M. Jackson, “Analysis of the Nuclear Nonproliferation Advantages in Multiple Recycling of Used Nuclear Reactor Fuel by Considering U-236 and Pu-238 Buildup”, M.S. Thesis, Nuclear Engineering, Texas A&M University, College Station, TX (2022).
The proliferation resistance enhancement of utilizing re-enriched reprocessed uranium due to accumulation of 236U and 238Pu was investigated. This study is expected to prove the theory that recycling the bulk of uranium in the used nuclear fuel can be an effective role in nonproliferation, specifically for prevention of uranium and plutonium use in weapons by the non-weapons states. The reprocessed uranium has higher concentrations of 236U in relation to natural uranium fuel. As the recycling process repeats it increases the number of other isotopes, specifically 238Pu. A higher concentration of this isotope can render the fuel mute to produce weapons. Additionally, besides decreasing material attractiveness by denaturing plutonium, this recycling process discourages the production of highly enriched uranium. This is due to the difficulty of only enriching 235U without enriching 234U and 236U in the fuel. This study was conducted using simulations of reactor fuel (re-enriched reprocessed uranium) irradiation by employing a Monte Carlo N-Particle Transport code, MCNP6.2. The study showed that utilizing re-enriched reprocessed uranium can decrease the proliferation risk in a closed fuel cycle operation scenario. The mathematical uranium enrichment process employed in this study was based on Matched Abundance Cascade Ratio (MARC) model, which uses a multicomponent mixture enrichment. The multicomponent separation is applied since there is an increased amount of 234U, as well as other isotopes of uranium.