ML23076A045
| ML23076A045 | |
| Person / Time | |
|---|---|
| Issue date: | 03/16/2023 |
| From: | Kenneth Kolaczyk NRC/NRR/DRO/IRAB |
| To: | |
| References | |
| Download: ML23076A045 (1) | |
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Inspector Seminar Overview of Regulatory Issue Summary 2022-02, Operational Leakage Team Members Jay Collins, NPHP Sheldon Clark, OGC/RAF Caroline Tilton, STSB Robert Elliott, STSB Thomas Scarbrough, EMIB March 9, 2023
- American Society of Mechanical Engineers (ASME)
- Boiler and Pressure Vessel Code (Code)
- Generic Letter (GL)
- Primary Water Stress Corrosion Cracking (PWSCC)
- ASME Pressure Vessel and Piping Conference (PVP)
- Regulatory Issue Summary (RIS)
- Risk Informed Safety Class (RISC)
- Standard Technical Specifications (STS)
- Systems, Structures and Components (SSC)
- Technical Specifications (TS)
- Title 10 of the Code of Federal Regulations (10 CFR) 3
Outline
- Operational Leakage RIS ADAMS Links
- Operational Leakage Issue Timeline for Reference
- RIS 2022 Background
- RIS 2022 Summary of the Issue
- NEI 18-03, NEI Operational Guidance
- Clarifying Paragraphs and FAQ
- Additional Questions/Discussion 4
Operational Leakage RIS Links
- Public Comment Resolution for RIS 2022-02
- Useful examples of in depth regulatory basis discussion as well as proposed alternative and violation example links for this area
- NRC Staff Presentation on RIS 2022-02 for CRGR
- Useful FAQ for potential license or staff questions on the regulatory applicability and safety concern for this issue 5
Timeline for Reference 1971 - Start of Codes & Standards Requirements - 50.55a 1980s - IGSCC in BWRs, PWSCC in PWRs 1990 - GL 90-05 Memorandum for implementation of GL 90-05 1991 - GL 91-18 1992 - Memo to address TIA 92-09 1993 - Final Policy Statement for improved STS Memorandum from TS branch on Structural Integrity and 50.55a 1996 - Reedy Letters Public meeting with ASME Re: GL 91-18 1999 - NRC endorses ASME Code Case N-513 2001 - NRC authored PVP paper on NRC Perspective on Through-Wall Leak 6
2005 - RIS 05-20, Rev 0 2006 - NRC Letter to ASME on OL ASME Response to develop a Project Team ASME publishes N-705 2008 - ASME Response - plan to address OL RIS 05-20, Rev 1 2015 - ASME Code update - closeout of project NRC Response acknowledged ASME activities and noted additional regulatory action RIS 05-20, Rev 2 - IMC 0326, Rev 1 2019 - NEI 18-03 Operability Guidance Doc
- NRC issues IMC 0326, Rev. 2 2020 - Public Meetings begin on OL clarification in 50.55a 2021 - Management/OGC decision to move forward with RIS as clarification tool 2022 - RIS 2022-02 issued in November
RIS 2022 Background
- Operational leakage and relation to TS The requirement for maintaining structural integrity is a fundamental assumption used in the development of the TS under 10 CFR 50.36, Technical specifications.
TS are derived from safety analyses that assume ASME BPV Code Class 1, 2, and 3 components continue to have structural integrity during operation.
- Explain purpose of 10 CFR 50.55a(g)
- History of NRC actions regarding this requirement
RIS 2022 Summary of Issue
- Defined Operational Leakage
- Leakage through a ASME Class 1, 2 or 3 component, which is required to be operable by TS, requires structural integrity to be verified.
- This requires analysis in accordance with the original construction code, or an NRC-approved ASME Code Case; performance of a repair/replacement activity; or NRC approval of an alternative/relief request.
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- NEI 18-03 is a NEI technical report providing guidance for operability determinations (ML19284C872)
- Section A.10 addresses flaw evaluation and operational leakage If NRC approved code cases or other NRC approved alternate methods are not available to be used, licensees technical resources should use other alternative evaluation methods In addition to the Operability Determination process, technical staff personnel should ensure actions IAW ASME Code Section XI are reviewed and followed in parallel to meet the regulatory requirements of 10CFR50.55a which may include submittal of a Code relief request for NRC approval.
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Added Clarification Paragraph Licensees are allowed to evaluate the location to determine if the leakage affects the structural integrity of an SSC governed by TS.
If operational leakage is from a component that does not need to maintain structural integrity for a system to perform its specified safety function, and the leak does not impact the ability of other SSCs governed by TS to perform their specified safety functions, then the leakage can be addressed through other processes (e.g.,
corrective action program).
For example, if the licensee identifies leakage from a drain line, the complete failure of which would not affect operability of any system (e.g., complete failure will not result in loss of adequate flow in the main system, will not result in room flooding that could result in loss of a specified safety function, etc.), then the requirements discussed in this RIS would not apply.
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Added Clarification Paragraph (cont)
- In contrast, any degradation in the main line of a system can challenge the structural integrity of that system and that systems specified safety function. This requires further action as identified in this RIS to demonstrate operability.
- Additionally, for leakage in ASME Class 1 systems, this condition is governed by the leakage allowances of the applicable TS, and any pressure boundary leakage requires repair of the reactor coolant pressure boundary, in accordance with this RIS.
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FAQ for Licensee Questions
- If structural integrity must be verified, what is the Section XI code path to address operational leakage?
- Operational leakage must be addressed in the same manner as leakage detected during an ASME BPV Code,Section XI, pressure test.
- How do we use alternatives then to Section XI requirements and code cases?
- 10 CFR 50.55a(z), Alternatives to codes and standards requirements, can be used as long as NRC staff authorization is granted before implementation
- Implementation is deemed to be the moment that the structural integrity of the component is required to be established (e.g., before expiration of the TS allowed completion time).
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- The discussion in this RIS applies to Risk Informed Safety Class (RISC) 1 and RISC 2 categorized components that are required to be operable by plant TS because 10 CFR 50.55a(g) continues to apply in full to RISC 1 and RISC 2 components.
- The NRC regulations in 10 CFR 50.55a(g) also continue to apply to those RISC 3 or RISC 4 categorized components classified as ASME BPV Code Class 1 and are required to be operable by plant TS.
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10 CFR 50.69 (cont)
- Operational leakage in other RISC 3 or RISC 4 categorized components that are classified as ASME BPV Code Class 2 and 3 and are required to be operable by plant TS must be treated in accordance with the licensees approved 10 CFR 50.69 requirements. (this includes corrective actions and repair/replacement activities)
- The NRC regulations in 10 CFR 50.69(d)(2)(i) require that, at a nuclear power plant implementing a 10 CFR 50.69 program, periodic inspection and testing activities must be conducted to ensure RISC 3 SSCs remain capable of performing their safety related functions under design basis conditions. The Commission provides information for the implementation of 10 CFR 50.69 in 69 FR 68008, dated November 22, 2004.
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Discussion 15