Assessment of Material Attractiveness in Light Water-Based Reactors: Evaluating Plutonium Isotope Composition and Burnup Impact on Proliferation Risk

The assessment of nuclear safety and the potential risks associated with proliferation is a critical area of research in the context of nuclear energy utilization. This study focuses on evaluating the Material Attractiveness (ATTR) in several light water-based reactor designs, specifically NuScale, ESBWR, BWRX-300, and PWR, both during reactor operation and post-operation. The analysis employed Origen 2.2 for modeling radioactive decay and MCNP4C for assessing material attractiveness. The findings reveal an increase in the production of plutonium isotopes, with the exception of Pu-239, which decreases as a result of the fission. Initially, the Pu-240 composition across all four reactors is classified as Super-grade plutonium. However, with increased burnup, the Pu-240 composition transitions to a reactor-grade plutonium level. At the initial of irradiation, the ATTR values were determined to be 0.19 for the ESBWR, 0.20 for the PWR, 0.16 for the BWRX-300, and 0.21 for NuScale, categorizing them within the weapon-grade range. By the end of reactor operation, these values had significantly decreased, with ESBWR at 0.0125, PWR at 0.0148, BWRX-300 at 0.0111, and NuScale at 0.0133, placing them in the un-usable grade category. This marked reduction in ATTR values, correlated with increased burnup, indicates an effective decrease from weapon-grade to un-usable grade by the end of the reactor^s operational period. This trend is primarily influenced by the increased production of isotopes Pu-238, Pu-240, Pu-242, and the corresponding decrease in Pu-239, the primary fissile material.