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Fe-55 and Te-125m in Liquid Waste
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  1. Fe-55 and Te-125m in Liquid Waste RETS REMP Workshop June 26-28, 2006 Richard Conatser Constellation Energy Group Calvert Cliffs Nuclear Power Plant

  2. Overview • Radwaste history, cost, and strategy • Empirical Data (Te-125m and Fe-55) • Radwaste System Overview • Corrective Actions/Recommendations • Questions

  3. CCNPP LRW History • Before 2003 releases were 3rd quartile • Large volume processed (2.2E6 gal/yr) • OEM used filters, IX, and evaporators • Filter use was excessive at times • High disposal costs

  4. Costs Before the “Skid” • $1.3M cost in 2001 (excluding labor) • Estimated $0.45/gal (excl. labor) • Processing used to be slow • Lots of dose associated with filters • LRW was typically 3rd Quartile • Evaluated advanced “skids” • Determined costs could be reduced

  5. Strategy • Lower Ci discharged • Reduce costs to $0.22/gallon • Reduce dose • Reduce man-hours • Achieve INPO 1st quartile

  6. Fe-55 • Produced from Fe-54 (5% abn.) • Fe-55 decays by electron capture • emits low-energy x-rays • emits Auger electrons • 2.77 year half life • Separation and scintillation counting

  7. Potential Causes Fe-55 • Analytical Method? • Composite Sample (prep.)? • Radwaste Processing? • Real System Anomaly?

  8. Analytical Method Fe-55 • Separate Fe-55 (precipitation, IX) • Liquid scintillation counting • Gross analysis (energy window) • Susceptible to interference • QC standards were good • “D.I. Blank” was high • No spike sample

  9. Composite Sample Fe-55 • Two sources of radwaste water • High Conductivity (soapy drains) • Low Conductivity • High cond waste is not processed • Qualitative trend appears normal • Some history ofsample prep problems

  10. Radwaste Process, Fe-55 • First noticed coincident with skid • Easily removed as a particulate • Expect removal similar to Cobalt • Data = Doesn’t follow other nuclides • Data = Concentrating Fe-55 • Data = Effectively bypassing skid

  11. Simplified Diagram 11 RCWRT 90,000 gal 12 RCWRT 90,000 gal Demin Booster Pump #4 IX UF 6 UF 5 UF 4 UF 3 UF 2 UF 1 #3 IX Recirculation Pump RCWRTpumps Chem Add Tank DI Water 0-RCW-518 #2 IX SCS 11 RCWMT 90,000 gal B/W Tk #1 IX 0-RCW-522 #14 IX #13 IX 0-RCW-526 11 RCWMT Pump 12 RCWMT 90,000 gal Bay

  12. Corrective Actions Fe-55 • Maintain spare composite sample • Include spiked samples • SCS samples analyzed for Fe-55 • Trace all flow paths for “skid”

  13. Te-125m • Te-125m is a gamma emitter • 57.4 day half life • From beta decay of Sb-125 • Te-125m emits 109 keV gamma • 109 keV Abundance = 0.283% • A few counts = “high” activity

  14. Corrective Actions Te-125m • This phenomena appears to be related to IXs • May be related to changes in feed water quality • Change IXs more often

  15. Questions?