ML13226A265

E-mail from D. Hubbard, Duke to J. Boska, NRR on Security Sensitive Version

ML13226A265
Person / Time
Site:	Oconee
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: ML13226A265 (34)

Text

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

Sent: Tuesday, April 23, 2013 11:11 AM To: Boska, John

Subject:

Security Sensitive Version Attachments: NRC Presentation March 25. 2013 FINAL Rev C (Security Sensitive).pdf Follow Up Flag: Follow up Flag Status: Completed John, Attached is the security sensitive version for the other side of Adams. I have added the security sensitive statement at the bottom of the slides.

Dean 1

'OEnergy Duke 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 "Wthl.Bmphi i~ie,, ,* **.23

9 Duke UEnergy 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 tho

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DDuke 1 j(ergy Aed Agenda

,:,Current Dam Failure Analysis -January 28, 2011

ý Breach Analysis Summary

ý Model Development

,:,Updated Dam Failure Evaluation - submitted March 12, 2013 Models Considered Selection of Xu &Zhang Update Breach Parameters Sensitivity Analysis Independent Review Comparative Analysis - Large Modern Dam Failures

• • Modifications Scope For Information Only

9 Duke 2011 Breach Analysis Summary

.:.Breach parameters developed using regression methodology and technical papers:

ý Froehlich 2008

ý Walder &O'Connor

ý MacDonald &Langridge-Monopolis

. 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.

Froehlich breach time of 5hours was reduced to 2.8 Maximum peak outflow was selected from all methods

, Breach times of Keowee dams/dikes adjusted to maximize water directed at the site Tailwater effect below Jocassee dam was not considered For Information Only

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• luke 2011 BreachAnalysis Summary Snergy Jocassee Dam (postulated dam failure)

Initial breach derived primarily from Froehlich regression equations.

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

ý Top Width - 1156 (64% of overall crest)

ý Bottom Width - 431 feet

ý Bottom Elevation - 800 msl

ý Breach Formation Time - 2.8 hrs,

ý Peak outflow 5,400,000 cfs For Information Only

Duke 2011 SE JocasseeDam Breach Energy Progressionand Stage-DischargeHydrographs For Information Only

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Pubklic DI'*._ ... uiuJ~r 10 CFR 2'.39

ROEnergy Duke 2011 Breach Analysis Summary Keowee Dam/Dikes (postulated cascading dam failures)

,:oOvertopping failure trigger of two feet over the crest

,:oCascading dam/dike failure on Keowee

ý Keowee main dam- 2.8 hrs

ý West Saddle Dam-0.5 hrs

ý Intake Canal Dike- 0.9 hrs

ý Little River Dam - 1.9 hrs

• .Conservative assumptions were made to maximize the water directed toward the power block For Information Only

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9 Duke Model Development UEergy HEC.RAS IDModel

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Model Development

• 9e SRH 2D Model 1nergy (57 thousand elements)

REW1ICOMIEATIONALfE For Information Only Withhold from DPulic 10 rle.o..re 4undcr -FR9-O

Puke 2011 Breach Analysis Summary

.nergy 2D Model WATER SURFACE ELEVATIONS AT KEOWEE DAM Jocassee-Keowee Dam Breach Study Pool Elevations at Keowee Dam 860 840

- Case 10OW o20 Case 0OOW 1 E -Case 100W2 C -- 4------

--- Case 10OW-3 0

Case 100W_4 4p 780 760 740 0 1 2 3 4 5 6 7 8 9 10 11 12 Model Time (hrs)

For Information Only

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OPuke wnergy Updated Dam Failure Evaluation For Information Only Withk*Id _rnrr public-nlkeIn_*,,rp ,-_-_r 1.0 CF.R 2.Q

• Duke UpdatedDam FailureEvaluation

1. Energy Fukushima 2.1 Attributes of updated and refined dam failure analysis

,:,Updated methodology and present day regulatory guidance

• .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

,:,Overtopping and Seismic are confirmed from the 2011 SE as not being credible failure modes For Information Only Twe un ,

P Duke UpdatedDam FailureEvaluation VEnergy Fukushima 2.1 Overtopping of the Jocassee dam was confirmed not to be acredible failure mode

• oThe Jocassee dam and dikes include 15 feet of freeboard o:oThe Jocassee watershed issmall relative to storage capacity - 148 square miles

• oThe top of the spillways are located at 1110 (full normal level)

ý Four diverse methods of assuring spillway gate operation

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

• oLake management procedures require consideration of lower level to anticipate additional storage needs for significant storms

ý Weekly rain forecast are prepared by Duke Energy to project rainfall for the basin

ý Precipitation monitoring has assured that no overtopping of the spillway gates has occurred in40 +years of operation

• oPMF using current HRR-51,52 results in3feet of freeboard margin

• o2011 SE also concluded that overtopping was not credible For Information Only 1 UII*itho I 4111 I V. GFRi.

DUke UpdatedDam FailureEvaluation S

VEnergy Fukushima2.1 Seismic Failure of the Dam was confirmed not to be a credible failure mode o:, Seismic evaluation based on current FERC criteria using the 1989 EPRI Hazard Curves The Jocassee dam isdesigned to a 0.12 ghorizontal ground acceleration (Oconee site isdesigned to a 0.1g horizontal ground acceleration).

• o 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 inthe area of seismic fragility

• The ARES report concluded the median centered fragility value for failure of the dam is1.64 g.

• Maximum Probabilistic Peak Ground Acceleration for a 2%probability of being exceeded within a 50 year period is0.191 g(using the United States Geologic Service hazard maps applicable to Jocassee).

• • Jocassee dam isincluded inthe seismic model of the Oconee Probable Risk Assessment.

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

ý Ina letter dated 11/20/07 and inthe 1/28/11 SE report, the NRC concluded that there isa negligible risk For Information Only WiVllLihJ fiui._Pdbch. DIcosu.viw1ef414FR+

9e Models Considered w.fnergy Regression Analysis

ý Froehlich 2008

ý Walder &O'Connor

ý MacDonald &Langridge-Monopolis 1984

ýXu&Zhang 2009 For Information Only

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R DUke Selection of Xu &Zhang 2009 lEnergy Bsis

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

ý 182 earth and rockfill dam failures compiled

ý 75 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)

• ,Applies to multi-zoned dams

.'.Method yields realistic but conservative breach parameters

.'.Recognized by industry experts For Information Only W*thhold eo-Publi isc7osure un-deriUiIK IM.3

Breach Parameters IDuDke POF~nergy Fukushima Update Jocassee Dam - Xu &Zhang

ý Starting reservoir elevation 1110 (normal full pond)

ý Rockfill dam with low erodibility classification

ý Piping failure initiating at 1020 feet msl (Sunny Day Failure)

ý Breach parameters:

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

/ Bottom Elevation - 870'

/Breach Formation Time:

Xu A &Zhang - 29.2 hrs.(1 3.2 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)

-/Peakoutflow: 1,760,000 cfs For Information Only lI IiIi~ Pr uJ uIIIIIU f"I C 2-c i~scosure Underld

Puke JocasseeDam

,nergy Low Erodibility Classification (b)(7)(F) mor inormauon unly

Duke FukushimaModel Energy V, JOCASSEE DAM BREACH PARAMETERS Reservoir Breach Bottom Breach Bottom Average Time to Top of Crest Structure Elevation Starting Failure Mode Elevation(D BreachWidth Breach Right Side Let Side Failure Breach Breach Initiation (amsl) Elevation ( msl) (fa) Width (0) Slope (i) Slope() (r) Width (at)Progression Elevation(ft ms!) Imsl) 1125 1,110 P0i4g 870 431 566 0.53 0.53 29.2 701 SieWave 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 For Information Only Withhold from Public D!losure unaer it CFR 2,39-

luke FukushimaModel JocasseeDam Breach rnergy ProgressionandStage-DischargeHydrographs Breach Formation Time; Xu &Zhang definiton: -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) Froehllch definition: -16.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> open weir For Information Only Withidfrom. Publi Difkyu Ude 10 CFR 2.390

Duke Breach Parameters (lEnergy Fukushima Update

,:,Keowee Dam

ý Starting reservoir elevation 800 (normal full pond)

ý 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 o:*Cascading dam/dike failure on Keowee

ý Keowee main dam-0.75 hrs

ý West Saddle Dam. 0.5 hrs (shorter than main dam, ratio of height)

For Information Only

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Fukushima Model Keowee Dam Oihergy PDuke Breach ProgressionHEC-RAS 0.9 0.8 .

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0.5 "0,.4 C3 0.2 0.1 0

0 0.1 0.2 0.3 0.4 0.5 0.6 0,7 0.8 0.9 Relative Time Progression For Informaton Only "ucDisc osureun.

Puke Fukushima IDModeling "nergy Keowee Dam -Headwater and Tailwater Stage Hydrographs Final BEP LE 1-D Model Performance 830 820 810 800 790 780 770

- 760 E

750 S740 730 720 710 700 690 680 670 660 650 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 Model Time - hours

-BEP LEHW -BEP LE TW For Information Only 0Mý IMCSCý. ,

Fukushima 21 2D Modeling Keowee Dam Breach Progression 1

0.9 0C8 C

-i 0.7 90.6 I0.5 2 0.4

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16.2 16.3 16.4 16.5 16.6 16,7 16.8 16.9 17 Time (hr)

For Information Only

-VllUl. Urom ull DisdusumUit: *iJ1 FR H90'

Duke nergy Fukushima 2D Modeling Velocity and Flow Pattern at l7 hrs.

t: 17.0 Val. Mal 0 2 4 6 8 10121416182022242628303234363840 WRTý For Information Only "Winhhoia from rubIk. Didusoure unde, 10 C;R 2,39 -

PDuke UEnera Fukushima 2D Modeling Velocity and Flow Pattern at 2O hrs.

0 viý 2 4 6 8 10121416182022242628303234363840 For Information Only Sltý cDiscoueudrt

PDuke Fukushima JD-2D lEnergy -

Modeling Results

4 Breaching Keowee Dam Intake Dike HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal lime Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time 817 16.28 817 16.24 n/a n/a n/a n/a Maximum Water Surfaces Keowee Dam Intake Dike HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal Time Elevation Decimal Time Elevation DecimalTimejElevation Decimal Time 818.4 16.53 820.1 16.58 10 17.17 807.2 17.67 Maximum Water Surfaces Swale Tailwater HEC-RAS 2-D HEC-RAS 2-D Elevation DecimalTime Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time 817.5 16.55 815.51 1653 17.52 790.4 18.41 For Information Only WiToi trom uu Dbcli'r e 10 F"

nUrg Sensitivity Analysis wiergy

~u.Ke Model Peak Oufflow (cfs)

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

Froehlich (with additional conservatism), 2008 5,440,000 Data inthis 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 For Information Only mAml$1l l im i Ivihonwa TromTTubuc MEMwOur under 10 CrK 4,19

N Independent Review

,nergy Breach Parameters IIndependent Peer Review Joe Ehasz, P.E.

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

, FERC Board of Consultant Review Gonzalo Castro, Ph.D., PRE.

James Michael Duncan, Ph.D., PRE.

James FRuff, Ph.D., RE.

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

For Information Only

- °un e e

b Duke ComparativeAnalysis rEnergy Large Modern Dam Failures

.', Taum Sauk Overtopping failure initiated by human error (previous overtopping events had occurred)

> Random 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 avery steep downstream slope of 1.3H to IVwith a 10 high concrete parapet wall along the crest of the dam

> Embankment was highly erodible and contained over 45% sand sized material (also evident inunusual level of surface erosion from rain events)

• .Teton earthen dam with majority of dam constructed of highly erodible windblown silt (infant mortality event)

. No transition zones (sand and/or fine filters) were included between the silt core and the sand &gravel

> Thin 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

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

> Failure caused by overtopping during construction due to an intense rain event that could not be passed through the construction diversion tunnel

> After 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 For Information Only

.ub 190

' Energy Duke Modification UpdatedScope

.'. 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):

ý Transformer relocation

ý Diversion walls and drainage canals

ý Aux building and Turbine building protection For Information Only it.'l P. Wdhlisclosuwro*

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luke Modification Options Inergy

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Duke Energy Questions and Feedback For Information Only Witkk-I,,l~t-

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