ML12363A134
| ML12363A134 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/11/2009 |
| From: | Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2012-0127 | |
| Download: ML12363A134 (39) | |
Text
PDuke VEnergy W=ftvs wfth ft Fro OdW Of IPVMrM" MMIA Oconee Nuclear Station External Flood NRR Meeting Rockville, MD May 11, 2009 Withhold fro lic d' closure 10 CF
.390
V Duke Duke Attendees OEnergy
ý Mike Glover, ONS General Manager, Nuclear Plant Projects
ý Rich Freudenberger, ONS Safety Assurance Manager
ý Bob Meixell, ONS Regulatory Compliance Manager STim Brown, ONS Project Manager
ý Ray McCoy, ONS Principal Engineer
ý Brad Keaton, Duke Hydro Licensing Engineer
> David Cummings, Duke Assistant General Counsel
ý Ed Luttrell, HDR/DTA Senior Vice President
ý Chris Ey, HDR/DTA Civil Engineering Manager it old from bli disclos2 un CFR 2.
PDuke VEnergy Agenda
>Mominq Session
,Opening Remarks
,Inundation Analysis Results oSummary of Previous Inundation Analyses oSummary of Current Inundation Analysis Withh r
discr
- ure under FRI"
- 2. 9 3
- Duke
[Energy Agenda 4Aftemoon Session Oconee Site External Flood Licensing Basis o Jocassee Design o External Flood Licensing Basis o Precedence o Status of Commitments Objectives of Risk Study m
Response to NRC Questions
. Summary
. Closing Remarks ithho from pu lic close und 10 FR 2.39 4
& Duke Opening tVEnergy Remarks
ý Duke has completed a new detailed inundation study, given a failure of Jocassee. The results of this analysis are significantly different than the results reported from previous 1992 inundation study.
, Today, we will describe a summary of the inputs to the new study and the results. We will then compare those inputs and results to those of the previous inundation study.
, Duke has located additional design information regarding the Jocassee design, including inspection records from construction.
ý We have completed additional licensing research that demonstrates that the AEC understood the design of Jocassee during the original licensing of ONS.
, We maintain that Jocassee is a well designed, well constructed, well maintained project, and meets all FERC requirements.
, We will describe the seismic analysis of Jocassee, as well as PMP/PMF analysis that have been completed, submitted to and accepted by FERC. #Wit o ublic dis5 I under1 lC f~romc
ý19
5 Duke Opening
!iVEnergy Remarks
, We will discuss Regulatory Guide 1.59 and ANSI N170-1976 and their possible application to this issue.
, We will then state our position regarding the licensing basis of the ONS for external flooding.
ý We will discuss precedence established at another NRC licensed facility regarding external flooding following the postulated failure of an upstream dam.
, We will provide a status of commitments.
ý We will describe what additional actions we plan to take.
> Finally, we will provide the objective of the risk analysis and how the results of that analysis will be used in the ONS risk assessment model for external events.
Withhold from pu i iscl 6
u unn 10FR27J9
PDuke VEnergy Morning Session
>Inundation Analysis Results
, Summary of Previous Inundation Analyses
, Summary of Current Inundation Analysis
- hold fro u ic discI9 u erA0OCF 2.3~
7.
Summary of
- Duke Previous Inundation
[lEnergy Studies 1983 Study
, DAMBRK Software
, Focused on Oconee for early PRA work.
, No Keowee Reservoir Dam failures assumed
, Level pool rise assumed over Keowee Reservoir basin
, Breach parameters were not well documented
, Results in 2.45 ft of water overtopping Keowee Dam and Oconee Intake Canal Dike
, Overtopping of Intake Canal Dike produces yard water height of 4.71 ft, considering a hydraulic jump.
> Action: Initial construction of 5 ft. SSF flood walls, as a PRA enhancement.
ithhold om p lie cl sure 8
under 0 FR 2.3
PDuke IEnergy Summary of Previous Inundation Studies
ýb)M7fl Action: PRA updated with results for IPEEE submittal, VV dfrom icdisclsure
/unde CF,.399sc 9
Duke Summary of fEnergy Inundation Studies
- September 2008 Study
, DAMBRK Software
, Focused on Oconee - resurrected 1992 FERC EAP model.
(b)(7)(F)
, The Jocassee breach parameters accepted by FERC for 1992 EAP work.
, Domino-effect assumes Keowee Dam failure.
- Jocassee and Keowee water levels varied for resultant sensitivity.
- Using nowe lake levels, 'Sunny Day' Jocassee Dam Failure resulted in:
o Flooded tailrace (ONS yard) to elev. 807.2, or 11.2 ft. of water in the yard Using 9Flod8 lake levels, 'Sunny Day' Jocassee Dam failure also resulted in:
o Flooded tailrace (ONS yard) to elev, 803, or 7 ft. of water in the yard Action: Designed and constructed an extension of the SSF Flood Wall to 7.5 ft to provide additional margin.
ithhold from blic discd re 10 nder 1C 2.3
- Duke Summary of UlEnergy Inundation Studies December 2008 Study
, HEC-RAS Software
, Oconee focused (b)()(F)
, Domino-effect assumes Keowee Dam failure.
Jocassee and Keowee water levels varied for resultant sensitivity.
, 'Keowee Connecting Channel' modeled with a focus on flow conveyance between Little River arm and Keowee arm.
, Significantly enhanced topography modeled upstream/downstream of ONS.
Model is 44 miles long, 149 input cross sections, and 468 interpolated cross-sections in model.
Withhold fro ublic di,sure 11 und 10C
. 90
- Duke Summary of
[VEnergy Inundation Studies December 2008 Study / continued
, New results compared to DAMBRK results for insights/direction.
, Using normal lake levels, 'Sunny Day' Jocassee Dam Failure resulted in:
o Flooded tailrace (ONS yard) to elev. 793.3, or 2.7 ft below the yard level.
o Flood overtops the Keowee Dam by 16.5 ft (water surface elev. 831.5).
o Water surface elev, at the Oconee Intake Canal Dike is not directly calculated.
- Action: Additional study warranted due to:
, New and different results with regard to tailrace elevation.
, Water elevation at Little River Dam and Oconee Intake Canal elevation now of interest.
, Assess sensitivity of the cross sections, flow path, and Manning's 'n' values.
With ron blic di lo.ure 12 under 10 C 2. 90
- Duke Summary of lEnergy Inundation Studies
- March 2009 Study
, HEC-RAS Software
- Based on December 2008 model with increased detail and extended model to Lake Hartwell Dam to determine downstream backwater impacts and sensitivity of cross section geometry.
, Areas of focus determined by review of December 2008 model:
o Verify storage volume in Keowee and Little River arms.
o Assess sensitivity of Manning's 'n' values.
o Confirm / modify active and inactive flow areas.
o Model ONS Intake Canal to determine flood elevation.
o Use momentum and energy equations, as needed, for more accurate results o Assume a breach in ONS Intake Canal Dike.
o Assure all flows from ONS Intake Canal Dike and Keowee Dam are combined and routed to the tailrace for complete backwater effect.
Id frod ue 13 un 10 CFR 2.390
- Duke UlEnergy Summary of Inundation Studies March 2009 Study / continued Dam Failures/Breaches o Modeled two different breaches - but results focused on '1992'.
o Jocassee Breach discharge rate compared to previous computed values for validation and previously suggested non-linear flow was not exercised.
o Failures of Keowee Dam, ONS Intake Canal Dike, and Little River Dam initiated due to overtopping.
re 14
5 Duke Summary of
[lEnergy Inundation Studies March 2009 Study / continued Flow Modeling o Jocassee and Keowee water levels varied for resultant sensitivity.
o Keowee Connecting Channel modeling examined to simulate realistic flow behavior using HEC-RAS built in options.
o All significant junctions re-examined for momentum vs. energy equation modeling considerations,
, Manning's'n' o Multiple Manning's 'n' values used to address changing flow channel conditions.
o Manning's 'n' sensitivity completed using peak water surface cases.
o Confirmed assumed 'n' values used by consistent outcomes when 'n' was varied over a range per'Open Channel Hydraulics' by Chow.
With from u 'cdisc ure 15 un CFR 9
RDuke Summary of
- Energy Inundation Studies March 2009 Study / continued Geometry o Significantly increase number of input cross sections to capture changes in topography and resulting impact, o Model is 44 miles long, 1411 input cross sections, and 5762 cross-sections interpolated in model.
o Lake Keowee Connecting channel bridge abutments (major contributor to possible fow restriction) included in the model, bridge piers and deck were not.
o Computed reservoir storage/volumes were ve.fied using input cross sections:
- Lake Keowee computed storage volume within 2.6% of the full pond storage from file data.
- Lake Hartwell was within 4.1% of the full pond storage.
b re 16
'ýuonderr 0~
FR'2.3ico
PDuke VEnergy Summary of Inundation Studies March 2009 Study / continued (b)(7)(F)
I from p ' 'c disclo re und 10P FRV.9 17
Duke VEnergy Summary of Inundation Studies
, March 2009 Study comparison to 1992 Study I
Result Tailrace elevation Intake Canal Dike overtop water elev.
3/2009 3.5 ft. below yard (elev.
792.5 ft. msl.)
4.5 ft. above dike (elev.
819.5 ft. msl.)
15.7 ft. above dam (elev.
830.7 ft. msl.)
Keowee Dam overtop water elev.
ONS Yard Elev, 796 ft. msl.
,Wit~o~
frm p~~Ii dic~ore 18 VJ urj#F R'NW
- Duke Summary of
[ Energy Inundation Studies
> March 2009 Study comparison to 1992 Study Factors contributing to differences:
o Software capabilities o More detailed topography o Number of cross sections and detail per cross section o Connecting channel flow conveyance o Capability of modeling intersections and storage areas o Manning's 'n' capability and use
, High confidence this model realistically predicts potential flooding at the Oconee site due to detailed internal reviews by expert consultants, including an independent review, in addition to a owner's review by Duke.
Withhold from pblic isclo 19 un FIR2.
VnDuke Afternoon Session eEnergy.
- Oconee Site External Flood Licensing Basis o Jocassee Design o External Flood Licensing Basis o Precedence o Status of Commitments
, Objectives of Risk Study
, Response to NRC Questions
, Summary
, Closing Remarks re 20
rDuke Jocassee Design PMP/PMF:
4Oconee SER Appendix D:
,AEC Consultant's Analysis conformed with AEC requirements, as summarized in the February 1972 draft, 'Standard Format and Contents of Safety Analysis Reports for Nuclear Power Plants'
,Runoff depth 26.6 inches in 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />,
,PMP hydrograph based on an infiltration rate of.05 inches per hour.
,Peak inflow was 245,000 cfs
'Peak reservoir stage was 1122.5 ft. msl. (2.5 feet of freeboard)
'Peak reservoir stage assumed flow through both spillway gates, with no units operating. Peak outflow through both gates was 72,000 cfs.
- hold from u 'c disclos e 21 er CFR.390
l Duke Jocassee Design rOEnery PMP/PMF:
SLatest (1991):
- Average Probable Maximum Storm (PMS) depth of 36.41 inches in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> PMP hydrograph based on an infiltration rate of.093 inches per hour, equivalent to a runoff CN of 60.
- Peak inflow was 522,734 cfs
, Peak reservoir stage was 1122.0 ft. msl. (3.0 feet of freeboard)
Peak reservoir stage assumed flow through both spillway gates, and four operating units. Peak outflow through the gates and units was 85,400 cfs.
However calculated outflow was based on a spillway gate width of 30 feet. Gates are actually 38 feet wide. The difference in flow over the spillway given a gate width of 38 feet is equivalent to two operating units.
With d fro publi isclos 22 un 10CFR2. 0
- Duke lEnergy Jocassee Design Seismic:
, Seismic Design of Jocassee was understood by AEC during the original licensing of ONS, (b)(7)(F)
Wit from ublic isco ure unde CFR 2.c 23
PDuke VEnergy Jocassee Design Core Material:
> Design Test Criteria:
, % Compaction: Greater than or equal to 93% of Standard Proctor
- Dry Density: Greater than or equal to 95 lbs/ft3
, Moisture Content:_+ 3% of optimum on Standard Proctor Curve
> Testing:
- Soil tests occurred periodically during construction and were evaluated monthly.
, All test results were presented to and approved by the Consulting Board.
" -from ub'c disclos 24 unde CFR.390
P Duke Jocassee Design Rock:
, Design - Compacted Unit Weight: 140 Ibs/ft3
, Random Rock:
, Design - Compacted Unit Weight: 124 Ibs/ft3
, Testing:
, Compaction tests occurred periodically during construction and were evaluated monthly.
, Due to variability in field density tests, periodic shear tests were performed.
, All test results were presented to and approved by the Consulting Board.
25
a Duke VEnergy External Flood Licensing Basis The ONS site flood licensing basis is predicated on the ability of both the Keowee and Jocassee to withstand natural phenomena,
ý The ONS site flood licensing basis is based on the amount of precipitation that could fall directly on ONS.
, Random failure of either dam is beyond licensing basis, however the failure of each has been included in the risk assessment for external events.
With d from p* idisclo e un ri FR 0*0 26
External Duke Flood Licensing VrEnergy Basis
ý The Oconee Nuclear Station (ONS), the Keowee Hydroelectric Station, and the Jocassee Pumped Storage Plant form part of the greater Keowee-Toxaway Project, All of these facilities were built at approximately the same time.
ý Duke's licensing research indicates that the Atomic Energy Commission (AEC) understood the design of Jocassee during the original licensing of ONS.
, These licensing documents indicate that the AEC requested information regarding the seismic design of Jocassee and the facility's ability to hold and pass a PMP/PMF.
, The AEC requested and obtained an independent consultant's hydrological analysis of the Jocassee reservoir.
ý This analysis confirmed the ability of Jocassee to hold and pass a PMF.
ý The consultant's report can be found in Appendix D of the ONS SER.
/
hold frm Pu disclos 27 lt r 10CFR.390
External SDuke Flood Licensing SVEnergy@
Basis NUREG 965 (10/31/83), "NRC Inventory of Dams" list those dams that could be considered in the NRC licensing process if dam failure could lead to flooding of a nuclear power plant.
Jocassee is listed among a group of dams that could be considered in the NRC licensing process,
- However, the NUREG also notes that Jocassee is among a group of dams regulated by other Federal agencies (FERC or TVA).
- The group of dams regulated by other federal agencies were not included in the group of dams for which the NRC was considered to be
'responsible.'
> Jocassee meets all FERC requirements.
With Id fro pu Ic discl sure 28 un er1OCFR.3
External O Duke Flood Licensing Energy Basis
ý Regulatory Guide 1.59 (8/1977), "Design Basis Flood for Nuclear Power Plants:
"Consideration of the most severe natural phenomena."
"Nuclear Power plants should be designed for the most severe flood conditions that can be reasonably predicted to occur as a result of severe hydro-meteorological conditions, seismic activity or both."
' "Flood conditions that could be caused by dam failures from earthquakes should also be considered."
, "Consideration of seismically induced floods should include the same range of seismic events as is postulated for the design of the nuclear plant."
ý Applicability: Although ONS is not committed to this REG Guide, Jocassee is designed to withstand the most severe natural phenomena events applicable to the facility, including a seismic event, and a PMP/PMF event.
" hold disclr e 29
\\
Uder 10 CFR 390
External Dkery Flood Licensing Basis
ý American National Standard ANSI N170-1976, "Standards for Determining Design Basis Flooding at Power Reactor Sites":
"Guidelines are to be developed to establish design basis flooding at Power Reactor Sites as a result of river, stream, seismically-induced dam failure, surge, seiche, and/or wave action flooding".
Scope: "Methodology is described to evaluate the flood having virtually no risk of exceedance that may be caused by: precipitation and snowmelt, and any resulting dam failures; seismically induced dam failures; surge or seiche and attendant wind-generated wave activity; or a reasonable combination of these events."
ý Applicability: Although ONS is not governed by the standard, Jocassee is designed such that it will not fail during either precipitation events or seismic events.
Wit ol m puq disclos re 30 under 1OFR 390
- Duke
[Energy External Flood Licensing Basis
ýConclusions:
, The external flood licensing basis of ONS is based on the consideration of natural phenomenological events and the analysis of these events for the Jocassee dam,
, As demonstrated the Jocassee dam can withstand a seismic event and PMP/PMF event.
, Consideration of random failures of Jocassee is outside of the licensing basis for ONS o,/"ld, from b'Cdsci, *ur u~OuF'2*K 31
SDuke Precedent Yankee Rowe Nuclear Plant -Integrated Plant System Assessment Systematic Evaluation Program
, Potential to inundate the Yankee Rowe site following a failure of the upstream Harriman dam (in Vermont).
, Yankee Rowe Nuclear Plant demonstrated that the Harriman dam met all FERC safety criteria Dynamic stability analyses demonstrated that Harriman was stable under seismic loads imposed by a composite spectrum with a peak ground acceleration of.1 g.
Hydrological analyses demonstrated that Harriman would not be overtopped and therefore that the dam does not fail during the maximum rainfall event.
Ultimately the NRC decided any corrective actions would be determined by the FERC Part 12 program for dam safety.
old from Vblic disc* sure 32 un er C 2.39
- Duke UlEnergy Status of Commitments Commitment Completion Date Perform flooding studies using HEC-RAS for 12/2008 (Complete) comparison with previous DAMBRK models.
Create interim guidance to address mitigation of 2/2009 (Complete) postulated flood events that could render the SSF inoperable.
Implement short term modifications to extend the 2/2009 (Complete) height of the existing SSF flood walls to 803 ft
- msl, Complete Risk Assessment Study by RAC and 2/2010 New Flood Study using HEC-RAS, by HDR/DTA.
hold from p.39c disclo0 re
- .. *le--tFIR.3 33
Duke Risk Study
,Objectives of Risk Study:
- Determination of risk profiles for each failure mode.
Determination of inundation level at the Oconee site for each failure mode.'
, Assignment of risk for each failure model inundation level.
1 Results of study to be incorporated in the ONS risk assessment model for external events.
Wi hold from ub discl ure 34 der CFR
P Duke lEnergy Future Actions I
M -- --
ýý Determination of inundation level in the ONS yard caused by overtopping of the Intake Canal Dike
, Conservative evaluation using a simplified methodology
,2D modeling Summary revision of UFSAR:
, Description of Jocassee seismic analysis
" Description of Jocassee PMP/PMF analysis AWithhold m pn
>yc disclpeure
%er 10CF -9 35
- Duke
[Energy.
Response to NRC Questions
ýSee attached handout, qithh~ol rom lic 'sclos re under CFR 23 0) 36
Duke VEnergy Summary
- Jocassee is a well designed, well constructed, well maintained project, and meets all FERC requirements
- Based on its design, Jocassee is not postulated to fail during either a PMP/PMF or a seismic event.
- Based on our licensing research, we believe the AEC understood the design of Jocassee during the original licensing of ONS.
, Our review of regulatory guides and precedent indicate that only phenomenological events should be considered in the failure analysis of dams upstream of nuclear facilities. Postulation of
'Sunny Day' failures is not included in these guides and not reflected in the precedent.
from bli isc ure 37 Iundk!
FR 2, 9
PDuke UEnergy Summary Duke has increased the height of the current SSF walls to provide additional safety margin against external flooding,
> Interim Guidance
, Duke has commissioned an independent risk study to determine appropriate dam failure probabilities and resulting inundation levels, for inclusion in the ONS External Events PRA, Duke plans additional actions to quantify the amount of inundation in the ONS yard, following a postulated failure of the Intake Canal Dike and to update the ONS UFSAR to more adequately describe the external flood licensing basis.
W1ithhold fro blic disclore
/ '.,.B* 10CF 3
38
Duke VEnergy Closing Remarks Duke has completed a detailed flood analysis focused on ONS, given a failure of Jocassee. The analysis demonstrates that the site will not be inundated from the Keowee talrace, based on previously evaluated breach sizes.
Duke maintains that a deterministic resolution of a random failure of the Jocassee dam is not warranted.
Given Duke's view of the safety significance and the complexity of the analysis to resolve this issue, we believe our actions have been timely.
Duke believes that resolution of this matter should be considered for transition from a site specific issue to a generic issue.
K it olodfronou c disc ure 39 u WdrAO CFR~3Q