ML11294A415
| ML11294A415 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 10/21/2011 |
| From: | Borchardt R NRC/EDO, NRC/OCM |
| To: | |
| References | |
| M111021 | |
| Download: ML11294A415 (64) | |
Text
U.S.NRC United States Nuclear Regulatory Commission Protecting People and the Environment North Anna Nuclear Power Station Seismic Event R. William Borchardt Executive Director for Operations October 21, 2011
Agenda
- NRC Initial Response
- Restart Requirements
" Technical Review
" Restart Inspection
" Path Forward
" Post Startup Activities 2
NRC Initial Response
- Inspectors On Site
- Agency in Monitoring Mode
- Augmented Inspection Team 3
Augmented Inspection Team
- Qualified, Multi-disciplined Team
- Public Exit Meeting Held on October 3
- Inspection Results 4
Restart Requirem ents
- Appendix A to 10 CFR Part 100
- Authority for Restart 5
Tech nical Review
- Regulatory Guidance RG 1.167
- Operating Experience
" Inspections, Testing, and EvaIuations 6
Restart Readiness Inspection
" Inspection Initiated on October 5, 2011
" Evaluate Licensee's Assessment
- Sample Using EPRI NP=6695 7
Path Forward
" Complete Technical Review and Inspection
" Public Meeting
- Restart Decision 8
Foliow-Up Activities
" Inspections During Restart
" Long Term Evaluations
" Licensing Basis Considerations 9
" AIT - Augmented Inspection Team
" CFR - Code of Federal Regulations
" EPRI - Electric Power Research Institute
- RG - Regulatory Guide 10
Dominion North Anna Power Station Restart Readiness October 21, 2011 Briefing David A. Heacock, President & Chief Nuclear Officer Eugene S. Grecheck, Vice President, Nuclear Development I
Dominion Assessment Consistent With Part 100, Appendix A:
- No Functional Damage to Safety SSCs
- No Undue Risk to Health and Safety
- Restart Readiness Demonstrated 2
Event Perspective & Margins
Response Spectra Comparisons Kinemetrics Data for Containment Basemat - Horizontal Direction 0.0
-5tDBE PC Bascrrat -
ri IPEEF Cflryairr r~t Basrrat 5,z -
oi
-5;tF PC Baert Pcrdsr Data -T N5 51P.: BaSS at R:Xd~ DatE -L EA
- 0. Llao recquency Ljm 4
Response Spectra Comparisons Kinemetrics Data for Containment Basemat - Vertical Direction 0.5 0.45 1
0.4 4 0.35 0.3
.2 0.25 1
-5%' OBE RC b~sernat-Vert
-5%
DBE RC Bm5emt-Vert IPEEE Containm~ent Baemerent - Vert
-5% RC BaertRecorcier Data - Vert 0 15 1
0.1 t 0
0.1 10 I00 Frequency (Hz) 5
Response Spectra Considerations
- Seismic Acceleration Response Spectra
- Used To Conservatively Design Plants
- Poor Indicators of Plant Damage
- Does Not Account for Duration
- Cumulative Absolute Velocity (CAV) takes Duration and Acceleration into Account
- Best Single Indicator of Energy Imparted
- Best Single Indicator of Damage 6
Acceleration Time Histories (very short, strong motion) 300 200 100 0
-100
.200 300 300 X
200 I100 0
-2
-100 200 300 300 200 100 0
-100
-200
-300 IP6 a
AOA ill k.-.J -PAIIA, L! ad, rom4ftb6010 IWA-8000w* 4A&
^OVWP**W**%",
W, 1~~I~~T-1
~Y Tf V 1-r
-- I East -West: 3.1 sec I
I I
0.31 0.20 0.10 0100
-0.10 0.20
-0.31 0.31 0.20 0.10 0.20
-0.31 0.31 0-20 0*10 0.00
-10.10 0.20 0.31 North - South: 1.0 sec i
-. 4 14 16 is 0
2 6
8 10 12 Time (sec)
Containment Basemat (elevation 216')
Time Histories With DBE Superimposed 0
'mm (U
I.a' a'
ONiO 0
WA)O 0 )I)4) 0, C.0
- f. a14cw 01'(.41 440K
'412 1
East-West Vertical North-South 2
4 6
8 10 12 14 16 seconds 18 20 8
Conservatism In Modeling Structures Horizontal Response Spectra vs. DBE @ Basemat & Elevation 291' Elevation 291' S
2.5 2
1.5 1
0.5 0
0.1 1
10 100 Frequency (Hz)
N-S Actual DBE E-W Actual 1
Elevation 216' m
=
C U
S 0.5 0 L 0.1 1
10 100 Frequency (Hz)
N-S Actual DBE E-W Actual 9
CAV Comparisons CAV CAV CAV Seismic Case North - South Direction East - West Direction Vertical Direction (g-sec)
(g-sec)
(g-sec)
August 23, 2011 Seismic Event 0.172 0.125 0o110 (data from containment basemat)
Design Base Earthquake (rock-founded; synthetic time-0a588 O.580 0.400 history used for containment structure)
IPEEE Review Earthquake (rock-founded; synthetic time-1x230 1.312
- 0. 875 history used for containment structure)
OBE exceedance criterion is CAV > 0. 16 g-sec (EPRI TR - 100082 & RG 1.166) 10
CAV Comparisons 1.4 1.2 1
(.)0.8
~0.6 0.4 0.2 0
LmRG Limit Horizontal (N-S)
Horizontal (E-W)
Vertical August 23, 2011 Earthquake Containment Basemat DBE - Rock-founded for Containment Basemat IPEEE Review - Rock-founded for Containment Basemat 11
Significant Design Margins
- Conservatism In Analytical Methods
" Conservatism in ASME Code e Accident. Load of Greater Capacity e Seismic Test Sta ndards 12
Seismic Margin Evaluated
- Safe Shutdown Components Previously Evaluated Capable in Excess of DBE
- Inspected - 1800 Safe Shutdown Components
- IPEEE evaluated to withstand > 0.3g
- Exceptions (- 50) capable to > 0.16g 13
The Plant Tells the Story
Unit 2 Turbine Building Non-Safety Related Powdex Demineralizer Tanks 15
U2 Turbine Building Powdex Demineralizer Tanks Base Pedestal 16
Turbine Building Hallway Crack In Unreinforced Non-Safety Related Block Wall 17
Unit 1 Containment Surface Crack In Interior Containment Wall 18
Dry Cask Storage 19
TN-32 Cask Movement f1 20
Application of Regulatory Guidance
10 CFR 100, Appendix A "Prior to resuming operations, the licensee will be required to demonstrate to the Commission that no functional damage has 1to50 occurred to those features asof.......
201 necessary for continued operation without undue risk to the health and safety of the public."
En Pat 22
Regulatory Guidance Station restart readiness assessment actions based on NRC endorsed guidance m,
d I
d m
h REGULATORY GUIDE N!OUL.ATONYO6$0 1.1era flN-Etfl
-U*in N A,
r QWI PtNT.WI RG 1.166, Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions, March 1997 RY GUIDE.
lW aMCEOARSI RG 1. 167, Restart of a Nuclear Power Plant Shut Down by a Seismic Event, March 1997 REOWAIDRO 00006 NEgTA0~
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Regulatory Guidance ER-2l Guidelines for Nuclear Plant Response to an Earthquake EPRI NP-6695, Guidelines for Nuclear Plant Response to an Earthquake, December 1989 WARNING~
l~ JPlease rea di Ex="r 'MIro
\\JJAgreemm~ent k=.
Technical Report Effective December 17, 2008, this report has been made publicly available in accordance with Section 734.30)(3) and published in accordance with Section 734.7 of the U.S. Export Administration Regulations. As a result of this publication, this report is subject to only copyright protection and does not require any license agreement from EPRI. This notice supersedes the export control restictions and any proprietary licensed matedal notices embedded in the document prior to putbiccaton.
I Rev. 2 24
EPRI NP 6695 Guidance Definition of Functional Damage:
"Significant damage to plant systems, components, and structures, either physical or other, which impairs the operability or reliability of the damaged item to perform its intended function. Minor damage such as slight or hairline cracking of concrete elements in structures does not constitute functional damage.
25
EPRI NP 6695 Guidance Recommended actions... are based on the following concepts:
"The plant itself, not damage information from nearby communities or recorded distant ground motion, is the best indicator of the severity of the earthquake at the plant site."
26
EPRI NP-6695 Figure 3-1 Short-Term Actions Felt Earthqulake 27
EPRI NP-6695 Figure 3.2 Flow Diagram of Post-Shutdown Inspections and Tests v
EPRI Damage Intensity of 0 M
- "LL"" -01111ý1 711,117 Note:
These actions are performed only if OBE is exceeded or damage found 28
Expanded Inspections
- Structural Component Inspections
- Inspections of Low HCLPF Items
- Electrical Inspections
- Hidden Damage Considerations
- Reservoir & Main Dam Inspections
- System Inspections
- Surveillance & Functional Testing
- Fuel & Vessel Internals Inspections
- ISFSI Pads and Casks 29
Demonstration Plan
- Conservatively Inspected Beyond EPRI Damage Intensity "0" Classification
- Assessments & Evaluations for NRC
- Requests for Additional Information (~ 130)
- Onsite Inspections
- Augmented Inspection Team
- Restart Readiness Inspection Team
- Root Cause Evaluation of Reactor Trip 30
Demonstration Plan Restart Readiness Assessment:
v/Completion of Demonstration Plan v.Review and Disposition of Open CRs Associated with Earthquake
/-FSRC Review/Approval of Evaluations Demonstrating SSC Operability, Functionality, and Restart Readiness 31
What We InspectedlTested
Inspection Effort Dominion Effort Expended:
e Coordination 2376 hrs 4320 hrs o Walk down teams e Civil inspections
- Electricians 3552 hrs 1440 hrs e I&C Technicians 192 hrs Total (as of Oct 9 th) 11880 hrs Extensive Contractor Resources Multiple External Consultants 33
Chemical Addition Tank HCLPF value 0.19 No seismic damage identified 34
Boric Acid Storage Tank HCLPF value
= 0.21 No seismic damage identified 35
Circulating Water Discharge Unit 2 Tunnel Inspection 36
Pump In-service Test & Verification Pump verification included assessing:
" Motor current
" Pump / motor vibration
" Pump flow
" Pump discharge pressure
- Oil analysis e Bearing temps 37
Snubber Testing Visual Inspections:
e 326 small bore Unit 1
. 4 tested due to visual - satisfactory
- 12 additional small bore
- 2 large bore Unit 2 Functional Testing:
- 5 tested due to visual - satisfactory
- 61 small bore for outage
- 2 large bore for outage 38
Fuel Inspections Unit 2 Refueling:
Visually inspected
- 35 fuel assemblies
- 20 most seismic susceptible RCCA drag load testing
- 48 fuel assemblies with rods from Cycle 21
- 48 assemblies with tion of RCCA hubs rods for Cycle 22 Visual inspeci 39
Fuel Inspections New Fuel Storage Area:
Visually inspected
- 18 new fuel assemblies
- 12 burnable poison assemblies IVerified self seating of
- 11 burnable poison assemblies Measured RCCA insertion force e 7 new fuel assemblies Spent Fuel Pool:
Examining the underside of a mid-span mixing grid Visually inspected
- 5 new fuel assemblies
- 5 burnable poison assemblies
- 10 irradiated fuel assemblies 40
Buried Piping 100 ft of safety related buried pipe visually inspected with wall thickness verified by UT 41
Buried Piping
~ 50 feet of Fire Protection piping visually inspected 42
Steam Generator Examinations
" Unitl -A S/G and Unit 2-A & C S/Gs
- Inspected ~3300 tubes per S/G
- Video examined channel heads
" Structural & material condition of secondary
- Steam Drum, Feedring, & J tubes
- Upper support plates
" No evidence of degradation due to event 43
NDE Inspections & Testing on Welds Outage scheduled weld inspections
- 34 PTs conducted
- 22 PT/UTs conducted
- 14 PTs at expected high stress locations
Inspection Results V 134 System inspections completed v/ 141 Structure inspections completed v/ 46 Low HCLPF inspections completed v/ ~ 445 Surveillance Tests/unit through Mode 5 29 tests/unit after exceeding Mode 4 Inspections Confirm EPRI Damage Intensity of "0" 45
Going Forward
Short-Term Actions
-/ Installed Temporary Free Field Seismic Monitor
,t Installed Qualified UPS to Seismic Monitoring Panel in MCR
/ Revised Abnormal Procedure O-AP-36
- Complete Start-Up WO Surveillances 47
Long-Term Actions
- Install permanent free-field seismic monitoring instrumentation
- Re-evaluate safe shutdown equipment identified in IPEEE review with HCLPF capacity < 0.3g
- Commit to RG 1. 166 and 1. 167 48
Long-Term Actions
- Perform seismic analysis of recorded event consistent with EPRI NP-6695
- Develop floor response spectra at various building levels based on recorded input motion
- Assess new floor spectra for exceedances with design base floor spectra
- Evaluate selected equipment based on exceedances identified with new floor spectra 49
Long-Term Actions
- Revise UFSAR to document:
- Recorded event
- Seismic analysis of recorded event
- Design controls on seismic margin
- Commitment to RG 1. 166 and 1. 167 e Perform seismic evaluation for NRC GI-199 50
Summary
- OBE and DBE acceleration criteria were exceeded in certain directions and for certain frequencies by a very short duration earthquake
" CAV calculations indicate that no significant damage should be expected
- Effective strong motion duration indicates no damage should be expected
" Inspections confirm an EPRI Damage Intensity of "0" 51
Summary
- IPEEE and A46 evaluations demonstrate safe shutdown SSCs capable of peak accelerations in excess of DBE
- No safety related SSCs have required repair due to the earthquake
- Results of expanded inspections and tests have confirmed expectations 52
Conclusions Part 100, Appendix A, Requirement Met
-./No Functional Damage to Safety SSCs
-./No Undue Risk to Health and Safety
-./Restart Readiness Demonstrated 53
Acronyms CAV - Cumulative Absolute Velocity CR - Condition Report DBE - Design Base Earthquake EPRI - Electric Power Research Institute FSRC - Facility Safety Review Committee HCLPF - High Confidence of Low Probability of Failure IPEEE - Individual Plant Examination of External Events MCR - Main Control Room PT - Penetrant Test S/G - Steam Generator SSC - Systems, Structures and Components RCCA - Rod Cluster Control Assembly RG - Regulatory Guide UPS - Uninterruptible Power Supply UT - Ultrasonic Test VT - Visual Test 54