Single phase melt processed powellite (Ba,Ca)MoO₄ for the immobilization of Mo-rich nuclear waste

Journal Article · Tue Oct 02 00:00:00 EDT 2012 · Journal of Alloys and Compounds

DOI:https://doi.org/10.1016/j.jallcom.2012.09.049· OSTI ID:1158504

Brinkman, Kyle ^[1]; Fox, Kevin M. ^[1]; Marra, James C. ^[1]; Reppert, Jason ^[1]; Crum, Jarrod V. ^[2]; Tang, Ming ^[3]

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1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Crystalline and glass composite materials are currently being investigated for the immobilization of combined High Level Waste (HLW) streams resulting from potential commercial fuel reprocessing scenarios. Several of these potential waste streams contain elevated levels of transition metal elements such as molybdenum (Mo). Molybdenum has limited solubility in typical silicate glasses used for nuclear waste immobilization. Under certain chemical and controlled cooling conditions, a powellite (Ba,Ca)MoO₄ crystalline structure can be formed by reaction with alkaline earth elements. In this study, single phase BaMoO₄ and CaMoO₄ were formed from carbonate and oxide precursors demonstrating the viability of Mo incorporation into glass, crystalline or glass composite materials by a melt and crystallization process. X-ray diffraction, photoluminescence, and Raman spectroscopy indicated a long range ordered crystalline structure. In situ electron irradiation studies indicated that both CaMoO4 and BaMoO₄ powellite phases exhibit radiation stability up to 1000 years at anticipated doses with a crystalline to amorphous transition observed after 1 x 10¹³ Gy. Aqueous durability determined from product consistency tests (PCT) showed low normalized release rates for Ba, Ca, and Mo (<0.05 g/m2).

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1158504
• Report Number(s): PNNL-SA-94806
• Journal Information: Journal of Alloys and Compounds, Vol. 551; ISSN 0925-8388
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
waste form
nuclear materials
radiation damage
chemical durability