Progress in Uranium Chemistry: Driving Advances in Front-End Nuclear Fuel Cycle Forensics

Abstract

The front-end of the nuclear fuel cycle encompasses several chemical and physical processes used to acquire and prepare uranium for use in a nuclear reactor. These same processes can also be used for weapons or nefarious purposes, necessitating the need for technical means to help detect, investigate, and prevent the nefarious use of nuclear material and nuclear fuel cycle technology. Over the past decade, a significant research effort has investigated uranium compounds associated with the front-end of the nuclear fuel cycle, including uranium ore concentrates (UOCs), UF 4 , UF 6 , and UO 2 F 2 . These efforts have furthered uranium chemistry with an aim to expand and improve the field of nuclear forensics. Focus has been given to the morphology of various uranium compounds, trace elemental and chemical impurities in process samples of uranium compounds, the degradation of uranium compounds, particularly under environmental conditions, and the development of improved or new techniques for analysis of uranium compounds. Overall, this research effort has identified relevant chemical and physical characteristics of uranium compounds that can be used to help discern the origin, process history, and postproduction history for a sample of uranium material. This effort has also identified analytical techniques that could be brought to bear for nuclear forensics purposes. Continued research into these uranium compounds should yield additional relevant chemical and physical characteristics and analytical approaches to further advance front-end nuclear fuel cycle forensics capabilities.

Oxygen Kinetic Isotope Effects in the Thermal Decomposition and Reduction of Ammonium Diuranate

“…1,3,4,9 T h i s c o n t e n t i s The fabrication route utilized to produce UO 2 fuel pellets for use in a reactor can depend upon the type of reactor the fuel is destined for. 10 A heavy water-moderated reactor, for example, may employ a uranium fuel of natural isotopic composition (99.3% 238 U, 0.7% 235 U, trace 234 U), while a light watermoderated reactor generally requires an enrichment of the fissile isotope, 235 U. 11 Fabrication of UO 2 can occur following either dry or wet routes.…”

Synthesis and structure of metal-TCPE (metal = Th, Ce) metal-organic frameworks based on 1,2,4,5-tetrakis(4-carboxyphenyl) ethylene

“…Actinides are by-products of spent fuel reprocessing, recycling and separation. Due to the unfilled 5f and 6d electron shells, the physical and chemical properties of actinides are unique [ 1 – 3 ], which attracts scientists worldwide to study compounds of tetravalent actinides including thorium, uranium and plutonium [ 4 , 5 ]. Yet, due to the complexity of their chemistry, the structure, chemical bonding nature and reaction mechanisms of these compounds are still not fully understood [ 6 , 7 ].…”

Structural Characterization of Uranium Tetrafluoride Hydrate (UF4·2.5H2O)

“…Improving understanding of the chemical and physical characteristics of nuclear materials remains an important goal in nuclear nonproliferation, nuclear forensics, and nuclear fuel cycle science. − Within these domains, recent focus has been given to characterizing environmentally relevant changes in nuclear materials caused by exposure to atmospheric water vapor, UV light, or precipitation. Recent efforts investigated several fuel cycle-relevant uranium compounds and identified changes in chemical speciation and morphology when these compounds are exposed to various environmental conditions. − Concerning the nuclear fuel cycle, environmentally driven alterations can affect the processability of uranium materials.…”