Advanced Radiological Scanning and Sorting of CNL’s Whiteshell Laboratories
Experimental Cesium Pond Effluent Soils
Steven D. Rima, CHP, CPM Michael P. McDonald, CHP, RRPT
Amec Foster Wheeler
Whiteshell Laboratories
► Near Pinawa, Manitoba ► 100 kilometers (km) northeast of Winnipeg
► Nuclear Research and Test Establishment ► Decommissioning since 2003
► Experimental Cesium Pond Soil ► Shielded Modular Above-Ground Storage
(SMAGS) facility soil ► Nuclear Reactor
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Whiteshell Laboratories Location
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Project Overview
Two ponds constructed in 1966 ► 2m deep by 19m diameter and lined with plastic ► Filled with water and allowed to develop “naturally” ► One pond spiked with 18.5 gigabecquerel (GBq)
cesium-137 (Cs137) ► Used for over 10 years to study the effect of Cs137
on various ecosystems, including insects ► Cs137 spread both laterally and vertically over the
years
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Project Overview
Cesium Pond soil was previously excavated and moved to a Waste Management Area (WMA) ► Approximately 1,700 cubic meters (m3) of soil
excavated and stockpiled ► WMA contained other stock-piled materials as well ► Amec Foster Wheeler awarded contract to sort and
segregate WMA soils into contaminated (needing eventual disposal as low-level radioactive waste [LLRW]) and “clean” (available for beneficial reuse on site)
► ScanSortSM system & operators deployed to site; operated through severe winter conditions
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Orion ScanSortSM
► Radiological Soil Sorting Survey System ► Large volume spectroscopy grade sodium iodide (NaI)
detectors ► Advanced scanning spectrometer operating software ► Advanced, computer-controlled, electro-mechanical
material handling and sorting equipment ► Detects gamma-emitting radionuclides as the soil on
the belt moves past the active area of the detector ► 100% assay of processed materials by laboratory
quality gamma spectroscopy analysis
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Orion ScanSortSM Configuration
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ScanSortSM Display
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Unconditional Clearance Levels (UCL)
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Radionuclides of Interest
Average activity concentration in Bq/gram
(Bq/g) Co60 0.1 Sr90 1
Cs137 0.1 Eu154 0.1 Pu238 0.1 Pu239 0.1 Pu240 0.1 Pu241 10 Am241 0.1
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Radionuclide Ratios
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Radionuclides of Interest % of Total Activity
Cs137 48.8 Sr/Y90 31.1 Pu241 13.8 Am241 3.6
Pu239+240 2.2 Pu238 0.34 Eu154 0.15 Co60 0.03
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UCL Sum-of-Ratios (SOR)
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Radionuclides of Interest (ROI)
Total Activity
(%)
Relative (to Cs137)
Activity
Net Activity (Bq/g) UCL (Bq/g)
Isotopic Contribution to UCL SOR
(net activity/ UCL) Cs137 48.8 1.00 0.08 0.1 0.800
Sr/Y90 31.1 0.64 0.05 1 0.051
Pu241 13.8 0.28 0.02 10 0.002
Am241 3.6 0.07 0.01 0.1 0.059
Pu239+240 2.2 0.05 0.00 0.1 0.036
Pu238 0.34 0.01 0.00 0.1 0.006
Eu154 0.15 0.00 0.00 0.1 0.002
Co60 0.03 0.00 0.00 0.1 0.000
UCL Sum Of Ratios 0.957
Project Overview
Mobilized to Whiteshell site in April 2013 ► Started sorting soil in early May ► Rapidly warming spring weather caused early
thawing of soils, resulting in material handling issues due to high clay content
► Demobilized staff, leaving equipment at site ► Remobilized January 2014 to work through winter
when soil was frozen
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“Manitoba Gumbo”
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Material Handling Issues with Clay
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Frozen on Remobilization -43C !!!
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Orion ScanSortSM System
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Orion ScanSortSM System
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Results
► ScanSortSM Results ► Over 2,300 metric tons of Cesium Pond material processed ► Over 163 metric tons of SMAGS material processed ► More than 65,000 measurements collected & processed ► Typical process rate of 50-100 tons/hour
► Cesium Pond Material ► Vast majority of material above UCL ► 100% assay of waste material for SMAGS waste acceptance
criteria (WAC) ► SMAGS Building Material ► 35% below UCL so suitable for beneficial reuse ► 100% assay for waste characterization for SMAGS WAC
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Lessons Learned
► Material Followability ► Material needs to be flowable, smaller sized material is better ► Frozen, conditioned material flows well, “Manitoba Gumbo”
does not ► Stock Piling In Advanced Is Advised ► Survey production rate is dependent on material conditioning
and feed rate to the system ► Condition material prior to stock piling
► Severe Weather Conditions ► Electronics don’t like -45oC (neither do I) ► System enclosure/tent is very helpful to combat weather
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Lessons Learned
► Equipment Contamination ► Surprisingly, not an issue. Self-cleaning? Send “clean
material” through at end of survey to clean ► Minimal spread of contamination (control the dust, control the
contamination) ► Survey Results (and Other) Reporting Criteria ► Educate the customer on what ScanSortSM can and can’t do ► Identify up-front what the survey results should look like and
agree on them ► Get your customer involved early (and often)
► Be Flexible ► Have a backup plan ready (low feed rate, support equipment
failure, weather issues, regulatory delays, etc.)
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Q&A
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