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Title: Interactions of HCl and H2O with the surface of PuO2

Abstract

In order to explore the potential of heat treatment to decontaminate chloride-contaminated legacy plutonium dioxide (PuO2) powders from the UK stockpile, samples retrieved from storage have been heated in air from 400 to 950 C. These samples also contain high levels of other adsorbed gases from the atmosphere, including water. The amounts of chloride remaining on the PuO2 particles after heat treatment (measured by a caustic leaching process) decrease whilst the amounts of volatilised chloride increase with increasing heat treatment temperature. Clear evidence for a non-leachable (strongly bound) chloride species on the PuO2 surface is found from the thermal treatments. The lattice parameter decreases with increasing heat treatment temperature, reflecting annealing of structural defects caused by over 35 years of radiation damage, with no change in the fcc Fm3m crystal structure. Heating chloride-contaminated PuO2 powder to ~230 C and cooling back to ambient temperature in a sealed vessel reveals the production of H2, He, NO and CO gases. Water adsorption/desorption behaviour with the untreated PuO2 powder is remarkably different than PuO2 which had previously been heat treated at 700 C. From thermal treatments in open and sealed systems it is concluded that water and chloride coadsorb and interact on themore » PuO2 surface and each affects the adsorption/desorption behaviour of the other. These data also support practical considerations for repackaging of chloride-contaminated PuO2 for long term safe and secure storage at Sellafield.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [5];  [1]
  1. University of Manchester
  2. UNIVERSITY OF MANCHESTER
  3. BATTELLE (PACIFIC NW LAB)
  4. Sellafield Ltd.
  5. National Nuclear Laboratory, Seascale, UK
  6. National Nuclear Lab
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1530589
Report Number(s):
PNNL-SA-142115
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 518
Country of Publication:
United States
Language:
English

Citation Formats

Sutherland-Harper, Sophie, Livens, Francis R., Pearce, Carolyn I., Hobbs, Jeff, Orr, Robin, Taylor, Robin, Webb, Kevin J., and Kaltsoyannis, Nikolas. Interactions of HCl and H2O with the surface of PuO2. United States: N. p., 2019. Web. doi:10.1016/j.jnucmat.2019.02.036.
Sutherland-Harper, Sophie, Livens, Francis R., Pearce, Carolyn I., Hobbs, Jeff, Orr, Robin, Taylor, Robin, Webb, Kevin J., & Kaltsoyannis, Nikolas. Interactions of HCl and H2O with the surface of PuO2. United States. doi:10.1016/j.jnucmat.2019.02.036.
Sutherland-Harper, Sophie, Livens, Francis R., Pearce, Carolyn I., Hobbs, Jeff, Orr, Robin, Taylor, Robin, Webb, Kevin J., and Kaltsoyannis, Nikolas. Mon . "Interactions of HCl and H2O with the surface of PuO2". United States. doi:10.1016/j.jnucmat.2019.02.036.
@article{osti_1530589,
title = {Interactions of HCl and H2O with the surface of PuO2},
author = {Sutherland-Harper, Sophie and Livens, Francis R. and Pearce, Carolyn I. and Hobbs, Jeff and Orr, Robin and Taylor, Robin and Webb, Kevin J. and Kaltsoyannis, Nikolas},
abstractNote = {In order to explore the potential of heat treatment to decontaminate chloride-contaminated legacy plutonium dioxide (PuO2) powders from the UK stockpile, samples retrieved from storage have been heated in air from 400 to 950 C. These samples also contain high levels of other adsorbed gases from the atmosphere, including water. The amounts of chloride remaining on the PuO2 particles after heat treatment (measured by a caustic leaching process) decrease whilst the amounts of volatilised chloride increase with increasing heat treatment temperature. Clear evidence for a non-leachable (strongly bound) chloride species on the PuO2 surface is found from the thermal treatments. The lattice parameter decreases with increasing heat treatment temperature, reflecting annealing of structural defects caused by over 35 years of radiation damage, with no change in the fcc Fm3m crystal structure. Heating chloride-contaminated PuO2 powder to ~230 C and cooling back to ambient temperature in a sealed vessel reveals the production of H2, He, NO and CO gases. Water adsorption/desorption behaviour with the untreated PuO2 powder is remarkably different than PuO2 which had previously been heat treated at 700 C. From thermal treatments in open and sealed systems it is concluded that water and chloride coadsorb and interact on the PuO2 surface and each affects the adsorption/desorption behaviour of the other. These data also support practical considerations for repackaging of chloride-contaminated PuO2 for long term safe and secure storage at Sellafield.},
doi = {10.1016/j.jnucmat.2019.02.036},
journal = {Journal of Nuclear Materials},
number = ,
volume = 518,
place = {United States},
year = {2019},
month = {5}
}