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Non-combustible waste vitrification with plasma torch melter
1Nuclear Environment Technology Institute, KEPCO, P.O. BOX 149, Yusung, Taejon, 305-600, Korea. parkjoki@kepco.co.kr
Summary
Plasma vitrification effectively immobilizes nuclear power plant wastes, creating durable glassy forms. Most contaminants show low leach rates, though cobalt and cesium require further study for optimal containment.
Area of Science:
- Nuclear waste management
- Materials science
- Environmental engineering
Background:
- Non-combustible radioactive wastes from nuclear power plants (NPPs) contain materials like concrete, glass, and metals.
- Effective immobilization is crucial for the safe disposal of these hazardous materials.
Purpose of the Study:
- To investigate the effectiveness of plasma vitrification for treating NPP wastes.
- To evaluate the characteristics of the resulting glassy waste forms, focusing on volume reduction and leachability.
Main Methods:
- Simulated radioactive wastes (including concrete, glass, sand, spent filters) were prepared with non-radioactive cobalt (Co) and cesium (Cs).
- A 60 kW plasma torch system was used to melt surrogate wastes into glassy forms.
- Volume reduction factor (VRF) was determined by density measurements.
- Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) was employed to assess leach rates of various elements.
Main Results:
- Glassy waste forms were successfully produced with volume reduction factors (VRFs) ranging from 1.2 to 2.4.
- Leach rates for most tested elements (As, Ba, Hg, Pb, Cd, Cr, Se) were below Universal Treatment Standard (UTS) limits.
- Cobalt (Co) and cesium (Cs) exhibited leach rates and indices approximately 10 times higher than other elements, with no established UTS limits for comparison.
Conclusions:
- Plasma vitrification is a viable method for reducing the volume of NPP wastes and creating stable glassy forms.
- While effective for many contaminants, the higher leachability of Co and Cs indicates a need for further research and potentially tailored treatment strategies for these specific elements.