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Scott Cameron Manager Radiation Protection 2008 International ALARA Symposium ALARA Performance at OPG
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Overview 1.Introduction 2.Dose Reduction Initiatives 3.Human Performance Improvements 4.Future Challenges
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Dose Reduction Initiatives: Darlington Installation of Submicron Filtration HTS bleed filter pore size reduced in steps from 2 uM to 0.45 uM in May/2002 and 0.1 uM in Dec/2003 Increased filter replacement rate was driven by dose rate not ΔP Contribution to dose savings: 130 rem for Unit 1 since 2004
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Dose Reduction Initiatives: Remote Monitoring Teledosimetry for dose monitoring and Rx face scan Remote readout of gamma and tritium levels at airlock (HP)
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Dose Reduction Initiatives: Shielding Applications Water wall for on-power Airlock EQ work – 3 rem dose and 4 M$ outage critical path savings Water bag for ECI hot spot shielding Face shielding Rx Shield Block Data: Each block weighs 22 lbs with a 7” hole cut out 15 min and 14 mrem to install 35 blocks Shielding effectiveness: Before shielding – 90 mrem/h, after shielding – 42 mrem/h
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Dose Reduction Initiatives: Decontamination Application of strippable Decon Gel Example: HX1 room floor Coated and peeled the next day Before – 5000 cpm After - 0 cpm Peeling - 4.5 mrem/h C
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Internal Dose Reduction: Outage Tritium Reduction ALARA Plan Action Levels established with pre-determined corrective actions Reduce closure plug leakage (CP tightening, PHT low level drain state to reduce static pressure) Install portable dryers (96% capacity factor, 24 drums of D2O, 1200 Ci extracted from vault air) Contain and reduce tritium @ airlocks (H3 <0.1 MPCa outside AL) Munter Dryer
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Human Performance Improvement: Impact of Worker Practice Human performance has a large impact on the effectiveness of RPPE: Good RP practice can increase protection factor (PF) by a factor of 2 Human performance can be improved by communication and focused O&C’s 1 st wave of intense communication
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Human Performance Improvement: Example of Worker Communication Campaign Communication campaign to emphasize impact of unplugged time on tritium uptake: Video presentation and posters Outage handbook Safety meetings
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Human Performance Improvement: Coaching, Monitoring & Follow-up Daily dose monitoring and follow-up of EPD dose and tritium uptake Action levels: 3 uCi/l or 10 mrem EPD – follow-up with worker/supervisor 10 uCi/l above planned or EPD alarm – department EFDR, SCR 35 uCi/l above planned or 100 mrem above EPD alarm – root cause investigation Performance management Focused observation and coaching (O&C) by RP staff Interview by RPM and RHP for significant events or repeats RP qualification review of worker and supervisor
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Three Consecutive WANO Strengths in ALARA 2007, 2008 WANO: High standards in RP have been set and achieved Robust controls prevent unplanned exposures Extensive ALARA planning, innovative shielding and aggressive tritium reduction Reactor face shielding On-line tritium / gamma system ALARA Achievement
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Future Challenges: 2. Reduce γ dose rate in HT system by 25% by 2011 Gamma scans identify Co-60 as the dominant source of radiation More than 80% of Co-60 originates from FM stellite ram balls Long term plan: COG joint/R&D project to develop replacement Short term plan: FM filtration improvement – submicron filters & IX
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