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Title: Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium

Abstract

The yield of molecular hydrogen, as a function of nitric acid concentration, from the a-radiolysis of aerated nitric acid and sulfuric acid mixtures containing plutonium or americium has been investigated. Comparison of experimental measurements with predictions of a Monte Carlo radiation track chemistry model shows that, in addition to scavenging of the hydrated electron, its precursor, and the hydrogen atom, the quenching of excited state water is important in controlling the yield of hydrogen. In addition, increases in solution acidity cause a significant change in the track reactions that can be explained as resulting from scavenging of e aq - by H aq + to form H . While plutonium has been shown to be an effective scavenger of precursors of molecular hydrogen below 0.1 mol dm-3 nitrate, previously reported effects of plutonium on G(H 2) a between 1 and 10 mol dm -3 nitric acid were not reproduced. Modelling results suggest that plutonium is unlikely to effectively compete with nitrate ions in scavenging the precursors of molecular hydrogen at higher nitric acid concentrations and this was confirmed by comparing hydrogen yields from plutonium solutions with those from americium. Finally, comparison between the radionuclide, ion accelerator experiments and model predictionsmore » leads to the conclusion that the high dose rate of accelerator studies does not significantly affect the measured hydrogen yield. These reactions provide insight into the important processes for liquors common in the reprocessing of spent nuclear fuel and the storage of highly radioactive liquid waste prior to vitrification.« less

Authors:
 [1]; ORCiD logo [2];  [1];  [2];  [1];  [1];  [1]
  1. National Nuclear Lab. (United Kingdom)
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Manchester (United Kingdom)
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE), Fuel Cycle Technologies (NE-5)
OSTI Identifier:
1556122
Report Number(s):
INL/JOU-17-43864-Rev000
Journal ID: ISSN 1520-6106
Grant/Contract Number:  
AC07-05ID14517
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 122; Journal Issue: 9; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; 38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; Radiation Chemistry; Americium; Plutonium; Molecular Hydrogen; Nitric Acid

Citation Formats

Gregson, Colin R., Horne, Gregory P., Orr, Robin M., Pimblott, Simon M., Sims, Howard E., Taylor, Robin J., and Webb, Kevin J. Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium. United States: N. p., 2018. Web. doi:10.1021/acs.jpcb.7b12267.
Gregson, Colin R., Horne, Gregory P., Orr, Robin M., Pimblott, Simon M., Sims, Howard E., Taylor, Robin J., & Webb, Kevin J. Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium. United States. doi:10.1021/acs.jpcb.7b12267.
Gregson, Colin R., Horne, Gregory P., Orr, Robin M., Pimblott, Simon M., Sims, Howard E., Taylor, Robin J., and Webb, Kevin J. Thu . "Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium". United States. doi:10.1021/acs.jpcb.7b12267. https://www.osti.gov/servlets/purl/1556122.
@article{osti_1556122,
title = {Molecular Hydrogen Yields from the Alpha Self-Radiolysis of Nitric Acid Solutions Containing Plutonium or Americium},
author = {Gregson, Colin R. and Horne, Gregory P. and Orr, Robin M. and Pimblott, Simon M. and Sims, Howard E. and Taylor, Robin J. and Webb, Kevin J.},
abstractNote = {The yield of molecular hydrogen, as a function of nitric acid concentration, from the a-radiolysis of aerated nitric acid and sulfuric acid mixtures containing plutonium or americium has been investigated. Comparison of experimental measurements with predictions of a Monte Carlo radiation track chemistry model shows that, in addition to scavenging of the hydrated electron, its precursor, and the hydrogen atom, the quenching of excited state water is important in controlling the yield of hydrogen. In addition, increases in solution acidity cause a significant change in the track reactions that can be explained as resulting from scavenging of eaq- by Haq+ to form H•. While plutonium has been shown to be an effective scavenger of precursors of molecular hydrogen below 0.1 mol dm-3 nitrate, previously reported effects of plutonium on G(H2)a between 1 and 10 mol dm-3 nitric acid were not reproduced. Modelling results suggest that plutonium is unlikely to effectively compete with nitrate ions in scavenging the precursors of molecular hydrogen at higher nitric acid concentrations and this was confirmed by comparing hydrogen yields from plutonium solutions with those from americium. Finally, comparison between the radionuclide, ion accelerator experiments and model predictions leads to the conclusion that the high dose rate of accelerator studies does not significantly affect the measured hydrogen yield. These reactions provide insight into the important processes for liquors common in the reprocessing of spent nuclear fuel and the storage of highly radioactive liquid waste prior to vitrification.},
doi = {10.1021/acs.jpcb.7b12267},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = 9,
volume = 122,
place = {United States},
year = {2018},
month = {2}
}

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