Explore the potential advantages of replacing UO2 with different thorium-based fuels in U.S. SCLWR

This work searches for enhancing the efficiency of the supercritical light water reactor SCLWR by introducing different fuels based on thorium as an alternative fuel to conventional fuel. United States fuel assembly model of SCLWR has been modeled using Monte Carlo code MCNPX, ed. 2.7. The burnup results, k_inf, fuel composition and most importantly actinides and non-actinides have been examined and compared with that of the UO₂. The neutronic safety coefficients such as reactivity temperature coefficient and control rod worth have been calculated for the suggested fuel cycles. Also, the radial and axial neutron flux as well as power distribution have been analyzed to verify the validity of the proposed fuels. Assessment results demonstrate the viability of the proposed fuel. Reactivity measurements indicate that the introduced fuels have an economic benefit as using ²³²Th with ²³³U as a fuel increased the fuel cycle by 140 EFPD compared to the standard fuel cycle of UO₂. The reactivity temperature coefficients show that the proposed fuel provides a suitable level of passive safety as the fuel temperature coefficient (FTC) and the moderator temperature coefficient (MTC) values of the investigated fuel range from −1.32 to −3.34 pcm/K and −8.8 to −25.9 pcm/K, respectively. The power distribution indicates that there will be no melting of the fuel. This is because the power is not accumulated in specific fuel rods for the investigated fuels. The analysis of actinides concentrations shows that SCLWR is a good consumer of rgPu where it consumed more than 69% of the rgPu used in the fuel at the beginning of the fuel cycle.