ML13226A259

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E-mail from D. Hubbard, Duke to J. Boska, NRR on Non-Security Sensitive Version of March 25th Presentation
ML13226A259
Person / Time
Site: Oconee  Duke Energy icon.png
Issue date: 04/23/2013
From: Hubbard D
Duke Energy Carolinas
To: Boska J
Division of Operating Reactor Licensing
References
FOIA/PA-2013-0264
Download: ML13226A259 (34)
v • d • e


Text

Boska, John From: Hubbard, Dean M <Dean.Hubbard@duke-energy.com>

Sent: Tuesday, April 23, 2013 10:50 AM To: Boska, John

Subject:

Non- Security Sensitive version of March 25th Presentation Attachments: NRC Presentation March 25. 2013 FINAL Rev C (Non-security Sensitive).pdf Follow Up Flag: Follow up Flag Status: Completed As discussed, slide 18 is now blank with a statement that the information was removed due to being security sensitive.

Thanks John Dean

PDuke 109 VEnergy Fukushima -

Flooding Hazard Reevaluation Upstream Dam Failure Analysis NCR Technical Presentation NRC Headquarters One White Flint North Rockville, MD March 25, 2013 For Information Only

OPuke unergy Dave Baxter, VP, Regulatory Project Completion Dean Hubbard, Oconee External Flood Licensing Manager Ray McCoy, Principal Engineer, ONS Civil Design Chris Ey, Civil Engineering Manager, HDR Dana Jones, Oconee Fukushima Engineering Supervisor Joe Ehasz, VP, URS Program Manager - Water Resources For Information Only 2

Rkr01 Duke 4Energiy Agenda

    • Current Dam Failure Analysis - January 28, 2011 SBreach Analysis Summary
Model Development
    • Updated Dam Failure Evaluation - submitted March 12, 2013

> Models Considered SSelection of Xu & Zhang

> Update Breach Parameters SSensitivity Analysis SIndependent Review

> Comparative Analysis - Large Modern Dam Failures

Modifications Scope 3

For Information Only

~Duke Eoergy 2011 Breach Analysis Summary S:* Breach parameters developed using regression methodology and technical papers:

SFroehlich 2008 SWalder & O'Connor SMacDonald & Langridge-Monopolis

  • o Breach analysis focused on maximizing flooding levels to provide a very conservative and bounding analysis:

) Breach dimensions maximized to assume loss of most of the dam embankment.

SFroehlich breach time of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> was reduced to 2.8 SMaximum peak outflow was selected from all methods SBreach times of Keowee dams/dikes adjusted to maximize water directed at the site STailwater effect below Jocassee dam was not considered 4

For Information Only

P Duke 2011 Breach Analysis Summary Jocassee Dam (postulated dam failure)

%%Initial breach derived primarily from Froehlich regression equations.

  • - Breach dimensions were adjusted based on physical constraints of natural valley
  • - Jocassee breach parameters:

STop Width - 1156 (64% of overall crest)

SBottom Width - 431 feet SBottom Elevation - 800 msl SBreach Formation Time - 2.8 hrs, SPeak outflow 5,400,000 cfs 5

For Information Only

Puke 2011 SE JocasseeDam Breach

.nergy Progressionand Stage-DischargeHydrographs Jocasseie Dam Breach Progression and Hydrographs Case 2(100W) 1.2 6,000,000 II0..8 5,000,000 4,000,000 3,000,000 0.4 2,M000.0 0.2 1,00~000D 0 A' . . . . . . . . . . . . . . . . . . . . .. 0 0,00 2.00 4.00 600 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0,00 2:00 4'00 600 8.00 10:00 12:00

- Headwater - Taihwater B-reach Progression -Breach Discharge 6

For Information Only

SDuke SEnergy 2011 Breach Analysis Summary Keowee Dam/Dikes (postulated cascading dam failures)

  • o Overtopping failure trigger of two feet over the crest o:o Cascading dam/dike failure on Keowee SKeowee main dam- 2.8 hrs SWest Saddle Dam - 0.5 hrs SIntake Canal Dike- 0.9 hrs SLittle River Dam - 1.9 hrs
  • o Conservative assumptions were made to maximize the water directed toward the power block 7

For Information Only

'uke Model Development

,*nergy HEC-RAS JD Model Jocame-K(soWee Damn Breach Study Don Bieach Model Schematic NOTE:o Sav anrah River

~annAh Rive 8

mation Only

Model Development Duke SRH 2D Model Energy (57 thousand elements)

REVISED COGIMrIAT1NAL. MESH 9

For Information Only

Duke 2011 Breach Analysis Summary mnergy 2D Model WATER SURFACE ELEVATIONS AT KEOWEE DAM Jocassee-Keowee Dam Breach Study Pool Elevations at Keowee Dam 840 820 E

am 780 760 740 5 6 7 121o Model Time (hrs)

Puke wnergy Updated Dam Failure Evaluation 11

Duke UpdatedDam FailureEvaluation olry Fukushima 2.1 Attributes of updated and refined dam failure analysis
  • . Updated methodology and present day regulatory guidance S:. Performed to meet NUREG CR/7046, 2011 &ANS 2.8, 1992
Realistic but still conservative assumptions
  • . Physical characteristics of the dams/dikes recognized including materials and method/quality of construction o:. Overtopping and Seismic are confirmed from the 2011 SE as not being credible failure modes 12 For Information Only

P ODuke UpdatedDam FailureEvaluation Uery Fukushima 2.1 Overtopping of the Jocassee dam was confirmed not to be a credible failure mode

  • . The Jocassee dam and dikes include 15 feet of freeboard
  • . The Jocassee watershed is small relative to storage capacity - 148 square miles
    • The top of the spillways are located at 1110 (full normal level)

SFour diverse methods of assuring spillway gate operation

'Rigorous spillway gate maintenance and surveillance testing as required and monitored by FERC

  • o Lake management procedures require consideration of lower level to anticipate additional storage needs for significant storms SWeekly rain forecast are prepared by Duke Energy to project rainfall for the basin SPrecipitation monitoring has assured that no overtopping of the spillway gates has occurred in 40 + years of operation
    • PMF using current HRR-51,52 results in 3 feet of freeboard margin
  • . 2011 SE also concluded that overtopping was not credible 13 For Information Only

P ODuke UpdatedDam FailureEvaluation rEEnergy Fukushima 2.1 Seismic Failure of the Dam was confirmed not to be a credible failure mode

  • - Seismic evaluation based on current FERC criteria using the 1989 EPRI Hazard Curves The Jocassee dam is designed to a 0.12 g horizontal ground acceleration (Oconee site is designed to a 0.1g horizontal ground acceleration).
  • . 2007 Updated Fragility Analysis High Confidence of a Low Probability of Failure (HCLPF) of the dam by sliding 0.305 g Evaluation was performed by Applied Research & Engineering Sciences (ARES) Corp., formerly EQE, a respected consulting firm in the area of seismic fragility The ARES report concluded the median centered fragility value for failure of the dam is 1.64 g.

> Maximum Probabilistic Peak Ground Acceleration for a 2% probability of being exceeded within a 50 year period is 0.197 g (using the United States Geologic Service hazard maps applicable to Jocassee).

  • . Jocassee dam is included in the seismic model of the Oconee Probable Risk Assessment.

The combination of the updated seismic fragility with the seismic hazard curve results in a negligible risk contribution from seismic events.

In a letter dated 11/20/07 and in the 1/28/11 SE report, the NRC concluded that there is a negligible risk 14 For Information Only

Duke Models Considered

nergy Regression Analysis Froehlich 2008 Walder & O'Connor SMacDonald & Langridge-Monopolis 1984 Xu & Zhang 2009 15 For Information Only

Duke Selection of Xu & Zhang 2009 eryBasis

  • . Most current regression method developed and validated with the largest data base of dam failures:

S182 earth and rockfill dam failures compiled S75 failures w/ sufficient info to develop breach regression models

  • . Empirical formulas that account for physical characteristics of dam/reservoir: dam type, failure mode, height, dam erodibility, reservoir shape/storage)
  • . 33 of the 75 failures were on large dams ( > 15 meters)

S:- Applies to multi-zoned dams

  • - Method yields realistic but conservative breach parameters
  • . Recognized by industry experts 16 For Information Only

Duke Breach Parameters EEnergy Fukushima Update S:* Jocassee Dam - Xu & Zhang

> Starting reservoir elevation 1110 (normal full pond)

SRockfill dam with low erodibility classification SPiping failure initiating at 1020 feet msl (Sunny Day Failure)

SBreach parameters:

v'Top Width - 701' (39% of overall crest) v Bottom Width - 431'

-/ Bottom Elevation - 870'

-. Breach Formation Time:

" Xu & Zhang - 29.2 hrs.(13.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> piping +16.0 open weir)

" Froehlich - 16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> (open weir)

,/Peak outflow: 1,760,000 cfs 17 For Information Only

Duke JocasseeDam

.nergy Low Erodibility Classification Diagram removed due to security sensitive information 18 For Information Only

Duke Fukushima Model Fnergy JOCASSEE DAM BREACH PARAMETERS Reservoir Breach Bottom Breach Bottom Average Time to Top of Crest Elevation Starting Failure Mode Elevation (ft Breach Width Breach Right Side Left Side Failure Breach Breach Initiation Structure (f ms Elevation (ft msl) (ft) Width (ft) Slope (Zr) Slope (71) (Hr) Width (ft) Progression Elevation (ft msl) msl)

Jocassee 1125 1,110 Piping 870 431 566 0.53 0.53 29.2 701 Sine Wave 1,020 Dam Breach Formation Time Xu & Zhang definition: 29.2 (13.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> piping + 16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> open weir)

Froehlich definition: 16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> open weir 19 For Information Only

W.uke FukushimaModel JocasseeDam Breach wnergy Progressionand Stage-DischargeHydrographs Jocassee Dam Breach Progression and Hydrographs SEP LE 1.20 3,000,000 1.00 2,500,000 I

z 2,000%000 I 0.60 0.40 1,000q00 DI 0.20 5013,000 0.00 000 2:00 400 6:00 8:00 10:00 12:0D 14:00 16:00 18:00 20:.00 22:00 000 2:00 4.:00 6.00 8:00 10:00 12:00 TkM

- Headwater Tailwater - Breach Progression Breach Discharge

Breach Initiation - - Pipe Collapse ---- Breach Formation Complete Breach Formation Time; Xu & Zhang definition: - 29.2 (13.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> piping + 16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> open weir) Froehlich definition: -16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> open weir 20 For Information Only

SDuke Breach Parameters r Energy Fukushima Update

  • . Keowee Dam

> Starting reservoir elevation 800 (normal full pond)

> Homogeneous earth fill dam

> Overtopping failure trigger of two feet over the crest at 817 msl by rapid rise of Keowee reservoir over the crest

) Multiple simultaneous breach initiation formation points across the Keowee dam and West Saddle dam S:. Cascading dam/dike failure on Keowee

> Keowee main dam- 0.75 hrs

> West Saddle Dam - 0.5 hrs (shorter than main dam, ratio of height) 21 For Information Only

luke rwne Fukushima Model Keowee Dam Breach ProgressionHEC-RAS 0.9 0.8 0.7 C

0.6 U

0.5 0.4 0.3 0.2 0.1 0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Relative Time Progression 22 For Information Only

DPuke Fukushima JD Modeling wnergy Keowee Dam - Headwater and Tailwater Stage Hydrographs Final BEP LE 1-D Model Performance 830 820 810 000\

800 790 780 770

-* 760 750

'Ilk

' 740

  • 730

. 720 710 700 690 680 670 660 650 0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Model Time - hours

-BEP LE HW -BEP LE TW 23 For Information Only

I m F EDuke e Keowee Fukushima Dam Breach 2.1 2D Modeling Progression 0.9 0

0.8

-1; IJA 0O.5

~0.6 - -__-Keowee___ Dam SieWv rac_ HCRS

-#-West Saddle Dam Sine Wave Breach (HEC-RAS) 0.2 I-West Saddle Dam 2-D Breach 0.1 _ Keowee Dam Sine Wave Breach (HEC-RAS)

-Keowee Dam 2-D Breach 0 ...

16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17 Time (hr) 24 For Information Only

Puke L ,nera ry Fukushima 2D Modeling Velocity and Flow Pattern at 17 hrs.

t= 17.0 Vel. Mai Is 0 2 4 6 8 10121416182022242628303234363840 I 'W" , I I 25 For Information Only

P4Wnergiy nDuke Fukushima 2D Modeling Velocity and Flow Pattern at 20 hrs.

t =620.0 2 4 6 8 10 1214 1618 2022 2426 2830 3234 3638 40 For Information Only

luke rwner~gy Fukushima JD-2D Modeling Results Breaching Keowee Dam Intake Dike HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal Time Elevation Decimal lime Elevation Decimal Time Elevation Decimal Time 817j 16.28 817 16.241 n/a Ia! n/at Maximum Water Surfaces Keowee Dam Intake Dike HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time 818.4 16.53 820.1 16.58 810 17.17 807.2 17.67 Maximum Water Surfaces Swale Tallwater HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time 817.5 16.55 815.5 16.53 787.41 17.52 790.41 18.41 27 For Information Only

Puke Sensitivity Analysis V MrPerg Model Peak Outflow (cfs)

McDonald & Langridge-Monopolis 1984 1,566,381 Costa, 1985 1,634,480 Xu & Zhang, 2009 1,760,000 Evans, 1986 1,803,331 SCS, 1981 2,647,711 Bureau of Reclamation, 1982 3,046,462 McDonald & Langridge-Monopolis 1984 5,093,603 (upper envelope)

Froehlich (with additional conservatism), 2008 5,440,000 Data in this table based on Wahl 2004, January 28, 2011 SE and updated Xu & Zhang data 100+ HEC-RAS studies performed with varied breach parameters and control variables Erodiblity was the most significant factor influencing the breach parameters for Xu & Zhang 2009 Bias of conservatism with realism 28 For Information Only

Dpuke IndependentReview rnergy Breach Parameters

  • Independent Peer Review Joe Ehasz, P.E.

David Bowles, Ph. D P.E. P.H.

  • FERC Board of Consultant Review Gonzalo Castro, Ph.D., P.E.

James Michael Duncan, Ph.D., P.E.

James F Ruff, Ph.D., P.E.

Gabriel Fernandez, Ph.D., P.E.

29 For Information Only

Puke ComparativeAnalysis vnergy Large Modern Dam Failures

  • - Taum Sauk SOvertopping failure initiated by human error (previous overtopping events had occurred)

SRandom rockfill embankment supporting the inner concrete liner loosely placed by end dumping the material without compaction except for the top 16' of 84' height

>' The embankment was constructed on a very steep downstream slope of 1 .3H to 1V with a 10 high concrete parapet wall along the crest of the dam SEmbankment was highly erodible and contained over 45% sand sized material (also evident in unusual level of surface erosion from rain events)

  • . Teton

>" earthen dam with majority of dam constructed of highly erodible windblown silt (infant mortality event)

SNo transition zones (sand and/or fine filters) were included between the silt core and the sand & gravel SThin layer of small rock fill on both up and downstream faces with a majority of protection relied upon mix of sand, gravel and cobble

>* Piping failure at 130' below the crest due to inadequate protection of impervious core trench material

>. Breach top width 781' (-25% of overall crest)

Hell Hole H:-

STrue rockfill dam,with upstream sloping impervious core with massive rock fill sections up and down stream to support and protect the core.

SFailure caused by overtopping during construction due to an intense rain event that could not be passed through the construction diversion tunnel SAfter overtopping of the core started, the dam took 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br /> to complete the breach and empty the upstream reservoir 30 For Information Only

Duke Modification Scope ergy Updated

  • . Modifications for protection from dam failure (under review):
1. Relocation of external backup power transmission line
2. Intake Dike embankment protection
3. East embankment protection
4. Discharge Diversion wall
  • . Modifications for Local Intense Precipitation (under review):

STransformer relocation SDiversion walls and drainage canals Aux building and Turbine building protection 31 For Information Only

luke Modification Options nergy 9.

y Jocassee Dam

-4.

N I 2..

N I

f/

~11~

/

/

32 For Information Only

Puke rnergy Questions and Feedback 33

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