ML13226A264
| ML13226A264 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/25/2013 |
| From: | Boska J Division of Operating Reactor Licensing |
| To: | Riccio J - No Known Affiliation |
| References | |
| FOIA/PA-2013-0264 | |
| Download: ML13226A264 (34) | |
Text
Boska, John From: Boska, John Sent: Monday, March 25, 2013 8:06 AM To: Riccio, Jim
Subject:
Slides for Oconee public meeting on 3/25/13 at 2pm Attachments: 2013-03-25 Oconee slides on flood hazard report.pdf See attached.
John Boska Oconee Project Manager, NRR/DORL U.S. Nuclear Regulatory Commission 301-415-2901 email: *ohn.boska(,nrc.Qov 1
L-5
9 Duke UEnergy 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
- OUKO ergy 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
Duke Agenda OEnergy e:.Current Dam Failure Analysis - January 28, 2011
, Breach Analysis Summary
, Model Development
- oUpdated Dam Failure Evaluation - submitted March 12, 2013
, Models Considered
, Selection of Xu &Zhang
, Update Breach Parameters
ý Sensitivity Analysis
, Independent Review
, Comparative Analysis Large Modern Dam Failures
.: Modifications Scope 3
For Information Only
9iEnergqy 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 4
For Information Only
ri 1nergy 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:
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,
, Peak outflow 5,400,000 cfs 5
For Information Only
Duke 2011 SE JocasseeDam Breach tillnergy ProgressionandStage-DischargeHydrographs Jocassee Dam Breach Progression and Hydrographs Case 2(100W) 1.2 61,00,000 OA 1 2,WQ*oJo 0 0 000 2:00 4110 650 8W.01(0. 120' 14100 16.C0 MV 2.00 22:00 0OW02110 4.90 600 8100 10.00 12:00
-Headwater -Tallwater -BreacbhProgression -BreachDischarge 6
For Information Only
P Duke2011 BreachAnalysis Summary.
Keowee Dam/Dikes (postulated cascading dam failures)
- .Overtopping failure trigger of two feet over the crest
- ,Cascading dam/dike failure on Keowee
, Keowee main dam- 2.8 hrs
, West Saddle Dam - 0.5 hrs
, 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 7
For Information Only
Duke Model Development
,,nergy HEC.RAS JD Model Domkuii*od.Ichwui NOTE Rr.
R~ve~
8 Only
Model Development Duke SRH 2D Model "nergy (57 thousand elements)
RMuSE COMMfATIONAL MESH 9
For Information Only
luke 2011 Breach Analysis Summary wnergy 2D Model WATER SURFACE ELEVATIONS AT KEOWEE DAM Inr' P".Kwnw"-a m R"r'ar-hqh-,id Pool Elevations at Keowee Dam 860 840 820 "a
E No w 780 7601 740 0 1 2 3 4 5 6 7 8 9 10 U 1210 Model Time (hrs)
[Puke
.nergy Updated Dam Failure Evaluation 11
DUke UpdatedDam FailureEvaluation lergy 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
.:oRealistic 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 12 For Information Only
- DUke UpdatedDam FailureEvaluation Energy 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 issmall relative to storage capacity - 148 square miles
- . The top of the spillways are located at 1110 (full normal level)
ý Four diverse methods of assuring spillway gate operation
, Rigorous spillway gate maintenance and surveillance testing as required and monitored by FERC
.:. Lake 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
- . PMF using current HRR-51,52 results in3feet of freeboard margin
.:*2011 SE also concluded that overtopping was not credible 13 For Information Only
DUke UpdatedDam FailureEvaluation V nergy Fukushima 2.1 Seismic Failure of the Dam was confirmed not to be a credible failure mode
> The Jocassee dam isdesigned to a0.12 ghorizontal ground acceleration (Oconee site isdesigned to a 0.1g horizontal ground acceleration).
,:, 2007 Updated Fragility Analysis
> High Confidence of aLow Probabilily 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 a2%probability of being exceeded within a50 year period is0.197 g(using the United States Geologic Service hazard maps applicable to Jocassee).
- , Jocassee dam isincluded inthe seismic model of the Oconee Probable Risk Assessment.
> The combination of the updated seismic fragility with the seismic hazard curve results inanegligible risk contribution from seismic events,
> Inaletter dated 11/20/07 and inthe 1/28/11 SE report, the NRC concluded that there isanegligible risk 14 For Information Only
Puke Models Considered
,inergy Regression Analysis Froehlich 2008 Walder &O'Connor MacDonald &Langridge-Monopolis 1984 Xu &Zhang 2009-15 For Information Only
5 Duke0 Selection ofXu &Zhang 2009 i ergy Basis
, Most current regression method developed and validated with the largest data base of dam failures:
ý 182 earth and rockfill dam failures compiled
, 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) 1:#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 16 For Information Only
SDuke Breach Parameters VEnergy 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:
VTop Width -701' (39% of overall crest)
/ Bottom Width - 431' VBottom Elevation - 870' VBreach Formation Time:
' Xu &Zhang - 29,2 hrs.(14.2 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)
VPeak oufflow: 1,760,000 cfs 17 For Information Only
Duke JocasseeDam
,nergy Low ErodibilityClassification 18 For Information Only
VuKe FukushimaModel nergy JOCASSEE DAM BREACH PARAMETERS Bottom Breach Bottom Averge Time to Top of Breach Crest Reservoir Structure Elevation Star ng Mode Elevation( Breac th Breach tSide Le de Failure Breach Breach niition
- 01) (1) WKMt(9) Slope (Zr) Slope (A r Wkth (1)Progression Elevation (t (am3l) msl) (A Elevation msl)
Jocassee 1125 1,110 Pip4g 870 431 566 0.53 0.53 29.2 701 Sie 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
L1UKO P FukushimaModel JocasseeDam Breach fnergy Progressionand Stage-DischargeHydrographs Jocassee Dam Breach Progression and Hydrographs BP LE 1.20 3,°O,0O 2,500,aDD 1.0 2,000,00
- 1 1,000o00-0O.40 0.I 500,000 D
A ow0 *-10-~
0 2~40 26S382 10:00 1200 14.0 1600 1&00 2M022:00 O0O2W 4:00 6:00 82 10:00 120D Time
-Headwater - Tailwater -Breach Progression -Breach Discharge
--- Breacinkiation ---PipColapse ---- Breach Fortnation Complete Breach Fomation 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
1 DUke Breach Parameters 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
- oCascading 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) 21 For Information Only
Duke FukushimaModel Keowee Dam w1 ergy Breach ProgressionHEC-RAS 0.9 0.8 0.4 0.3 0.2 0.5 0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Relative Time Progreuion 22 For Information Ony
iDuke Fukushima IDModeling
-I FEnergy Keowee Dam -Headwater and Tailwater Stage Hydrographs Final BEP LE I-D Model Performance 830 820 810 800 790 780 770
.~760
- 750 S740 -- 1--.00 730 W720 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
-BEPLEHW -BEPLETW 23 For Information Only
9 Duke Fukushima 21 2D Modeling UEnergy Keowee Dam Breach Progression 1
0.9 0.8 C
' 0.7 a'
1A
,0.6 IL
.C t0.5 IN 0.3 0.2 0.1 0
16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 17 Time (hr) 24 For Information Only
luke L ',nergy Fukushima2D Modeling Velocity and Flow Pattern at l7 hrs.
- 17.0 fl9AA 303234363840 25 For Information Only
Duke L ry Fukushima 2D Modeling Velocity and Flow Pattern at 20 hrs.
2 4 6 8 10121416182022242628303234363840 For Information Only
Puke Fukushima JD-2D nergy Modeling Results Breaching Keowee Dam Intake Dike HEC-RAS 2-D HEC-RAS 2-D Elevation Decimal Time Elevation Decimal Time Elevation Decimal Time Elevation Decimal lime 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 H Decimal Time Elevation Decimal Time 818.4 16.53 820.1 16.58 8101 17.17 807.2 17.67 Maximum Water Surfaces Swale Tailwater 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 16.53 787.4 17.52. 790.4 18.41
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27 For Information Only
Duke Sensitivity Analysis
.nergy Model Peak Oufflow (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 inthis table based on Wahl 2004, Januaqy 28, 2011 SE and updated Xu &Zhang data 100+ HEC-RAS studies performed with vared 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
luke IndependentReview inergy Breach Parameters
- Independent Peer Review Joe Ehasz, P.E.
David Bowles, Ph. DP.E. P.H.
- FERC Board of Consultant Review Gonzalo Castro, Ph.D., P.E.
James Michael Duncan, Ph.D., P.E.
James FRuff, Ph.D., P.E.
Gabriel Fernandez, Ph.D., P.E.
29 For Information Only
luke ComparativeAnalysis nergy 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 lV with 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 30 For Information Only
RDuke ModificationScope lEnergy 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):
Transformer relocation
- Diversion walls and drainage canals
- Aux building and Turbine building protection 31 For Information Only
ýuke Modification Options
, nergy N j
/
/-
/
---I
/
.2*:
5-. AK 32 For Information Only
Duke rnergy Questions and Feedback 33