Development of in Situ Vitrification for Remediation of ORNL Contaminated Soils
Development of in Situ Vitrification for Remediation of ORNL Contaminated Soils

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Published: 1994

Total Pages: 7

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A full-scale field treatability study of in situ vitrification (ISV) is underway at the Oak Ridge National Laboratory (ORNL) for the remediation of radioactive liquid waste seepage pits and trenches that received over one million curies of mixed fission products (mostly 137Cs and 9°Sr) during the 1950s and 1960s. The treatability study is being conducted on a portion of the original seepage pit and will support an Interim Record of Decision (IROD) for closure of one or more of the seven seepage pits and trenches in early fiscal year (FY) 1996. Mr treatability study will establish ft technical performance of ISV for remediation of the contaminated soil sites. Melt operations at ORNL are expected to begin in early FY 1994. This paper presents the latest accomplishments of the project in preparation for the field testing. Discussion centers on the results of a parametric crucible melt study, a description of the site characterization efforts, and the salient features of a new hood design.

Implementation of in Situ Vitrification Technology for Remediation of Oak Ridge Contaminated Soil Sites
Implementation of in Situ Vitrification Technology for Remediation of Oak Ridge Contaminated Soil Sites

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Published: 1993

Total Pages: 13

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In situ vitrification is a thermal treatment technology being developed for remediation of contaminated soils. The process transforms easily leached, contaminated soils into a durable, leach-resistant. vitreous and crystalline monolith. This paper presents the results of the recent highly successful ISV demonstration conducted jointly by PNL and ORNL on a tracer-level quantity of radioactive sludge in a model trench at ORNL. A retention of [sup 90]r in the vitreous and crystalline product of greater than 99.9999% was measured with a reduction in potential environmental mobility of more than two orders of magnitude. The paper also presents the current plans for continued collaboration on a two-setting treatability test on one portion of an old seepage pit at ORNL.

Recent Advances in in Situ Vitrification
Recent Advances in in Situ Vitrification

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Published: 1992

Total Pages: 9

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In Situ Vitrification (ISV) is an innovative mobile remediation technology for soils and other underground contamination: Developed by the US Department of Energy's Pacific Northwest Laboratory (PNL), ISV has advanced during the past decade from a laboratory concept to a remediation technology commercially available for contaminated soils. ISV technology is currently being developed for remediation of DOE waste sites at Hanford, Oak Ridge National Laboratory (ORNL) Idaho National Laboratory (INEL), and other sites. The incentives for application of ISV can convert contaminated sites to a solid, highly durable block similar to naturally occurring obsidian. The ISV product has been shown capable of passing US Environmental Protection Agency (EPA) tests such as the Toxic Characteristic Leach Procedure (TCLP). Retrieval, handling and transport of untreated hazardous material would normally not be required after application of ISV. Therefore, costs, exposure to personnel, risk of releases to the environment, and generation of secondary wastes are greatly reduced compared with remove-and-treat technologies.

In Situ Vitrification
In Situ Vitrification

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Published: 1993

Total Pages: 7

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A large-scale demonstration of the in situ vitrification (ISV) process was performed in April 1990 on the 116-B-6A Crib in the 100 Area of the Hanford Site in southeastern Washington. The 116-B-6A Crib is a radioactive mixed waste site and was selected to demonstrate the applicability of ISV to soils contaminated with mixed wastes common to many US Department of Energy (DOE) sites. Results from the demonstration show that the ISV process is a viable remediation technology for contaminated soils. The demonstration of the ISV process on an actual contaminated soil site followed research and development efforts by the Pacific Northwest Laboratory (PNL) over the last 10 years. PNL's research has led to the development of the ISV process as a viable remediation technology for contaminated soils and the creation of a commercial supplier of ISV services, Geosafe Corporation. Development efforts for ISV applications other than treatment of contaminated soils, by PNL and in collaboration with Oak Ridge National Laboratory (ORNL) and Idaho National Engineering Laboratory (INEL), show the ISV process has potential applicability for remediating buried waste sites, remediating underground storage tanks, and enabling the placement of subsurface vitrified barriers and engineered structures. This paper discusses the results from the April 1990 large-scale demonstration and provides a general overview of the current capabilities of the ISV process for contaminated soils. In addition, this paper outlines some of the technical issues associated with other ISV applications and provides a qualitative discussion of the level of effort needed to resolve these technical issues.

In Situ Vitrification Demonstration for the Stabilization of Buried Wastes at the Oak Ridge National Laboratory
In Situ Vitrification Demonstration for the Stabilization of Buried Wastes at the Oak Ridge National Laboratory

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Published: 1987

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A demonstration of In Situ Vitrification (ISV) technology for the stabilization of radioactively contaminated soil sites at the Oak Ridge National Laboratory (ORNL) was successfully completed during July 1987. This demonstration is the first application of the ISV process not performed at the Hanford Site, where the technology was developed. The joint ORNL-PNL pilot-scale demonstration was performed on a 3/8-scale trench (2 m deep x 1 m wide x 10 m long) that was constructed to simulate a typical seepage trench used for liquid low-level radioactive waste disposal at ORNL from 1951 to 1966. In the ISV process, electrodes are inserted around a volume of contaminated soil, power is applied to the electrodes, and the entire mass is melted from the surface of the soil down through the contaminated zone, thus making a glassy-to-microcrystalline waste form that incorporates the contaminants. Gases produced during the melting are collected, treated, monitored, and released through an off-gas process trailer. In the ORNL demonstration, a 25-t mass of melted rock approximately 1.2 m thick x 2.1 m wide x 4.9 m long was formed during 110 h of operation that consumed approximately 29 MWh of power. Data obtained on the operational performance of the test and waste-form durability will be used to assess the feasibility of applying the ISV technology to an actual waste trench.