutronic-CFD code, the multidimensional and multi-physical fields of the smDFR can be better represented, providing important references for the future design and analyses of smDFR systems.