Nuclear Waste Vitrification in the United States: Recent Developments and Future Options

Abstract

Nuclear power plays a key role in maintaining current worldwide energy growth while minimizing the greenhouse gas emissions. A disposition path for used nuclear fuel (UNF) must be found for this technology to achieve its promise. One likely option is to recycle UNF and immobilize the high‐level waste (HLW) by vitrification. Vitrification is the technology of choice for immobilizing HLW from defense and commercial fuel reprocessing around the world. Recent advances in both recycling technology and vitrification show great promise in closing the U.S. nuclear fuel cycle in an efficient fashion. This article summarizes the recent trends, developments, and future options in waste vitrification for both defense waste cleanup and closing the nuclear fuel cycle in the United States.

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

“…The materials synthesis focus was to prepare single phase CaMoO 4 and BaMoO 4 from a melt process using oxide and carbonate precursors for subsequent structure/property investigations. Powders of 99.5% pure calcium carbonate (CaCO 3 ), barium carbonate (BaCO 3 ) and molybdenum oxide (MoO 3 ) from Aldrich (Milwaukee, WI) were used as precursors for powellite material synthesis.…”

“…Normalized release rates were calculated based on the measured compositions using the averages of the common logarithms of the leachate concentrations measured against the amount of exposed sample surface area using the BET surface area measurements. Figure 1 displays the calculated free energy (kJ/mol) change for BaMoO 4 and CaMoO 4 powellite formation from carbonate and oxide precursors versus temperature [32]. The calcium containing powellite structure CaMoO 4 has a more negative enthalpy of formation (-1542 kJ/mol versus -1507 for BaMoO 4 ) and a more negative free energy of formation, resulting in the preferred powellite structure.…”

“…High level waste has been incorporated into borosilicate glass waste forms at the industrial scale for several decades and is an established technology [3][4][5][6].…”

“…Powellite is a molybdate mineral with a chemical formula of CaMoO 4 or BaMoO 4 , and a tetragonal structure. Due to its structural variability, powellite can accommodate considerable chemical substitutions including trivalent actinides and lanthanide elements [19].…”

Thermal behaviour of zircon/zirconia-added chemically durable borosilicate porous glass

“…It is known for its superior usability in membrane technology, size exclusion and affinity protein chromatography (separation science) [1][2][3]. For more than thirty years, borosilicate glass has been used for the entrapment/immobilisation of high level waste from nuclear power plants and arms industries [4][5][6]. A low dielectric constant and negligible thermal expansion coefficient make it suitable for microelectronic packaging [7,8].…”