ML031220331
| ML031220331 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/30/2003 |
| From: | Olshan L NRC/NRR/DLPM/LPD2 |
| To: | |
| References | |
| TAC MB6651, TAC MB6652, TAC MB6653 | |
| Download: ML031220331 (46) | |
Text
NRC FORM 658 U.S. NUCLEAR REGULATORY COMMISSION (9-1999)
TRANSMITTAL OF MEETING HANDOUT MATERIALS FOR IMMEDIATE PLACEMENT IN THE PUBLIC DOMAIN This form is to be filled out (typed or hand-printed) by the person who announced the meeting (i.e., the person who issued the meeting notice). The completed form, and the attached copy of meeting handout materials, will be sent to the Document Control Desk on the same day of the meeting; under no circumstances will this be done later than the working day after the meeting.
Do not include proprietary materials.
DATE OF MEETING The attached document(s), which was/were handed out in this meeting, is/are to be placed 04/30/2003 in the public domain as soon as possible. The minutes of the meeting will be issued in the near future. Following are administrative details regarding this meeting:
Docket Number(s) 50-269,50-270,50-287 Plant/Facility Name OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 TAC Number(s) (if available)
MB6651, MB6652, AND MB6653 Reference Meeting Notice APRIL 3,2003 Purpose of Meeting (copy from meeting notice)
TO DISCUSS NON-SEISMIC PIPING IN THE OCONEE AUXILIARY BUILDING NAME OF PERSON WHO ISSUED MEETING NOTICE TITLE L. N. OLSHAN PROJECT MANAGER OFFICE NRR DIVISION DLPM BRANCH PD 11-1 Distribution of this form and attachments:
Docket File/Central File PUBLIC NRC FORM 658 (9-1999)
PRINTED ON RECYCLED PAPER This form was designed using InForms
Duke Energy..
Auxiliary Building Flooding Licensing Amendment Request - RAI Responses Oconee Nuclear Station April 30, 2003
A Duke AB Flooding LAR - RAI rE Energysm
Response
Duke Attendees Larry Nicholson, Regulatory Compliance Manager Reene' Gambrell, Regulatory Compliance Engineer Boyd Shingleton, Regulatory Compliance Engineer Duncan Brewer, Severe Accident Analysis Group Manager Steve Nader, SAAG Engineer Ed Burchfield, Engineering Supervisor Jeff Robertson, Senior Engineer George Mc Aninch, Engineering Supervisor John Richards, Sr. Civil Engineer 2
Duke AB Flooding LAR - RAI D Energysm
Response
Introduction
- Duke met with NRC on 8/22/02 to describe licensing strategy to resolve non-conforming condition related to the impact of non-seismic piping failure in the Auxiliary Building on safety-related equipment
- Duke submitted LAR on 11/1/02 requesting NRC to allow certain portions of the non-seismic piping in the Auxiliary Building to remain non-seismic based on low risk significance 3
I Duke AB Flooding LAR - RAI LW Energym
Response
Introduction (continued)
- Duke received Request for Additional Information (RAI) on the PRA justification for the change on 1/1 6/03; provided response on 2/11/03
- Duke received another RAI related to HSPW and LPSW piping design and the ABS calculation on 2/13/03 & 3/6/03; provided response on 4/3/03 4
k Duke P Energy..
Response
PRA Discussion - Steve Nader Civil Discussion - John Richards 5
h Duke P Energys.
PRA Evaluation-Overview
- Overview
) Piping has been identified that could have an effect on safety related equipment if it failed in a seismic event
> Solution: Design study concluded that upgrading piping to seismic is the most practical solution
- Estimated cost - $1 million
> PRA Task: Evaluate the decreased risk if the pipe is upgraded to seismic 6
h Duke P Energy..
PRA Evaluation-Overview Base Seism ic PRA model
)Part of IPEEE submittal PSubmitted to NRC 12-28-95
)SER received 3-15-00
)Model periodically updated (2003)
>Self initiated internal audit Spring 2003
- Reviewed model, inputs, etc.
Conclusion:
Model is complete, thorough
- No items identified that affect AB flood issues 7
Duke PRA Evaluation-W Energy..
Overview
- Base Seismic PRA model (continued)
> Based on internal events PRA
> Internal events PRA evaluated internal flooding (from pipe breaks)
> Internal events PRA concluded that the important consequence of flooding in the AB is failure of the HPI pumps (piping failures from any cause)
> Internal events PRA flooding analysis also concluded that TB floods were much more important than AB floods; therefore AB floods screened out 8
, Duke Energysm PRA Evaluation-Overview Base Seismic PRA model (continued)
)Internal events PRA conclusions were carried forward into the seismic PRA
)No AB floods due to pipe breaks are modeled
)Piping breaks are modeled as one input to the system reliability
)TB floods are modeled joints)
)TB floods fail equipmen EFW, cooling water to (Condenser expansion it in TB basement (e.g.,
9
Duke PRA Evaluation-W Energysm Overview
- Base Case Risk Calculation
> Start with the base seismic model
> Add AB piping failures to the model
> Determine consequences
> Input appropriate fragilities for the piping
> Run the seismic model with new failure mode(s)
Duke Energy.M PRA Evaluation-Overview Modified Plant Risk Calculation Input new fragility value for piping based on ONS seismic design requirements
)Re-run the seismic PRA model Results: CDF decreased by3E-07 11
, Duke Energysm PRA Evaluation-Important Inputs Assu mption: AB Piping Failures Fail HPI Pumps
)Internal events PRA:
- Plant layout, physical arrangement of AB
- AB drain system
- Walkdown results
)Most rooms of AB screened out
- Minimal flood potential (rate, volume)
- Adequate drainage
)HPI, LPI, RBS located in basement
- Vulnerable to flood 12
, Duke Energy..
PRA Evaluation-Important Inputs
) RBS, LPI used to mitigate large LOCA
- Probability of large LOCA and seismic failure of this piping is very small-screened out
) LPI, RBS used in other transients-however always with HPI
Conclusion:
HPI pumps are important for evaluation of AB piping failure. HPI bounds failure of other AB equipment.
13
Duke PRA Evaluation-TE Energy..
Important Inputs U Assumption: AB Piping Failures Fail HPI Pumps (continued)
> Are other important safety functions potentially lost?
> Use same screening methods as IPEEE model
- Secondary side heat removal-no
- Ability to trip reactor-no
- Loss of power-no
- Standby Shutdown Facility - no
- Component cooling water - possibly lost 14
Duke PRA Evaluation-7W Energy..
Important Inputs U Assumption: AB Piping Failures Fail CC Pumps
> Large floods (high flow rate, unisolated)
> 500,000 gallons to fill to next level Operating experience shows the largest AB flood is 164,000 gallons at WNP-2 (June 1998)
> IPEEE concluded CC Pump motor control centers would not be flooded
> LAR evaluation conservatively assumed CC is lost as a consequence of the flood 15
Duke Energysm PRA Evaluation-Important Inputs HPI cc Important For Seal LOCAs
)ONS mitigates seal LOCAs with
- HPI seal injection
- Component Cooling of RCP thermal barrier
- Standby Shutdown Facility primary make-up 16
, Duke Energysm PRA Evaluation-Important Inputs I
New Core Melt Sequences Added to the Seism ic PRA Model
)Seismic Pipe Break
- Assume large, unisolated-HPI, CC fails SSSF fails
- Could fail due to seismic event
- Could fail randomly 17
k Duke P Energysm PRA Evaluation-Event Tree Seismic Pipe Event Survives IPEEE Tree SSF Survives SSF Is Seismic Successful NCM 18
Duke Energy.M PRA Evaluation-Uncertainties Uncertainties
)Base Case Results
- Mean = 3.89E-05
- Std Dev = 1.16E-05
- Best Estimate = 3.25E-05
)Upgrade to Seismic Case
- Mean = 3.86E-05
- Std Dev = 1.17E-05
- Best Estimate = 3.23E-05 kDelta: 3.89E 3.86E-05 = 3E-07 19
, Duke Energysm PRA Evaluation-Uncertainties Seismic CDF 0A*
PE" e.
en 1
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
UP_
Seis
=
__das I
rade to mc Case
- 7 led line)
-- Bak
- /
'~1-0 e Case (solid line)
L.OE-05 L.OE-04 Core Damage Frequency 20
, Duke Energysm Computation of Piping Fragilities Compute piping fragilities to support two cases
>Currently installed piping
)Upgraded piping consistent with Oconee design requirements 21
, Duke Energysm Currently Installed Piping I
Primarily rod hung piping Does not include seismic design Large diameter piping ( 3") Is welded carbon or stainless steel Small diameter piping (< 21/2 ) is threaded or welded carbon or stainless steel 22
, Duke Energy..
Currently Installed Piping Fragility Calculations
-Performed walkdowns of installed piping with contract technical experts (Bob Cam pbell, ABS)
)Confirmed installed piping consistent with piping in earthquake experience data
- Materials, design and construction similar
- Vulnerabilities leading to failures evaluated
>Selected controlling supports for analysis 23
h Duke P Energy.M Currently Installed Piping Fragility Calculations (continued)
)Computed fragility using UHS for Oconee
)Controlling fragilities based on experience of Fire Protection Piping in the Loma Prieta earthquake
)Am = 0.85g PR = 0 3 Pu= 0.46
> HCLPF = 0.24g (ONS SSE is 0.1Og) 24
Duke 0 Energysm Upgraded Piping EComputed fragility assuming existing piping is upgraded to comply with Oconee design requirements EConsidered piping, supports, anchors EComputed fragility using UHS for Oconee 25
Duke EnergyM Upgraded Piping Fragility Calculations
- Investigated numerous components to determine governing element (pipe, supports, anchors, welds, etc.)
- Controlling fragilities conservatively based on welds in the supports
,Am = 1.95g PR = 0.33 mU= 0.59
= 0.43g
>Upgraded piping would be approximately twice as rugged as the installed piping 26
Duke 0 Energy..
Follow-Up Questions
- Received follow-up questions on 2/13/03 and 3/6/03
- Responded on 4/3/03
- Key outstanding issues from conference call on 4/10/03
> Haven't shown experience is applicable to ONS piping
> Experience vertical spectrum doesn't envelope ONS UHS spectrum at high frequencies
> Uncertainty for the analysis case seems unreasonably high
> Reports of corrosion problems 27
h Duke F EnergyM Applicability of Experience Data
- Experience data primarily from about 20 sites in the 1989 Loma Prieta earthquake (NUREG/CR-5580, Appendix C)
- Includes experience from sprinkler systems 1,000 water
- Construction dates range from about 1930 to the present
- Construction generally complies with pre-1989 versions of NFPA-1 3
- Some piping included lateral bracing and some did not 28
Duke Applicability of rEnergysm Experience Data
- Only 13 Direct Piping Related Failures Including
> Inadvertent actuation of deluge valves
> Minor pipe leaks
> Support failures not resulting in leaks
> Connection failures
> Sprinkler head interaction failures
- Other Failures Not Considered Direct Piping Related
> Several failures due to soil liquefaction
> Several pipe connection and sprinkler head failures in extensively damaged buildings 29
Duke Energysm Applicability of Experience Data Primary Causes of Damage
>Soil liquefaction
)Large deformation and damage to structures poorly designed for earthquakes
)Groove type victaulic couplings
)Loss of support from C-clamp supports None of these conditions exist in the Service Water piping at Oconee 30
Duke Energy..
Distribution of Experience vs.
Peak Ground Acceleration Peak Ground Acceleration
- Systems / # Failures Facility 0.lg 0.2g 0.3g 0.4g Almeda Navel Air Station 90 2
Oakland Army Base 22 1
Oakland Naval Station 9
9' Port of Oakland 50 32 Treasure Island/Hunters Pt 34 2
San Francisco Airport 80 1
California Hospitals 61 0
26 1
4 0
Lockheed 300 0
20 1
Moffett Navel Air Station 280 0
Hewlett Packard 20 2
23 2
Totals 61 0
660 5
251 5
47 3
Failure Rate 0.00%
0.76%
1.99%
6.38%
Notes:
- 1) Failures due to soil liquefaction or C-Clamp supports (therefore, not included in totals)
- 2) Two of these failures are related to structure failures (therefore, not included in totals) 31
Duke Applicability of r
SEnergy.M Experience Data
- Huge volume of data permits development of generic fragility
- Support design considerations at Oconee (vertical and lateral) evaluated by separate analyses of bounding cases
- From that analysis, Oconee supports have higher fragility than experience data results, therefore, supports were not controlling
- Experience data is an acceptable estimate of Oconee Service Water Piping fragility 32
Duke Energysm Response to High Frequency Accelerations 6
5 High frequency input does not excite low frequency modes 0
.2 i-E U
E
.0 0
4 3
2 I
I 0
I xp/
2 3
33
Duke Response to High USEnergy.M Frequency Accelerations U Analysis of multi-degree of freedom systems shows that
> response (amplification, stress, etc) is typically dominated by lower frequency modes where
- the majority of the system mass is vibrating
- participation factors are largest
- Higher frequency modes have low participation and do not significantly contribute to displacements and stresses 34
Spectral Displacement SM Comparison 10 8
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-, 1- - -
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0-Oconee UHS, Elev 858' Vert.
Oakland Wharf-Vert Oakland Wharf-305 deg Oakland Wharf-35 deg SF Airport - 90 deg SF Airport - 0 deg Treasure Island - 0 deg Treasure Island - 90 deg CI.
1-0
%:c 6
II1 J
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F FF F
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F F
F F
F F[tl
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F~~-r F
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F--n----r------r-l-'-'--
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-F E
F F
F Fl F>
F F\\
F F
F F
Fl F
Fl F
F F
F FN F
F F2j l
F 1
10 Frequency (Hz)
CV1 35
Duke Energy.M Uncertainty for the Analysis Case M --
M-
- Pu in the analysis case doesn't significantly affect the final results
- Performed sensitivity analysis assuming knowledge about the analyzed piping near perfect (PR = 0O 1 ° PU = ° 1 0) was
- This conservatively increases the seismic capacity (HCLPF would be 1.40g, >300% increase)
- Negligible impact on CDF
- Therefore, even if the Puwas sign ificantly reduced, the results would be the same 36
Duke Energy.M CorrosionConcerns Corrosion concerns from conference call on 4/10/03
)Picture of valve LPSW-373 which shows corrosion
> Question regarding leaks in system
> Question regarding piping replacement 37
Duke 0 Energy SW Corrosion HInternal Pitting
)Lake water (clean by most standards)
)Crud Corrosion Products collect over many years of operation
- LPSW surface corrosion
)Anti sweat insulation
)Anti corrosion paint Moisture intrusion over many years 38
h Duke P Energysm Leakage Past Threads
h Duke F Energy..
Leakage Past Threads E
I M
Drops per minute Liquid Management goal Is 0 leakage
)Work order to replace nipple
)Leak management to evaluate
- Corrosion
- Structural 40
, Duke EnergysM Pin Leak on Pipe 41
, Duke Energy..
Pin Leak on Pipe Not a structural issue Work order written to replace pipe PIP written to evaluate pipe
)Required by NSD-413
) Screened using pre-established criteria 42
Duke Energy..
Pipe Replacement Leaking components are replaced SW Inspection Program performs UT Small bore piping refurbishment
>Life extension
)To minimize resistance to flow
)Not related to structural integrity 43
, Duke
'Energy..
Leakage Summary Zero Leakage Threshold SW Inspection Program Isolated pin hole leaks
)Evaluated via PIP
) Screened using pre-existing criteria Not a structural issue 44
h Duke P Energy..
Response
---I 0 ----
I ---
Conclusion - Larry Nicholson 45