Brookhaven National Laboratory Process for the Continuous Conversion of High-Level Radioactive Waste to Phosphate Glass

Tuthill, E.J.; Weth, G.; Emma, L.C.; Strickland, G.; Hatch, L.P.

doi:10.2172/4538819

Cited by 2 publications

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“…Phosphate glasses have some advantages over borosilicate glasses, such as a lower melting temperature and higher solubility for problematic elements, such as sulfur, and were investigated as early as the 1960s (Clark et al 1966, Tuthill et al 1966. Later work on sodium-aluminum phosphate glass (van Geel 1976) and iron-aluminum phosphate glass (Grambow and Lutze 1980) showed that some of these glasses had comparable or better chemical durability than the borosilicate glasses.…”

Section: Phosphate Glassesmentioning

confidence: 99%

Phosphates as Nuclear Waste Forms

Ewing

Wang²

2002

Reviews in Mineralogy and Geochemistry

171

102

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INTRODUCTIONThe disposal of radioactive "waste" generated by the nuclear fuel cycle is among the most pressing and potentially costly environmental problems of the 21st century, a heritage from the Atomic Age of the 20th century. Proposed disposal strategies are complicated, not only because of the large volumes and activities of waste, but also because of the political and public-policy issues associated with the long times required for containment and disposal (10 4 to 10 6 years). The development and use of highly durable waste forms, materials that have a high chemical durability and resistance to radiation damage effects, can simplify the disposal strategy (Ewing 2001).An interest in phosphate-based waste forms has developed because the high-level waste generated by reprocessing of spent nuclear fuel can contain substantial amounts of phosphates (up to 15 wt % P 2 O 5 ) that result from processing technologies that utilized either a bismuth phosphate or tributylphosphate process (Bunker et al. 1995). In addition to the high phosphate content, other metal oxides may achieve significant proportions (up to 15 wt % Fe 2 O 3 ; up to 30 wt % Bi 2 O 3 ; up to 30 wt % UO 2 ) (Lambert and Kim 1994). These complex compositions have presented special challenges in developing crystalline ceramics that can accommodate the full compositional range of the waste streams.The early work on phosphate glasses led to the idea that crystalline phosphates might make extremely durable waste forms, particularly for actinides. The earliest suggestion was for the use of monazite (Boatner 1978, Boatner et al. 1980, McCarthy et al. 1978, 1980. The attractive qualities of monazite as a nuclear waste form are: (1) a high solubility for actinides and rare earths (10 to 20 wt %); (2) evidence from natural occurrences of good chemical durability; (3) an apparent resistance to radiation damage, as natural monazites are seldom found in the metamict state, despite very high alphadecay event doses (Boatner and Sales 1988). There have been extensive studies of monazite and apatite as potential waste form phases, and a considerable amount of work on a number of synthetic phosphate phases has been completed.The crystal chemistry of monazite, apatite, and related phosphate minerals, has been discussed in detail (see this volume, Chapters 1, 2, and 4 by Hughes and Rakovan, Pan and Fleet, and Boatner, respectively) and will not be repeated here. Rather, we will summarize the work relevant to the consideration of these phosphate phases as nuclear waste forms. TYPES OF NUCLEAR WASTEThe design and evaluation of nuclear waste forms requires some understanding of the sources, volumes, compositions and activities of the various waste streams generated by the nuclear fuel cycle. There are three primary sources of radioactive waste in the United States (DOE 1997): the high-level waste (HLW) from the reprocessing of spent nuclear fuel, the spent nuclear fuel itself, and plutonium reclaimed by reprocessing or obtained by the dismantlement of nuclear weapons. 67...

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Section: Phosphate Glassesmentioning

confidence: 99%

Phosphates as Nuclear Waste Forms

Ewing

Wang²

2002

Reviews in Mineralogy and Geochemistry

171

102

View full text Add to dashboard Cite

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“…|tJ|olecular sieves are unique among industrial adsorbents in their ability to separate molecules on the basis of molecular size. Recent applications (2,3,5,7) in separating and purifying gases and liquids have placed molecular sieve adsorption processes among the major separation operations used in some process industries.…”

Section: Discussionmentioning

confidence: 99%