WR-1 Reactor Decommissioning Update Reactor Characterization - B. Wilcox, Director of Reactor Decommissioning J. Miller, Technical Lead
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WR-1 Reactor Decommissioning Update
Reactor Characterization
B. Wilcox, Director of Reactor Decommissioning
J. Miller, Technical Lead
2019 November 12
Proposed In Situ Decommissioning
Multiple Barriers Protect the Environment
WM Main Campus (circa 2002)
4
WM Main Campus (planned 2026)
5
Current Activities • Crawlspace and Ventilation System Characterization • Design of the Cap and Cover System • Updates to the Environmental Impact Statement • Updates to the Safety Assessment • Revisions to the Detailed Decommissioning Plan • Preparing submission packages for the Environmental Assessment and licence Amendment • Planning for lead removal and laboratory D&D
Project timeline update
Characterization Update
Outline
• Why Characterize?
• Historical Characterization Work
• Summary of Data, Review and Gap Identification
• Characterization Plan Development
• Characterization Performed
• Preliminary Results
Why Characterize? • First of Many Steps • Provides Confidence to Regulator • Supports Long Term Safety Case Modelling • Supports Worker Safety and Dose Estimates • Supports Strategic Decisions for Decommissioning
Historical Work
• 1990 – Dose Rate Measurements taken in Fuel Channels
• 1992 - Modelling Estimates of Inventory and Dose Rate
• 1994 – Survey of Contamination in Restricted Access Area
Rooms (swipes)
• 1997 – Core Sample of Biological Shield analyzed
• 2011 – Axial Dose Profiling of Fuel Channel
• 2015 – Sample Collection from Moderator System
• Various Routine Surveyor Logs of Building 100 and Reactor
Systems
• Ongoing Effluent Monitoring (Air and Liquid)Characterization Summary & 3rd Party Review
• Summary document produced for historical characterization
work (WLDP-26100-041-000-0001).
• Submitted for 3rd party review Oak Ridge Associated
Universities (ORAU), recognized experts in characterization
work.
• Opportunities identified by ORAU
• Suggested additional characterization samples be taken to
improve confidence.Characterization Plan
• Developed by ORAU, Ranked Set Sample Methodology
• Using 80% confidence intervals to determine number of
samples
• Survey 3 – Cut 1
• Separated by System
• Primary Heat Transport • Experimental Loops
• Moderator • Fuel Transfer Systems
• Biological and Thermal • Active and Process Drainage
Shield CoolingCharacterization Work Performed
• 2017-2018
• 121 coupon samples cut and analyzed – 363 Survey points
• 4 Fuel Channel Scrape Samples from centre line of flux
• Table Top Review of installed non-radiological contaminants
• Lead • Cadmium
• Chromium • Boron
• Mercury • Xylene
• PCB • Potassium Hydroxide
• Field Characterization for Lead and PCBsRadiological Results • Coupon Results • No unexpected results were observed. • Coupon results matched well with estimated radionuclide ‘fingerprint’. • Confirmed Primary Heat Transport System is main contributor to ‘out of core’ inventory. • Showed Historical Inventory Estimate conservative by factor of 5-20.
Radiological Results
• Coupon Results – Primary Heat Transport System
No. of 99% UCL
Mean @ 90%
Nuclide Sample # >MDA SD (Bq/cm2) (Bq)
Confidence (Bq/cm2)
s
Ag-108m 39 1 5.99E-02 2.84E-02 1.62E+06
Am-241 39 25 3.20E+01 2.43E+01 1.09E+09
C-14 39 35 3.31E+00 3.03E+00 1.26E+08
Cm-243/244 3/1a 3 4.38E-01 5.58E-02 8.78E+06
Co-60 39 26 1.53E+00 1.30E+00 5.55E+07
Cs-137 39 39 9.73E+02 5.90E+02 2.96E+10
Fe-55 3/1 2 2.82E+00 2.88E-01 5.40E+07
H-3 39 31 1.33E+01 6.44E+00 3.65E+08
Nb-94 39 13 2.19E-01 2.02E-01 8.36E+06
Ni-59 3/1 0 -8.59E-02 7.96E-01 2.73E+07
Ni-63 3/1 2 8.72E+00 8.60E-01 1.66E+08
Pu-238 3/1 4 8.75E+00 8.38E-01 1.65E+08
Pu-239/240 3/1 4 1.70E+01 1.27E+00 3.09E+08
Pu-241 3/1 4 1.60E+02 1.48E+01 3.00E+09
Sr-90 3/1 4 5.98E+02 9.47E+01 1.26E+10
U-235 39 6 7.77E-02 1.41E-01 4.67E+06
U-238 3/1 4 2.64E-02 4.66E-01 2.07E+07
Total Inventory 4.70E+10Radiological Results • Coupon Results - Tritium • Found little to no H-3 on moderator coupons. • Increase in Tritium measured in air effluent during couponing. • Indicated two possibilities: • 1. Tritium was released from sample during couponing (heat and vibration). • 2. Tritium on coupons is very low and effluent increases were due to trapped tritium vapour released by opening the system. • CNL explored several potential causes.
Radiological Results
• Coupon Results - Tritium
Method Activity (Bq)
1% Remaining Estimate 1.27x1014
Absorbed Tritium Analysis 1.11x109
Amount of 3H Released (2015) 2.47x1015
Amount of 3H Released (2017) 3.80 x1014
Rate of 3H Release (2015) 2.26 x1015
Rate of 3H Release (2017) 3.14 x1014
H Solubility Limit in SS 5.31 x1012Radiological Results • Fuel Channel Scrape Samples Results
Radiological Results • Fuel Channel Scrape Samples Results
Radiological Results • Fuel Channel Scrape Samples Results
Radiological Results • Fuel Channel Scrape Samples Results
Radiological Results
• Previous Estimate v. New Characterization Results
System Pre-2018 (Bq) Post-2018 (Bq) Assessment Value (Bq)
Bioshield 4.1E+09 N/A 4.1E+09
Core 1.1E+15 4.77E+14 1.1E+15
Out of Core 1.1E+12 8.45E+10 1.1E12
Total H-3 Out of Core 1.27E+14 2.47E+15 2.47E+15
Totals 1.18E+15 2.95E+15 3.53E+15Non-Radiological Results
• Desktop Review
Contaminant Quantity
Potassium Hydroxide 0.01 kg
Boron 0.0009 kg
Lead 40,800 kg
Xylene 1.9 kg
Palladium 15.5 kg
Chromium 148 kg
Cadmium 91.4 kg
HB-40 (aka OS-84, Hydrogenated Terphenyl) 87,700 kg
Mercury 0.74 kgNon-Radiological Results
• Lead Survey
Not Removable 20,846 kg
Potentially Removable 514 kg
Removable 103,119 kg
Within ISD Envelope 24,037 kg
Outside of ISD Envelope 100,443 kg
Grand Total 124,480 kgNon-Radiological Results • Polychlorinated Biphenyls (PCBs) • Survey of paint, caulking, other materials show no PCB’s within the ISD envelope above exemption quantities (50 mg/kg). • Some exterior window glazing found to contain PCB’s will be remediated prior to demolition. • Identified fluorescent light ballasts as possible PCB source. • All ballasts will be removed from the building prior to grouting and demolition.
Uncertainty in Results
• How is uncertainty dealt with?
• All results have an associated uncertainty
• Confidence is improved through:
1. Multiple methods of estimation
2. Conservative assumptions
3. Adherence to accepted best practices
4. Examination of effects of uncertainty through model sensitivity analysisConclusions
Conclusions • What do these results tell us? • Confirm that most of the remaining radioactivity is in the reactor core • Confirm that estimates made on historical data were conservative • Provide additional evidence of the confidence in the inventory estimates • Allow us to compare WR-1 to natural analogues
Conclusions • Natural Analogue
Jeff Miller, EIT (204)-753-2311 x63121 Jeffrey.Miller@cnl.ca
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