RHENIUM SOLUBILITY IN BOROSILICATE NUCLEAR WASTE GLASS IMPLICATIONS FOR THE PROCESSING AND IMMOBILIZATION OF TECHNETIUM-99 (AND SUPPORTING INFORMATION WITH GRAPHICAL ABSTRACT)
The immobilization of 99Tc in a suitable host matrix has proved a challenging task for researchers in the nuclear waste community around the world. At the Hanford site in Washington State in the U.S., the total amount of 99Tc in low-activity waste (LAW) is {approx} 1,300 kg and the current strategy is to immobilize the 99Tc in borosilicate glass with vitrification. In this context, the present article reports on the solubility and retention of rhenium, a nonradioactive surrogate for 99Tc, in a LAW sodium borosilicate glass. Due to the radioactive nature of technetium, rhenium was chosen as a simulant because of previously established similarities in ionic radii and other chemical aspects. The glasses containing target Re concentrations varying from 0 to10,000 ppm by mass were synthesized in vacuum-sealed quartz ampoules to minimize the loss of Re by volatilization during melting at 1000 DC. The rhenium was found to be present predominantly as Re7 + in all the glasses as observed by X-ray absorption near-edge structure (XANES). The solubility of Re in borosilicate glasses was determined to be {approx}3,000 ppm (by mass) using inductively coupled plasma-optical emission spectroscopy (ICP-OES). At higher rhenium concentrations, some additional material was retained in the glasses in the form of alkali perrhenate crystalline inclusions detected by X-ray diffraction (XRD) and laser ablation-ICP mass spectrometry (LA-ICP-MS). Assuming justifiably substantial similarities between Re7 + and Tc 7+ behavior in this glass system, these results implied that the processing and immobilization of 99Tc from radioactive wastes should not be limited by the solubility of 99Tc in borosilicate LAW glasses.
- Research Organization:
- Hanford Site (HNF), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM)
- DOE Contract Number:
- DE-AC27-08RV14800
- OSTI ID:
- 1050037
- Report Number(s):
- ORP-52758-00; TRN: US1204529
- Journal Information:
- PRE-PUBLICATION ARTICLE TO JOURNAL OF MATERIALS CHEMISTRY, ROYAL SOCIETY OF CHEMISTRY, Journal Name: PRE-PUBLICATION ARTICLE TO JOURNAL OF MATERIALS CHEMISTRY, ROYAL SOCIETY OF CHEMISTRY
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION
BOROSILICATE GLASS
EMISSION SPECTROSCOPY
EVAPORATION
GLASS
LASERS
MASS SPECTROSCOPY
MELTING
PERRHENATES
QUARTZ
RADIOACTIVE WASTES
RETENTION
RHENIUM
SODIUM
SOLUBILITY
TARGETS
TECHNETIUM
TECHNETIUM 99
VITRIFICATION
WASTES
X-RAY DIFFRACTION