HATCH UNIT 1 CONDENSER HOTWELL DAMAGE LONG CYCLE

HATCH UNIT 1 CONDENSER HOTWELL DAMAGE & LONG CYCLE CLEANUP VALVE LEAKAGE FORCED OUTAGES JAN 2013 & OCT 2013

1 A MAIN CONDENSER HOTWELL 2012 REFUELING OUTAGE

1 A MAIN CONDENSER HOTWELL 2012 REFUELING OUTAGE Divider wall section broken

1 A MAIN CONDENSER HOTWELL 2012 REFUELING OUTAGE

1 A MAIN CONDENSER HOTWELL 2012 REFUELING OUTAGE False bottom cracks on Southeast corner tube sheet supports (8)

1 A MAIN CONDENSER HOTWELL 2012 REFUELING OUTAGE Divider wall separated from hotwell floor False Bottom topside

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

JUNE 2012 Banging sounds identified from 1 A 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

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

1 A HOTWELL DAMAGE

1 A HOTWELL DAMAGE FEBRUARY 2013

FALSE BOTTOM DAMAGE

TUBE RUPTURE

CAUSE DETERMINATION No PMs on hotwell level transmitters “A” transmitter crosstied to 1 B hotwell Level recorder displayed 1 B hotwell level twice 1 A hotwell level maintained too high Long cycle cleanup valve leakby

HOTWELL LEVEL 1 A Hotwell 72”+ 1 B Hotwell ~40”

LONG CYCLE CLEANUP 1 N 21 F 165 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

1 N 21 F 165 14” CCI DRAG VALVE

LONG CYCLE CLEANUP FLOWPATH

1 N 21 F 165 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

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

VALVE BODY BLOWOUT External leakage exceeded the capacity of the conbay floor drain sumps Shutdown required as flooding neared the 3” setpoint to trip circwater pumps

~1” THOUGH BODY HOLE 2” VALVE BODY

REPAIRS 7” X 2” PLATE

CAUSES Inadequate valve design No PMs (installed mid 1990’s) Leaking upstream valves Inadequate thermal performance monitoring § No temperature indication downstream of 1 N 21 F 165

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 1 N 21 F 027 A/B valves were not fully understood, and were not acted upon § Indicated leakby from those valves PMs on 1 N 21 F 027 A/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

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

QUESTIONS?