ARI; Experimental and Computational Assessment of Unique Trace Elements and Isotope Ratios in Plutonium from Depleted Uranium Irradiated in Fast Reactor Blankets

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

1140018 (Chirayath). This project will use computational and experimental methods to determine whether it is possible to reliably predict and measure a unique intrinsic physical signature in weapons-grade plutonium (Pu) produced by certain reactor types. The particular reactors of interest are (a) fast breeder reactors (FBR) of the type under development in India and China, which employ depleted uranium in their core blankets and (b) CANDU-type reactors fueled by natural uranium. Both of these reactor types in India will likely be operating in non-safeguarded circumstances in the future. When the developmental FBRs in India and China (and perhaps elsewhere) begin operating in the near future, it would be useful for the DNDO?s global nuclear detection architecture to understand the details of a potentially unique ?fingerprint? associated with Pu produced from depleted uranium in the FBR blankets. It would also be helpful to have a similar understanding of potentially unique identifying characteristics of Pu generated in CANDU power reactors when the fuel is ejected with lower than standard burn-up. Detailed understanding of these unique characteristics, such as the Pu isotope content, signatures of uranium, fission product, and trace elemental residues after chemical processing of Pu separation would aid nuclear forensics activities aimed at source attribution in the case of interdicted smuggled plutonium (pre-detonation material) as well as to some extent for post-detonation analyses. The main thrust areas of the project are: [1] Computational modeling of FBR and CANDU reactors to generate isotopic signatures through nuclide inventory estimation in used fuel, [2] Neutron irradiation of uranium dioxide (UO2) fuel pellets in fast spectrum (to simulate FBR) and thermal spectrum (to simulate CANDU) at ORNL-high flux isotope reactor (HFIR) for experimental validation of computed results of thrust area 1, and [3] Experimental investigations of irradiated UO2 pellets through chemical separations of plutonium from fission products and uranium and its characterization using destructive and non-destructive analyses. Features of the project include: (1) fingerprinting weapon-grade plutonium produced in fast reactor blankets and thermal reactor low-burned fuel, (2) experimental validation of weapon-grade Pu fingerprint originating from unique nuclear fuel cycles, (3) development of a national nuclear forensics capability for targeting weapon-grade plutonium produced from low burned fuel assemblies in foreign nuclear fuel cycles, (4) plutonium separation from fission products and uranium using PUREX and its characterization by destructive and non-destructive analyses will be highly valuable to teach and demonstrate to graduate and undergraduate students, (5) mentor, educate and support postdoctoral researcher, graduate and undergraduate students, (6) publications through student presentations in technical conferences and scholarly publications.