ML20207C216
| ML20207C216 | |
| Person / Time | |
|---|---|
| Issue date: | 05/26/1999 |
| From: | Wen P NRC (Affiliation Not Assigned) |
| To: | Carpenter C NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9906020229 | |
| Download: ML20207C216 (32) | |
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,j NUCLEAR REGULATORY COMMISSION WASHINoTON, D.C. 30666 4001
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May 26, 1999 MEMORANDUM TO: Cynthia A. Carpenter, Chief Generic issues, Environmental, Financial and Rulemaking Branch Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation Peter C. Wen, Project Manager [d C. W FROM:
Generic issues, Environmental, Financial and Rulemaking Branch Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF MAY 4,1999, MEETING WITH WESTINGHOUSE OWNERS GROUP REGARDING ISSUES RELATED TO RISK-INFORMED INSERVICE INSPECTIOi4 On May 4,1999, a public meeting was held at the U.S. Nuclear Regulatory Commission's (NRC's) office in Rockville, Maryland, between members of the Westinghouse Owners Group (WOG) and NRC staff. Attachment i lists attendees at the meeting.
During the meeting, the WOG presented its long-range plans for incorporating the NRC approved risk-informed inservice inspection (RI-ISI) methodology for piping to (1) the license renewal (LR) process, (2) ASME Xl Section IWE and IWL for co itainment inspection, (3) Class 1 piping application only, (4) augmented inspections for high energy line breaks, and (5) other components such as heat exchangers, tanks, and vessels. The purpose of the meeting was for WOG to begin a dialogue with the staff on these initiatives. The WOG's presentation material is contained in, Attachment 2. The staff provided comments on the discussions as summarized below:
Relationshio of RI-ISI to License Renewal:
The WOG has developed programs for both RI-ISI and LR for several years. Turkey Point Unit 3 is the lead WOG plant for Class 1 Rl-ISI partial scope piping application and LR app'ication. Since the mission of RI-ISI for operating plants and LR is the same and technicalissues are similar, the staff suggested that Turkey Point Unit 3 application be submitted for both RI-ISI and LR at the same time. The WOG representative indicated that the current need for the WOG members is to expedite RI-ISI applications; not all WOG members are interested in LR. However, WOG will consider the staff's suggestion in its future deliberation.
77 97 The staff further stated that WOG should consider all options incluing increased ISl as e
appropriate when integrating RI-ISI plans with the LR application for the plant.
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k C. Carpenter May 26, 1999 Rl Aoolication to ASME XI IWE/lWL:
Given recent insights and experience from RI ISI piping application and Maintenance e
Rule implementation, WOG felt that use of an RI-ISI approach for containment examinations may be beneficial.
There was some discussion on whether LERF is the appropriate risk metric for e
containment RI-ISI. LERF tends to be dominated by containment by-pass and isolation failure, with a lesser contribution by high pressure events that greatly exceed the containment design parameters. The staff requested that WOG further explain which containment inspection programs would be changed and how LERF, or perhaps some other more appropriate metric, would be used to investigate the specific changes.
The staff indicated that the method of containment surface inspection could be improved e
to ensure probability of detecting surface flaws and cautioned that the inspection of stainless steel bellows and areas behind the liner need to be performed.
RI-ISI Class 1 Pioina:
The staff indicated that partial scope RI-ISI applications are generally acceptable.
e However, partial scope applications do not take full advantage of the oppot.'nity to reduce risk in a proposed program, and in proposed changes to that program.
Consequently, the staff cautioned that, for a given set of systems, structures and components, partial scope applications should expect fewer changes in inspections or reduction in risk than within a full scope application.
RI-ISI Acolication to Auamo,Med insoection Proarams. Soecifically for Hioh Enerav Line Break:
The staff expressed concern that commitments to some previously ongoing programs e
may be voided under the new RI-ISI approach. The WOG stated that the new RI-ISI approach will have no impact on those previously committed programs.
Both the staff and the WOG agreed to meet again to discuss this issue, especially the e
basis for the augmented inspection plans for high energy lines.
Other RI-ISI aoolications (Heat Exchanaers. Tanks. amd Vesselst The staff expressed concem that WOG's approach may get ahead of the ASME code e
case, and suggested that the proper process be followed.
The WOG plans to resubmit Reactor Coolant Pump Motor Flywheel inspection topical for staff's review.
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C. Carpenter May 26, 1999 l
l Overall, the staff and WOG agreed that a continuous dialogue should expedite development and review of these initiatives.
Attachments: As stated cc w/atts: See next page DISTRIBUTION: See attached page DOCUMENT NAME:G:\\PXW\\MSUM0504.WPD
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OFFICE PM:RGEB: DRIP SC:EMCB,,,
(A)SCM NAME PWen:cws pCd TSullivan h TBe k [ '
DATE 05//4./99 05/1D /99 05/N99 OFFICIAL OFFICE COPY
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May 26, 1999 Overall, the staff and WOG agreed that a continuous dialogue should expedite development and review of these initiatives.
Attachments: As stated cc w/atts: See next page L
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Mr. Nicholas Liparuto, Manager Regulatory and Engineering Networks Westinghouse Electric Corporation i
Mail Stop ECE 4-15 l
P.O. Box 355 i
Pittsburgh, PA 15230-0355 Jack Bastin, Director Westinghouse Electric Corporation 11g21 Rockville Pike, Suite 107 i
Rockville, MD 20852 Mr. Hank Sepp, Manager Regalatory and Licensing Engineering Westinghouse Electric Corporation PO Box 355 Pittsburgh, PA 15230-0355 Mr. Andrew Drake Westinghouse Owners Group Westinghouse Electric Corporation Mail Stop ECE 5-16 P.O. Box 355 Pittsburgh, Pennsylvania 15320-0355 i
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Distribution: Mtg. Summary w/ WOG Re RI-ISI Dated Hard Coov socket F#e!!!
PUBLIC PGEB R/F OGC ACRS Pwen SDinsmore SAli EMail SCollins/RZimmerman BSheron WKane JStrosnider/RWessman E. Imbro W. Bateman Goutam Bagchi Ted Sullivan Keith Wichman Robert Hermann David Terao Hans Ashar Gholahan/TCollins RBarrett MRubin DMatthews/SNnewberry C. Grimes Pao-Tsin Kuo Sam Lee CCarpenter I-FAkstulewicz TBergman GTracy, EDO Wallace Norris, RES I
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MEETING ON Risk-Informed ISI LIST OF ATTENDEES May 4,1999 NAMEi ORGANIZATION Dick Wessman NRR/DE Goutam Bagchi NRR/DE Ted Sullivan NRR/DE/EMCB Keith Wichman NRR/DE/EMCB Robert Hermann NRR/DE/EMCB Syed Ali NRR/DE/EMCB David Terao NRR/DE/EMEB Hans Ashar NRR/DE/EMEB Stephen Dinsmore NRR/DSSA/SPSB Pao-Tsin Kuo NRR/ DRIP /RLSB Sam Lee NRR/ DRIP /RLSB Peter Wen NRR/ DRIP /RGEB Wa!! ace Norris RES/DET/MEB Bruce Bishop Westinghouse Kenneth Balkey Westinghouse Nancy Closky Westinghouse Ted Meyer Westinghouse Warren Banford Westinghouse Jeff Mitman EPRI Patrick O'Regan EPRI Henry Stephens EPRI Dennis Weaktand Duguesne Light Ray West Northeast Utilities Mike Moran FPL Altheia Wyche SERCH Licensing /Bechtel
WOG Risk-Informed ISI Developments and Potential Initiatives woo M55E00001 Meeting With U.S. Nuclear Regulatory Commission Staff May 4,1999 Rockville, Maryland Dennis Weakland -
WOG Materials Subcommittee /Duquesne Light Ken Balkey, Warren Bamford, Nancy Closky -
WOG Risk-informed ISI Supporting Team woo MEE000DI m Mike Moran - Florida Power & Light a Ray West - Northeast Utilities a Bruce Bishop, Ted Meyer - Westinghouse 2
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Overview of Agenda woG 5E500001 m Objectives a introduction and Background a Relationship of RI-ISI to License Renewal e Risk-informed Application to ASME XI IWE/lWL a Rl-ISI Class 1 Piping Lead Plant / Use of WOG Generic Submittal a RI-ISI Application to Augmented Inspection Programs, Specifically for High Energy Line Break u Other RI-ISI Applications (HX, Tanks, Vessels) a Summary 3
Meeting Objectives was MMBE00001 m To inform cognizant NRC Staff of -
- Latest risk-informed inservice inspection developments
- Potential related risk-informed initiatives under consideration by WOG m To obtain initial NRC Staff response and guidance on these developments a To determine appropriate interface to continue dialogue with NRC Staff on these initiatives 4
2
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Introduction and Background WOG EE0800l m NRC safety evaluation report issued 12-15-98 for WOG Topical Report on risk informed ISI of piping; WCAP-14572 Revision 1-NP A issued 2 99 as a Non Proprietary document u WOG process built from ASME Research RI ISI process which suggested many applications beyond selection of examination locations for piping a WOG views the approved RI-ISI approach as a framework to support and allow for other applications that integrates well with the NRC risk-informed, decision-making process in Regulatory Guide 1.174 m Strategic sessions held within WOG to determine current and new initiatives that can be impacted by RI ISI approach 5
Introduction and Background woo M
MEE00001 Current Initiatives a Lead plant partial scope Class 1 piping application at Turkey Point Unit 3 a Relationship of RI-ISI to license renewal efforts e Use of RI-ISIin supporting changes to ASME XI requirements for vessels, tanks, heat exchangers Initiatives Under Consideration a Use of RI ISI to address augmented ISI requirements to ensure protection from high energy line breaks a RI-ISI application to ASME XI IWE/lWL containment examinations 3
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Relationship of RI-ISI to License Renewal
7 Background
MEEDQQBl WOG.
m The WOG has developed programs for both RI-ISI and license renewal (LR) for several years a Turkey Point Unit 3 selected as WOG lead plant for Class 1 RI ISI partial scope piping application in 1999 m Given that Turkey Point Unit 3 is also the WOG lead plant for LR; the need and opportunity now exists to relate the programs a Both the RI-ISI and LR are in early stages of development for Turkey Point 3 8
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RI-ISI and LR Have Same Mission and Common Attributes woo ME500001 m Both programs focus resources on areas of degradation a Both programs address time-related effects a Both programs can address augmented programs and areas not addressed to date m Both programs offer the flexibility to move resources to new areas of concem as new information becomes available, i.e., both are "living" processes a The RI ISI program brings risk insights te the application, which is beyond current LR efforts, but not precluded by the LR Rule e information and insights can be exchanged between both programs that enhances each of them 9
Suggested Relationship Between RI-ISI and LR Programs for Piping wOG T
M ' EB00001 Risk-infor ed ISI License Renewal e"**O.
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Suggested Relationship Between RI-ISI and LR Programs for Piping was KE MMMEDDDDI a From initial RI-Isl and LR 6+fo!ts at Turkey Point, the transient cycle counting effort for the LR program will provide valuable plant-specific experience for use in thrs RI-Isl structural reliability calculations a The transient cycle information supplements any t.vailable stress analysis information m The RI-Isl program can substitute for the AsME XI portion of the LR program, and should be viewed as an integral part of the LR aging management program Il Purpose of Inservice Inspection MMME00001 m To identify conditions, such as flaw indications, that are precursors to leaks and ruptures, which violate pressure boundary integrity principles 12 6
O Current ASME Section XI Requirements for Piping EE00001 a Originally based on pre-nuclear operating experience (boiler and pressure vessel industries) a Based on Class 1,2 and 3 m Based on expert opinion through a consensus process a Examination areas
- Based on stress and fatigue
- includes terminal ends, dissimilar metal welds, and areas of high stress until percentage achieved ASME Section XI Versus Risk-Informed ISI for Piping woo a300ggi AsME section XI
' Risk-informed ISI Process
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~Faiiure Hgh design stress
> Exercising of S5iffA-~
Probability and fatiguelocabons,model, including augmented by random design, experience and selecbon operations focusedon areas of highest failure potential i4 7
Suggested Approach for Developing RI-ISI / LR Program for Piping woG EE00001 m Develop RI-ISI program using calculations that are based on current licensed life (usually 40 years) m At time of LR submittal, use the same locations as defined by the living RI-ISI program
- Perform sensitivity study to address potential effects of extended LR life on failure probability estimates using larger uncertainties for degradation characteristics, as appropriate
- Define additional locations that may need to be included (Recent RI ISI work performed at Surry-1 to address 60-year life showed three additional segments to be included) m The RI-ISI program is a living process that can continue to be updated through the LR extended life 15 woG' 5E00001 Risk-Informed Application to ASME XI IWE/lWL ie i
1
O Current Rules
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E00001 m The 1992 Edition with the 1992 Addenda of Subsection IWE and Subsection lWL of ASME Section XI endorsed in 10 CFR 50.55a(a) as the ISI requirements for containment examinations a Subsection IWE provides rules to inspect the surface of metal containments, steel liners of concrete containments, and moisture barriers as modified by the Rule a Subsection IWL provides rules for examination of concrete pressure-retaining shells and shell components, and for examination of unbonded post tensioning systems 17 Initiation of Rules was M
EMD0001 m Rulemaking initiated because the rate of occurrence of corrosion and degradation of containment structures has been increasing at operating plants m About 1/2 of these occurrences identified via NRC inspections / audits or by licensees alerted to degradation at another site a From survey, NRC observed large variation among plants related to performance and effectiveness of 10 CFR 50, App. J required visual exams a New rules ensure that acceptable margins in containment structural integrity are maintained 18 9
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Current Status woo 5 0 0001 m ASME Section XI has continued to further develop Subsections IWE/lWL m EPRI Technical Advisory Group has been developing industry guidance for implementing IWE/lWL requirements a Utilities incorporating new rules into their ISI plans; need to complete first exams within 5 years (9/9/01) 1 m Utilities have filed relief requests to use 1998 Edition of ASME XI that provides flexibility to ISI engineer in development of containment examination program a A number of utilities have begun inspections and results can be used to support risk-informed approach 19 Potential Role of RI-ISI woo e
E00001 m New rules developed using traditional approach of experience, engineering judgment, and deterministic insights a Given recent insights and experience from RI-ISI piping application and Maintenance Rule implementation, WOG felt that use of an RI ISI approach for containment exams may be beneficial e Rl-ISI offers the potential to modify the scope, methods, frequency and acceptance criteria to allow for more effective containment examinations a RI-ISI focus exams on high safety significant areas &
define exam methods based on inspection for cause 20 10
Potential Use of Overall WOG Risk-l Informed ISI Process j
-W EE00001 Expert Panel Comance Categorization Evaluation Scope Risk-DE
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Implement Definition Evaluation Program g;,
Structural Area Failure Probability Feedback Assessment Loop 21 Suggested Steps to introduce RI-ISI for Containment Exams woo 5E00001 PERFORM SURVEY INTERFACE WITH ASME XI, EPRITAG, AND NRC STAFF n
PREPARE WORK PLAN TO DEVELOP / IMPLEMENT RI-ISI 22
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Elements of Survey woo 0 0001 m Containment type of construction, materials, and volume a Results of any Maintenance Rule efforts and NRC audits e identification of general areas / locations of degradation and postulated m9chanisms a Current Code and regulatory commitments, items viewed as unnecessary burden, time to implement each requirement, incurred or expected costs a State of PRA model for severe accidents including LERF definition and value, Level 2 PRA postulated mechanisms, locations and distribution of max hole sizes, design and best estimate containment pressures a Related 10 CFR 50 Appendix J containment leak rate test information Expected Benefits em E00001 m Provide preliminary qualitative risk insights as initial support for WOG utility members who are filing relief requests to use the 1998 Edition of the ASME XI a Should achieve safety and economic benefits similar to that achieved for the RI-ISI piping application -
- maintain or reduce risks associated with containment integrity
- reductions to personnel radiation exposure
- reductions in projected inspection costs 24 n
N M5500001 RI-ISI Class 1 Piping Lead Plant and Use of WOG Generic Submittal u
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Overall WOG Risk-Informed ISI Process for Piping WWEEDDDDI Expert Panel Concequence Categorization Evaluation E
env and Risk.
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implement Definition Selection Program Structural Element Failure Probability Feedback Assessment Loop 26 13
Key Technical Aspects of the WOG Topical Report Methodology woo 0 0001 m Makes use of plant-specific PRA models to evaluate interactions and responses among multiple systems from direct and indirect effects of potential piping integrity failure modes - small leak, large leak, rupture a Uses structural reliability / risk assessment tool to estimate the likelihood of the various piping failure modes, accounting for generic industry and plant-specific operating experience a Risk-importance measures applied to initially define high and low safety significant (HSS/LSS) piping segment categories (with credit for existing augmented ISI programs) l 27 Key Technical Aspects of the WOG lopical Report Methodology E00001 m Plant expert panel systematically reviews the probabilistic models, failure mode / probability information and risk-importance measures along with other deterministic and operational insights to make final categorization of each piping segment a 2x2 structural element selection matrix used to guide location and method of examination; statistical model used to define minimum number of locations for examination in HSS segments e inspection program requirements defined using latest ASME Code Case and industry guidance a Guidance for estimating / addressing change in risk is provided a How the methodology meets the steps and principles of Regulatory Guide 1.174 is described 28 14
Risk-informed ISI Limited Scope (Class 1 Piping Only) Lead Plant E00001 Why this is beina performed a WOG wants a detailed step-by-step example application so that the approved methodology would not be misused or misapplied; the steps in the WOG Topical are primarily outlined for a full scope program.
m Further explanation of a few specific aspects of the methodology for a partial scope program may be required including:
a) actual scope of piping b) risk evaluation including the use of the importance measures and the threshold criteria c) the statistically determined % of welds to be inspected along with the change in risk 29 Risk-Informed ISI Limited Scope (Class 1 Piping Only) Lead Plant NW E00001 Why this is beina performed a Application would provide a clear understanding of what is i
required for a partial scope submittal based on the WOG method that hopefully expedites the review of follow-on plants a Partial scope RI-ISI program may show possible slight risk increase over the current Section XI program; discussion to support a risk increase is not currently available in WOG topical u Lead Plant application would provide a better understanding as to the amount of risk increase which may be acceptable (not so much that it increases but where does one stop inspections in considering detta risk when it takes for example 100 exams to get a decimal point change in delta risk) as well as an understanding as to NRC acceptance of this situation 30 15
=
Risk-Informed ISI Limited Scope (Class 1 Piping Only) Lead Plant woo ME500001 a WOG Lead Plant
- FP&L Turkey Point unit 3
- Expected to submit program to NRC by November 1999 m initial Insights
- Scope of Class 1 piping systems varies significantly depending on the plant vintage and interpretation of the Class definitions; shows need for plant-specific application
- Turkey Point unit 3
= Class 1 boundaries extend through the Regen and
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Excess letdown HXs and also include instrumentation piping
= About 160 piping segments for Class 1 RI-ISI Follow-on Plant Example Submittal Contents woo '
MEE00DDI m Developed based on meetings between NRC I
and industry on October 8,1998 and January 5,1999 m Contents of submittals to NRC will consist of brief statements and results of program development with details available as retrievable onsite documentation for potential NRC audits 32 16
Approach for Follow-on Plants (PWRs and BWRs)
E00001 m Utility provides a summary of information in a submittal to NRC which references the NRC-approved generic WOG Topical Report with a standardized format agreed to by industry and NRC a NRC review and approval could then be expedited based on generic WOG Topical approval u Utility would then be able to implement RI-ISI a Utility maintains documentation on-site for NRC review and audit a Utility updates program and provides report to NRC on a period basis 33 RI-ISI Follow-on Plant Example Submittal Contents wos 5E00001 (1) Justification for statement that PRA is of sufficient quality (2) Summary of riskimpact (3) Current inspection Code (4) impact on previous relief requests (5) Revised FSAR pages impacted by the change, if any (6) Process followed (WCAP, Code Case, and exceptions to methodology, if any)
(7) Summary of results of each step (e.g., number of segments, number of HSS and LSS segments, number of locations to be inspected, etc.)
(8) A statement that RG principles are met (or any exceptions)
(9) Summary of changes from current ISI program (10) Summary of any augmented inspections that would be impacted u
17
l Additional RI-ISI Follow-on Plants woo M M M E E D O [lDI a Several WOG utility members are currently evaluating the benefits of applying RI-ISI
- Scope ranges from:
= Full scope (Class 1,2, and 3)
= Class 1 and 2 only
= Class 1 only
- Evaluating impact on other plant programs and license renewal e Expect about 10 WOG plants to pursue RI-ISI in the next 12-18 months 35
. woG MMMEE000DI Application of WOG Risk-Informed ISI (RI-ISI) Methods to High Energy Line Break (HELB)
Augmented Examination Requirements 36 18
B 3
A Application of WOG RI-ISI Methods to HELB Augmented Inspections im m re -
MMMEROD001 37 Application of WOG RI-ISI Methods to HELB Augmented Inspections woa MMMEE00001 m Augmented ISI has been permitted to provide assurance of protection in specific instances where the installation of restraints or shields is not practical e Plants have identified break exclusion zones where augmented ISI is performed to assure protection
- Certain high energy piping systems in the containment penetration areas m Augmented inspections generally comply with the requirements of the applicable edition of ASME i
Section XI, including location selection 1
38 l
19
4 Application of WOG RI-ISI Methods to HELB Augmented Inspections WOG MEB00001 m Frequency of these inspections can be increased over that required by Section XI such that some plants inspect these locations three times during each 10-yearinspection interval a The number of locations associated with these augmented programs can reach 500 locations depending on pant-specific requirements 39 Application of WOG RI-ISI Methods to HELB Augmented inspections woo M5500001 m objective
- Gain NRC approval of the extension of WOG Risk-Informed ISI for piping methodology to incorporate HELB Augmented ISI Programs under the risk-informed piping ISI umbrella a Scope of Work
- WOG Plant Survey of High Energy Une Break Augmented ISI Requirements
- Lead Plant Application
- Support Lead Plant Submittal to NRC
- Expected Completion in March 2000 e
20
af Application of WOG RI-ISI Methods to HELB Augmented Inspections ME500001 m Key Aspects of Program
- WOG RI-ISI methodology directly applicable
- For full plant applications, the piping is already considered and augmented ISI is credited in the change to the Section XI program
- This program would re-evaluate impact of HELB augmented ISI through
= In-depth evaluation of HELB Isl requirernents
= Further evaluation of postulated indirect effects
- Further evaluation of piping failure probabilities
= identification of the irnpact on the risk-ranking and overall results 41 Application of WOG RI-ISI Methods to HELB Augmented inspections M.-
MEE00001 m Expected Benefits
- Maintain or enhance safety
-Integration of ISI programs (paperwork, cross-referencing, etc.)
- Reduced O&M costs
- Reduced personnel radiation exposure 42 21
b woo M M M M E E 0 0 0DI Other RI-ISI Applications 3
i 43 Risk-informed Applications to
)
Component inspection Requirements woo MMMMME00001 m introduction a Completed Projects a Active Projects a Future Projects o
22 U
Introduction woo um3500001 m Major changes have come to ASME Section XI in past 10 years - nearly all Code revisions have led to cost savings a Key issue is how to demonstrate that safety is maintained a Key challenges are a,bitrary requirements a Many WOG projects have aimed at these goals a Risk is a key technology in accomplishing these changes 45 Risk-Informed Applications to Component inspection Requirements woo MMME00001 m Completed Projects
- RC Pump Motor Flywheel Inspection Changes
- RC Pump Casing inspection Elimination
-Class 1 Vessel Nozzle Inner Radius Steam Generator Pressurizer
- Part-Length CRDM Inspections
-RV Head Penetration inspections
.6 23
Risk-Informed Applications to Component inspection Requirements mummmmmmmmmmmmmmmusumssmannnni e Active Projects
-Class 1 Vessel Nozzle Inner Radius
- Reactor Vessel
-Class 2 Tanks and Heat Exchangers a Future Projects
-Optimization of Surface Examinations in Class 1 Equipment
-Elimination of Pump FlywheelInspections 47 woo MMMMEODDDI J
Summary 24
4 Summary MIME-M55500001 m The WOG wants to build upon and extend the NRC-approved RI-ISI methodology for piping to other areas for safety & economic benefits a A number of new applications have been identified from strategic discussions a WOG would like to continue active dialogue with NRC Staff as risk-informed regulation is further embraced for pressure boundary and structuralintegrity applications 49 t
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