HATCH UNIT 1CONDENSER HOTWELL DAMAGE

& LONG CYCLE CLEANUP VALVE LEAKAGE

FORCED OUTAGES JAN 2013 & OCT 2013

1A MAIN CONDENSER HOTWELL2012 REFUELING OUTAGE

Divider wall section broken

1A MAIN CONDENSER HOTWELL2012 REFUELING OUTAGE

1A MAIN CONDENSER HOTWELL2012 REFUELING OUTAGE

False bottom cracks on Southeast corner tube sheet supports (8)

1A MAIN CONDENSER HOTWELL2012 REFUELING OUTAGE

Divider wall separated from hotwell floor False Bottom topside

1A MAIN CONDENSER HOTWELL2012 REFUELING OUTAGE

Cyclic fatigue due to large variations in circwater temperatures

Condenser design deficienciesCorrective actions:

Repair to previous condition System Engineer to identify condenser design deficiencies

and initiate design changes

INITIAL CAUSE DETERMINATION

Banging sounds identified from 1A HotwellSame general area as previous damaged areaODMI created, evaluated to most likely be an FME

issue (Grating)Sounds only heard when operating at or near 100%

power

JUNE 2012

Unit 1 Forced shutdown due to high conductivityCondenser tube rupture, circwater entered the

hotwell24 hours before planned Unit 2 refueling outage

FEBRUARY 2013

1A HOTWELL DAMAGE

1A HOTWELL DAMAGEFEBRUARY 2013

FALSE BOTTOM DAMAGE

TUBE RUPTURE

No PMs on hotwell level transmitters“A” transmitter crosstied to 1B hotwellLevel recorder displayed 1B hotwell level twice1A hotwell level maintained too highLong cycle cleanup valve leakby

CAUSE DETERMINATION

1A Hotwell72”+

1B Hotwell~40”

HOTWELL LEVEL

1N21F165 valveOpen during startup onlyShort 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

LONG CYCLE CLEANUP

1N21F16514” CCI DRAG VALVE

LONG CYCLE CLEANUP FLOWPATH

F romC ondB oo s te rP um pD is ch

AO

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

1N21F165 LEAK BY EFFECTS

“A” level transmitter valved back to 1A hotwellTransmitters recalibrated1A hotwell level loweredStopple valve plug considered, but rejected

~75 REM dose projectionAugust & September, patches placed on valve body

due to external leakage

MARCH – OCTOBER 2013

External leakage exceeded the capacity of the conbay floor drain sumps

Shutdown required as flooding neared the 3” setpoint to trip circwater pumps

VALVE BODY BLOWOUT

~1” THOUGH BODY HOLE2” VALVE BODY

REPAIRS7” X 7” X 2” PLATE

Inadequate valve designNo PMs (installed mid 1990’s)Leaking upstream valves Inadequate thermal performance monitoring

No temperature indication downstream of 1N21F165

CAUSES

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 not acted upon Indicated leakby from those valves

PMs on 1N21F027A/B moved out of 2012 refueling outage with little technical justifi cation

Inadequate ACD from 2012 condenser damage Incorrect assessment of June 2012 banging noises in ODMI No action taken from increasing off gas fl owrates, as

recommended in the ODMI Possibility of external valve leakage not identifi ed, despite

similar occurrences in similar applications

MISSED OPPORTUNITIES

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 valvesHotwell level

False bottom impacts PMs for Level Controls

LESSONS LEARNED

QUESTIONS?