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Laboratory stabilizations/solidification of tank sludges: MVST/BVEST
1Chemical Technology Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6202, USA. spencerd@ornl.gov
Journal of Environmental Management
|March 24, 2004
Summary
Oak Ridge tank sludge stabilization using grout formulations effectively immobilizes hazardous metals and radionuclides. This process ensures safe treatment and disposal of radioactive mixed-waste sludges, meeting regulatory standards.
Area of Science:
- Environmental Science
- Chemical Engineering
- Waste Management
Background:
- Oak Ridge tank sludges require stabilization before combined treatment and disposal.
- Decades of accumulated radioactive, mixed-waste sludges necessitate robust stabilization methods.
Purpose of the Study:
- Evaluate grout formulations for stabilizing Melton Valley Storage Tank (MVST)/Bethel Valley Evaporator Storage Tank sludge.
- Assess the effectiveness of grout in immobilizing Resource Conservation and Recovery Act (RCRA) metals and radionuclides.
Main Methods:
- Laboratory testing of grout formulations using both surrogate and actual MVST W-25 sludge.
- Analysis of wasteform strength, free water presence, and volume increase at 50-60wt% wet-sludge loading.
- Leachability testing for RCRA metals (Cd, Cr, Pb, Se, Tl, Hg) and radionuclides (Sr-85, Cs-137).
Main Results:
- Grout formulations achieved high wet-sludge loadings (50-60wt%) producing stable wasteforms with no free water.
- Stabilized RCRA metals (mercury and chromium) within Universal Treatment Standard (UTS) limits.
- Measured grout leachability index of 9.0-10.0 for Sr-85 and Cs-137, exceeding the >6.0 requirement.
Conclusions:
- Grout stabilization is an effective method for treating Oak Ridge tank sludges.
- The tested grout formulations meet regulatory requirements for hazardous metal and radionuclide immobilization.
- This approach supports the safe and compliant disposal of radioactive mixed-waste.