Interactions of HCl and H2O with the surface of PuO2

JOURNAL OF NUCLEAR MATERIALS

卷:518

Article

Sutherland-Harper, Sophie¹  Livens, Francis¹  Pearce, Carolyn^1,2  Hobbs, Jeff³  Orr, Robin⁴  Taylor, Robin⁴  Webb, Kevin⁴  Kaltsoyannis, Nikolas¹ 

[1] Univ Manchester, Sch Chem, Oxford Rd, Manchester M13 9PL, Lancs, England

[2] Pacific Northwest Natl Lab, Richland, WA 99354 USA

[3] Sellafield Ltd, Seascale CA20 1PG, Cumbria, England

[4] Natl Nucl Lab, Cent Lab, Seascale CA20 1PG, Cumbria, England

关键词: Chloride;    Plutonium dioxide;    Water;    Adsorption;    Desorption;    Thermal treatment;   

DOI  :  10.1016/j.jnucmat.2019.02.036

来源: Elsevier

【 摘 要 】

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 degrees 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 Fm (3) over barm crystal structure. Heating chloride-contaminated PuO2 powder to similar to 230 degrees C and cooling back to ambient temperature in a sealed vessel reveals the production of H-2, 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 degrees 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. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

Free