Speaker
Description
As energy demands increase due to technological advancements like data centers and AI-technology, discussion surrounding the reprocessing of used nuclear fuel has been escalating. The US is at risk of undermining its status as a world leader in nuclear by having no clear plan to deal with the nearly 100,000 MTHM of used nuclear fuel currently in interim storage. An expansion of the well-known Actinide Lanthanide SEParation (ALSEP) in the form of a two-cycle, single-solvent flowsheet termed Group Actinide Separation Process (GrASP) is a modern answer to UNF reprocessing in the US.
The solvent in GrASP is comprised of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and N,N,N′,N′-tetra(2- ethylhexyl)diglycolamide (T2EHDGA). To start the first cycle, the UNF feed solution is treated with the common carboxylic acid trans-1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid (CDTA), suppressing zirconium and palladium extraction. Acetohydroxamic acid (AHA) and hydrogen peroxide are used to reduce neptunium to Np(IV), ensuring its extraction with uranium and plutonium. Molybdenum and technetium are scrubbed after the initial extraction, leaving only U, Pu, and Np in the loaded solvent. A group actinide strip solution strips >99% of Pu and Np, with a tunable fraction of U. The remaining U is then stripped with phosphoric acid or a carbonate solution.
The second cycle of GrASP closely resembles ALSEP. The initial raffinate is contacted with the stripped solvent and has been demonstrated to perform as well as fresh solvent based on Eu/Am separation factors. Inductively coupled plasma mass spectroscopy and optical emission spectroscopy (ICP-MS and OES) were used to determine the behavior of the stable fission products during extraction and scrub steps. Liquid scintillation counting (LSC) was used to obtain D-ratios for the major actinides.
GrASP provides several advantages over traditional reprocessing schemes. The efficient management of Np, Tc, and the trivalent actinides has historically remained elusive, but GrASP effectively handles theses problematic elements. Additionally, the lack of an isolated Pu stream contributes to proliferation resistance. Finally, the single-solvent nature increases safety by reducing the complexity of the process and may reduce build costs by reducing necessary tank storage for reprocessing plants.