ML12156A076
| ML12156A076 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar, Sequoyah  |
| Issue date: | 05/31/2012 |
| From: | Lyon C Watts Bar Special Projects Branch |
| To: | |
| Lyon F | |
| References | |
| TAC MD7169 | |
| Download: ML12156A076 (62) | |
Text
Nuclear TVA Hydrology Reanalysis May 31, 2012
Discussion Points Introduction Overview of the Tennessee River System Overview of Current Licensing Basis Overview of Current Licensing Basis Reanalysis Watts Bar Current Licensing Basis Evaluation of Rim Leakage Effect Flood Protection and Flood Mode Operation at WBN Sequoyah Current Licensing Basis Flood Protection and Flood Mode Operation at SQN Modular Flood Barriers Fukushima Flooding Reevaluation Plan
Introduction TVA conducts extensive analysis of the of the hydrology of Tennessee River As needed to manage the operation of the river Reanalysis of nuclear plant flooding events since 2008 TVA has reacted as analyses unfolded to ensure operability of nuclear plants Reviewed plant systems, structures and components to updated flood levels Implemented and maintained appropriate compensatory measures TVA implementation of permanent resolution has been delayed Inadequate performance in submitting timely License Amendments to reflect revised licensing basis: less than timely implementation of permanent additional flood barriers Replacement of temporary flood barriers on upstream must follow NEPA process TVA is committed to High quality hydrology analyses Ensuring operability of nuclear plants Improved timeliness of permanent resolution
Cumberland River Green River Ohio River Tennessee River System Overview Clinch River Doakes Creek Holston River Ft. Patrick Henry John Sevier Bristol Projects (2)
Boone 'f_ South Holston
,.""' Watauga Wilbur Nolichucky French Broad River Little Tennessee
-Thorpe (N)
Nantahala (N)
Cherokee
"'<=>""
"II<=J'~""""'!,.. Douglas
~Font ana Norris Melton Hill Watts Bar Plant Sequoyah Plant Elk River Browns Ferry Plant Duck River Cheoall,..
(T)
Calderwood (T) _
Ft. L~
...., -Chilhowee Tellico Santeetlah (T)
(~ Chatuge Chickamauga -
~
Hiwassee Apalachia --
Ocoee 1, 2, 3 Nottely N ickaja.ck~
........ ~~
Raccoon Mountain
....:....,__,. Guntersville Wheeler Bear Creek Projects (4)
Tennessee-Tombigbee Waterway Pickwick Note:
Hiwassee River Blue Ridge (C)
U.S. Army Corps of Engineers Dams (N)
Nantahala Power & Light Company (subsidiary of Duke Energy)
(T)
Tapoco, Inc. (subsidiary of ALCOA) rvlississippi River
Tennessee River System Overview
- Tennessee River Dams are Operated for Multiple Purposes Flood Control and Storm Water Management Irrigation Hydro Electric Navigation Water Supply Recreation
- Operating Responsibilities for Tennessee River Dams and Locks TVA controls and/or schedules the releases from all flood storage dams above the nuclear sites as an integrated system.
US Army Corps of Engineers operate the locks on Tennessee River
6 Overview of Current Licensing Basis
- Regulatory Guide 1.59 defines two regulatory positions Position 1-All Safety-Related SSCs as identified by RG 1.29 designed to withstand and retain capability for cold shutdown and maintenance thereof during the worst site-related flood probable with attendant wind-generated wave action Position 2-As an alternative to designing hardened protection for all safety related SSCs, provide hardened protection for some of these features if Sufficient warning time-plant shutdown and emergency procedures Safety-related SSCs indentified in RG 1.29 are designed to withstand the flood conditions resulting from a Standard Project event with wind waves from worst wind on record.
Reasonable combinations of less-severe flood conditions are also considered SSCs necessary for cold shutdown and maintenance designed with hardened protective features for the worst site-related flood probable with attendant wind -generated wave action
7 Overview of Current Licensing Basis
- Terminology and Definitions Probable Maximum Precipitation (PMP)
Maximum possible rainfall based on historic events, considering maximum moisture, transposition effects, and interpolation of data from hydrometeorological reports Probable Maximum Storm (PMS)
Maximum storm characteristics considering coverage area, spatial variability, orientat ion, and temporal patterns Probable Maximum Flood (PMF)
Maximum limiting flood elevation at the site based on consideration of the contributing watershed area, use of limiting PMS as an input, an iterative hydrologic model execution, and dam stability assessment Seismically-Induced Dam Failure Flood Level Maximum limiting flood level at the site during Operating Basis Earthquake (OBE) and Safe Shutdown Earthquake (SSE) seismic events postulated at specific locations to cause various dam failure permutations, concurrent with either one-half of the calculated PMF from the PMS or the 500-year flood value as an input to an iterative hydrologic model execution, respect ively Design Basis Flood (DBF) Levels Maximum flood levels either at external walls of flood-protected buildings, or within buildings allowed to flood at the locations of flood-protected equipment, based on the limiting flood event of either the PMF or the seismically-induced dam failure flood level, with consideration for wind-wave run-up outside the buildings, or the expected surge levels inside t he buildings
Overview of Current Licensing Basis Probable Maximum Precipitation
- Various storms evaluated to determine most severe.
- Average rainfall amount within the basin provided below:
Dry 3 days 3 days 3 days
Overview of Current Licensing Basis uare Miles Downstream)
--...... --- ~--- ---- ---- --------- -----------------------
(/...-**.\\
72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> lsohyets
-..... 1
\\
10 Overview of Licensing Basis Reanalysis 2008-2012 NRC issued violations on Bellefonte 3, 4 COL Docket in February 2008 (VIO 05200014/2008-001-01, -02,-03 and 05200015/2008-001-01, -02, -03)
TVA initiated project in March 2008 to Validate and verify legacy hydrology software Verify or regenerate all model inputs During process, changes/discrepancies were found to input parameters Dam Spillway Coefficients (original input 1970s vintage)
- textbook values vs. model data Reservoir Operations
- starting elevations (changed in 2004)
- special operations (original input 1970s vintage)
Overview of Licensing Basis Reanalysis 2008-2012 1972 1999 & 2001 Watts Bar & Sequoyah U FSAR change reflect PMF reevaluation Browns Ferry Hydrology Analysis Approved by NRC 1982-1997 TVA Dam Safety Modification Program I
respectively Feb/March 2008 Bellefonte NOV &
Hydrology model reconstitution project started 1979 & 1982 Sequoyah & Watts Bar Hydrology Analysis approved by NRC, respectively 1997-1998 PMF re-evaluated for TVA Dam Safety Mods 2004 TVA Reservoir
- Operation Study
- completed I
Dec 2009 HESCO barriers installed June 2012 Completion of "Rim Leakage" analysis 11
L Overview of WBN Current Licensing Basis At WBN, PMF is the controlling flood level used to determine DBF. PMF bounds the most limiting seismically-induced dam failure flood level.
WBN PMF Elevation Original Licensing Basis: 738.1' Current Licensing Basis: 734.9' (Based on 1997-1998 reevaluation)
WBN Unit 2 FSAR Submittal: 738.8' (Based on 2008-2009 reevaluation)
Potential Calculated PMF Based on 2012 Evaluation of Rim Leakage: 739.2' Discussed in Subsequent Slides WBN DBF Elevations Wind-wave run-up elevation varies at the flood-protected structures Auxiliary Building surge elevation is PMF+O.S' WBN Flood-Protected Structures Elevations Reactor Building Diesel Generator Building lowest floor level is 742.0'
Evaluation of Rim Leakage Effect
- Rim leakage occurs when water contained in a reservoir finds an alternate path around the dam.
- Rim Leaks occurs when the reservoir elevation reaches high levels.
- New aerial surveys conducted as part of evaluating the Clinch River Site for a new project revealed previously undetected Rim Leaks.
.3
Evaluation of Rim Leakage Effect
- Issue identified in early 2012.
- Analysis due to TVA for final owner's review on May 31, 2012.
- Draft results to date:
Increase in PMF elevation at Watts Bar to 739.2' (increase of 0.4' from WBN2 FSAR Submittal)
Decrease in Watts Bar warning time to 26.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />
- WBN DBF Elevations Wind-wave run-up elevation varies at the flood-protected structures.
Auxiliary Building surge elevation is PMF+O.S' (739.7')
14
JS Flood Protection and Flood Mode Operation at Watts Bar
- WBN Elevations for Flooded Structures
- Service Building, Turbine Building, Auxiliary Building and Control Building are permitted to flood
- Four System/Structure/Components {SSC) are near the critical flood elevation (including surge/wind wave run-up)
Thermal Barrier Booster Pumps (TBBP)
Essential Raw Cooling Water (ERCW) Valves 1-FCV-67-213
& -215 Spent Fuel Pool (SFP)/TBBP Space Cooler ERCW Supply Spent Fuel Pit Cooling Pumps Intake Pumping Station
lo Flood Protection and Flood Mode Operation at Watts Bar
- Modifications are necessary for some of these SSCs to regain margin due to the PMF total increase (including Rim Leakage Effect)
-Temporary Modifications and Compensatory Measures Are In Place
- Permanent Modifications are Scheduled
- Modifications for Affected SSC's Discussed on following pages
Flood Protection and Flood Mode Operation at Watts Bar NOTE:
Values shown in square brackets are the ou tside-building rainfall-induced PMF; values noted are these levels with a 0.5' surge elevation (DBF elevation).
- -- TACF Barrier 740.5'
-- LAR Submittal Pl'v1F 739.7' [739.2']
--Original PMF (1995) 738.6' [738.1 ']
--Current FSAR PIVIF (1998 Reassessment) 735.4' [734.9']
Thermal Barrier Booster Pumps-(Elevations Reflect Rim Leakage Impact) 0
~-
0 1 7
Flood Protection and Flood Mode Operation at Watts Bar Thermal Barrier Booster Pumps
- Actual field elevation to motor base 739.3'
- TACF currently installed to regain margin
- Rim Leakage Consideration
- Margin with TACF
- Planned Modification will construct permanent wall to regain at least 2.0' of margin.
- Modification Installation is scheduled for completion by March, 2013.
Concrete Wall Flood Protection and Flood Mode Operation at Watts Bar Steel Panel Thermal Barrier Booster Pumps-Permanent Modification
Flood Protection and Flood Mode
. Operation at Watts Bar Spent Fuel Pit Cooling Pumps
Flood Protection and Flood Mode Operation at Watts Bar Spent Fuel Pit Cooling Pumps
- Actual field elevation to motor base 740.4'
- No TACF or compensatory measures currently required (PMF plus surge 739.7'- based on Rim Leakage)
- Planned construction of permanent wall to regain at least 2' of margin Concrete wing wall in combination with removable steel wall bolted to embedded anchors on floor and existing floor berm.
- Modification Installation is scheduled for completion by March, 2013.
1
~.l
Flood Protection and Flood Mode Operation at Watts Bar Concrete Wing Wall Removable Steel Panels
Flood Protection and Flood Mode Operation at Watts Bar ERCW Valves 1-FCV-67-213 & -215
Flood Protection and Flood Mode Operation at Watts Bar ERCW Valves 1-FCV-67-213 & -215
- Actual field elevation 741.0' to control components
- Existing margin available is 1.3' when surge is considered.
- No modification necessary for protection or need for additional margin 2Ll
Flood Protection and Flood Mode Operation at Watts Bar Intake Pumping Station
- Opening for discharge from ERCW Intake Screens allows floodwater to enter building.
- Discharge opening is a 20" wide and 27" high. Bottom of opening is at El. 738.67' and is located on the west face of the structure.
- All critical SSC's in the Intake Pumping Station are located above El. 741.0'.
- Modification to protect the Discharge opening will be implemented by March, 2013.
ERCW Pump Wells Trash Sluice Trash Sluice Discharge Intake Pumping Station Intake Fore bay Travelling Water Screen Wells
WBN Flood Mode Operation
- 10 hr duration
- Pre-flood preparations
- Notification from River Operations
- Conditions are possible to produce flood above plant grade
- Rx shutdown started (hot shutdown)
- 17 hr duration
- Flood mode preparations
- Notification from River Operations based on prediction of flood elevation 727 (1' below plant grade to account for wind wave)
Total Flood Warning Time= 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> L. l
Flood Protection and Flood Mode Operation at Watts Bar Initial Conditions: plant at 100% power. Stage 1 Flood Warning issued.
Key Items:
All equipment required for flood mode is above maximum probable flood elevation or installed and protected prior to flooding such as spool pieces and the Thermal Barrier Booster Pumps.
Training is incorporated in the Licensed Operator Requa I program and site E-plan dril ls.
At stage 1 WBN will accomplish the following:
A "Notification of Unusual Event" would be declared per the Emergency Plan and support via staffing of the Technical Support Center would be initiated.
Rapid shutdown of the unit using an approved "Rapid Load Reduction" procedure.
Cooldown the RCS to Mode 4, 340-345°F Shutdown Main Steam Stabilize RCS temperature using SG PORVs and monitor natural circulation conditions Other preparations and contingency actions as necessary; for example, ensuring Emergency DGs in service to shutdown boards if offsite power is lost.
Flood Protection and Flood Mode Operation at Watts Bar When flooding escalates to Stage II Warning or RSO confirms plant elevation 727 is likely to be exceeded WBN will accomplish the following:
An "Alert" declared per the Emergency Plan.
Isolate Steam supply to the Turbine Driven AFW pump.
Vent and fill tanks that will be submerged to prevent collapsing or floating of tanks or radioactive release.
Align auxiliary charging pumps which are located in the Aux bldg elevation 757 for flood mode boration supply.
Placing Aux air on elevation 757' in service and shutdown control and station service air compressors.
Shutdown of the ees system and realign to ERew via spool pieces to essential components such as spent fuel pool} RHRJ thermal barrier and sample HXs. Once cooling via EReW is established the normal charging pump is shutdown and eves isolated.
Heat sink is maintained using SGs supplied by HPFP and Res inventory by starting and stopping the auxiliary boration system charging pumps locally.
Phase A containment isolation manual initiation.
Overview of SQN Current Licensing Basis At SQNJ PMF is the controlling flood level used to determine DBF.
PMF bounds the most limiting seismically-induced dam failure flood level.
SQN PMF Elevation Original Licensing Basis: 722.6' Current Licensing Basis: 719.6' (Based on 1997-1998 reevaluation)
Calculated PMF Reported in LER 327 and 328/2009-009: 722.0' Potential Calculated PMF (Includes 2012 Evaluation of Rim Leakage): 722.0' (Unchanged from Value Reported in LER 327 and 328/2009-09)
SQN DBF Elevations Diesel Generator Building wind-wave run-up is PMF+1.2' Auxiliary Building surge elevation is PMF+O.S' SQN Flood-Protected Structures Elevations Reactor Building Diesel Generator Building grade level is 722.0'
Overview of SQN Current Licensing Basis
- Sequoyah implemented compensatory measures for Diesel Generator Sets and Spent Fuel Pool Pumps at first indication of potential exceedance of the licensing basis PMF elevation prior to updated PMF calculation issuance (Feb 2009)
- TVA submitted LER 50-327{328)/2009-009, Revision 1, on April 14, 2010
-Compensatory measures remain in place 31
Flood Protection and Flood Mode Operation at Sequoyah
- External Flooding Response is provided by Procedure AOP-N.03
- SQN Elevations for Flooded Structures
-Service Building, Turbine Building, Auxiliary Building and Control Building are permitted to flood.
- Two SSC's are near the critical flood elevation (including surge/wind wave run-up)
Diesel Generator Building
- Spent Fuel Pit Cooling Pumps
Flood Protection and Flood Mode Operation at Sequoyah
-Compensatory Measures Are In Place
- Permanent Modifications are Scheduled
- Compensatory Measures and Modifications for Affected SSC's Discussed on following pages
Flood Protection and Flood Mode Operation at Sequoyah
- Compensatory Measures-Diesel Generator Building
- AOP calls for implementation of following actions:
- Sand bag dikes (pre-filled and located on on-site} would be constructed at least 3' high {elevation 725.0'}
External fuel storage tank fill ports are sealed to prevent water in-leakage
Flood Protection and Flood Mode Operation at Sequoyah
- Compensatory Measures-Spent Fuel Pool Cooling Pit Pumps
- Installed SPFC Pump Enclosure Caps as protection.
Flood Protection and Flood Mode Operation at Sequoyah SQN Flood Protection Permanent Modifications Diesel Generator Building
- The openings (doors) are to be protected from flooding through removable aluminum flood barriers.
The RIG I DAM system by Flood Barrier Inc. or a similar system are planned The system will have the ability to protect the openings up to a total flood elevation of 7'-0" (above slab elevation 722.0'}.
Panels would interlock to create a watertight seal, be lightweight, removable, and simple to install.
- Outdoor fill ports will be extended above PMF levels to ensure that water does not penetrate as well as ensure that the tanks may be filled during a flood.
Spent Fuel Pit Cooling Pumps
- No physical modification required. Engineering document change only.
Schedule Modification Installation is scheduled for completion by March, 2013.
3S
SQN Flood Mode Operation
- 10 hr duration
- Pre-flood preparations
- Notification from River Operations
- Conditions are possible to produce flood above plant grade
- Reactor is shutdown and cooldown to Mode 4 (hot shutdown) is initiated
- 17 hr duration
- Flood mode preparations
- Notification from River Operations based on prediction of flood elevation 703 (2' below plant grade to account for wind wave)
Total Flood Warning Time= 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br />
Flood Protection and Flood Mode Operation at Sequoyah The two-stage approach in the flood protection plan is intended to prevent unnecessarily impacting the plant in case a predicted flood does not fully develop.
During Stage 1, SQN will accomplish the following {assuming that units are initially at 100% power):
A ((Notification of Unusual Event" would be declared per the Emergency Plan and staffing of the Technical Support Center would be initiated.
Shutdown to Mode 3 (Hot Standby) would be commenced using AOP-C.03, Rapid Shutdown.
The RCS is cooled down to Mode 4 (less than 350°F) by dumping steam and then RHR Shutdown Cooling is placed in service.
The RCS is borated to maintain shutdown margin.
Preparations are made to place the Aux Charging/Flood Mode Boration system in servtce.
Various other preparations are completed such as moving necessary supplies above the maximum flood elevation and filling tanks to prevent floating.
Flood Protection and Flood Mode Operation at Sequoyah When flooding escalates to Stage II Warning, SQN will perform the following:
An "Alert" declared per the Emergency Plan.
If off-site power is still supply the shutdown boards, the shutdown boards will be manually transferred to the D/Gs.
AFW pumps will be stopped and the HPFP water to the S/Gs will be established, including aligning valves and installation of spool pieces. This requires S/G pressure less than 90 psig.
When decay heat removal is established by HPFP to the S/Gs, RHR Shutdown Cooling will be removed from service.
Other spool pieces will be installed to establish ERCW cooling to Spent Fuel Pool Cooling heat exchangers and RCP thermal barriers.
Heat sink is maintained by releasing steam via S/G atmospheric relief valves with secondary makeup water supplied by HPFP.
RCS inventory will be maintained using Auxiliary Charging pumps.
RCS pressure will be maintained less than 500 psig with RCS temperature less than 328°F (to assure that Fire/Flood Mode pumps can supply HPFP to S/Gs}.
39
Modular Flood Barriers at TVA Dams
41 Modular Flood Barriers
- In 2009, TVA installed temporary modular flood barriers to increase the height of embankment at four dams upstream ofWBN Fort Loudon
-Cherokee Tellico
-Watts Bar Dam
- The reanalysis of the probable maximum flood (PMF) ana lysis accounts for, or credits, the increased height of embankment at these dams.
- The increased height prevents overtopping and failure of these embankments in a PMF.
Modular Flood Barriers Barriers are engineered, interconnected, geotextile lined, and crush stoned filled Hesco Concentrainer Baskets.
Geotextile is a heavy-duty, non-woven, permeable, interlocked, polypropylene fabric Welded Wire Mesh, coil, and pins Alu-Zinc coated Steel, wire diameter of 0.16 inch. With spacing of 3 11 x 3 11 Size: 3'X3'X3' or 3'X3'X4' Weight of One Section: 1.6-2.2 tons Fill Material: #1 0 crushed stone meeting TOOT Specifications 903.01 (e), 903.01 (f) or 903.22
Modular Flood Barriers at Cherokee Dam 3
Modular Flood Barriers at Cherokee Dam 44
Modular Flood Barriers at Tellico Dam
Modular Flood Barriers at Tellico Dam
Modular Flood Barriers at Fort Loudon Dam 4'
Modular Flood Barriers at Fort Loudon Dam 48
Modular Flood Barriers at Watts Bar Dam 49
Modular Flood Barriers at Watts Bar Dam Sl
t;l Modular Flood Barriers at TVA Dams
- Top of Dam Max Flood Top of Barriers Cherokee 1089.0 1090.8 1092.0 Fort Loudoun 830.0 835.6 836.9
~--------~~~--------
~~----
Tellico 830.0 833.3 834.0 Watts Bar 767.2 768.1 770.3
Modular Flood Barriers at TVA Dams The HESCO barrier floodwalls are intended to be temporary structures.
At least 5 year design life expectancy under normal environmental conditions.
TVA River Operations examines dams monthly including examination of modular flood barriers and notify NPG of issues that affect potential concern with the modular barriers.
NPG Engineering will perform inspections on a 6-month frequency.
These inspections will verify condition of baskets, covers, and fill; verify quantity and location of spare materials; review emergency action procedures and critical contacts; and verify that no modifications have impacted the modular flood barriers ability to function as designed.
TVA intends to replace the HESCO barrier floodwalls with permanent modifications by October 2015 NEPA EIS currently underway, preferred alternative to be selected by September 2012 Designed for all applicable loading conditions used in the design of floodwalls.
Design Phase (6-9 months)
Construction Phase (18-21 months)
S2
Modular Flood Barriers at TVA Dams Openings in the modular flood barriers are required to permit public access to recreational areas.
Procedures are in place to close openings as part of flood mode preparations.
Procedures are implemented by TVA River Operations as part of the Emergency Action Plan for each dam.
Closure materials are stored at each dam adjacent to the modular flood barrier Closure materials are verified by River Operations every month and will be by NPG every 6 months.
1
~~~~~~ ~~~r~: ~cJ 0
~~~~::~"~:~:
with tne sti.lpte d. Qeo tex tlle to p polntlnq aw<Jy r rom t he d ir e ction the wall i s to be crecte a.
4 Butt t o gether t he two unfilled u n Us t o be joined.
2 ::~e~:~oet~~he~::~t:;eel~CJth o?
de~lred d lrec! lon. TI"' C' unit will un#o ra rrom cne h orizontal co the vertic a l a n d be self suppo rt ing.
Pull t/H~ u n it o u t t o Its Tu tr len q t h.
Ensur e It Is In the cor rect position.
5 Pull t he c orner co ils ot bott, units t o ge ther until they o verlllp.
3 O u t.: k.t v <lCJiu st tr,e outer walls of the
$eQments so t hey,ve P~lr.JIIo? l or a s c/ ~Y.>e a s the q,rouna w lll.:lllow.
En su~ tht!' f la p s a t the base of eacn cgll ant tucked ln.
6 Insert,, lo ln lno p in down th e center o~ rne overlappeo coils thu:!. loJnlnQ then' toqether.
7
~!~7~;;~v ~:;~::~~~~~~~~~~
5 un it Yo u w lll n ot be able to j oin
,, atlltlona l u n Ju. o nce til~ enr1 c l?lls a r..:_. ru ll.
Modular Flood Barriers at TVA Dams
~ Structural debris impact testing performed with a floating log. The debris impact testing was based on two different log sizes: 12" and 17" diameter logs (12 feet long) with an impact speed of 5 mph.
~ The USACOE performed hydrostatic testing, wave-induced hydrodynamic testing, and overtopping testing.
~ Testing by the US Dept of State showed their ability to withstand impact from a 15,000 lb vehicle traveling SO mph.
~ Used by the US Military to protect personnel from terrorist bomb attacks in Iraq and Afghanistan.
12-in. and 17-in. log impact Wave-induced hydrodynamic action Static Overtopping
Modular Flood Barriers at TVA Dams Watts Bar Dam Earth Embankment Armoring
56 Modular Flood* Barriers
- Qualitative Assessment of Barge Impacts
- Barge Traffic Assessment No barge traffic on Cherokee Reservoir Very infrequent barge traffic on Tellico Limited to moderate barge traffic on Fort Loudoun and Watts Bar Reservoirs
- Direct barge impacts on HESCO containers considered unlikely, stream flow will be directed toward concrete overflow portion of dams Glancing blows are possible
- TVA currently plans to perform analysis of basket barrier breaches by August 30, 2012.
Modular Flood Barriers at TVA Dams Preliminary Potential Barge Impact Assessment-Watts Bar Dam
' Conservatively assume the barge is empty r Will run aground closer to barriers
,_Typical barge dimensions r Typical modular flood barrier configurations r::.]
Modular Flood Barriers at TVA Dams Preliminary Potential Barge Impact Assessment-Watts Bar Dam
,. Barge runs aground, does not impact modular flood barriers
,. The barriers need to be at least 9.0 feet away from the edge of the embankment
, Location drawings indicate the barriers are at least this distance from the edge of t he embankment
Modular Flood Barriers at TVA Dams Preliminary Potential Barge Impact Assessment Fort Loudoun Dam barriers have the highest risk of barges striking Typical barges will not hit them when full. They will run aground first.
Tellico Dam barriers have lower risk.
Typical barges would have to be less than Yz full to be able to hit them.
- Watts Bar Dam barriers are not in danger of being struck by the barges.
Cherokee reservoir has no barge traffic.
Fort Loudoun Limited to moderate Yes Less than 70-80% full Tellico Very infrequent Yes Less than 40-50% full Watts Bar Limited to moderate No N/A Cherokee None No N/A
Fukushima-Hazard Reevaluation Report-Current Plans Award Contract to Prepare Hazard Reevaluation Report (HRR)
Gather Information to Develop HRR Reevaluate PMF Using HEC-RAS through Chickamauga Dam (Watts Bar and Sequoyah)
Prepare HRR for Watts Bar and Sequoyah TVA Submit HRR for Watts Bar and Sequoyah Reevaluate PMF Using HEC-RAS through Wheeler Dam (Browns Ferry)
Prepare HRR for Browns Ferry TVA Submit HRR for Browns Ferry 60 TVA TVA/Contractor Contractor Contractor TVA Contractor Contractor TVA June 5, 2012 July 18, 2012 January 10, 2013 February 1, 2013 (Current Plan-SQN Time Frame Under Assessment)
March 12, 2013 January 10, 2014 February 1, 2014 March 12, 2014
61 Hydrology Commitments and Current Plans Submit WBN Hydrology LAR Commitment July 20, 2012 SubmitSQN Hydrology LAR Commitment August 10, 2012 Complete Modifications to WBN TBB Flood Commitment March 2013 Protection Complete Modifications to WBN SFP Flood Commitment March 2013 Protection Complete Modifications to SQN DG Buildmg Flood Comm1tment March 2013 Protection Implement Permanent Modifications to Prevent Current Plans October 2015 Overtopprng of Upstream Dams Complete Breach Analysis of Modular Flood Current Plans August 2.012 Barriers
Conclusion
- TVA is committed to:
High quality hydrology analyses Ensuring operability of nuclear plants Aggressively pursuing resolution of current set of flooding issues.
6.