Improving the Characterization and Treatment of Radioactive Wastes for the Department of Energy's Accelerated Site Cleanup Program (2005) / Chapter Skim
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3 Facilities and Technologies
3 Facilities and Technologies
Pages 28-43
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and from the collective knowledge of committee members. In accordance with its task statement, the committee focused on facilities and technologies with applicability to problematic or "orphan" wastes, for which effective disposition paths are needed to achieve accelerated cleanup.
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Recommendation: EM should consider managing the following facilities as corporate assets for the characterization or treatment of both mainstream and special-case or "orphans wastes: · Tonic Substances Control Act (TSCA) manerator at Oak Ridge · H-Canyon at Savannah River · T-P/ant at Hanford · H'gh-level waste (HLW)
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depending on the original waste composition High-volume INEEL Characterization, Packaged waste for WIPP transuranic~ or AMWTF sorting, low-level wastes compaction Small-volume, Savannah River Encapsulation in highly radio- DWPF; vitrified HLW active sources Hanford WTP or iissile materials aIncluding bu led TRU that Slav be retrieved (NRC, 2002b)
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2Mixed wastes contain low-level radioactive wastes mixed with RCRA and ot TSCA chemicals 3The committee noted that the large capacity supetcompactot, used for ctushing metal components tram the gaseous diffusion plant decommissioning and which provided another t nique t eatment capabi ity at Oak Ridge, is being dismantled 4Ptoject teams modeled on those used by fot-ptofit COtpOtahOns were organized within EM in November 2002 to insulate top-down reforms in the cleanup program They provided thei tesuits to EM management in Novembet 2003,
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Unreprocessed spent fuels from Sln enriched uranium the proportion of u-235 has been increased relauve to that in naturally occurring uranium, usually for use in weapons or nuclear reactors.
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It seems likely that spent fuels that do not meet Yucca Mountain acceptance criteria will be identified during these 20 years. H-Canyon would have a unique capability to reprocess or otherwise treat these materials.
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INEEL Calciner The fluidized bed calciner at INEEL is an existing facility that has potential extended use in treating the approximately one million gallons of sodium-bearing acidic waste (SBW) from reprocessing naval nuclear reactor fuel at that site, as well as a wide variety of other liquid wastes and slurries.
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, which is under construction at Hanford, could provide CIC capability for relatively smallvolume problematic or orphan wastes, especially those that are highly radioactive (such as the Sr-90 and Cs-137 capsules stored at Hanford) or that contain fissile materials.
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Steam reforming is a commercially developed technology that can potentially treat a wide variety of orphan wastes. High-level waste vitrification is EM's single most expensive waste treatment process.
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In a typical steam reforming process, superheated steam along with the material to be treated and co-reactants are introduced into a fluidized bed reactor where water evaporates, organic materials are destroyed, and the waste constituents are converted to a granular, leach-resistant solid. Steam reforming is in commercial use at Erwin, Tennessee, for treatment and destruction of radioactively contaminated ion exchange resins, oils, and solvents from commercial nuclear power plants In the steam reformer, superheated steam is directed through a bed of refractory particles, which are partially suspended by the steam so that collectively they behave like a fluid.
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Some additional process development and chemistry studies will likely be required to optimize the operating conditions for these various waste compositions. As noted in the previous discussion of the INEEL calciner, converting that unit to a steam reformer for treating sodium-bearing waste appears straightforward, based on the committee's limited fact finding.
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Hanford has a frit composition for the initial waste feed but is challenged by a much wider range of waste compositions than SRS. Therefore the committee believes that continued investments in frit and glass chemistry provide an important opportunity for enhanced vitrification capability.
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, dealt with the flammable gas issue by requiring that hydrogen and other flammable gases comprise less than 5 percent by volume of the total gas inventory in any confined space within the cask, e.g., a drum or bag within a drum (NRC, 2001a)
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Modern, nonnnvasive geophysical sensor techniques, such as electromagnetic and electrical methods, seismic methods, and ground-penetrating radar can substantially improve current practices and lead to cost-effective means to implement long-term monitoring after site closure. Geophysical sensor technology can provide continuous measurements in tame and space that could fill knowledge gaps between monitoring wells; enable rapid mapping of large areas, Including soundings to depth; deliver information on waste characteristics as well as subsurface hydrogeology; and be developed onto long-term monitoring networks (EPA, 2000)
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. Subsequent excavations conducted tO retrieve Pit 9 waste provided actual sampling data to compare with and help verify the geophysical measurements.
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This procedure, referred to as the Glovebox Excavator Method (GEM) allowed the use of both non-invasive geophysical measurements and actual sampling of the excavated material for characterizing the waste.
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