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Title: Telemetry system for monitoring melt depth during in situ vitrification

Conference · · Trans. Am. Nucl. Soc.; (United States)
OSTI ID:5660847

A depth telemetry system has been selected for monitoring the melting progress during in situ vitrification (ISV). The ISV technology is being developed and tested by Pacific Northwest Lab. (PNL) for the US Dept. of Energy Richland Operations office as a potential method for in-place stabilization of existing transuranic contaminated soil sites. The ISV process is carried out by inserting four electrodes into the soil in a square array at the appropriate electrode spacing for the specific waste site. Electrode separations up to 5.5 m (18 ft) are possible with existing ISV equipment. A conductive mixture of flaked graphite and glass frit is placed in an X pattern between the electrodes in shallow trenches on the soil surface to permit initial electrical conductance. A specially designed power system applies voltage to the electrodes, quickly heating the graphite mixture to soil-melting temperatures (1100 to 1600/sup 0/C). As the surrounding soil melts, it becomes electrically conductive and grows downward and outward until the desired soil volume has been completely vitrified. A depth-monitoring system is needed to verify the depth of the molten soil at specific times during ISV and to assure that the desired depth is reached before the ISV operation is stopped. After an extensive evaluation of several concepts, the depth telemetry system was selected for further development and demonstration.

Research Organization:
Pacific Northwest Lab., Richland, WA
OSTI ID:
5660847
Report Number(s):
CONF-870601-Summs.; TRN: 88-009663
Journal Information:
Trans. Am. Nucl. Soc.; (United States), Vol. 54; Conference: Annual meeting of the American Nuclear Society, Dallas, TX, USA, 7 Jun 1987
Country of Publication:
United States
Language:
English