- Hand-held unit weighing about 30 lbs
- Components include spalling bit, removable metal shroud, hydraulic cylinder rated at 9 tons, and hydraulic pump rated at 10,000 psi
- Pre-drill holes in surface (2.5-cm diameter) in a honeycomb pattern
- Spaller bit inserted into hole, the hydraulic valve opened causing bit to expand and breaking off a chunk of concrete; concrete chunks were collected in the metal shroud
- A water spray was used to control dust emissions during the demonstration
- Beta and gamma radioactivty
Nuclear processing operations
Type/Quantity of Media Treated:
- Debris - 4.6m2
- Contaminated concrete walls and floors
Purpose/Significance of Application:
First demonstration of the hand-held concrete spaller on contaminated surfaces
Regulatory Requirements/Cleanup Goals:
- The objectives of the demonstration were to evaluate the capabilities and design features of the concrete spaller for removing contaminated concrete surfaces
- No specific cleanup goals were identified
- During the demonstration, the concrete spaller removed concrete from an area of 4.6 m2 to a depth of 3 mm to 50 mm; the removal rate was 1.3m2/hr
- Pre-drilling was relatively slow; however, faster drills are available for this step
- Little dust was generated by the spaller:
- Operating costs for the demonstration were about 22% higher than the baseline technology (scabbler and scaler) because of the problems encountered with the drill (slower than expected and inexperienced crew)
- For the cost analysis, operating costs were estimated for an improved concrete spaller technology (adequate drill and experienced crew) - $128/m2, assuming a depth of 3-mm
- Operating costs for the improved spaller are 15% less the costs for the baseline tools (scaler at $155/m2 and scabbler at $156/m2).
The concrete spaller, developed by the Pacific Northwest National Laboratory, is a hand-held tool used for decontaminating concrete surfaces. The spaller includes a 9-ton hydraulic cylinder and a patented spalling bit that is run by a 10,000 psi hydraulic pump. Holes are drilled into the concrete in a honeycomb pattern and the spaller bit inserted into each hole. The hydraulic valve is opened, expanding the bit, and the concrete is removed in chunks up to 2 inches thick and collected in a metal shroud attached to the spaller. The unit can be used on flat or slightly curved concrete walls and floors, and can be equipped with a vacuum filtration unit for particulate control.
The concrete spaller was demonstrated at DOE's Hanford site in Richland, WA on two wall areas in the fan room of the C Reactor facility. The walls were contaminated with beta/gamma radioactivity. During the demonstration, the spaller removed 4.6 m2 of contaminated surface to a depth of 3 mm to 50 mm, which was deeper than the baseline technologies (scaler and scabbler). The operating cost of the spaller under optimal conditions is $128/m2, which is less than the costs for the baseline tools (scaler at $155/m2 and scabbler at $156/m2). Considerations for future development and use of the technology include the need for a simplified design or manufacturing technique for the spalling bit (which was found to be fairly difficult to manufacture), the addition of a water spray nozzle to the drill to eliminate the need for a second worker to manually apply water during drilling, and the additional of an automatic hydraulic control valve.