Reactor Characterization B. Wilcox, Director of Reactor - - PowerPoint PPT Presentation

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Reactor Characterization B. Wilcox, Director of Reactor - - PowerPoint PPT Presentation

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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

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SLIDE 1

WR-1 Reactor Decommissioning Update Reactor Characterization

2019 November 12

  • B. Wilcox, Director of Reactor Decommissioning
  • J. Miller, Technical Lead
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SLIDE 2

Proposed In Situ Decommissioning

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SLIDE 3

Multiple Barriers Protect the Environment

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SLIDE 4

4

WM Main Campus (circa 2002)

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SLIDE 5

5

WM Main Campus (planned 2026)

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SLIDE 6

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
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SLIDE 7

Project timeline update

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SLIDE 8

Characterization Update

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SLIDE 9

Outline

  • Why Characterize?
  • Historical Characterization Work
  • Summary of Data, Review and Gap Identification
  • Characterization Plan Development
  • Characterization Performed
  • Preliminary Results
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SLIDE 10

Why Characterize?

  • Provides Confidence to Regulator
  • Supports Long Term Safety Case Modelling
  • Supports Worker Safety and Dose Estimates
  • Supports Strategic Decisions for Decommissioning
  • First of Many Steps
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SLIDE 11

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)
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SLIDE 12
  • 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 Summary & 3rd Party Review

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SLIDE 13

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
  • Moderator
  • Biological and Thermal

Shield Cooling

  • Experimental Loops
  • Fuel Transfer Systems
  • Active and Process Drainage
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SLIDE 14

Characterization Work Performed

  • 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
  • 2017-2018
  • Lead
  • Chromium
  • Mercury
  • PCB
  • Cadmium
  • Boron
  • Xylene
  • Potassium Hydroxide
  • Field Characterization for Lead and PCBs
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SLIDE 15
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SLIDE 16
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SLIDE 17
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SLIDE 18

Radiological 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.
  • Coupon Results
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SLIDE 19

Radiological Results

  • Coupon Results – Primary Heat Transport System

Nuclide

  • No. of

Sample s # >MDA Mean @ 90% Confidence (Bq/cm2) SD (Bq/cm2) 99% UCL (Bq) 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

  • 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+10

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SLIDE 20

Radiological Results

  • 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.
  • Coupon Results - Tritium
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SLIDE 21

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 x1012

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SLIDE 22

Radiological Results

  • Fuel Channel Scrape Samples Results
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SLIDE 23

Radiological Results

  • Fuel Channel Scrape Samples Results
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SLIDE 24

Radiological Results

  • Fuel Channel Scrape Samples Results
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SLIDE 25

Radiological Results

  • Fuel Channel Scrape Samples Results
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SLIDE 26

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+15

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SLIDE 27

Non-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 kg

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SLIDE 28

Non-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 kg

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SLIDE 29

Non-Radiological Results

  • 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.
  • Polychlorinated Biphenyls (PCBs)
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SLIDE 30

Uncertainty in Results

  • 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 analysis

  • How is uncertainty dealt with?
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SLIDE 31

Conclusions

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SLIDE 32

Conclusions

  • 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
  • What do these results tell us?
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SLIDE 33

Conclusions

  • Natural Analogue
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SLIDE 34

Jeff Miller, EIT (204)-753-2311 x63121 Jeffrey.Miller@cnl.ca