Enhanced ⁹⁹Tc retention in glass waste form using Tc(IV)-incorporated Fe minerals

Journal Article · Thu Sep 07 00:00:00 EDT 2017 · Journal of Nuclear Materials

DOI:https://doi.org/10.1016/j.jnucmat.2017.09.007· OSTI ID:1395273

Um, Wooyong ^[1]; Luksic, Steven A. ^[2]; Wang, Guohui ^[2]; Saslow, Sarah  ^[2]; Kim, Dong-Sang  ^[2]; Schweiger, Michael J. ^[2]; Soderquist, Chuck Z. ^[2]; Bowden, Mark E.  ^[3]; Lukens, Wayne W.  ^[4]; Kruger, Albert A. ^[5]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pohang University of Science and Technology (POSTECH) (South Korea). Division of Advanced Nuclear Engineering (DANE), Division of Environmental Science and Engineering (DESE)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
5. United States Department of Energy, Office of River Protection, Richland, WA (United States)

Technetium (⁹⁹Tc) immobilization by doping into iron oxide mineral phases may alleviate the problems with Tc volatility during vitrification of nuclear waste. Because reduced Tc, Tc(IV), substitutes for Fe(III) in the crystal structure by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation of Fe oxide minerals, two Tc-incorporated Fe minerals (Tc-goethite and Tc-magnetite/maghemite) were prepared and tested for Tc retention in glass melt samples at temperatures between 600 and 1000 °C. After being cooled, the solid glass specimens prepared at different temperatures at 600, 800, and 1000 °C were analyzed for Tc oxidation state using Tc K-edge XANES. In most samples, Tc was partially (<60%) oxidized from Tc(IV) to Tc(VII) as the melt temperature increased up to 600 °C. However, most of Tc(IV) was completely (>95%) oxidized to Tc(VII) at temperature above 800 °C. In conclusion, Tc retention in glass melt samples prepared using Tc-incorporated Fe minerals were slightly higher (~10%) than in glass prepared using KTcO4 because of limited and delayed Tc volatilization.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-76RL01830; AC02-05CH11231; NRF-2015M2A7A1000191
• OSTI ID: 1395273
• Alternate ID(s): OSTI ID: 1408487; OSTI ID: 1495572
• Report Number(s): PNNL-SA-123344; PII: S0022311517301198
• Journal Information: Journal of Nuclear Materials, Vol. 495, Issue C; ISSN 0022-3115
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
Technetium
Tc-incorporated goethite
Tc-incorporated magnetite
Tc volatilization
Glass waste form
Tc retention in glass