Analysis of Criticality and Reactivity Control of NuScale Fuel Assemblies

A hopeful development for the nuclear industry's future is NuScale's Small Modular Reactor (SMR), which is based on the Pressurized Water Reactor (PWR) architecture. NuScale has more flexibility because to its modular architecture and 160 MW thermal power output. Using the ENDF/B-VII library and the MCNP6 code, this study examines the criticality and reactivity characteristics of the NuScale fuel assembly. The findings indicate that, in comparison to other types, type D fuel assemblies, which include fuel pins composed entirely of UO2 and devoid of Gd2O3, have the highest criticality. Because of the Doppler broadening impact on the resonance area of the U238 capture cross-section, which has the highest concentration in this region, fuel assembly type C also has the largest negative Doppler Temperature Coefficient (DTC). Fuel assembly type D has the lowest Moderator Temperature Coefficient (MTC) of any assembly type. Overall, by thoroughly assessing the criticality and reactivity characteristics, our work provides a strong foundation for future neutronic exploration of the whole NuScale reactor core.