Design and Neutronic, Thermal-Hydraulic Analysis of DSCF Assembly for a SMR and Investigation of the Effect on the Thermal Power Uprate

Small modular reactors (SMRs) can be a significant option for developing countries with low energy demand. Due to the lack of sufficient experience in the field of SMRs, extensive research should be done on SMRs to improve the performance of these systems. Using dual surface-cooled fuel (DSCF) is one of the methods that can increase the performance of SMRs. In this study, for the first time the core of a NuScale reactor (as a SMR) is designed based on DSCF without any change in core dimensions by analyzing neutronic, thermal-hydraulic, and natural circulation parameters. In addition, according to the departure from nucleate boiling ratio, the uprate of the thermal power in a reactor using DSCF is investigated. For this purpose, typical solid fuels as well as DSCFs under clean-cold and full-power conditions are primarily modeled for the four different lattices that maintain the same assembly dimensions, mass, and enrichment fuels as the original fuel assembly. The effective multiplication factor, and power peaking factor, as important neutronic parameters, are calculated. Then the departure from nucleate boiling, pressure drop, velocity, and temperature distribution calculations, as important thermal-hydraulic and natural circulation parameters, are accomplished via a computational fluid dynamics code. The best core configuration of DSCF for the NuScale core is determined based on comparing the neutronic, thermal-hydraulic, and natural circulation parameters of various lattices and typical solid fuels. Regarding the final result, a DSCF assembly configuration, called a 12 × 12 assembly, is suggested.