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DOE OSTI · 3376113

Experimental and Multiscale Modeling Insights for Radiation-Driven Neptunium Redox Processes at Elevated Temperatures

Kynman, Amy E. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000345325792)·Grimes, Travis S. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000327510492)·Mezyk, Stephen P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States); California State University, Long Beach, CA (United States)] (ORCID:0000000178381999)·Layne, Bobby [Brookhaven National Laboratory (BNL), Upton, NY (United States)]·Cook, Andrew R. [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000166333447)·Horne, Gregory P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000305960660)
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Abstract

Studies of the radiation-driven reactions of actinide elements at elevated temperatures are extremely limited, but important given that radiation heating of used nuclear fuel can affect the radiolytically promoted actinide redox processes occurring in hydroprocessing environments. Under these conditions, the high concentration of nitric acid present makes the reaction of actinides, such as neptunium, with nitric acid radiolysis products significant. Therefore, here we present derivation of the rate coefficients for the reaction of pentavalent neptunium with the nitrate radical at elevated temperature, resulting in Eyring and Arrhenius parameters for this important reaction. Here, we also revisit our previously published multiscale model predictions for radiation-induced neptunium redox chemistry and present an iteration which successfully operates over a wider range of nitric acid concentrations, 0.1–6.0 M.

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38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRYDissociationInorganic acids and basesOxidationRedox reactionsThermodynamic properties

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Kynman, Amy E. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000345325792), Grimes, Travis S. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000327510492), Mezyk, Stephen P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States); California State University, Long Beach, CA (United States)] (ORCID:0000000178381999), Layne, Bobby [Brookhaven National Laboratory (BNL), Upton, NY (United States)], Cook, Andrew R. [Brookhaven National Laboratory (BNL), Upton, NY (United States)] (ORCID:0000000166333447), Horne, Gregory P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:0000000305960660). 2026-06-25. Experimental and Multiscale Modeling Insights for Radiation-Driven Neptunium Redox Processes at Elevated Temperatures. https://doi.org/10.1021/acs.jpca.6c01267

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