Technology:
Soft Media Blasting
- Compressed air is used to propel soft blast media through a hose onto the contaminated surface; soft media traps and absorbs contaminants on impact
- Air compressor - minimum requirements (250 ft3/min of air; 120 psi line pressure at the feed unit); for demonstration- 375 ft3/min, 150 psi
- Feed unit - contains media mixture; connected to a hose (1 1/4-in. diameter; 25-ft long) fitted with a venturi-style tungsten carbide blast nozzle (3/8 in and 1/2 in nozzles tested during demonstration)
- Blast pressure - 45 psi; media flow - 20-25 lbs
- Six grades of media available (color-coded by grade); two grades of media were tested - green media containing no abrasive; brown media containing Starblast® abrasive
- Demonstration involved cleaning a settling tank contaminated with enriched uranium process residue
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Cleanup Authority:
Not identified
Technical Contacts:
Larry Stebbins
Fluor Daniel Fernald
513-648-4785
larry.stebbins@fernald.gov
Steve Bossart
Federal Energy Technology Center
304-285-4643
sbossa@fetc.doe.gov |
Contaminants:
Radionuclides
- Enriched uranium (1.34 wt-% U-235)
- Contaminant levels of 18,000 dpm/100 cm2 measured prior to demonstration |
Waste Source:
Residue from enriched uranium processing operations |
Type/Quantity of Media Treated:
Debris |
Purpose/Significance of Application:
Demonstration of soft blast media to clean surfaces contaminated with uranium |
Regulatory Requirements/Cleanup Goals:
- Performance objectives included cleaning effectiveness (based on amount of residual radioactivity) and production rate
- Evaluate the technology for use in cleaning radioactive-contaminated surfaces |
Results:
- Radiation levels were below the minimum detectable count rate (MDCR) following the demonstration
- Production rate was 92 ft2/hr; rate was slower than expected - worker time was limited to 1 hr/day because of the noise generated by the system (106 to 113 dB)
- Brown media was effective on thick dirt; brown media generated more dust than the green media |
Cost Factors:
- Demonstration cost for soft media blasting - $4.60/ft2
- Projected full-scale costs are comparable to baseline technology (high-pressure water washing) for an area of 900ft2 or larger |
Description:
A field demonstration of Soft Media Blasting Technology (SMBT) was performed at the Fernald Site to evaluate the capability of the technology for cleaning radioactively-contaminated surfaces. SMBT uses compressed air to propel soft blast media onto the contaminated surface, with the soft media trapping and absorbing contaminants on impact. Six grades of media are available for the SMBT, manufactured by AEA Technologies, Inc. For the demonstration, two grades were tested - one containing no abrasive and one containing the Starblast® abrasive. A settling tank contaminated with enriched uranium process residue was used for the demonstration.
The results of the demonstration showed that the SMBT reduced radiation levels from 18,000 dpm/100 cm2 to MDCR. The production rate of 92 ft2/hr was slower than the baseline technology of high-pressure washing. Because the system was noisy, the time an individual could work was limited. The demonstration cost for soft media blasting was $4.60/ft2, more expensive than the baseline technology. However, the projected full-scale costs for SMBT are comparable to the baseline technology for an area of 900ft2 or larger. Issues associated with full-scale implementation include the noise level produced by the system and improving the ergonomic design of the nozzle/hose assembly to make it less awkward to use. While the media was not recycled during the demonstration, a unit (Classifier Unit) can be added to the system for this purpose. The decision to not recycle the media during the demonstration was based on a concern that the feed and classifier units would not be successfully decontaminated following repeated recycling of the contaminated media. |
