Transportable Vitrification System at Oak Ridge National Laboratory, Oak Ridge, Tennessee

Site Name:

Oak Ridge National Laboratory

Location:

Oak Ridge, TN

Period of
Operation:

October 1997

Cleanup
Type:

Field demonstration

Technology:
Vitrification
Transportable Vitrification System (TVS):

- Waste and Additives and Materials Processing Module - 240-gal melter feed blend tank equipped with a load cell and agitator, centrifugal pump, feed tank, melter module, and emission control module
- Melter Module - joule-heated glass melter equipped with molybdenum rod electrodes and lined with heavy flux contact refractory
- Melter capacity - up to 300 lb/hr; operating temperature - 1,150 to 1,400C; heated with a 500,000-BTU/hr propane burner
- Melter equipped with a drain bay chamber to remove waste glass and salt tap side chamber to remove corrosive salts
- Waste glass poured from drain bay chamber into 8-cubic foot stainless steel containers
- Emission Control Module included quench tower, packed bed cooler, variable throat venturi, mist eliminator, reheater, and high-efficiency particulate air filters
- Control and Services Module - used to control and monitor equipment operation

Cleanup Authority:
RCRA and NRC

Principal Investigator:
Frank Van Ryn
Bechtel Jacobs Company
ORNL
P.O. Box 2003
Oak Ridge, TN 37831
Telephone: 423-574-1907
Fax: 423-574-9786
E-mail: xs2@ornl.gov
DOE Technical Program Manager:
Dave Hutchins
Environmental Technology Group, EM-93
U.S. DOE
Oak Ridge Operations Office
P.O. Box 2001
Oak Ridge, TN 37831
Telephone: 423-241-6420
Fax: 423-576-5333
E-mail: hutchinsda@oro.doe.gov

Contaminants:
Metals and Radionuclides

Waste Source:
Mixed low-level waste sludges from DOE operations - included pond sludge and sludge from a neutralization facility

Type/Quantity of Media Treated:
Sludge
- Pond sludge and mixtures of pond and neutralization sludge - 16,000 lbs

Purpose/Significance of Application:
Demonstration of a transportable vitrification system to treat low-level mixed waste sludges

Regulatory Requirements/Cleanup Goals:
- RCRA Land Disposal Restriction (LDR) standards and NRC guidelines
- Air emissions limits were specified in a State of Tennessee air permit

Results:
- The waste form produced by the TVS met the RCRA LDR standards and NRC guidelines, was stable and durable, and represented a 60% volume reduction of the waste
- The TVS system operated within the required emissions limits
- The melting rate decreased during the demonstration, resulting in lower average throughput rate (450 kg/day versus expected 900 kg/day); attributed to high iron content of waste which decreased heat transfer characteristics of glass material

Cost Factors:
Projected costs for a full-scale system include:

- Capital costs, including all equipment - $5 million
- Operating costs - $10 to $44/kg of waste, assuming analytical expenses similar to those incurred for the demonstration; assuming less extensive analytical requirements for normal operations, operating costs were estimated at $7 to $17/kg of waste

Description:
In October 1997, following completion of process development and testing, demonstration of the TVS was conducted at ORNL, using actual low-level mixed waste containing metals. The waste used for the demonstration was B&C pond sludge and a mix of B&C pond sludge and sludge from a neutralization facility. The objectives of the demonstration included meeting the RCRA LDR standards and NRC guidelines for the glass waste form, meeting the air emissions limits for the operation of the TVS, and collecting operating and performance data for the process for use in scale-up.

The results of the demonstration showed that the TVS was capable of treating low-level mixed waste sludges to the RCRA LDR levels and the NRC guidelines, and of operating within the required air emission standards. The waste form produced by the TVS is highly durable with long-term integrity, and significant reductions in waste volumes were achieved. For different waste compositions from those tested, additional process development would be required to determine the process controls and scale-up methods needed to achieve optimal glass waste forms, consistent melter operation, and to avoid adverse melter conditions. Treatability studies are recommended for any waste stream to be treated using TVS.