ML12348A208

12/13/12 Meeting Slides Re TVA Hydrology Update Slides

ML12348A208
Person / Time
Site:	Watts Bar
Issue date:	12/13/2012
From:	Tennessee Valley Authority
To:	Hon A L Plant Licensing Branch II
Hon, Andy
References
Download: ML12348A208 (56)

Text

NlTVAHydrologyUpdate N uc l earTVA Hydrology Update December 13, 2012 Pur p ose p*License Amendment Request (LAR) Review Status

• Updated Information on Temporary Dam Modifications

• Status of Fukushima NTTFRecommendation 2.1 Flood Hazards Reevaluation

• Update on June 2012 Commitments 2

A g enda g*Introduction

• Updated Hydrology Analysis Tools

• License Amendment Request (LAR) Review

• Temporary Flood Barriers at TVA Dams

• NTTFRecommendation 2.1 Flood Hazards Reevaluation

• TVA Flood Mode Operation Improvement Strategy

• Commitment Status

• Closing Remarks 3

Introduction 4

Introduction

• TVA is performing continued analysis of the hydrology fhTRi o f t h e T ennessee River*TVA is implementing commitments fromJ132012ltt J une 13 , 2012 l e tt er*TVA is deploying a Fleet Flood Mode Operation ImprovementStrategyImprovement Strategy 5 Tennessee River System OverviewSequoyah PlantBrowns Ferry Plant 6

Updated Hydrology Analysis Tools 7

Updated Hydrology Analysis Tools

• TVA conversion of hydraulic modeling tools in progress

• TVA converting from SOCH to USACE HEC-RAS for flood routing calculations for the Tennessee River and selected tributariesUSACEHECRASsedetensielinrecentlapproedCombinedLicense

-USACE HEC-RAS u sed e xtensi v el y in recentl y appro v ed Combined License Applications

-USACEHEC-RAS is easier to implement, shorter computing times

-Easily adopted to Tennessee River Watershed with minimal refinements to inputs*Can accommodate more refined geographical input than SOCHmodel

• Volume check performed in SOCHand HEC-RAS to confirm storage input data

• Consistent with Fukushima NTTFRecommendation 2.1 Flood HazardsReevaluationguidance 8Hazards Reevaluation guidance Updated Hydrology Analysis Tools

• HEC-RAS conversion process

-Input updates for HEC-RAS requirements

-HEC-RAS unsteady flow models for each reservoir calibrated against March 1973 and May 2003 floods

-Certain current licensing basis legacy codes are not used, and will no longer be needed*CONVEY* WWIDTH

-Certain current licensing basis legacy codes are currently retained, may be replaced in future by USACEHEC-HMS

• FLDHYDRO* TRBROUTE

-Certain current licensing basis legacy codes may be retained in the future

• CHANROUT* UNIGRAPH* DBREACH 9

Updated Hydrology Analysis Tools

• Status of conversion from SOCH to USACEHEC-RAS

-Updates of inputs to match HEC-RAS requirements -COMPLETE

-Verification and validation of software -COMPLETE

• ValidatedUSACEHEC-RAScodeunderTVAQualityAssurancePlanValidated USACEHEC RAS code under TVA Quality Assurance Plan*Significant oversight by TVA Nuclear Power Group of Contractor during implementation

-Application of HEC-RAS to date includes:

• Examinedselectedcurrentlicensingbasiscases

• Examined selected current licensing basis cases*Evaluated consequence of overtopping and breaching selected upstream dam embankments

-PlannedapplicationofHEC-RASincludes:

Planned application of HEC RAS includes:*NTTFRecommendation 2.1 Flood Hazards Reevaluation

• Sensitivity analyses related to HESCOmodular flood barrier performance

• Reanalysisofcurrentlicensingbasiscases 10Reanalysis of current licensing basis cases License Amendment Request (LAR) ReviewReview 11 License Amendment Request (LAR)ReviewReview*WBNUnit 1 LARsubmitted Jul y 19, 2012 y*SQNUnits 1 and 2 LARsubmitted August 10, 2012

• Updaterequiredto WBNUnit1 LARtoreflectUpdate required to WBN Unit 1 LAR to reflect emergent issue involving Main Control Room (MCR) and 6.9kV Shutdown Board Room (SDBR) Chillers ()-Does not affect the hydrologic analysis as described in the LAR-Supplement to be submitted by January 31, 2013 12 License Amendment Request (LAR)ReviewReview*Selected current licensin g basis cases simulated usin g ggHEC-RAS-Rainfall induced PMFcases:

• WBNand SQN21,400 sq mile winter storm

• WBNand SQN7,980 sq mile winter storm

• Calculation complete for WBN

• Letter report complete for SQN

-Seismically induced dam failure case:

• CombinationNorrisTellicoDamseismicallyinduceddamfailure(WBN only)*Combination Norris-Tellico Dam seismically induced dam failure (WBN only)*Operating Basis Earthquake (OBE) with one-half PMF

• Selected because current limiting WBNflood warning time event 13*Letter report complete License Amendment Request (LAR)ReviewReview*Results of selected current licensin g basis cases usin g ggHEC-RAS-WBNrainfall induced PMF l'*7,980 sq mi le winter storm PMF= 738.0

'*21,400 sq mile winter storm PMF= 738.7' (WBNLARPMFlevel = 739.2')

• Surge level in Auxiliary Building = 739.2' (WBNLARsurge level = 739.7')

SQifllidd-SQNra i n f a ll i n d uce d PMF*7,980 sq mile winter storm PMF= 718.7'

• 21,400 sq mile winter storm PMF= 720.5' (SQNLARPMFlevel = 722.0')

• Wind wave runupfor SQNDiesel Generator Building below operating floor elevation

-WBNNorris-Tellico Dam seismically induced dam failure case

• OBEand one-half PMF= 727.8' (below plant grade of 728.0', WBNLARlevel = 728.7')

14*Current limiting WBNflood wave travel time event

• Flood wave travel time = 28.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (WBNLARtime = 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br />)

License Amendment Request (LAR)ReviewReview*Plans forward for reanalysis of all current licensing basis cases using HEC-RAS

-Update of following hydrologic analyses methodology/results

• Rainfallinduced PMFcasesRainfall induced PMFcases*Seismically induced dam failure cases

• Flood warning time cases

-TVAisevaluatingthesequencingforreanalyzingthecurrentlicensingTVA is evaluating the sequencing for reanalyzing the current licensing basis cases with HEC-RAS

-WBNand SQNUFSAR updates will be submitted to reflect these cases uponcompletionofthereanalysiseffort upon completion of the reanalysis effort*TVA requests continued review of WBNand SQNLARs 15 Temporary Flood BarriersatTVADams at TVA Dams 16 Temporary Flood BarriersatTVADams at TVA Dams*Background

• Design of Temporary Flood Barriers

• Actions Completed for Temporary Flood Barriers

• Status of Permanent Modifications at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams

• ResultsofInspectionsofTemporaryFloodBarriersResults of Inspections of Temporary Flood Barriers*Results of Breach Analysis

• Results of Anal ysis with No Tem porar y Flood Barriersypy*Status of Actions to Address Breach Initiators

• Results of Computational Fluid Dynamics (CFD) Analysis 17*Regulatory Process for Temporary Flood Barriers Temporary Flood BarriersatTVADams at TVA Dams*In 2009, TVA installed temporary modular flood barriers to preserve the assumption of no embankment failure by overtopping during a rainfall induced PMFevent

-FortLoudonDam

-CherokeeDamFort Loudon DamCherokee Dam-Tellico Dam

-Watts Bar Dam

• Rainfall induced PMFanalysis in the LARscredits increased hhfhbkhd h eig h t o f t h e em b an kments at t h ese d ams-Preserves assumption of no embankment failures by overtopping

• SeismicallyinduceddamfailureanalysisdoesnotcreditfloodSeismically induced dam failure analysis does not credit flood barriers-Embankments can fail if overtopped in analysis 18 Temporary Flood BarriersatTVADams at TVA Dams 19 Temporary Flood BarriersatTVADams at TVA Dams*Barriers are engineered, interconnected, geotextilelined, and crushed compacted stone filled HESCOConcertainerBaskets

• Geotextileis a heavy-duty, non-woven, permeable, interlocked, llfbiWlddWiMhildi Al Zi po lypropy l ene f a b r i c W e ld e d Wire M es h, co il , an d p i ns Al u-Zi nc coated Steel, wire diameter of 0.16 inch, with spacing of 3" x 3"

• Size:3'X3'X3'or3'X3'X4'WeightofOneSection:16

-22tonsSize: 3X3X3 or 3X3X4 Weight of One Section: 1.6 2.2 tons *Fill Material: #10 crushed stone meeting TDOTSpecifications 903.01 (e), 903.01 (f) or 903.22(),()20 Temporary Flood BarriersatTVADams at TVA Dams 21Temporary Flood Barriers at Fort Loudoun Dam Temporary Flood BarriersatTVADams at TVA Dams*Since the May 31, 2012 TVA presentation, the following actions have been ildilihHESCOdlfldbi i mp lemente d invo l v ing t he temporary HESCO mo d u l ar fl oo d b arr iers-Made progress on permanent modifications

-Implemented procedures for semi-annual inspections

• Inspection frequency increased to monthly in December 2012

-Submitted summary of the results of an analysis of flood levels at SQNUnits 1 and 2 and WBNUnit 1 using SOCHfor the 21,400 sq mile storm that assumes a failure ftifthbidthbkt o f a sec tion o f th e b arr iers an d ear then em b an k men t s-Completed an analysis of flood levels at SQNUnits 1 and 2 and WBNUnit 1 using HEC-RAS for the 7,980 winter storm without the barriersCltdCttilFlidDi(CFD)dlfFtLdd-C omp l e t e d a C ompu t a ti ona l Fl u id D ynam i cs (CFD) mo d e l f or F or t L ou d oun an d Tellico Reservoirs to demonstrate flow velocity profiles in the reservoirs at PMF levels, and to calculate velocities and trajectories of large objects as they

a pproach Fort Loudoun Dam 22 pp-Initiating corrective actions to ensure 2009 decision to install temporary HESCO modular flood barriers addresses required regulatory process Temporary Flood BarriersatTVADams at TVA Dams*Modifications at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams to be ildlHESCOdlfldbi i mp lemente d to rep l ace HESCO mo d u l ar fl oo d b arr iers*Project Status

-TVA published a Notice of Intent (NOI) in the Federal Register in June 2011

-Scoping completed for the Draft Environmental Impact Statement (DEIS) in September 2011

-Initial conceptual design and alternatives developed to support DEIS

-DEISissued September 2012

-Public meeting to discuss the project and accept comments held on October 25, 2012

• Schedule-Public comments for DEISreceived and being addressed

-Final Environmental Impact Statement (FEIS) scheduled to be complete by February 4, 2013, and Notice of Availability published on February 11, 2013

-TVA Senior Vice President of River Operations and Renewablesfinal decision will be documentedinaRecordofDecision(ROD)scheduledforMarch132013 23documented in a Record of Decision (ROD) scheduled for March 13 , 2013-Completion of modifications scheduled by October 2015 Temporary Flood BarriersatTVADams at TVA Dams*Results of TVA Nuclear Power Group inspections of the temporary HESCOfldbiilldChkFLdTllidWB fl oo d b arr iers insta ll e d at Chero k ee, F ort L ou d oun, T e llico, an d Watts B ar reservoirs

-Minor deficiencies from visual inspection of modular flood barriersdfffdlflfbl

-No d e f iciencies from inspection o f stage d materia l s for c losure o f pu blic access gaps in modular flood barriers

-Procedures used to close public access gaps found to be up-to-date

-ContactinformationintheRiverOperationsandRenewablesEmergencyActionPlanContact information in the River Operations and RenewablesEmergency Action Plan Supplements found to be up-to-date

• TVA River Operations performs independent inspections on a monthly basis

• TVANuclearPowerGroupincreasedfrequencyofindependentinspectionsTVA Nuclear Power Group increased frequency of independent inspections to monthly

• TVA has performed reasonable simulation of TVA procedures for closure of gapsinthetemporaryfloodbarriers 24gaps in the temporary flood barriers Temporary Flood BarriersatTVADams at TVA Dams*Analysis of flood levels at SQNUnits 1 and 2 and WBNUnit 1 assuming HESCObibhHESCO b arr i er breac h es-Failure of HESCOflood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar Dams modeledSegment1ofboth21400sqmileand7980sqmilestormsrevisedinmodel

-Segment 1 of both 21 , 400 sq mile and 7 , 980 sq mile storms revised in model-SOCHhydraulic modeling consistent with SQNand WBNLAR

-Dam rating curves revised to model embankment failures

-NewoutflowhydrographrequiredforCherokeeDamduringthe7980sqmilestorm

-New outflow hydrograph required for Cherokee Dam during the 7 , 980 sq mile storm-Barriers stay in place and then fail at peak headwater elevation or when overtopped

-Portion of embankments with flood barriers at Fort Loudoun and Tellico Dams fails

-FloodwaveovertopseastwallatWattsBarDamcausingbreachofWattsBarEast Flood wave overtops east wall at Watts Bar Dam , causing breach of Watts Bar East Embankment

-Segment 1A and 2 of the models same as SQNand WBNLARs

-No downstream dams, including embankments or gates, are assumed to fail 25 Temporary Flood BarriersatTVADams at TVA Dams*Analysis of flood levels at SQNUnits 1 and 2 and WBNUnit 1 assuming HESCObibh('d)HESCO b arr i er breac h es (cont'd)-Breach configurations based on review of different methods discussed in Prediction of Embankment Dam Breach Parameters(U.S. Department of the Interior)BreachconfigurationbasedonFederalEnergyRegulatoryCommission(FERC)approach

-Breach configuration based on Federal Energy Regulatory Commission (FERC) approach-Single embankment at each dam postulated to fail

-Size of breach a function of breach depth, assumed failure down to bedrock

-Mainembankmentadjacenttoeachdamspillwayselectedwherebedrockelevationsknown

-Main embankment adjacent to each dam spillway selected where bedrock elevations known-Cherokee Dam has barriers on North Embankment, South Embankment, and three Saddle Dams; South Embankment modeled to partially fail

-Fort Loudoun Dam has barriers on South Embankment and the Marina Saddle Dam; South Embankment modeled to partially fail

-Tellico Dam has barriers on Right Bank Saddle Dam, Main Dam Works Embankment, Saddle Dam 2, and Saddle Dam 3; Main Dam Works Embankment modeled to partially failWttBDhbiEtEthEbktEtEthEbktdldt 26-W a tt s B ar D am h as b arr iers on E as t E ar th E m b an k men t; E as t E ar th E m b an k men t mo d e l e d t o partially fail Temporary Flood BarriersatTVADams at TVA Dams*Results provided to NRC by letter dated October 30, 2012

• Results demonstrate need for HESCOmodular flood barriers to prevent overtopping of the earthen embankments during PMFeventsevents 27 Temporary Flood BarriersatTVADams at TVA Dams*Analysis of flood levels at WBNUnit 1 assuming HESCObarriers are not illdddd insta ll e d -an d dams are overtoppe d-Failure of earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar Dams modeled7980sqmileMarchstormmodeled

-7 , 980 sq mile March storm modeled-Validated and verified HEC-RAS hydraulic modeling

-DBREACH, a validated and verified code, utilized to establish timing of the failure of the West Saddle Dam at Watts Bar Dam

-No downstream dams, including embankments or gates, are assumed to fail

-Breach failures assumed progressive in nature rather than instantaneous

-Revision of unsteady flow rules required because of breaches

-If upstream dam operating deck overtopped, spillway gates remain open and cannot be closed-Earthen structures upstream of the site fail at two ft of overtopping, West Saddle Dam at WttBDfilbdDBREACHtii 28 W a tt s B ar D am f a il s b ase d on DBREACH ti m i ng-Melton Hill non-overflow dam is stable to a flood elevation of 817 ft Temporary Flood BarriersatTVADams at TVA Dams*Analysis of flood levels at WBNUnit 1 assuming no HESCObarriers (cont'd)

-Breach configurations based on review of different methods discussed in Prediction of Embankment Dam Breach Parameters (U.S. Department of the Interior)

-Breach configuration based on Federal Energy Regulatory Commission (FERC) approachSingleembankmentateachdampostulatedtofail

-Single embankment at each dam postulated to fail-Size of breach a function of breach depth, assumed failure down to bedrock

-Main embankment adjacent to each dam spillway selected where bedrock elevations known

-CherokeeDamSouthEmbankmentmodeledtopartiallyfailprogressivelyoveronehour

-Cherokee Dam South Embankment modeled to partially fail progressively over one hour starting at peak headwater elevation

-Fort Loudoun Dam Section 1 of the South Embankment modeled to partially fail progressively over one hour starting at two ft overtopping

-Tellico Dam Main Dam Works Embankment modeled to partially fail progressively over one hour starting at same time as Fort Loudoun Dam failure at 1.32 ft overtopping

-Watts Bar Dam East Earth Embankment modeled to partially fail progressively over one hour startingatoneftovertopping 29starting at one ft overtopping

-Total failure of West Saddle Dam at Watts Bar Dam modeled Temporary Flood BarriersatTVADams at TVA Dams*Result confirms the need for HESCOmodular flood barriers to prevent overtopping during PMFevents

• Two breach analyses performed:AnalsisofbreachofHESCObarriersandsbseqentoertoppingofdams

-Anal y sis of breach of HESCObarriers and s ubseq uent o vertopping of dams under PMFconditions

-Analysis of overtopping of dams under PMFconditions (without HESCObiitlld)b arr iers i ns t a ll e d)-Results are similar 30 Temporary Flood BarriersatTVADams at TVA Dams*A Computational Fluid Dynamics (CFD) Model for Fort Loudoun and Tellico Reservoirs has been developed

-Demonstrate flow velocity profiles in the reservoirs at PMFlevels

-CalculatevelocitiesandtrajectoriesoflargeobjectsCalculate velocities and trajectories of large objects*Sources of data include:

-Existing land area elevation data from United States Geological Survey

-Bathymetry data available from TVA (via USACE)

-Boundary conditions available from the TVA SOCHone-dimensional model

• CFDsolution al gorithms develo ped at the Universit y of gpyTennessee -Chattanooga (UTC) SimCenter 31 Temporary Flood BarriersatTVADams at TVA Dams*Boundary conditions for determining flows:

-Data from the SOCHmodel from TVA used to determine the inlet heights and flow velocities during the peak of the PMFevent at approximately Little Tennessee River Mile (LTRM) 3.6 and Tennessee River Mile (TRM) 605.75Cdiid-C on di t i ons use d:*Little Tennessee River Inlet: Water height = 833.0 ft, incoming velocity = 2.3 ft/sec

• Tennessee River Inlet: Water height = 835.6 ft, incoming velocity = 7.48 ft/secWhennecessary(dependingonthedomainextentusedintheflowsimulation

-When necessary (depending on the domain extent used in the flow simulation and the type of simulation used), outflow targets at the Fort Loudoun and Tellico Dams were:

• Tellico Dam Outlet: Water hei ght = 833.28 ft

, dischar ge = 601 ,898 cfsg,g,*Fort Loudoun Dam Outlet: Water height = 835.45 ft, discharge = 640,356 cfs 32 Temporary Flood BarriersatTVADams at TVA Dams*Tenasi/Incompressible solution method offered the best tradeoff between time to solution and solution fidelity

• Solution domain truncated at the Tellico and Fort Loudoun Dams Dams-Top boundary defined for the domain at the PMFheight of 835 ft

• Flowratesat the dams matched to an PMFSOCHsimulation

-Overall mass balance for the domain at solution terminus of 1%

• Solution algorithms used to predict the Tennessee River and LittleTennesseeRierflosat PMFconditionsLittle Tennessee Ri v er flo w s at PMFconditions

• Given the flows at PMFconditions, the trajectory of large ob jects like bar ges under a zero-power condition com puted for 33 jg ppa range of release parameters Temporary Flood BarriersatTVADams at TVA DamsFlow solution obtained using Tenasi/Incompressible solution showing velocity magnitudeFortLoudounandTellicoDamsDepicted 34Fort Loudoun and Tellico Dams Depicted Temporary Flood BarriersatTVADams at TVA DamsVelocity vectors in the Tellico Channel (connecting Fort Loudoun and Tellico Reservoirs) showing flow from Fort Loudoun to Tellico Reservoir at PMFconditions 35 Temporary Flood BarriersatTVADams at TVA Dams*Trajectories computed for objects simulating barges using the inclusion of iililihflli i nert i a l part i c l es into t h e fl ow so l ut i on*Trajectory of each particle in the computational domain computed by solving ordinary differential equations for location and velocity

• Barges simulated using a sphere whose wetted area equals that of a195 ft barge with a width of 35 ft and a draft of 6 ft

-Sphere density chosen as 1000 tons to match the laden weight of a barge

-Continuous phase velocities used to drive the time integration are computed at the free-surface or just below it in order to account for the draft of a barge

• Similar computation performed for 100-ton and 10-ton floating objects

-Simulates a range of objects and debris in the flowstream

• 400,000 independent simulations performed for each case and for each object size 36 Temporary Flood BarriersatTVADams at TVA Dams*Four cases run simulating barges and other objects (as independent inertial particles) released at several locations:

-TRM 608.3 located approximately at the northern inlet of the computational domain-First Class Harbor on western shore between TRM 608 and TRM 609

-First Class Harbor located on southern shore between TRM 606 and TRM 607

-FirstClassLandinglocatedonoppositeshorefromFortLoudounDamatTRM603First Class Landing located on opposite shore from Fort Loudoun Dam at TRM 603 37 Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 1000-ton objects, aerial view

• SimulationofobjectsreleasedatTRM6083 38*Simulation of objects released at TRM 608.3*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 1000-ton objects, perspective view

• SimulationofobjectsreleasedatTRM6083 39*Simulation of objects released at TRM 608.3*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 100-ton objects, aerial view

• SimulationofobjectsreleasedatTRM6083 40*Simulation of objects released at TRM 608.3*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 10-ton objects, aerial view

• SimulationofobjectsreleasedatTRM6083 41*Simulation of objects released at TRM 608.3*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 1000-ton objects, aerial view

• SimulationofobjectsreleasedbetweenTRM608andTRM609 42*Simulation of objects released between TRM 608 and TRM 609*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 1000-ton objects, aerial view

• SimulationofobjectsreleasedbetweenTRM606andTRM607 43*Simulation of objects released between TRM 606 and TRM 607*All objects approach Fort Loudoun Dam, and do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA DamsComputed trajectories for 1000-ton objects, aerial view

• SimulationofobjectsreleasedatapproximatelyTRM603 44*Simulation of objects released at approximately TRM 603*83% of the objects approach Fort Loudon Dam, with the rest (17%) becoming beached

• Do not impact the HESCOmodular flood barriers Temporary Flood BarriersatTVADams at TVA Dams*The combined flow and object computational solutions show that the trajectories do not impact the HESCOmodular flood barriers placed near the Fort Loudoun Dam

• 1000tonobjectssimulatingbargesandsmaller100tonand*1000-ton objects simulating barges , and smaller 100-ton and 10-ton objects, have enough momentum to overcome the Fort Loudoun/Tellico channel suction and therefore approach the Fort Loudoun Dam, rather than being pulled down toward the south and potentially impacting the HESCOmodular flood barriers*Additional modeling considerations 45 TVA Flood Mode OperationImprovementStrategyImprovement Strategy 46 TVA Flood Mode OperationImprovementStrategyImprovement Strategy*TVA Fleet Flood Mode Operation Improvement StrategyCtSd-Corpora t e Sponsore d-Living Document

-Issuance Ex pected b y December 17

, 2012py,*Key Personnel

-Corporate Senior Leadership -Jim Morris and Don Jernigan

-Corporate Lead -TBD

-WBNSponsor -Don Grissette

-WBN Lead-DarleneViscusie WBN Lead Darlene Viscusie-SQNSponsor -John Carlin

-SQNLead -Melissa Meade 47-BFNSponsor -Keith Polson TVA Flood Mode OperationImprovementStrategyImprovement Strategy*Key Elements of StrategyFldMdAliItdPltMdifiti

-Fl oo d M o d e A na l ys i s Improvemen t s an d Pl an t M o difi ca ti ons*Evaluate Modifications to Improve Stage I -Stage II Implementation

• Oversi ght of S QNAnal ysis of RHRCoolin g g Q y g-Flood Mode Procedure Improvements

• Oversight of Site Procedure Improvements

• Joint Review of Flood Mode Procedures to Obtain Improvement

-Flood Mode Equipment Reliability Improvement

• EquipmentIdentificationandClassificationEquipment Identification and Classification

• Equipment Assessment

• Long Term Equipment Reliability 48*Infrastructure Improvements Commitment Status 49 Commitment StatusCommitmentStatusTVAwillsubmitaLicenseAmendmentRequesttoupdatethe WBNUnit1UpdatedFinalSafetyCommitmentdateTVA will submit a License Amendment Request to update the WBN Unit 1 Updated Final Safety Analysis Report to reflect the updated hydrologic analysis methods and results, including the analysis of the rim leakage paths discussed at the May 31, 2012 public meeting between TVA and NRC Staff.Commitment dateJuly 20, 2012 Submitted July 19, 2012TVAwillsubmitaLicenseAmendmentRequesttoupdatethe SQNUnits1and2UpdatedFinalCommitmentdateTVA will submit a License Amendment Request to update the SQN Units 1 and 2 Updated Final Safety Analysis Report to reflect the updated hydrologic analysis methods and results, including the analysis of the rim leakage paths discussed at the May 31, 2012 public meeting between TVA and NRC Staff.Commitment dateAugust 10, 2012 Submitted August 10, 2012TVA's N uc l ea r P o w e r G r oup TVA will i ssue a n d ini t i a ll y pe rf o rm a p r ocedu r e f o r a se mi-a nn ua l Co mmi t m e n t datesuceaoeGoupssueadtaypeoapocedueoaseauainspection of the compensatory measure for flood protection of the WBNUnit 1 Thermal Barrier Booster pumps and motors. The inspection will verify: a. The condition of the permanent building attachments; and b. The inventory, storage, physical protection, and condition of the materials and consumables required for erection of the temporary flood protection panels ditltdPMFtItiilltitilthtiCotetdateAugust 31, 2012 First inspection conducted August 30, 2012 d ur ing a pos t u l a t e d PMF even t. I nspec ti ons w ill con ti nue un til the compensa tory measure i s replaced by a permanent plant modification.

50 Commitment StatusCommitmentStatusTVA'sNuclearPowerGroupwillissueandinitiallyperformaprocedureforasemi annualCommitmentdateTVAs Nuclear Power Group will issue and initially perform a procedure for a semi-annual inspection to verify the condition of the SQNUnits 1 and 2 Spent Fuel Pit Cooling Pump Enclosure caps. Inspections will continue until the design change is completed to document the SQNUnits 1 and 2 Spent Fuel Pit Cooling Pump Enclosure caps as a permanent plant feature.Commitment dateAugust 31, 2012First inspection conducted August 28, 2012TVA's Nuclear Power Group will issue and initially perform a procedure for a semi-annual inspection to verify the inventory, storage, physical protection, and condition of the materials and consumables required to implement the compensatory measure for the common SQNUnits 1 and 2 Diesel Generator Building. Inspections will continue until the compensatory measure is ldbldifiiCommitment dateAugust 31, 2012 First inspection conductedrep l ace d by a permanent p lant mo difi cat ion.August 28, 2012TVA will perform an analysis of the Design Basis Flood for SQNUnits 1 and 2 and WBNUnit 1 that assumes a failure of a section of the HESCOflood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar dams.Commitment dateAugust 31, 2012 CompletedAugust312012August 31 , 2012 51 Commitment StatusCommitmentStatusTVA'sNuclearPowerGroupwillissueandinitiallyperformproceduresforsemi annualCommitmentdateTVAs Nuclear Power Group will issue and initially perform procedures for semi-annual inspections of the temporary HESCOflood barriers installed at Cherokee, Fort Loudoun, Tellico, and Watts Bar reservoirs. These inspections will: a. Ensure the temporary HESCOflood barriers remain in place and are not structurally degraded as specified by the manufacturer's written specifications and recommendations; b. Verify the inventory and staging of the material Commitment dateAugust 31, 2012First inspection conducted August 29, 2012required to fill the gaps that exist; and c. Ensure that adequate physical security (e.g., fences and locks) is provided for the staged material against theft. These inspections will continue until a permanent modification is implemented to prevent overtopping the Cherokee, Fort Loudoun, Tellico, and Watts Bar dams due to the Probable Maximum Flood.TVAwill review the information contained in the updated hydrologic analysis and determine if any information provided in the Final Environmental Statement (FES) related to the operation of WBNUnits 1 and 2 (NUREG-0498, Supplement 1, November 1994), and the WBNUnit 2 Draft Final Environmental Impact Statement (FEIS) (Draft NUREG-0498, Supplement 2, September 2011) is affected

, and submit the results of this review to the NRC.Commitment date from WBNLAR October 1, 2012 Submitted October 1 , 2012), ,TVA to provide a summary of the results of TVA's analysis of the Design Basis Flood for SQNUnits 1 and 2 and WBNUnit 1 that assumes a failure of a section of the HESCOflood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar dams to the NRC within 60 days after its completion.Obligationdate from CAL October 30, 2012 Submitted 52October 30, 2012 NTTFRecommendation 2.1 Flood HazardsReevaluationHazards Reevaluation 53 NTTFRecommendation 2.1FloodHazardsReevaluation Flood Hazards Reevaluation

• Anal yses to be com pleted b y March, 2013ypy-Sunny day upstream dam failure

-Updated PMFfor 21,400 and 7,980 sq mile March stormsLfdtdith21400ilMht PMF-L oss o f d owns tream d am w ith 21 , 400 sq m il e Marc h s t orm PMF-Local intense precipitation flooding with partially blocked site drainage channels and existing conditions

-Cherokee and Douglas Dam partial failure and Ft. Patrick Henry Dam failure with 21,400 sq mile March storm PMF 54 NTTFRecommendation 2.1FloodHazardsReevaluation Flood Hazards Reevaluation

• Challen ges to March, 2013 com pletion gp-Methodology and analyses for seismic dam failures and combinations of seismic dam failures pending NRC guidance development

-TVAcompletingevaluationofupstreamdamstabilityduring PMF andTVA completing evaluation of upstream dam stability during PMF and seismic conditions using FERC criteria

-Sensitivity analyses as necessary to quantify uncertaintiesSditttithdbktfildith

-S e di men t transpor t w ith sunny day em b an k men t f a ilures an d w ith21,400 sq mile March storm PMF 55 Closing Remarks 56