ML13150A181

Trade-Off Between Tank Vortexing Margin and ECCS Function

ML13150A181
Person / Time
Site:	Diablo Canyon
Issue date:	11/19/2013
From:	Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation
Warren Lyon
References
Download: ML13150A181 (8)

Text

Trade Trade--Off Between Tank Off Between Tank Vortexing Vortexing Mi MidECCS dECCSFti Fti M arg i n M arg i n an d ECCS an d ECCS F unc ti on F unc ti on VolumeControlTank VolumeControlTank Volume Control Tank Volume Control Tank Refuelin g Water Tank Refuelin g Water Tank g

g Containment Recirculation Sump

Containment Recirculation Sump NRC Meeting On VortexingApril182013Anderson LinDiabloCanyonPowerPlant April 18 , 2013 Diablo Canyon Power Plant (805) 545-4286 Axle@pge.com TransferFromVCTtoRWSTTransferFromVCTtoRWST Transfer From VCT to RWST Transfer From VCT to RWSTUpon"S"signalCCPsuctionsarealignedto Upon"S"signalCCPsuctionsarealignedtoUpon S signal , CCP suctions are aligned to Upon S signal , CCP suctions are aligned to the RWST the RWST RWSTwaterlevelisatthehighestto RWSTwaterlevelisatthehighestto RWST water level is at the highest to RWST water level is at the highest to compress any entrained gas from the VCTcompress any entrained gas from the VCT CCPsareboostedbytheRWSTstatichead CCPsareboostedbytheRWSTstatichead CCPs are boosted by the RWST static head CCPs are boosted by the RWST static head CCPs are multi

CCPs are multi--stage pumps tolerate void well stage pumps tolerate void well (recenttestsandRoadmapReport)

(recenttestsandRoadmapReport)(recent tests and Roadmap Report)(recent tests and Roadmap Report)

If VCT level were increased to prevent any If VCT level were increased to prevent any vortexlessVCTvolumeavailableforcharging vortexlessVCTvolumeavailableforcharging vortex , less VCT volume available for charging vortex , less VCT volume available for charging & letdown inventory control and H2 control& letdown inventory control and H2 control TransferFromtheRWSTtoSumpTransferFromtheRWSTtoSump Transfer From the RWST to Sump Transfer From the RWST to Sump TransferFromtheRWSTtoSumpTransferFromtheRWSTtoSump Transfer From the RWST to Sump Transfer From the RWST to SumpFora40'diameterRWSTitsitisFora40'diameterRWSTitsitisFor a 40 diameter RWST , its it is For a 40 diameter RWST , its it is ~9,400 gal/ft. ~9,400 gal/ft.

A conservative 9' requirement to A conservative 9' requirement to p revent vortexin g q uarantines p revent vortexin g q uarantines 84

, 000 84 , 000 pgq pgq ,

, gallon of RWST inventory

gallon of RWST inventory TransferFromtheRWSTtoSumpTransferFromtheRWSTtoSump Transfer From the RWST to Sump Transfer From the RWST to SumpRWSTinventoryisrelieduponforcoreRWSTinventoryisrelieduponforcoreRWST inventory is relied upon for core RWST inventory is relied upon for core cooling and containment cooling and containment depressurization

depressurization depressurization

depressurization If too much RWST inventory was

If too much RWST inventory was reservedtopreventvortexing reservedtopreventvortexing reserved to prevent vortexing , reserved to prevent vortexing ,

EOP setpoint revision EOP setpoint revision Reduce credited core delta BTU transfer Reduce credited core delta BTU transfer Increase containment post LOCA P / T Increase containment post LOCA P / T TransferFromtheRWSTtoSumpTransferFromtheRWSTtoSump Transfer From the RWST to Sump Transfer From the RWST to SumpRWST inventory is credited to submerge

RWST inventory is credited to submerge sump screens

sump screens Withoutsubmergethesumpscreens, Withoutsubmergethesumpscreens, Without submerge the sump screens, Without submerge the sump screens, screen performance would change from screen performance would change from "pipe"flowto"channel"flow"pipe"flowto"channel"flow pipe flow to channel flow pipe flow to channel flow Flowrate through the screen relies on Flowrate through the screen relies on tlldiidth tlldiidth wa t er l eve l d rops i ns id e th e screen wa t er l eve l d rops i ns id e th e screen Lowered the water level inside the sump Lowered the water level inside the sump screen creates even worse vortexin g screen creates even worse vortexin g concerns to pump suctions concerns to pump suctions TransferFromtheRWSTtoSumpTransferFromtheRWSTtoSump Transfer From the RWST to Sump Transfer From the RWST to SumpRWSTinventorytodeliverboronforRWSTinventorytodeliverboronforRWST inventory to deliver boron for RWST inventory to deliver boron for sump pH control sump pH control bd bd Sump pH must b e maintaine d 8.0 Sump pH must b e maintaine d 8.0 -

-9.5 9.5 Too much RWST inventory quarantined in

Too much RWST inventory quarantined in the RWST could result in hi g her pHthe RWST could result in hi g her pH PostLOCAequipmentqualificationmay PostLOCAequipmentqualificationmay Post LOCA equipment qualification may Post LOCA equipment qualification may need to be revised need to be revised What Would Be A Reasonable What Would Be A Reasonable Permissible Air Ingestion

Permissible Air Ingestion NoVoidAtAll?

NoVoidAtAll?

No Void At All ?No Void At All ?

MinimalSporadicIngestion?

MinimalSporadicIngestion?

Minimal Sporadic Ingestion ?Minimal Sporadic Ingestion ?

2% ?

2% ?

3% ?

3% ?

Continuous 1% ?

Continuous 1% ?

What is the reasonable air ingestion ?

What is the reasonable air ingestion ?