ML12348A208
| ML12348A208 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 12/13/2012 |
| From: | Tennessee Valley Authority |
| To: | Andrew Hon Plant Licensing Branch II |
| Hon, Andy | |
| References | |
| Download: ML12348A208 (56) | |
Text
N l
TVA Hydrology Update Nuclear TVA Hydrology Update December 13, 2012
Purpose p
- License Amendment Request (LAR) Review Status
- Updated Information on Temporary Dam Modifications
- Status of Fukushima NTTF Recommendation 2.1 Flood Hazards Reevaluation
- Update on June 2012 Commitments 2
Agenda g
- Introduction
- Updated Hydrology Analysis Tools
- License Amendment Request (LAR) Review
- Temporary Flood Barriers at TVA Dams
- NTTF Recommendation 2.1 Flood Hazards Reevaluation
- TVA Flood Mode Operation Improvement Strategy
- Commitment Status
- Closing Remarks 3
Introduction 4
Introduction
- TVA is implementing commitments from J
13 2012 l tt June 13, 2012 letter
- TVA is deploying a Fleet Flood Mode Operation Improvement Strategy Improvement Strategy 5
Tennessee River System Overview Sequoyah Plant Browns 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 tributaries USACE HEC RAS sed e tensi el in recentl appro ed Combined License
- USACE HEC-RAS used extensively in recently approved Combined License Applications
- USACE HEC-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 SOCH model
- Volume check performed in SOCH and HEC-RAS to confirm storage input data
- Consistent with Fukushima NTTF Recommendation 2.1 Flood Hazards Reevaluation guidance 8
Hazards 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 USACE HEC-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 USACE HEC-RAS
- Updates of inputs to match HEC-RAS requirements - COMPLETE
- Verification and validation of software - COMPLETE
- Validated USACE HEC-RAS code under TVA Quality Assurance Plan Validated USACE HEC 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:
- Examined selected current licensing basis cases
- Examined selected current licensing basis cases
- Evaluated consequence of overtopping and breaching selected upstream dam embankments
- Planned application of HEC-RAS includes:
Planned application of HEC RAS includes:
- NTTF Recommendation 2.1 Flood Hazards Reevaluation
- Sensitivity analyses related to HESCO modular flood barrier performance
- Reanalysis of current licensing basis cases 10 Reanalysis of current licensing basis cases
License Amendment Request (LAR)
Review Review 11
License Amendment Request (LAR)
Review Review
- Update required to WBN Unit 1 LAR to reflect Update 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)
Review Review
- Selected current licensing basis cases simulated using g
g HEC-RAS
-Rainfall induced PMF cases:
- WBN and SQN 21,400 sq mile winter storm
- WBN and SQN 7,980 sq mile winter storm
- Calculation complete for WBN
- Letter report complete for SQN
-Seismically induced dam failure case:
- Combination Norris Tellico Dam seismically induced dam failure (WBN only)
- Combination Norris-Tellico Dam seismically induced dam failure (WBN only)
- Operating Basis Earthquake (OBE) with one-half PMF
- Selected because current limiting WBN flood warning time event 13
- Letter report complete
License Amendment Request (LAR)
Review Review
- Results of selected current licensing basis cases using g
g HEC-RAS
- 7,980 sq mile winter storm PMF = 738.0
- 21,400 sq mile winter storm PMF = 738.7 (WBN LAR PMF level = 739.2)
SQ i f ll i d d
- 7,980 sq mile winter storm PMF = 718.7
- 21,400 sq mile winter storm PMF = 720.5 (SQN LAR PMF level = 722.0)
- Wind wave runup for SQN Diesel Generator Building below operating floor elevation
- WBN Norris-Tellico Dam seismically induced dam failure case
- Current limiting WBN flood 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 /> (WBN LAR time = 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br />)
License Amendment Request (LAR)
Review Review
- Plans forward for reanalysis of all current licensing basis cases using HEC-RAS
- Update of following hydrologic analyses methodology/results
- Seismically induced dam failure cases
- Flood warning time cases
- TVA is evaluating the sequencing for reanalyzing the current licensing TVA is evaluating the sequencing for reanalyzing the current licensing basis cases with HEC-RAS
- WBN and SQN UFSAR updates will be submitted to reflect these cases upon completion of the reanalysis effort upon completion of the reanalysis effort
Temporary Flood Barriers at TVA Dams at TVA Dams 16
Temporary Flood Barriers at TVA Dams 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
- Results of Inspections of Temporary Flood Barriers Results of Inspections of Temporary Flood Barriers
- Results of Breach Analysis
- Results of Analysis with No Temporary Flood Barriers y
p y
- Status of Actions to Address Breach Initiators
- Results of Computational Fluid Dynamics (CFD) Analysis 17
- Regulatory Process for Temporary Flood Barriers
Temporary Flood Barriers at TVA Dams 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 PMF event
- Fort Loudon Dam
- Cherokee Dam Fort Loudon Dam Cherokee Dam
- Tellico Dam
- Watts Bar Dam
h f h b
k h
d height of the embankments at these dams
- Preserves assumption of no embankment failures by overtopping
- Seismically induced dam failure analysis does not credit flood Seismically induced dam failure analysis does not credit flood barriers
- Embankments can fail if overtopped in analysis 18
Temporary Flood Barriers at TVA Dams at TVA Dams 19
Temporary Flood Barriers at TVA Dams at TVA Dams
- Barriers are engineered, interconnected, geotextile lined, and crushed compacted stone filled HESCO Concertainer Baskets
- Geotextile is a heavy-duty, non-woven, permeable, interlocked, l
l f b i W ld d Wi M
h il d i Al Zi polypropylene fabric Welded Wire Mesh, coil, and pins Alu-Zinc coated Steel, wire diameter of 0.16 inch, with spacing of 3" x 3
- Size: 3X3X3 or 3X3X4 Weight of One Section: 1 6 - 2 2 tons Size: 3 X3 X3 or 3 X3 X4 Weight of One Section: 1.6 2.2 tons
- Fill Material: #10 crushed stone meeting TDOT Specifications 903.01(e), 903.01(f) or 903.22
( ),
( )
20
Temporary Flood Barriers at TVA Dams at TVA Dams 21 Temporary Flood Barriers at Fort Loudoun Dam
Temporary Flood Barriers at TVA Dams at TVA Dams
- Since the May 31, 2012 TVA presentation, the following actions have been i
l d i l i h
HESCO d l fl d b i
implemented involving the temporary HESCO modular flood barriers
- 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 SQN Units 1 and 2 and WBN Unit 1 using SOCH for the 21,400 sq mile storm that assumes a failure f
ti f th b i
d th b
k t
of a section of the barriers and earthen embankments
- Completed an analysis of flood levels at SQN Units 1 and 2 and WBN Unit 1 using HEC-RAS for the 7,980 winter storm without the barriers C
l t d C
t ti l Fl id D i
(CFD) d l f F
t L d
d
- Completed a Computational Fluid Dynamics (CFD) model for Fort Loudoun and Tellico Reservoirs to demonstrate flow velocity profiles in the reservoirs at PMF levels, and to calculate velocities and trajectories of large objects as they approach 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 Barriers at TVA Dams at TVA Dams
- Modifications at Cherokee, Fort Loudoun, Tellico, and Watts Bar Dams to be i
l d
l HESCO d l fl d b i
implemented to replace HESCO modular flood barriers
- 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
- DEIS issued September 2012
- Public meeting to discuss the project and accept comments held on October 25, 2012
- Schedule
- Public comments for DEIS received 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 Renewables final decision will be documented in a Record of Decision (ROD) scheduled for March 13 2013 23 documented in a Record of Decision (ROD) scheduled for March 13, 2013
- Completion of modifications scheduled by October 2015
Temporary Flood Barriers at TVA Dams at TVA Dams
- Results of TVA Nuclear Power Group inspections of the temporary HESCO fl d b i
i ll d Ch k
F L
d T lli d W B
flood barriers installed at Cherokee, Fort Loudoun, Tellico, and Watts Bar reservoirs
- Minor deficiencies from visual inspection of modular flood barriers d f f
f d
l f l
f bl
- No deficiencies from inspection of staged materials for closure of public access gaps in modular flood barriers
- Procedures used to close public access gaps found to be up-to-date
- Contact information in the River Operations and Renewables Emergency Action Plan Contact information in the River Operations and Renewables Emergency Action Plan Supplements found to be up-to-date
- TVA River Operations performs independent inspections on a monthly basis
- TVA Nuclear Power Group increased frequency of independent inspections TVA Nuclear Power Group increased frequency of independent inspections to monthly
- TVA has performed reasonable simulation of TVA procedures for closure of gaps in the temporary flood barriers 24 gaps in the temporary flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams
b h
HESCO barrier breaches
- Failure of HESCO flood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar Dams modeled Segment 1 of both 21 400 sq mile and 7 980 sq mile storms revised in model
- Segment 1 of both 21,400 sq mile and 7,980 sq mile storms revised in model
- SOCH hydraulic modeling consistent with SQN and WBN LAR
- Dam rating curves revised to model embankment failures
- New outflow hydrograph required for Cherokee Dam during the 7 980 sq mile storm
- 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
- Flood wave overtops east wall at Watts Bar Dam causing breach of Watts Bar East 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 SQN and WBN LARs
- No downstream dams, including embankments or gates, are assumed to fail 25
Temporary Flood Barriers at TVA Dams at TVA Dams
b h
(
d)
HESCO barrier breaches (contd)
- 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) 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
- Main embankment adjacent to each dam spillway selected where bedrock elevations known
- 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 fail W tt B D
h b
i E
t E th E b k
t E t E th E b k
t d l d t 26
- Watts Bar Dam has barriers on East Earth Embankment; East Earth Embankment modeled to partially fail
Temporary Flood Barriers at TVA Dams at TVA Dams
- Results provided to NRC by letter dated October 30, 2012
- Results demonstrate need for HESCO modular flood barriers to prevent overtopping of the earthen embankments during PMF events events 27
Temporary Flood Barriers at TVA Dams at TVA Dams
- Analysis of flood levels at WBN Unit 1 assuming HESCO barriers are not i
ll d d d d
installed - and dams are overtopped
- Failure of earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar Dams modeled 7 980 sq mile March storm modeled
- 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 W tt B D
f il b d
DBREACH ti i 28 Watts Bar Dam fails based on DBREACH timing
- Melton Hill non-overflow dam is stable to a flood elevation of 817 ft
Temporary Flood Barriers at TVA Dams at TVA Dams
- Analysis of flood levels at WBN Unit 1 assuming no HESCO barriers (contd)
- 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) approach Single embankment at each dam postulated to fail
- 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
- Cherokee Dam South Embankment modeled to partially fail progressively over one hour
- 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 starting at one ft overtopping 29 starting at one ft overtopping
- Total failure of West Saddle Dam at Watts Bar Dam modeled
Temporary Flood Barriers at TVA Dams at TVA Dams
- Result confirms the need for HESCO modular flood barriers to prevent overtopping during PMF events
- Two breach analyses performed:
Anal sis of breach of HESCO barriers and s bseq ent o ertopping of dams
- Analysis of breach of HESCO barriers and subsequent overtopping of dams under PMF conditions
- Analysis of overtopping of dams under PMF conditions (without HESCO b
i i
t ll d) barriers installed)
- Results are similar 30
Temporary Flood Barriers at TVA Dams 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 PMF levels
- Calculate velocities and trajectories of large objects Calculate 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 SOCH one-dimensional model
- CFD solution algorithms developed at the University of g
p y
Tennessee - Chattanooga (UTC) SimCenter 31
Temporary Flood Barriers at TVA Dams at TVA Dams
- Boundary conditions for determining flows:
- Data from the SOCH model from TVA used to determine the inlet heights and flow velocities during the peak of the PMF event at approximately Little Tennessee River Mile (LTRM) 3.6 and Tennessee River Mile (TRM) 605.75 C
di i d
- Conditions used:
- 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/sec When necessary (depending on the domain extent used in the flow simulation
- 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 height = 833.28 ft, discharge = 601,898 cfs g
g
- Fort Loudoun Dam Outlet: Water height = 835.45 ft, discharge = 640,356 cfs 32
Temporary Flood Barriers at TVA Dams 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 PMF height of 835 ft
- Flowrates at the dams matched to an PMF SOCH simulation
- Overall mass balance for the domain at solution terminus of 1%
- Solution algorithms used to predict the Tennessee River and Little Tennessee Ri er flo s at PMF conditions Little Tennessee River flows at PMF conditions
- Given the flows at PMF conditions, the trajectory of large objects like barges under a zero-power condition computed for 33 j
g p
p a range of release parameters
Temporary Flood Barriers at TVA Dams at TVA Dams Flow solution obtained using Tenasi/Incompressible solution showing velocity magnitude Fort Loudoun and Tellico Dams Depicted 34 Fort Loudoun and Tellico Dams Depicted
Temporary Flood Barriers at TVA Dams at TVA Dams Velocity vectors in the Tellico Channel (connecting Fort Loudoun and Tellico Reservoirs) showing flow from Fort Loudoun to Tellico Reservoir at PMF conditions 35
Temporary Flood Barriers at TVA Dams at TVA Dams
- Trajectories computed for objects simulating barges using the inclusion of i
i l i l i
h fl l
i inertial particles into the flow solution
- 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 a 195 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 Barriers at TVA Dams 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
- First Class Landing located on opposite shore from Fort Loudoun Dam at TRM 603 First Class Landing located on opposite shore from Fort Loudoun Dam at TRM 603 37
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 1000-ton objects, aerial view
- Simulation of objects released at TRM 608 3 38
- Simulation of objects released at TRM 608.3
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 1000-ton objects, perspective view
- Simulation of objects released at TRM 608 3 39
- Simulation of objects released at TRM 608.3
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 100-ton objects, aerial view
- Simulation of objects released at TRM 608 3 40
- Simulation of objects released at TRM 608.3
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 10-ton objects, aerial view
- Simulation of objects released at TRM 608 3 41
- Simulation of objects released at TRM 608.3
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 1000-ton objects, aerial view
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 1000-ton objects, aerial view
- All objects approach Fort Loudoun Dam, and do not impact the HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams Computed trajectories for 1000-ton objects, aerial view
- Simulation of objects released at approximately TRM 603 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 HESCO modular flood barriers
Temporary Flood Barriers at TVA Dams at TVA Dams
- The combined flow and object computational solutions show that the trajectories do not impact the HESCO modular flood barriers placed near the Fort Loudoun Dam
- 1000 ton objects simulating barges and smaller 100 ton and
- 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 HESCO modular flood barriers
- Additional modeling considerations 45
TVA Flood Mode Operation Improvement Strategy Improvement Strategy 46
TVA Flood Mode Operation Improvement Strategy Improvement Strategy
- TVA Fleet Flood Mode Operation Improvement Strategy C
t S d
-Corporate Sponsored
-Living Document
-Issuance Expected by December 17, 2012 p
y
- Key Personnel
-Corporate Senior Leadership - Jim Morris and Don Jernigan
-WBN Sponsor - Don Grissette
-WBN Lead - Darlene Viscusie WBN Lead Darlene Viscusie
-SQN Sponsor - John Carlin
-SQN Lead - Melissa Meade 47
-BFN Sponsor - Keith Polson
TVA Flood Mode Operation Improvement Strategy Improvement Strategy
- Key Elements of Strategy Fl d M d A l
i I t
d Pl t M difi ti
-Flood Mode Analysis Improvements and Plant Modifications
- Evaluate Modifications to Improve Stage I - Stage II Implementation
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
- Equipment Identification and Classification Equipment Identification and Classification
- Equipment Assessment
- Long Term Equipment Reliability 48
- Infrastructure Improvements
Commitment Status 49
Commitment Status Commitment Status TVA will submit a License Amendment Request to update the WBN Unit 1 Updated Final Safety Commitment date TVA 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 date July 20, 2012 Submitted July 19, 2012 TVA will submit a License Amendment Request to update the SQN Units 1 and 2 Updated Final Commitment date TVA 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 date August 10, 2012 Submitted August 10, 2012 TVAs Nuclear Power Group TVA will issue and initially perform a procedure for a semi-annual Commitment date s
uc ea o e G oup ssue a d t a y pe o a p ocedu e o a se a
ua inspection of the compensatory measure for flood protection of the WBN Unit 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 d
i t l t d PMF t I ti ill ti til th t
i Co t e t date August 31, 2012 First inspection conducted August 30, 2012 during a postulated PMF event. Inspections will continue until the compensatory measure is replaced by a permanent plant modification.
50
Commitment Status Commitment Status TVAs Nuclear Power Group will issue and initially perform a procedure for a semi annual Commitment date TVA s Nuclear Power Group will issue and initially perform a procedure for a semi-annual inspection to verify the condition of the SQN Units 1 and 2 Spent Fuel Pit Cooling Pump Enclosure caps. Inspections will continue until the design change is completed to document the SQN Units 1 and 2 Spent Fuel Pit Cooling Pump Enclosure caps as a permanent plant feature.
Commitment date August 31, 2012 First inspection conducted August 28, 2012 TVAs 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 SQN Units 1 and 2 Diesel Generator Building. Inspections will continue until the compensatory measure is l
d b l
difi i
Commitment date August 31, 2012 First inspection conducted replaced by a permanent plant modification.
August 28, 2012 TVA will perform an analysis of the Design Basis Flood for SQN Units 1 and 2 and WBN Unit 1 that assumes a failure of a section of the HESCO flood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar dams.
Commitment date August 31, 2012 Completed August 31 2012 August 31, 2012 51
Commitment Status Commitment Status TVAs Nuclear Power Group will issue and initially perform procedures for semi annual Commitment date TVA s Nuclear Power Group will issue and initially perform procedures for semi-annual inspections of the temporary HESCO flood barriers installed at Cherokee, Fort Loudoun, Tellico, and Watts Bar reservoirs. These inspections will: a. Ensure the temporary HESCO flood barriers remain in place and are not structurally degraded as specified by the manufacturers written specifications and recommendations; b. Verify the inventory and staging of the material Commitment date August 31, 2012 First inspection conducted August 29, 2012 required 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.
TVA will 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 WBN Units 1 and 2 (NUREG-0498, Supplement 1, November 1994), and the WBN Unit 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 WBN LAR 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 SQN Units 1 and 2 and WBN Unit 1 that assumes a failure of a section of the HESCO flood barriers and earthen embankments at Fort Loudoun, Cherokee, Tellico, and Watts Bar dams to the NRC within 60 days after its completion.
Obligation date from CAL October 30, 2012 Submitted 52 October 30, 2012
NTTF Recommendation 2.1 Flood Hazards Reevaluation Hazards Reevaluation 53
NTTF Recommendation 2.1 Flood Hazards Reevaluation Flood Hazards Reevaluation
- Analyses to be completed by March, 2013 y
p y
- Sunny day upstream dam failure
- Updated PMF for 21,400 and 7,980 sq mile March storms L
f d t
d ith 21 400 il M h t PMF
- Loss of downstream dam with 21,400 sq mile March storm 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
NTTF Recommendation 2.1 Flood Hazards Reevaluation Flood Hazards Reevaluation
- Challenges to March, 2013 completion g
p
- Methodology and analyses for seismic dam failures and combinations of seismic dam failures pending NRC guidance development
- TVA completing evaluation of upstream dam stability during PMF and TVA completing evaluation of upstream dam stability during PMF and seismic conditions using FERC criteria
- Sensitivity analyses as necessary to quantify uncertainties S di t t t
ith d
b k
t f il d
ith
- Sediment transport with sunny day embankment failures and with 21,400 sq mile March storm PMF 55
Closing Remarks 56