Technology:
Segmented Gate System (SGS)
- SGS is a combination of conveyer systems, radiation detectors (primarily gamma radiation), and computer control
- Contaminated soil on conveyer belt was diverted by segmented gates into stockpiles
- Detectors monitored radioactivity content of soil traveling on belt and computer opened specified gates to separate portions of soil based on radioactivity criteria
- Operating parameters included a belt speed of 30 ft/min, belt length of 16 -18 ft, soil layer thickness of 2 inches by width of 30.75 inches, and soil density of 0.95 g/cm3
- Actual run time was 4.12 hours for Area A, and 2.98 hours for Area C
|
Cleanup Authority:
CERCLA
Site Contact:
Frank Webber
INEEL
(208) 526-8507 | Technical Contact:
Ray Patteson
Sandia National Laboratories
(505) 844-1904 |
|
Contaminants:
Radionuclides
- Cesium 137 levels greater than 45 pCi/g |
Waste Source:
Accidental destruction of reactor |
Type/Quantity of Media Treated:
Soil
- 442 yds3 of soil were processed, consisting of 124 yds3 from Area A (Sediment Radionuclide Deposition), 219 yds3 from Area C (Windblown Radionuclide Deposition), and 99 yds3 of oversized material from Areas A and C
- Soils generally consisted of fine-grained eolian soil deposits, with some fluvial gravel and gravelly sands; sieve analysis not performed
- Moisture content relatively high; soil contained clumps of grass with root systems and grass stems |
Purpose/Significance of Application:
Use of a gate system to reduce volume of radioactive-contaminated soil requiring off-site disposal |
Regulatory Requirements/Cleanup Goals:
- Reduce the volume of contaminated soil that was above the specified criteria and that would require storage and disposal, from soil that was below the criteria
- The sorting criterion was 23 pCi/g |
Results:
- Overall volume reduction was measured as 2.7% for Area A soils and 0% for Area C soils
- Several additional tests were performed to determine the cause of the relatively poor results, including a set point test, shine test, and direct haul tests |
Cost Factors:
- The vendor's cost was $205,800, including $17,000 for pre-deployment activities, $69,000 for mobilization, $77,000 for processing, $39,000 for demobilization, and $3,800 for final report; INEEL's costs were $365,000 |
Description:
Idaho National Engineering and Environmental Laboratory (INEEL), located 34 miles west of Idaho Falls, Idaho, encompasses an area of 890 square miles. The site was established in 1949 for building and testing a variety of nuclear facilities. INEEL supports the engineering and operations efforts of DOE and other federal agencies in the areas of nuclear safety research, reactor development, reactor operations and training, nuclear defense materials production, waste management technology, energy technology, and conservation programs. Auxiliary Reactor Area 23 is a 41.8 acre CERCLA site at INEEL containing windblown contamination. Most of the contamination came from the accidental destruction of the SL-1 reactor in 1961. The contaminant of concern at ARA 23 is 137Cs.
A Segmented Gate System (SGS) was used to reduce the volume of contaminated soil that required off-site disposal. SGS is a combination of conveyer systems, radiation detectors, and computer control, where contaminated soil on a conveyer belt is diverted by segmented gates into stockpiles. Detectors monitor the radioactivity content of the soil traveling on the belt and a computer opens specified gates to separate portions of soil based on radioactivity criteria. At this site, the overall volume reduction was measured as less than 3%, and several tests were performed to determine the cause of the relatively poor results. The vendor's cost for the project was $205,800, and INEEL's cost was $365,000. |
