ML20210N066
| ML20210N066 | |
| Person / Time | |
|---|---|
| Issue date: | 08/03/1999 |
| From: | Birmingham J NRC (Affiliation Not Assigned) |
| To: | Carpenter C NRC (Affiliation Not Assigned) |
| References | |
| NUDOCS 9908100284 | |
| Download: ML20210N066 (22) | |
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pMer 3-UNITED STATES g
NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20566-0001 o
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,o August 3,1999 MEMORANDUM TO: Cynthia A. Carpenter, Chief Generic issues, Environmental, Financial and Rulemaking Branch Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation I
y FROM:
Joseph L. Birmingham, Project Manager Generic issues, Environmental, Financi and Rulemaking Branch Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF JULY 23,1999, MEETING WITH THE INDUSTRY ON HIGH PRESSURE INJECTION LINE CRACKINGTI'HERMAL FATIGUE On July 23,1999, the NRC staff met with representatives of the Electric Power Research Institute (EPRI) Materials Reliability Project (MRP) Issues Task Group (ITG) on thermal fatigue of primary system piping and the inspection of small diameter (less than 4 inch), Class 1, high pressure safety injection (HPSI) system piping. The MRP is a body representing member utilities with pressurized water reactors (PWRs), EPRI, and the Nuclear Energy Institute for the purpose of dealing generically with PWR-specific technicalissues. This meeting was requested by the MRP to provide them with an opportunity to discuss with the NRC staff their industry-initiative to resolve issues associated with the above topics. This industry-initiative was developed in response to a proposed Generic Letter and a proposed rulemaking activity by the NRC staff which would have required the volumetric inspection of small diameter, Class 1, HPSI piping to look for inside diameter cracking which could be initiated by thermal fatigue.
After opening comments by Richard Wessman, Deputy Director of the Office of Nuclear Reactor Regulation's Division of Engineering, Mr. Michael R. Robinson from Duke Energy made the MRP presentation. Mr. Robinson's presentation slides are provided in Attachment 1. In response to the NRC staff's concern over the lack of volumetric examinations required by the American Society for Mechanical Engineers (ASME) Code for small diameter, Class 1, HPSI piping, the MRP proposed to initiate a program to deal with the broader issue of thermal fatigue
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in Class 1 piping systems by mid-to-late 2001. Mr. Robinson noted that out-year funding for this I{
program had not yet been secured from the industry executive group which determines where MRP resources will be allocated. He indicated that the funding issue would be addressed in NIRP internal meetings on July 29,1999.
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The technicul aspects of the proposed MRP program were as follows. In the interim between the present and when the MRP program is to be completed, no additional plant monitoring or inspections (beyond the surface examinations already required by the ASME Code) would be
. proposed. The MRP would then develop a multi-pronged approach for dealing with thermal wnoen MC FRF(MITEf!COPb l
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C. Carpenter August 3, 1999 fatigue based on domestic and foreign industry experience as well as experimental and analytic resu!ts. Screening criteria would be developed to identify piping which could be subject to thermal fatigue. Operations and maintenance guidance would be developed which could eliminate the ccnditions which lead to thermal fatigue initiation in vulnerable systems. Where elimination of the initiating conditions could not be achieved, additional guidance on the use of monitoring and analytical assessment to demonstrate that thermal fatigue would not compramise the integrity of subject piping would be provided. Fina'lly, in the event that none of the above could be used to show ; hat piping integrity would be maintained throughout the life of the facility, additional guidancc on the inspection, permanent monitoring, and/or repair or replacement of the subject piping would be given.
j The principal comments provided by the NRC staff throughout the meeting can be summarized as follows. It was not clear to the staff that not performing some limited (based on a sampling basis) volumetric examination of the weld locations in the small diameter, Class 1, HPSI system piping in the interim before the MRP program was completed was acceptable. The staff's view was based on consideration of: (1) the Code-mandated surface examinations are completely ineffective in identifying thermal fatigue cracking until the piping had already been cracked through-wall, (2) the staff's perception that minimal additional burden would ba incurred if licensees performed volumetric' examinations in lieu of surface examinations since much of the i
same preparatory work (erecting scaffolding, removal of insulation, etc.) would be done in either i
case, and (3) risk-informed inservice inspection studies have indicated that unisolable Class 1 HPSI piping may be highly risk significant. Regarding their long-term program proposal, the NRC staff was generally supportive of the MRP plan and would consider the potential for some joint NRC-industry activities for resolving technical issues. However the staff was skeptical about how well analytical questions regarding the prediction of thermal fatigue could be addressed given the inability of cunent analytic methodologies to adequately predict the known failures.
A list of the attendees is provided in Attachment 2.
Attachments: As stated i
cc w/atts: See next page l
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August 3, 1999
-2 C. Carpenter fatigue based on domestic and foreign industry experience as well as experimental and analytic results. Screening criteria would be developed to identify piping which could be subject to thermal fatigue. Operations and maintenance guidance would be developed which could eliminate the conditions which lead to thermal fatigue initiation in vulnerable systems. Where elimination of the initiating conditions could not be achieved, additional guidance on the use of monitoring and analytical assessment to demonstrate that thermal fatigue would not compromise the integrity of subject piping would be provided. Finally,in the event that none of the above could be used to show that piping integrity would be maintained throughout the life of the facility, additional guidance on the inspection, permanent monitoring, and/or repair or replacement of the subject piping would be given.
The principal comments provided by the NRC staff throughout the meeting can be summarized as follows. It was not clear to the staff that not performing some limited (based on a sampling basis) volumetric examination of the weld locations in the small diameter, Class 1, HPSI system piping in the interim before the MRP program was completed was acceptable. The staff's view was based on consideration of: (1) the Code-mandated surf ace examinations are completely ineffective in identifying thermal fatigue cracking until the piping had alreads/ been cracked through-wall, (2) the staff's perception that minimal additional burden would be incurred if licensees performed volumetric examinations in lieu of surface examinations since much of the same preparatory work (erecting scaffolding, removal of insulation, etc.) would be done in either case, and (3) risk-informed inservice inspection studies have indicated that unisolable Class 1 HPSI piping may be highly risk significant. Regarding their long-term program proposal, the NRC staff was generally supportive of the MRP plan and would consider the potential for some joint NRC-industry activities for resolving technicalissues. However the staff was skeptical about how well analytical questions regarding the prediction of thermal fatigue could be addressed given the inabili+y of current analytic methodologies to adequately predict the known failures.
A list of the attendees is provided in Attachment 2.
Attachments: As stated cc w/atts: See next page DISTRIBUTION: See attached page
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SC(RGhik DD;DE NAME JBirmin[am:sw FAkklewicz RWessman DATE 07/27 /99 Og/3 /99 0750/99 l
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R EPRI MRP Thermal Fatigue ITG l
and USNRC Meeting l
July 23,1999 Washington, DC l
l Agenda
- Welcome and Introductions
- Purpose ofMeeting
- Brief Background Review and Stattts
- MRP ITG Expectations of NRC in this Project
- Review Thermal Fatigue Preliminary Project Plan
- NRC Comments / Response to Project Plans
- Meeting Conclusion and Adjourn 1
e Meeting Purpose
- Establish early dialogue and communications between NRC and the MRP Issue Task Group (ITG)
- Discuss ITG expectations of NRC in this Project
- Inform NRC on the Preliminary Thermal Fatigue Project Plan
- NRC questions
- TimelyITG actions
- Justification for pursuing analytical resolution vs inspection or monitoring
- Coordination with ASME Section XI WG activities
- Request NRC feedback on Project Plan
Background
- Proposed GL on augmented inspection of PWR Class 1 HPSI piping, March 1998
- Identify inconsistenc"in ASME Code inspection requirements for ISI of those portions of HPb1 lines designated as Class I and <4" diameter
- Emphasize requirement to maintain the integrity of reactor coolant pressure bounduy piping (GDC-14) through life of plant
- Repon to NRC licensee actions for veritying RCPB integrity and future i
piping inspection plans,if any
- NEI, at NRC request, approached EPRI requesting leadership for long term resolution of the issues identified in proposed GL.
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Background
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- EPRI MRP ad hoc team formed in late '98 to investigate the issue and provide a recommendation to the MRP. Ad hoc team met w/ NRC staff on 2/9/99 to assess NRC concems:
- GL was not best method to address their concerns
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- Monitoring most reliable method to provide assurance against TFC
- Current programs are not sufficiently reliable to form basis of regulation
- Concems with use of analysis including EPRI TASCS model l
- EPRI MRP Executive Group and Senior Reps approved the formation of the HPSI Thermal Fatigue ITG on 3/10/99.
- Selected Chair for ITG, Executive sponsor and requested utility representation to work on ITG
Background
- ITG is composed of representatives from 10 member utilities:
- FPC, CPL,SCE,NU,BGE,TVA,VaPwr,SNC,DPC, Con Ed l
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- ITG focus has been to organize the team, to develop the project scope, schedule, and budget information.
- 6 days of meeting w/ utilities, EPRI, SIA, NSSS vendors
- Approval of the project plans and budget scheduled 7/29/99
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1 MRP Expectations ofNRC
- Participation in project activities (meetings, technical discussions, workshops, etc.) either by invitation or at NRC request j
- Identification of NRC technical contact or SPOC
- NRC concurrence, at appropriate time, that issue is being addressed
- Acceptance of fmal products, conclusions, result
- Assistance in gaining access to relevant international data l
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Thermal Fatigue ITG Project Plan Review 4
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Project Goal i
Provide the EPRI member utilities with a consistent set of guidelines and methodology for addressing piping thermal fatigue issues in 2001.
Project Scope
- The scope of this Project is thermal fatigue issues for those portions of ASME Code Class I small bore (<4 inch) piping systems that are connected to the Reactor Coolant Pressure Boundary AND are not isolatable from the Reactor Coolant Pressure Boundary. Included in the scope are effects due to cyclic thermal stratification.
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Strategic Approach
- Respond to NRC request for industry leadership and action.
- Provide the industry w/ tools to manage thermal fatigue concerns through current license life and any renewal periods.
- Validate tools against known failures
- Take advantage of earlier thermal fatigue work performed and supplement that with new ideas and enhanced thermal fatigue management capabilities.
Strategic Approach
- Establish relationships & partnerships that allow access to new data and information and use that to improve the Project Plan.
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- Identify and select demonstration plant (s) for testing the Project products and conclusions.
- Address implementation issues.
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1 What actions are planned while generic analytical l
s analyses are developed?
No additional plant monitoring or inspections are planned at this time.
Pipe failures attributed to cyclic thermal fatigue are event driven, e.g., leaking valves
- US failures are small in number and do not represent a trend Analytical approach advances the state of knowledge.
- Enhances identification of sensitive locations
- Provides improved guidance for pipe inspections or monitoring activities
- Reduces uncertainties associated with thennal fatigue management Project Flowchart
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7i Thermal Fatigue ITG Project Task Descriptions 8
I ask 3: Industry Operating Experience
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Description:==
Existing industry databases are assembled based on leaks or identified flaws. Industry experiences and tL sharing ofinformation of events that do not meet some higher reporting threshold could provide added value and new insights.
Outcome: A database that collects utility thermal anomaly observations which do not reach the level of recording through LERs or other means. A database to contain historical experiences and to capture and make available such information in the future.
1he vision is being able to collect information on lower level thermal anomalies which would indicate non design thermal fatigue mechanisms and have the potential to cause thermal fatigue damage.
Task 4: Thermal Fatigue Screening f,\\
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Description:==
This task will review the EPRI TASCS model and FT! SCATS program for w
needed enhancements for improved screenmg and evaluabon capabihty. A simple screening model, in the form of EPRI software, based on the enhanced rnethodology will be developed. The screening model will describe the thermal fangue phenomena, factors necessary for thermal fatigue to occur, and the logic process for making this detemiination. When screening identifies a location as susceptible to thermal fatigue, a prediction of the thermalloading magnitude will be made,includmg number of cycles.The methodology will have a technically defensible basis and will be vahdated agamst known instances of thermal fangue failures.
Outcome: A tool for determining when and where significant thermal fangue damage may occur in PWR piping systems.
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f sk 5: Thermal Fatigue Monitoring Guidelines
Description:
his task will provide guidance in the following areas:
- basis for implernenting a rnonitoring program
- identification of stateef-the-art monitoring technology
- effective placement of rnonitoring sensors interpretation of rnonitoring data
- basis for discontinuing rnonitoring
- Outcome: Prsctical guidance on the use of rnonitoring to detect potential thermal fatigue phenomena.
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e Task 6: NDE Inspection Guidelines
Description:
nis task wiii assemble previous guidance on NDE rnethodologies (such as RT or UT) and make recommendations for specific NDE technology and variables. Recomrnendations will be made on the appropriate quahfication of NDE examiners and procedures. The recommended rneans of evaluating NDE data and reporting levels will be provided. Contacts will be rnade intemationally to determine any difficulties reached in applying NDE for thermal fatigue and laboratory investigations to verify performance. Research will be conducted to determine capabihties ice producing therrnal fatigue cracks and then mockups will be designed and fabricated. A siet of rnockups with individual cracks due to thermal fatigue will be needed, along with mockups containmg thermal craze crackmg.
- Outcome: Guidance on NDE methodologies and recommendations of specific NDE technology and variables to use when inspecting for suspected thermal fatigue damage.
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Task 7: Plant O&M Guidelines
Description:
nis task focuses on how O&M practices can lead to thermal fatigue damage and identifying necessary changes to eliminate the damage potential. PWR Operating Experience will be used to identify plant practices and corrective actions implemented at afTected plants. Guidance will be developed for use by utility engineers to aid in identifying O&M practices which may lead to fatigue damage and what actions may be taken to mitigate the consequences.
- Outcome: Guidance for use by plant personnel to identify how o&M practices can create or minimize the potential for causing thermal fatigue events.
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ask 8: Thermal Fatigue Evaluation 1
Description:
This Task will develop both a Simplified Disposition Too! and a more rigorous Analysis Guide to aid the engineer in evaluating thermal fatigue situations.
- Outcome:
- A simphfied thennal fatigue evaluation taol, in the form of EPRI software, will be developed to assist the engineer in estimatmg fatigue usage.
- An analysis guide, documenting the techniques and describing comprehensive methodologies for analytical reconciliation of thermd fatigue phenomena usmg or based on ASME Section 111 methodology will be developed for the ngorous treatmmt,
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i Task 9: Plant Modification Guidelines
Description:
nis task will identify and describe plant modifications that are successful at avoiding the potential for thermal fatigue.
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- Outcome: Identification of cost effective plant changes that would climinate need for future monitoring and piping augmented inspections.
Task 10: International Technical Exchange
Description:
nis task will support identification of and possible participation in important foreign R&D activities which could contribute to resolution of the thermal fatigue issue. An international workshop on thermal fatigue experience and R&D is being considered by EPRI by mid-2000.
- Outcome: Awareness of and access to foreign information of value to US utilities for detection, assessment, mitigation, and prevention of thermal fatigue damage.
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ask 11: Thermal Fatigue Management Guidelines
Description:
nis task represents the principal product of this ITG. It assembles the results of the other tasks, documents conclusions drawn from that work, and provides recommendations for managing thermal fatigue.
- Outcome: The "TFMG" will be a compilation of methods for assessment, screening, monitoring, analysis, and remediation for and management of thermal fatigue. The ITG will seek NRC staff acceptance of guideline.
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ask 12: Develop & Deliver Training Plan T
Description:
This task develops and delivers the training plan for utility engineers and others in applying the "TFMG". This task is aimed at utility personnel (operations, maintenance, engineering) to increase their overall knowledge and awareness of cyclic thermal fatigue and how plant operations and maintenance may be contributors to the phenomena.
- Outcome: More knowledgeable and experienced personnel and more effective management of thermal fatigue issues.
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ask 13: Monitor ASME Section XI WG Changes
Description:
This task monitors the activities of the ASME Section XI Working Group on Inspection Systems and Components. Inspection guidance developed by this ITO will be reviewed with appropriate Code groups to determine if such guidance should form basis for other Code revisions.
- Outcome: Coordination ofITG and ASME Code activities What role will MRP take in resolving the ASME Code Class 1 & 2 inspection inconsistency?
- Resolving the ASME Code Class 1 & 2 inconsistency question is not in the scope of this ITG.
- Thennal fatigue inspection selection criteria, developed by this ITG, will be discussed with the appropriate A.SME Code Working Groups and Subgroups to determine if such guidance should form the basis for a Code revision or if such guidance is best managed through licensee augmented inspection programs.
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--What is next for the ITG?
- Meet with MRP Senior Reps on 7/29/99 for plan and budget approval.
- Commence project work on Tasks 4 and 8.
- Meet with NRC technical staff to go into further detail.
NRC Feedback and Questions
- NRC feedback on ITG Project Plan 15
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4 NRC/ INDUSTRY MEETING ON HPl LINE CRACKING / THERMAL FATIGUE July 23,1999 List of Attendees NAME ORGANIZATION John Carey EPRI Kud Cozens NEl David Modeen NEl Tim Baumstark Consolidated Edison Larry Rinaca TVA Todd Connor Baltimore Gas & Electric Glenn Gardner Northeast Utilities J. Michael Davis Duke Energy Michael Robinson Duke Energy John Martin Florida Power & Light i
Sherm Shaw Southern California Edison
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Leslie Spain Virginia Power David Stellfox McGraw Hill Althea Wyche SERCH Licensing /Bechtel Wallace Norris NRC/RES/DET Matthew Mitchell NRC/NRR/EMCB Tom Scarbrough NRC/NRR/EMEB
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Dick Wessman NRC/NRR/DE Mark Hartzman NRC/NRR/EMEB Jack Rosenthal NRC/RES/REAHF Jocelyn Mitchell NRC/OEDO Noel Dudley NRC/ACRS l
Kamal Manoly NRC/NRR/EMEB Michael Mayfield NRC/RES/MEM l
Keith Wichman NRC/NRR/EMCB Gene Imbro NRC/NRR/EMEB i
Project _No. 669 Electric Power Research Institute Mr. Kurt Yeager President and CEO
. Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 Robin Jones Vice President and Chief Nuclear Officer Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303
' Mr. Raymond C. Torok
~ Project Manager, Nuclear Power Group Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 Mr. Gary L. Vine Senior Washington Representative Electric Power Research Institute 2000 L Street, N.W., Suite 805 Washington, DC 20036 Mr. Bindi Chexal Electric Power Research Institute Post Office Box 10412 Palo Alto, CA 94303 r
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t Distribution: Mtg. Summary w/EPRI on HPlline cracking Dated August 3.1999_
Hard Coov PUBLIC RGEB R/F OGC ACRS JBirmingham EMail SCollins/RZimmerman BSheron WKane GHolahan TCollins RWessman Gimbro KWichman WNorris PBoehnert, ACRS GTiacy, EDO JBirmingham JRosenthat DMatthews SNewberry CCarpenter FAkstulewicz PWen SDembek