Evidence of technetium and iodine release from a sodalite-bearing ceramic waste form

Journal Article · Thu Dec 31 00:00:00 EST 2015 · Applied Geochemistry

DOI:https://doi.org/10.1016/j.apgeochem.2015.12.017· OSTI ID:1265816

Neeway, James J. ^[1]; Qafoku, Nikolla P. ^[1]; Williams, Benjamin D. ^[1]; Snyder, Michelle M. V. ^[1]; Brown, Christopher F. ^[1]; Pierce, Eric M. ^[2]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

We proposed sodalites as a possible host of certain radioactive species, specifically ⁹⁹Tc and ¹²⁹I, which may be encapsulated into the cage structure of the mineral. To demonstrate the ability of this framework silicate mineral to encapsulate and immobilize ⁹⁹Tc and ¹²⁹I, single-pass flow-through (SPFT) tests were conducted on a sodalite-bearing multi-phase ceramic waste form produced through a steam reforming process. We produced two samples made using a steam reformer samples using nonradioactive I and Re (as a surrogate for Tc), while a third sample was produced using actual radioactive tank waste containing Tc and added Re. One of the non-radioactive samples was produced with an engineering-scale steam reformer while the other non-radioactive sample and the radioactive sample were produced using a bench-scale steam reformer. For all three steam reformer products, the similar steady-state dilute-solution release rates for Re, I, and Tc at pH (25 C) 9 and 40 C were measured. However, it was found that the Re, I, and Tc releases were equal or up to 4.5x higher compared to the release rates of the network-forming elements, Na, Al, and Si. Moreover, the similar releases of Re and Tc in the SPFT test, and the similar time-dependent shapes of the release curves for samples containing I, suggest that Re, Tc, and I partition to the sodalite minerals during the steam reforming process.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Environmental Management (EM)
• Grant/Contract Number: AC05-00OR22725; AC06-76RLO 1830
• OSTI ID: 1265816
• Alternate ID(s): OSTI ID: 1249912
• Journal Information: Applied Geochemistry, Vol. 66, Issue C; ISSN 0883-2927
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
Technetium
Radioactive waste form
Mineral dissolution
Sodalite