The use of positrons to survey alteration layers on synthetic nuclear waste glasses

作者：Reiser Joelle T; Parruzot Benjamin; Weber Marc H; Ryan Joseph V; McCloy John S; Wall Nathalie A

来源：Journal of Nuclear Materials, 2017, 490: 75-84.

DOI：10.1016/j.jnucmat.2017.03.007

• Doppler Broadening Positron Annihilation
• Spectroscopy
• Nuclear waste glass
• Monte Carlo simulations
• Scanning Electron Microscopy

In order to safeguard society and the environment, understanding radioactive waste glass alteration mechanisms in interactions with solutions and near-field materials, such as Fe, is essential to nuclear waste repository performance assessments. Alteration products are formed at the surface of glasses after reaction with solution. In this study, glass altered in the presence of Fe in aqueous solution formed two alteration layers: one embedded with Fe closer to the surface and one without Fe found deeper in the sample. Both layers were found to be thinner than the alteration layer found in glass altered in aqueous solution only. For the first time, Doppler Broadening Positron Annihilation Spectroscopy (DB-PAS) is used to non-destructively characterize the pore structures of glass altered in the presence of Fe. Advantages and disadvantages of DB-PAS compared to other techniques used to analyze pore structures for altered glass samples are discussed. Ultimately, DB-PAS has shown to be an excellent choice for pore structure characterization for glasses with multiple alteration layers. Monte Carlo modeling predicted positron trajectories through the layers, and helped explain DB-PAS data, which showed that the deeper alteration layer without Fe had a similar composition and pore structure to layers on glass altered in water only.

• 出版日期2017-7