'''GeoMelt''' is a process by which dangerous, contaminated material (such as radioactive waste<ref name=asbestos3>{{cite journal |author=K.G. Finucane |author2=L.E. Thompson |author3=T. Abuku |author4=H. Nakauchi |title=Treatment of Asbestos Waste Using the GeoMeltⓇ Vitrification Process |journal=Waste Management 2008 Conference |date=24–28 February 2008 |page=3 |url=http://www.wmsym.org/archives/2008/pdfs/8261.pdf |access-date=October 11, 2013}}</ref> and heavy metals<ref name=basel>{{cite web |author=John Vijgen |author2=Ron McDowall |url=http://www.ihpa.info/docs/library/reports/Pops/June2009/SBC_LogoGEOMELTMainSheet_190109_Prov.pdf |access-date=October 22, 2013 |title=GeoMelt Technology Specification and Data Sheet}}</ref>) is mixed with clean soil, a blend of industrial minerals, and/or glass frit and melted to create an extremely hard and leach-resistant glass product.<ref name=kurion>{{cite web|last=Kurion, Inc. |url=http://www.kurion.com/technology/stabilization/geomelt |access-date=October 11, 2013 |title=GeoMelt |archive-url=https://web.archive.org/web/20131013044615/http://www.kurion.com/technology/stabilization/geomelt |archive-date=2013-10-13}}</ref> Vitrification immobilizes nearly all of the inorganic contaminants (i.e., radionuclides and heavy metals) present in the initial mixture by incorporation into the glass matrix.<ref name=process553>{{cite conference |last=Fraser|first=Don|author2=Leo Thompson|title=GeoMelt Process: An alternative for pesticides waste and soil treatment |conference=6th International HCH and Pesticides Forum |page=553|url=http://www.hchforum.com/6th/forum_book/C.4.6.pdf}}</ref> Organic wastes in the melt are destroyed by pyrolysis, and gaseous contaminants released during the melting process are treated separately.<ref name=subsurface2/>
Developed in 1980 by the U.S. Department of Energy's Pacific Northwest National Laboratory<ref name=kurionpress>{{cite web|last=Kurion, Inc.|url=http://www.kurion.com/newsroom/press-releases/kurion-acquires-geomelt-to-expand-vitrification-solutions|access-date=October 22, 2013|title= Kurion Acquires GeoMelt® to Expand Vitrification Solutions}}</ref> (PNNL), the GeoMelt process is deployed in one of two ways: in-situ (in-place) treatment of buried radioactive and hazardous wastes, and In-Container Vitrification (ICV), which is ex-situ treatment where radioactive and hazardous wastes are vitrified in a refractory-lined steel container.<ref name=kurion/>
==Process==
===Vitrification=== Geomelting is based on the principle of vitrification, the process by which a glass is formed. To effectively vitrify any mixture of materials, substances that contribute to glass formation (called glass formers) must be present.<ref name=asbestos3/> These glass formers usually contain silicon and oxygen and are present in most soils.
Much of the efficiency of this process has to do with how much waste material can be mixed with glass formers. Industrial-scale melts have shown that a stable glass compound is formed even when the original melt mixture is up to 33-40% waste material by weight,<ref name=asbestos3/><ref name=kurion/><ref name=subsurface2>{{cite journal|last=Morse|first=M.K. |author2=B.R. Nowack |author3=L.E. Thompson|title=Subsurface Planar Vitrification Treatment of Problematic TRU Wastes: Status of a Technology Demonstration Program|journal=WM '06 Conference|date=Feb 26 – Mar 2, 2006|page=2|url=http://www.wmsym.org/archives/2006/pdfs/6050.pdf}}</ref> depending on the type of waste.
===Melting===
First, waste is mixed with soil containing glass formers in a large container installed with electrodes (electrical conductors) suitable for heating the mixture. The container used is either underground<ref name=mixedwaste>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analysis for a Range of GeoMelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium, Tucson, AZ (US), 02/24/2002--02/28/2002 |date=27 February 2002 |osti=828961}}</ref> (subsurface planar vitrification, or SPV) or above ground (in-container vitrification, or ICV).<ref name=mixedwaste/> In both cases, the waste/soil mixture is loaded into the container and the heating processes begins when the electrodes are turned on. Due to spatial restrictions, the entire mixture cannot melt at the same time. The materials closest to the electrodes are melted first, and convection currents (movements of substances in a fluid) within the molten mixture continue to add more solid material into the molten material. After about 36-58<ref name=asbestos6>{{cite journal |author=K.G. Finucane |author2=L.E. Thompson |author3=T. Abuku |author4=H. Nakauchi |title=Treatment of Asbestos Waste Using the GeoMeltⓇ Vitrification Process|journal=Waste Management 2008 Conference|date=24–28 February 2008|page=6|url=http://www.wmsym.org/archives/2008/pdfs/8261.pdf|access-date=October 11, 2013}}</ref> hours, all of the mixture is molten and the convection currents create homogeneity (equal distribution of components) within the resultant mixture.<ref name="subsurface10">{{cite journal|last=Morse|first=M.K. |author2=B.R. Nowack |author3=L.E. Thompson|title=Subsurface Planar Vitrification Treatment of Problematic TRU Wastes: Status of a Technology Demonstration Program|journal=WM '06 Conference |date=Feb 26 – Mar 2, 2006|page=7|url=http://www.wmsym.org/archives/2006/pdfs/6050.pdf}}</ref>
====Subsurface Planar Vitrification (SPV)====
In subsurface planar vitrification, all melting operations are performed at the site of contamination. A very tall (around 6 meters deep),<ref name="subsurface10"/> narrow cavern is dug into the contaminated soil, which serves as the melting container. Very large electrodes are positioned within the cavern to optimize melting times.<ref name=subsurface2/> The hazardous waste is then mixed with soil inside the cavern and the melt is initiated. After the glass product has been formed, it is either left in the ground<ref name=subsurface3/> or transferred to a disposal facility.
=====Advantages=====
SPV melts do not require much capital investment, because the only construction necessary is the cavern that must be dug and the retrieval of the vitrified mass after the melt.<ref name=mixedwastetreatment7>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analyses for a Range of Geomelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium |date=24–28 February 2002|page=7|url=http://www.wmsym.org/archives/2002/Proceedings/39B/323.pdf}}</ref> SPV melts cost roughly $355–461 per ton<ref name=mixedwastetreatment1>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analayses for a Range of Geomelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium |date=24–28 February 2002|page=1|url=http://www.wmsym.org/archives/2002/Proceedings/39B/323.pdf}}</ref> of processed waste. When compared to the disposal cost of $555 per kilogram<ref name=nuclearwaste9>{{cite web |last=Orszag|first=Peter R.|title=Costs of Reprocessing Versus Directly Disposing of Spent Nuclear Fuel |website=Congressional Budget Office |date=14 November 2007|page=9|url=http://www.cbo.gov/sites/default/files/cbofiles/ftpdocs/88xx/doc8808/11-14-nuclearfuel.pdf}}</ref> (or $500,000 per ton) of nuclear waste, SPV is very cost-effective. There is also very little risk of worker injury on the job because the melting process happens underground and away from the workers at the site.<ref name=subsurface3>{{cite journal|last=Morse|first=M.K. |author2=B.R. Nowack |author3=L.E. Thompson|title=Subsurface Planar Vitrification Treatment of Problematic TRU Wastes: Status of a Technology Demonstration Program|journal=WM '06 Conference|date=Feb 26 – Mar 2, 2006|page=3|url=http://www.wmsym.org/archives/2006/pdfs/6050.pdf}}</ref> Finally, the melt caverns have no size restrictions,<ref name=subsurface2/> so SPV can handle very large volumes of waste at once.
=====Disadvantages=====
SPV does not come without its drawbacks. In order to perform an SPV melt, all materials and personnel must be moved to the melting site,<ref name=subsurface10/> so the costs of transportation for both must be taken into consideration. Once all contaminants have been removed or destroyed at the site, the project must relocate to continue operations. Melts cannot begin immediately after a treatment team arrives because it takes a few hours to dig the caverns and position the electrodes inside.<ref name=subsurface2/>
====In-Container Vitrification (ICV)====
In-container vitrification melts are carried out above ground in a container made of heat-resistant metal coated with a protective layer of sand.<ref name=testing20>{{cite web |last=Hrma|first=P.R. |author2=D.-S. Kim |author3=J. D. Vienna |author4=J. Matyáš |author5=D. E. Smith |author6=M. J. Schweiger |author7=J. D. Yeager |title=Testing of Large-Scale ICV Glasses with Hanford LAW Simulant |website=Pacific Northwest National Laboratory |date=March 2005|page=20|url=http://www.pnl.gov/main/publications/external/technical_reports/PNNL-15107.pdf}}</ref> The sand separates the container walls from the molten mixture and shapes the glass product after it has cooled.<ref name=testing3.19>{{cite web |last=Hrma|first=P.R. |author2=D.-S. Kim |author3=J. D. Vienna |author4=J. Matyáš |author5=D. E. Smith |author6=M. J. Schweiger |author7=J. D. Yeager |title=Testing of Large-Scale ICV Glasses with Hanford LAW Simulant |website=Pacific Northwest National Laboratory |date=March 2005|page=3.19|url=http://www.pnl.gov/main/publications/external/technical_reports/PNNL-15107.pdf}}</ref> Melts are carried out in quick succession; once one melt has cooled, another waste container is loaded with electrodes and the process begins again. The vitrified glass is then sent to a disposal facility.<ref name=asbestos3/>
=====Advantages=====
Because these melts are carried out at a treatment facility, all melts are efficient and centralized to that location.<ref name=mixedwastetreatment4>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analyses for a Range of Geomelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium |date=24–28 February 2002|page=4|url=http://www.wmsym.org/archives/2002/Proceedings/39B/323.pdf}}</ref> Waste/soil mixtures are systematically loaded and processed in the facility. Since the mixtures are melted above ground, machines do not have to dig up the glass product like in SPV melts. The melt containers are also the containers used to transport the glass,<ref name=kurion/> so there are fewer transfers involved in the glass's disposal.
=====Disadvantages=====
ICV melts have their downsides as well. The most immediate concern of ICV melts is the cost. ICV requires a treatment facility, meaning either a new facility must be built or an existing facility must be renovated to accommodate the new process. Both methods require considerable capital investment. Even after the facility is prepared for the process, ICV melts cost about $1,585 per ton<ref name=mixedwastetreatment1/> of processed waste (3-4 times the cost of an SPV melt). This extra cost is due to the necessary safety precautions in the facility. For example, the melting process occurs at very high (1200 to 2000 °C) temperatures,<ref name=ilw>{{cite web|website=Nuclear Decommissioning Authority|title=GeoMelt Vitrification of ILW (Pre-Conceptual stage) Summary of Assessment Report|date=30 May 2008|page=1|url=https://www.nda.gov.uk/documents/upload/Executive-Summary-Letter-of-Compliance-Assessment-Report-GeoMelt-Vitrification-of-ILW-May-2008.pdf|access-date=13 November 2013|archive-date=13 November 2013|archive-url=https://web.archive.org/web/20131113050539/https://www.nda.gov.uk/documents/upload/Executive-Summary-Letter-of-Compliance-Assessment-Report-GeoMelt-Vitrification-of-ILW-May-2008.pdf|url-status=dead}}</ref> and some of this heat is dispersed throughout the facility; so adequate cooling and ventilation are needed for areas where workers are present.<ref name=heat>{{cite web|last=US Department of Labor|title=Occupational Heat Exposure|url=https://www.osha.gov/SLTC/heatstress/}}</ref>
===Off-Gas Treatment===
While the contaminated mixture is melting, gases (called off-gases) are released,<ref name=aquadecks>{{cite web|last=Aquadecks Group|title=Geo-Melt Thermal Treatment Process|url=http://aquadecksgroup.com/index.php/subsidiaries/moncoupain-nig-ltd/geo-melt-thermal-treatment-process.html|access-date=Oct 30, 2013|archive-date=November 13, 2013|archive-url=https://web.archive.org/web/20131113045229/http://aquadecksgroup.com/index.php/subsidiaries/moncoupain-nig-ltd/geo-melt-thermal-treatment-process.html|url-status=dead}}</ref> which are hazardous substances themselves. These gases are captured by a steel fume hood<ref name=mixedwastetreatment3>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analyses for a Range of Geomelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium |date=24–28 February 2002|page=3|url=http://www.wmsym.org/archives/2002/Proceedings/39B/323.pdf}}</ref> and sent through a treatment system<ref name=asbestos3/> that then removes about 99.9999% of the contaminants.<ref name = asbestos3/><ref name=mixedwastetreatment2>{{cite conference |last=Thompson|first=L.E.|title=Mixed Waste Treatment Cost Analyses for a Range of Geomelt Vitrification Process Configurations |conference=Waste Management 2002 Symposium |date=24–28 February 2002|page=2|url=http://www.wmsym.org/archives/2002/Proceedings/39B/323.pdf}}</ref> Standard treatment procedures span from filtration<ref name = asbestos3/> to wet scrubbing<ref name="mixedwastetreatment3"/><ref name=hexachlorobenzene5>{{cite conference |last=Thompson|first=Leo E.|author2=Nicholas Megalos |author3=David Osborne |title=Hexachlorobenzene Destruction With the Geomelt Process |conference=Waste Management 2000 Symposium |date=Feb 27 – Mar 2, 2000|page=5|url=http://www.wmsym.org/archives/2000/pdf/43/43-5.pdf}}</ref> (using liquid to remove gaseous contaminants), though the exact procedures depend on the gases being treated.
==Applications==
Hazardous materials are often very difficult to remove and treat.<ref name=decontamination>{{cite web|last=US Department of Labor|title=Decontamination|url=https://www.osha.gov/SLTC/hazardouswaste/training/decon.html}}</ref> The contaminants might be seeped into the soil,<ref name=soil>{{cite web|last=US EPA|title=Soil Contamination|url=http://www.epa.gov/superfund/students/wastsite/soilspil.htm|archive-url=https://archive.today/20131113032801/http://www.epa.gov/superfund/students/wastsite/soilspil.htm|url-status=dead|archive-date=November 13, 2013}}</ref> contained within a sludge,<ref name=sludge>{{cite web|last=UN Environment Programme|title=Sludge Treatment, Reuse and Disposal|url=http://www.unep.or.jp/ietc/publications/freshwater/sb_summary/10.asp|access-date=2013-11-13|archive-date=2013-11-13|archive-url=https://web.archive.org/web/20131113050644/http://www.unep.or.jp/ietc/publications/freshwater/sb_summary/10.asp|url-status=dead}}</ref> or present within spent nuclear reactor cores.<ref name=nuclearhazard>{{cite journal|last=Frogatt|first=Anthonhy|title=Nuclear Reactor Hazards|journal=Nuclear Power: Myth and Reality|date=2 Nov 2005|page=23}}</ref> No matter where a hazard exists, each requires a different method of treatment and disposal using standard waste management processes. With geomelting, however, the treatment (melting) process is essentially the same<ref name=asbestos5>{{cite journal |author=K.G. Finucane |author2=L.E. Thompson |author3=T. Abuku |author4=H. Nakauchi |title=Treatment of Asbestos Waste Using the GeoMeltⓇ Vitrification Process|journal=Waste Management 2008 Conference|date=24–28 February 2008|page=5|url=http://www.wmsym.org/archives/2008/pdfs/8261.pdf|access-date=October 11, 2013}}</ref> for each batch, as is the glass produced, regardless of the contaminants in the mixture. Due to this versatility, geomelting is employed in many hazard-control operations.<ref name=kurion/>
===Organics===
GeoMelt is used to treat a variety of organic wastes including oils, pesticides<ref name=toxins>{{cite web|last=Department of Environmental Protection|first=Florida|title=Synthetic Organic Contaminants and their Standards|url=http://www.dep.state.fl.us/water/drinkingwater/syn_con.htm|access-date=2013-11-13|archive-date=2013-11-13|archive-url=https://web.archive.org/web/20131113050635/http://www.dep.state.fl.us/water/drinkingwater/syn_con.htm|url-status=dead}}</ref> and herbicides, solvents<ref name=organicsolvents>{{cite web|last=National Institute for Occupational Safety|title=Organic Solvents|date=3 December 2020 |url=https://www.cdc.gov/niosh/topics/organsolv/}}</ref> and persistent organic pollutants including polychlorinated biphenyls (PCBs), dioxins, and furans (GeoMelt is permitted by the U.S. Environmental Protection Agency (EPA) as an approved thermal treatment method for PCBs throughout the U.S.<ref>{{Cite web|url=https://www.epa.gov/sites/production/files/2017-02/documents/kurion_final_approval_signed_1-25-17.pdf|title=Approval issued pursuant to Section 6(e)(1) of the Toxic Substances Control Act of 1976 (TSCA), Public Law No. 94-469, and the Federal Polychlorinated Biphenyls (PCB) Regulation, 40 CFR 761.60|last=U.S. Environmental Protection Agency|date=January 25, 2017|website=epa.gov|access-date=May 30, 2017}}</ref> These wastes are carcinogens<ref name=neurotoxicity>{{cite periodical |title=Organic Solvent Neurotoxicity |periodical=Current Intelligence Bulletin |number=48 |publisher=Centers for Disease Control and Prevention |date=March 1987 |doi=10.26616/NIOSHPUB87104 |doi-access=free}}</ref> (cancer-causing substances) and often impair critical bodily functions (e.g. breathing) over time. The melting process destroys organic compounds because no organic materials are able to survive the high temperatures of the melt process.<ref name=asbestos3/>
===Inorganics===
Inorganic contaminants like heavy metals (toxic metals including mercury, cadmium, and lead<ref name=toxicmetals>{{cite web|last=US Department of Labor|title=Toxic Metals|url=https://www.osha.gov/SLTC/metalsheavy/}}</ref>) are released into the environment via industrial leaks and automobile waste.<ref name=heavymetals>{{cite web|last=Fairfax County VA|title=Heavy Metal Pollution Is More Common Than You Think|url=http://www.fairfaxcounty.gov/nvswcd/newsletter/heavymetal.htm}}</ref> If left unattended, these inorganic hazards can deteriorate ecosystems<ref name=ecosystem>{{Cite journal|last=Singh|first=Reena|title=Heavy metals and living systems: An overview|journal=Indian Journal of Pharmacology|volume=43|issue=3|pages=246–253|pmc=3113373|author2=Neeta Gautam |author3=Anurag Mishra |author4=Rajiv Gupta |year=2011|pmid=21713085|doi=10.4103/0253-7613.81505 |doi-access=free }}</ref> and cause mental/physical illnesses<ref name=toxicmetals/> in humans. Regardless of the mixture of metals, geomelting isolates these heavy metals in a glass matrix and prevents them from entering the environment,<ref name=kurionpress/> eliminating the threat posed to the surroundings.
===Radioactive materials===
{{main|Radioactive waste vitrification}}
Since the advent of nuclear power plants, nuclear pollution (the dispersal of radioactive materials) has become a problem for the environment. The amount of radiation in radioactive materials may not be safe for living organisms,<ref name=NRC>{{cite web|last=NRC|title=Radiation Protection|url=https://www.nrc.gov/about-nrc/radiation.html}}</ref> so it is important for all nuclear pollution to be removed. Nuclear waste naturally remains hazardous for hundreds of years,<ref name=overview>{{cite web|last=World Nuclear Association|title=Waste management: Overview|url=http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Waste-Management-Overview/|access-date=2013-11-13|archive-date=2013-11-13|archive-url=https://web.archive.org/web/20131113045821/http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Nuclear-Wastes/Waste-Management-Overview/|url-status=dead}}</ref> but when processed with geomelting, radioactive materials are immobilized.<ref name=asbestos1>{{cite journal |author=K.G. Finucane |author2=L.E. Thompson |author3=T. Abuku |author4=H. Nakauchi |title=Treatment of Asbestos Waste Using the GeoMeltⓇ Vitrification Process|journal=Waste Management 2008 Conference|date=24–28 February 2008|page=1|url=http://www.wmsym.org/archives/2008/pdfs/8261.pdf|access-date=October 11, 2013}}</ref>
== References == <!--- See http://en.wikipedia.org/wiki/Wikipedia:Footnotes on how to create references using <ref></ref> tags which will then appear here automatically --> {{Reflist}}
==External links== * [http://www.energybulletin.net/2297.html Energy bulletin article] {{Webarchive|url=https://web.archive.org/web/20060923223839/http://www.energybulletin.net/2297.html |date=2006-09-23 }}
Category:Nuclear reprocessing Category:Waste management