Tag: nuclear forensics

Originally for my project this summer I wanted to try to model the IR-40 pressurized heavy water reactor (PHWR) to test if the thermohydraulics of the reactor were still sound even at an enrichment level different from the natural uranium design. Ultimately my project was changed and now I am going to be researching minor uranium isotopes. These are a few brief comments on what I hope to learn and accomplish from this research project.

Uranium enrichment today is done one of two major ways, gaseous diffusion and centrifugation. These two processes take uranium in the gaseous uranium-hexaflouride form (UF6) and use the (slight) mass difference between uranium 235 (U-235) and uranium 238 (U-238) to separate the isotopes and enrich the percentage of U-235 per unit mass of total uranium metal. The significance of this information is that in nature another isotope exists: U-234. This isotope due to being significantly smaller than the U-238 atoms, tends to “stick” with the U-235 during enrichment. In reprocessed uranium fuel several different isotopes are created through irradiation and decay. These include U-232, U-233, and U-236 in addition to the U-234 already present in the system. While these isotopes increase the complexity of the system when it comes to separation for enrichment, they have potential nuclear forensic applications.

In binary systems and models we would only deal with separating U-235 and U-238, unfortunately this is an oversimplified model given the previously stated information. In order to more accurately and realistically model the enrichment of natural or reprocessed uranium a model must be used that takes into account the multiple species that are present in the system. Using this information I aim to answer if it is possible to use the minor isotopes to determine the enrichment capabilities of a state and can it be attributed to a state in the case of smuggled material all by the concentrations of the minor isotopes in either the product stream or the tails. In order to do so I am researching mathematical models of isotope enrichment per stage in a cascade and computing the separation factors of each species and unit.

Ultimately I aim to assess the feasibility of using these minor isotopes as a “forensic fingerprint” by identifying the separation processes and the effects the different feeds can have in the minor isotope concentrations at different parts of the enrichment cycle.

-Cervando Banuelos is currently a Nuclear Safeguards Intern at Lawrence Livermore National Laboratory, a Graduate Research Assistant at the Monterey Institute of International Studies where he is currently pursuing a master’s of arts in nonproliferation and terrorism studies, and holds a bachelor’s of science degree in nuclear engineering, with a minor in radiological health engineering, from Texas A&M University. His interests include passive cooling systems in boiling water reactors, nuclear forensics, arms control treaties, treaty verification, and steaks wrapped in bacon. He hopes to some day work for the United Nations, a national laboratory, or the CTBTO.