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Cook Nuclear Plant Experience with Storm Water Tritium Discharges

Cook Nuclear Plant Experience with Storm Water Tritium Discharges. Jason T. Harris Purdue University/NATC David W. Miller UIUC/NATC/Cook NP Terry Brown RPM, Cook NP. Discovery. May 30, 2007 Cook Nuclear Plant staff detected tritium on-site

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Cook Nuclear Plant Experience with Storm Water Tritium Discharges

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  1. Cook Nuclear Plant Experience with Storm Water Tritium Discharges Jason T. Harris Purdue University/NATC David W. Miller UIUC/NATC/Cook NP Terry Brown RPM, Cook NP 17th Annual RETS-REMP Workshop Philadelphia, PA June 25-27, 2007

  2. Discovery • May 30, 2007 Cook Nuclear Plant staff detected tritium on-site • Led to increased sampling of various locations on site including wells and outfalls • Ground water wells did not indicate the presence of tritium • Initial North Storm Drain Outfall to beach sample found to contain tritium at 5540 pCi/L • Subsequent samples ranged from 2300-8870 pCi/L • South outfall samples <LLD • North outfall catch basins sampled (5000-17000 pCI/L) • Condensate from air conditioning units (4500-16000 pCi/L)

  3. Initial Steps • Early June – notifications were made to several stakeholders (NRC, NEI, INPO, government) • North outfall re-directed back into plant to the turbine room sump (monitored release path to the absorption pond) • Sampling protocol set up for north and south outfalls, and turbine room sump and absorption pond • Supporting/refuting analysis developed to validate hypothesis that the source of elevated tritium levels is from downwash and air conditioning condensate • Evaluation of initial leak continues

  4. Initial Storm Drain Sample Locations North Outfall N

  5. Initial AC Condensate Sample Locations RPAC Security OBA N

  6. Tritium Samples for Split Analysis

  7. Initial Rain Gauge Locations TSOC Brass Shack Guard House Visitor N

  8. Early Results • Constant sampling showed that tritium found only in samples north of Unit 1 • “plume” of tritium migrated from plant and up service road • AC condensate and North Outfall continued to show presence of tritium

  9. North Outfall Tritium

  10. Pathway Hypotheses • By early June, two pathways were verified and identified by sampling to be the probable sources of tritium • Condensate from the air conditioning units in the Radiation Protection Building located immediately adjacent to containment release points for Units 1 & 2, North Security Guardhouse and Administrative Office Buildings (including annexes). • Downwash from the station vents located at the top of each containment building during rainfall episodes.

  11. Additional Rain Gauges • An additional 28 rain gauges (32 total) were placed throughout the site • Collections revealed similar patterns (tritium in prevailing wind samples N-NW) • Positive samples • Guard house lawn • Unit 1 and 2 roof vents • RPAC

  12. Current Rain Gauge Locations N

  13. Current Rain Fall Locations Control

  14. Dose Consequences • Initial dose analysis performed on three highest tritium concentration samples • Assumed 24 hour release @ 1000 gal w/ 230,000 gpm dilution • REMP pathways also assessed at highest annual Χ/Q (insignificant) • Max = vegetation, 3.30 E-08 • 10 CFR 50 results • Max = particulates, 6.76 E-08

  15. Dose Consequences

  16. Current Progress • Continuing to monitor, sample, and test rain gauges (and ac condensate) • Study impact of humidity and rainfall amount • Investigating building freezer ice (David Miller) • Categorize site throughout the year (wind changes, humidity, etc.)

  17. Conclusions • Air conditioning condensate and rainfall contributing to outfall tritium • Tritium levels in rainfall downwash are influenced primarily by 2 factors • Prevailing wind direction • Amount of rainfall • For Cook (sandy soil), water percolating to Lake Michigan through monitored pathways • To best categorize site, need several rainfalls throughout the year (different prevailing winds)

  18. Additional Areas of Investigation • Evaluate sublimation as it relates to hydrogen/tritium water evaporation rates • Maintain spent fuel water at higher temperature in winter (when drier) for better evaporation (and use large surface area, like roof, for evaporation • Longer rain event more important than short thunderstorms for seeing tritium • For irrigation purposes – trickle underground to avoid standing water that may show increased tritium levels

  19. Additional Areas of Investigation • Don’t release in rain event • Sites with single gaseous release points 2.5 x highest structure/elevated release (e.g., LaSalle and Browns Ferry) –aren’t seeing this phenomenon • Purchase more land

  20. Acknowledgements • Cook Tritium Investigation Team • John Harner, Lead • Dave Faulkner, Chemistry • Bill Hannah, Maintenance • Walt McCrory, Engineering • Doug Foster, Environmental • Joe Beer, RP

  21. Questions? Thank You! 17th Annual RETS-REMP Workshop Philadelphia, PA June 25-27, 2007

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