ML13210A404
| ML13210A404 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar, Sequoyah  (NPF-090, DPR-077, DPR-079) |
| Issue date: | 07/30/2013 |
| From: | Tennessee Valley Authority |
| To: | Andrew Hon Plant Licensing Branch II |
| Hon A | |
| References | |
| Download: ML13210A404 (37) | |
Text
1 HydrologyLicenseAmendmentRequests WattsBarandSequoyahNuclearPlants July3031,2013
2 Background
InFeb2008,NRCinspectionofthequalityassurance processesandproceduresforthehydrologyand hydraulicsmodel,SimulatedOpenChannel Hydraulics(SOCH),fortheBellefonteCombined LicenseApplication(COLA)resultedinviolations regarding:
- SOCHsoftwarewasnotincompliancewiththeprocedure forsoftwarevalidationandverification
- Designinputsforthehydrologymodelwerenot documentedinaccordancewithprocedure
- Computerinputfileswerenotcontrolledinaccordance withtheprocedure
3 Background
TVAutilizedresultsfromanupdatedhydrology calculation(circa 1998)forBellefonteCOLA
- PrimarysubjectoftheFeb2008inspection ThiscalculationwasusedasthebasisforUFSAR Section2.4revisions
- WattsBarinitiatedUFSARchangesin1998
- SequoyahinitiatedUFSARchangesin2002 ThiscalculationwasupdatedforTennesseeRiver damsafetyimprovements(modifications).Allother inputsremainedthesame.
4 HistoricalTimelineofPMF 1972 Browns Ferry Hydrology Analysis Approved by NRC 1979 & 1982 Sequoyah & Watts Bar Hydrology Analysis approved by NRC, respectively 1982 - 1997 TVA Dam Safety Modification Program 1997-1998 PMF re-evaluated for TVA Dam Safety Mods 1999 & 2001 Watts Bar & Sequoyah UFSAR change reflect PMF reevaluation, respectively Feb/March 2008 Bellefonte NOV &
Hydrology model reconstitution project started Dec 2009 HESCO barriers installed June & Aug 2012 Completion of WBN
& SQN analysis, respectively 2004 TVA Reservoir Operation Study completed
5 TennesseeRiverSystemOverview 5
Tims Ford Normandy Raccoon Mountain Tennessee-Tombigbee Waterway Pickwick Norris Melton Hill Cherokee Douglas Fontana Nantahala (N)
Thorpe (N)
Santeetlah (T)
Chatuge Nottely Hiwassee Apalachia Blue Ridge Ocoee 1, 2, 3 Tellico Chilhowee (T)
Calderwood (T)
Cheoah (T)
Watauga Wilbur South Holston Boone Ft. Patrick Henry Kentucky Barkley (C)
Wilson Wheeler Guntersville Nickajack Chickamauga Watts Bar Ft. Loudoun Mississippi River Ohio River Green River Cumberland River Duck River Elk River Clinch River Holston River French Broad River Little Tennessee Hiwassee River Note:
(C)
U.S. Army Corps of Engineers Dams (N)
Nantahala Power & Light Company (subsidiary of Duke Energy)
(T)
Brookfield Smokey Mountain Hydro Power (Formerly Tapoco)
Beech River Projects (8)
Bear Creek Projects (4)
John Sevier Bristol Projects (2)
Nolichucky Doakes Creek Watts Bar Plant Sequoyah Plant Browns Ferry Plant
6 HydrologicCalculationFlowChart
7 UpdatedAnalysis TVAinitiatedprojectinMarch2008to
- Validateandverifylegacyhydrologysoftware
- Verifyorregenerateallmodelinputs Originalmodelassumptionskeptthesameunless discrepanciesfound
- Damdischargeratingcurves
- ReservoirOperations
8 ModelResults WBN SQN LAR Proposed PMF Elevation 739.2 722.0 Original Licensing PMF Elevation 738.1 722.6 1998 Calculation PMF Elevation 734.9 719.6
9 SOCHSegment1
10 SOCHSegment2
11 ProbableMaximumFlood PotentialSeismicDamFailures
- Reevaluationofthecontrollingdamcombinationsfrom theoriginalanalysis(plusadditionofanassumedseismic failureofTellicodam)
- NorrisDamFailureforLoadCaseOBE+1/2PMF
- FontanaDamFailureforLoadCaseOBE+1/2PMF
- CherokeeandDouglasforLoadCaseOBE+1/2PMF
- Fontana,Hiwassee,Apalachia,andBlueRidgeDamFailuresforLoadCaseOBE+1/2 PMF
- Norris,CherokeeandDouglasFailuresforLoadCaseSSE+25yearflood
- PMFelevationshaveenvelopedthecalculatedPotential DamFailureelevationsinpreviousanalyses;Potential DamFailureanalyseshavedeterminedwarningtimesin previousanalyses
12 UnitHydrographs UnitHydrographsexcludingWheeler(usedforWBN&SQN)
- 33directlyvalidated
- 14indirectlyvalidated UnitHydrographsaboveWheelerDam(usedforBLNmodel 2009)
- 39directlyvalidated
- 23indirectlyvalidated Norriswaspreviouslydividedintofourgagedsubareasand lagroutedtoNorrisDaminearly1970s.Thecombinedarea wasvalidatedasasinglesubbasinin2009.
MeltonHillwaspreviouslydividedinto10subbasinswith syntheticunithydrographs.Itwasreplacedbyasingleunit hydrographin1984.
13 UnitHydrographsRevisions AllrevisionsadministrativeortechnicalforBrownsFerryNuclearonly
CDQ000020080059GuntersvilleUH(49&50)Revision2
CDQ000020080060NickajackUH(47A&47B)Revision3
CDQ000020080061ChickamaugaUH(38,39,40,41,43)Revision2
CDQ000020080062LittlePigeonUH(7)Revision2
CDQ000020080064ChickamaugaLocalUH(44B&45)Revision3
CDQ000020080070LittleTennesseeaboveChilhoweeUH(1923)Revision2
14 InflowHydrographRouting BlueRidgeDam HECRAS CherokeeDam HECHMS ChilhoweeDam HECRAS DouglasDam HECHMS FontanaDam HECHMS HiwasseeDam HECRAS NorrisDam HECHMS HECProductsusedforDamFailureOutflows
15 ComputationalTimeStep Useofdifferentmodelconfigurationsandtimestepsinthe SOCHmodelcanproducereasonable,butdifferent,results.
Downstreamimpact(BLN&BFN)isgreaterthanupstream impact(SQN&WBN).
Modelconfigurationrevised(forBLN&BFN)toallowforan increasedtimestep.
Testsimulationwithrevisedmodelconfigurationwithlonger timestepsresultsinthesameelevationatWBNandaslightly lowerelevationatSQN.
16 RevisedConfiguration Segment1(forWBNandSQN)
- Norevisions.Limitedto5secondtimestepduetoFort LoudounTellicoCanal.
Segment2(forWBNandSQN)
- Norevisions.Limitedto5secondtimestepduetoLick Branch.
17 RevisionstoCalculationsResultingfrom TimeStepIssue
CDQ000020080059GuntersvilleUH(49&50)Revision2duetotimestep issue
CDQ000020080060Nickajack UH(47A&47B)Revision4duetotimestep issue
CDQ000020080064ChickamaugaLocalUH(44B&45)Revision3dueto timestepissue
CDQ000020080039ChickamaugaCalibrationRevision3
CDQ000020080040Nickajack CalibrationRevision3
CDQ000020080041GuntersvilleCalibrationRevision3
Othersevaluated,butnotchangedforWBNandSQNtimestep:
CDQ000020080054,CDQ000020080080,CDQ000020080081,CDQ000020080082
18 GeometryRevisions Ingeneral,thetwomaintypesofchangesto geometryare:
- Extensionofcrosssectionsbecauseofovertoppingduring simulations
- Additionorremovalofinterpolatedcrosssectionsfor modelstability Additionaltypesofchangesinclude:
- Additionofslotsinchannelbottomsforstability
- AdjustmentofManningsnforstability
- Additionofachannelgeometrycrosssectioninplaceofa faileddam
- Revisionofstoragecalculationfordraindownanalysis
19 RevisionstoGeometryDifferingfrom thoseusedbyPNNL Calculation GeometryAffected Modification CDQ80 AppendicesE&F,CDQ82 AppendixA 15crosssections Extendedcrosssectiontohigher elevation.
CDQ80 Fort Loudoun-TellicoCanal 1footslotaddedforstability CDQ80AppendixB FortLoudoun-TellicoCanal 14 footslotaddedforstability.
CDQ82AppendixA Interpolated sectionbetweenTRM 0.3and33.6inTellicoReservoir Crosssectionremoved CDQ80AppendixA 5crosssections Extended crosssectiontohigher elevation CDQ80 AppendixA CRM23.1 CopiedcrosssectionfromLowerClinch CDQ80AppendixB 5crosssections Extendedcrosssectiontohigher elevation CDQ54AppendicesA,B,H,K,andM CDQ80 AppendixB 7crosssections Extended crosssectiontohigher elevation CDQ82AppendixA - FontanaFailure 38crosssections Extended crosssectiontohigher elevation CDQ54 RM2.86 Manningsnvaluechanged forstability andconsistency CDQ54Appendices E-HandM RM2.62 Interpolated crosssectionremoved
20 RevisionstoGeometryDifferingfrom thoseusedbyPNNL Calculation GeometryAffected Modification CDQ54 Crosssections betweenTRM480.5 and471.0 Removalofinterpolatedcrosssections CDQ80 RM2.86 Manningsnvaluechanged forstability andconsistency CDQ80 RM2.62 Interpolated crosssectionremoved CDQ80 Crosssections betweenTRM480.5 and471.0 Removalofinterpolatedcrosssections CDQ82 RM2.86 Manningsnvaluechanged forstability andconsistency CDQ82 Crosssections betweenTRM480.5 and471.0 Removalofinterpolatedcrosssections CDQ82 30Crosssections Extendedcrosssectiontohigher elevation.
CDQ54Appendices E,F,andG 5crosssections Extendedcrosssectiontohigher elevation.
CDQ54AppendicesHandM 3crosssections Extendedcrosssectiontohigher elevation.
CDQ81 3crosssections Crosssection revisedtoincludestorage availableatLickBranchandNorth ChickamaugaCreek
21 DamRatingCurveDifferences ChangesfromFSARtoLAR Assumedmaximumopenings Orificedischargecoefficients Submergenceeffects
- referencedataforspillwayfreeflowused
- modeldatafororificeflowavailable HESCOConcertainers Turbinedischarge RimLeaks
22 HESCOConcertainers
Cherokee
- NorthEmbankment
- SouthEmbankment
- ThreeSaddleDams
FortLoudounDam
- SouthEmbankment
- MarinaSaddleDam
TellicoDam
- SaddleDams2and3
- RightBankSaddleDam
- MainDamWorks
WattsBarDam
- EastEmbankment
23 DamRatingCurveRevisions FortLoudounDamRatingCurve-CDQ00002008009 Revision3(6/12)- addedrimleaks TellicoDamRatingCurve-CDQ000020080018-Revision2(7/10)- correctedsaddledamelevation andHESCObarrierelevations MeltonHillDamRatingCurve-CDQ000020080013-Revision2(1/10)- correctedturbineshutofftime WattsBarDamRatingCurve-CDQ000020080020-Revision3(12/11) correctedoverflowlengthinEast Embankmentfailure,correctedbarrierelevations Revision4(6/12)- addedrimleaks
24 DamRatingCurveRevisions ChickamaugaDamRatingCurve-CDQ000020080006
- Revision2(6/11) addedcaseforsouth embankmentfailurefordraindownanalysis Nickajack DamRatingCurve-CDQ000020080014-Revision2(6/12)- addedrimleaks GuntersvilleDamRatingCurve-CDQ000020080011
- Revision3(6/11)- addedcaseforBFN,noimpact toWBN/SQN
25 LockGateFailure Flowoverthelockgatesisaccountedforinthedamrating curves StabilityofthelockgatesevaluatedforPMFloading
- HydrostaticloadofthePMFwascomparedtothedesignimpactload ofthelockgate
- Designmarginratiosdevelopedforeachdam
- NocatastrophicfailureduringaPMFevent
- Operabilityofthegatesduringandaftertheeventwasnotconsidered
- Assumedunavailableduringandaftertheevent
26 FortLoudounRimLeak ArimleakwasidentifiedatFortLoudoun Lowestelevationoftherimleakwaselevation 835.15feet PMFelevationis835.63feet ImpacttoPMFisnegligible
27 FortLoudounRimLeak
28 NickajackRimLeak ArimleakwasidentifiedatNickajack2,500feet northeastoftheDam.
Lowestelevationoftherimleakwaselevation 654.54feet PMFelevationis667.41feet ImpacttoPMFisnegligiblegiventhatNickajackisa significantdistancedownstreamofWattsBarand Sequoyahnuclearplants Nickajack isnotfailedduringtheanalysisofWatts BarandSequoyahnuclearplants
29 NickajackRimLeak Q max = 2,533cfs
30 WattsBarRimLeaks
31 WattsBarRimLeakRouting SevenRimLeakswereidentified
- 4eastofthedam
- 3westofthedam Dischargeofrimleaks16arecombinedwithWatts BarDamdischargeforSegment1simulations Rimleak7wasremovedatTRM538.40forSegment 1simulations
32 WattsBarRimLeakRouting Segment2simulationsseparatedtherimleak dischargefromthemaindamdischarge Westrimleakswereaddedasaconcentratedlocalat YellowCreekatTRM526.82withoutattenuation.
Eastrimleakswereaddedasaconcentratedlocalat WattsCreekatTRM528withoutattenuation
33 WattsBarWestSaddleDam TotalfailurepostulatedforWestSaddleDam (consistentwithpreviousmodelassumption)
DischargeofWestSaddleDamcombinedwithWatts BarDamdischargeforSegment1simulations Segment2simulationsseparatedtheWestSaddle Damdischargeandaddeditasaconcentratedlocal atYellowCreekatTRM526.82withoutattenuation.
- YellowCreekisthenaturaldrainagepath
- HECRASstudymodelforYellowCreekdetermined negligibleattenuationeffectonflowfromtheWestSaddle DamtothemouthofYellowCreek.
34 WattsBarWestSaddleDam
35 DallasBayRouting DallasBay,LickBranch,andNorthChickamauga Creekgeometry
- Takeadvantageofstorageinthereaches
- Accountforthesubmergenceeffectsoftherimleakonthe ChickamaugaDamtailwater UseSOCHtodevelopanelevation/discharge relationshipattherimleak Onlyvalidwhennofailuresarepostulatedat ChickamaugaDam
36 DallasBay/LickBranchRimLeak
37 Assumptions Assumption FSAR LAR Chickamauga Lock Configuration Current Lock Current Lock Dallas Bay/Lick Branch/North Chickamauga Cr Modeled as a rating curve at Chickamauga Dam Included in the unsteady SOCH model West Saddle Dam Failure Total Failure Total Failure West Saddle Dam Routing Modeled as a rating curve at Watts Bar Dam Discharge separated as a local in Yellow Creek Correction for Submergence The average tailwater rating curve used for each event Correction for submergence was performed for each event HESCO Concertainers Not included Included for PMF simulations Operational Allowances Not included Evaluated for each simulation Rim Leaks at Fort Loudoun, Watts Bar, and Nickajack Not included Included Melton Hill Reservoir Level pool routing Unsteady SOCH model Hiwassee River (mouth to HRM 18.9)
Lag routed Unsteady SOCH model Turbine Discharge Evaluated for main river dams Evaluated for all dams with turbines Operational Deck/Gate operability Not considered If operating deck was overtopped then the gates are assumed to be inoperable on the recession side Downstream Dams No failures assumed No failures assumed Loss Method API API Norris Subbasins 4
1 Melton Hill Subbasins 10 1