1A Main Condenser Hotwell 2012 Refueling Outage

1. Hatch Unit 1Condenser Hotwell Damage&Long Cycle Cleanup Valve LeakageForced outages Jan 2013 & Oct 2013

2. 1A Main Condenser Hotwell2012 Refueling Outage

3. 1A Main Condenser Hotwell2012 Refueling Outage Divider wall section broken

4. 1A Main Condenser Hotwell2012 Refueling Outage

5. 1A Main Condenser Hotwell2012 Refueling Outage False bottom cracks on Southeast corner tube sheet supports (8)

6. 1A Main Condenser Hotwell2012 Refueling Outage Divider wall separated from hotwell floor False Bottom topside

7. Initial Cause Determination • Cyclic fatigue due to large variations in circwater temperatures • Condenser design deficiencies • Corrective actions: • Repair to previous condition • System Engineer to identify condenser design deficiencies and initiate design changes

8. June 2012 • Banging sounds identified from 1A Hotwell • Same general area as previous damaged area • ODMI created, evaluated to most likely be an FME issue (Grating) • Sounds only heard when operating at or near 100% power

9. February 2013 • Unit 1 Forced shutdown due to high conductivity • Condenser tube rupture, circwater entered the hotwell • 24 hours before planned Unit 2 refueling outage

10. 1A Hotwell Damage

11. 1A Hotwell DamageFebruary 2013

12. False Bottom Damage

13. Tube Rupture

14. Cause Determination • No PMs on hotwell level transmitters • “A” transmitter crosstied to 1B hotwell • Level recorder displayed 1B hotwell level twice • 1A hotwell level maintained too high • Long cycle cleanup valve leakby

15. Hotwell Level 1A Hotwell 72”+ 1B Hotwell ~40”

16. Long Cycle Cleanup • 1N21F165 valve • Open during startup only • Short cycles condensate/feedwater from the condenser hotwell, through the condensate demins, through all FWHs, then back to the condenser hotwell • Also used during low power operations for RWL control

17. 1N21F16514” CCI Drag Valve

18. Long Cycle Cleanup Flowpath

19. 1N21F165 leak by effects • Feedwater (~350 degrees, 1000 psi) short cycled back to hotwell • Drains below hotwell false bottom (under water) • Result: • Flashing of feedwater within hotwell • Water hammer inside hotwell

20. March – October 2013 • “A” level transmitter valved back to 1A hotwell • Transmitters recalibrated • 1A hotwell level lowered • Stopple valve plug considered, but rejected • ~75 REM dose projection • August & September, patches placed on valve body due to external leakage

21. Valve Body Blowout • Shutdown required as flooding neared the 3” setpoint to trip circwater pumps • External leakage exceeded the capacity of the conbay floor drain sumps

22. ~1” though body hole2” valve body

23. Repairs7” x 7” x 2” plate

24. Causes • Inadequate valve design • No PMs (installed mid 1990’s) • Leaking upstream valves • Inadequate thermal performance monitoring • No temperature indication downstream of 1N21F165

25. Missed Opportunities • Since 2007, both Unit 1 RFPT RPMs were noted to have increased by about 150 RPMs • Indications of feedwater being short cycled to the hotwell. RPMS increased to maintain RWL • Thermal performance trends of upstream 1N21F027A/B valves were not fully understood, and were notacted upon • Indicated leakby from those valves • PMs on 1N21F027A/B moved out of 2012 refueling outage with little technical justification • Inadequate ACD from 2012 condenser damage • Incorrect assessment of June 2012 banging noises in ODMI • No action taken from increasing offgas flowrates, as recommended in the ODMI • Possibility of external valve leakage not identified, despite similar occurrences in similar applications

26. Lessons Learned • Need PMs on all high energy source drains to condensers • FWH high level dump valves • Feed Pump min flow valves • Long cycle Cleanup valves • Thermal Performance monitoring • Permanent thermocouples • Heat gun • UT thickness measurements for suspect valves • Hotwell level • False bottom impacts • PMs for Level Controls

27. Questions?