ML22220A012
| ML22220A012 | |
| Person / Time | |
|---|---|
| Issue date: | 06/07/2022 |
| From: | Sheldon Clark, Jay Collins, Robert Elliott, Thomas Scarbrough, Caroline Tilton Office of Nuclear Reactor Regulation, NRC/OGC |
| To: | |
| References | |
| Download: ML22220A012 (1) | |
Text
Response to CRGR Questions on Regulatory Issue Summary for Operational Leakage Jay Collins, NPHP Sheldon Clark, OGC/RAF Caroline Tilton, STSB Robert Elliott, STSB Thomas Scarbrough, EMIB June 7, 2022
- 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) 2
Outline For CRGR Presentation Slides
- Timeline for Reference
- Background on Regulatory Basis and Backfit
- CRGR Question and Staff Responses
- Summary of Staff Position
- Additional Questions/Discussion 3
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 4
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 2018 - NEI 18-03 2019 - 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
License Requirements
- Initial license identifies SSC necessary for safety
- Design of SSC by Construction Code is based on maintaining structural integrity for license duration
- Technical specifications
- Specify the SSC required for safe operation
- Operability requirements for safety
- Structural integrity fundamental basis for performing intended function of SSC 10 CFR 50.55a(g) mandates the use of Section XI for inservice requirements to provide reasonable assurance of structural integrity 5
NRC Backfit Assessment A backfit is a modification, the position in this RIS is not a change NRC staff first clarified this position in GL 90-05 It was determined not to be a backfit in 1990 The NRC has maintained the position in many communications and documents since 1990 The NRC has not taken a contrary position 6
Statements of Consideration and Regulatory History Question 1 -
- Industry disputes intent of paragraph (g). Please describe how the SOCs from previous 50.55a rulemakings were examined and what did you find to support the staff position regarding its meaning, including the 1976 and 1992 rulemakings Response 1 -
- Staff reviewed the SOCs for previous rulemakings regarding 50.55a from 1971 to 2004
- The SOCs were consistently limited in scope in discussing 50.55a(g)(4)
- Neither the 1976 nor the 1992 SOCs discuss the requirements for repair/replacement The difference between the NRC position and NEIs position is an interpretation of 10 CFR 50.55a(g)(4) 7
Throughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements, except design and access provisions and preservice examination requirements, set forth in Section XI of editions and addenda of the ASME BPV Code (or ASME OM Code for snubber examination and testing) that become effective subsequent to editions specified in paragraphs (g)(2) and (3) of this section 8
Statements of Consideration and Regulatory History
- Question 2 -
- Industry does not agree that past communications support the staff interpretation of the intent of 50.55a(g). Please describe staff response to industry comments on GL 90-05 and the Reedy letters.
- Question 2a -
- Could the staff provide its perspectives on what language in the letter indicates that only methods specified in the code be used to assess operability?
- Staff Response 2 and 2a -
- GL 90-05 required an ASME Code Repair, at that time, because repair/replacement was the only available option to address operational leakage
- The only option to address through-wall leakage at the time of the Reedy letters was IWA-4000 of Section XI (repair/replacement) or GL 90-05 9
Generic Communications - GL 90-05 Purpose is to provide a method for NRC staff to approve relief for OL for ASME Class 3 SSC if a repair or replacement action would require shutdown of the plant At the time of issuance, ASME Code mandated repair/replacement for components with through-wall defects, with no NRC approved method for temporary acceptance of these defects Introduction statement of GL 90-05 (ML031140590)
- Section XI of the ASME Boiler and Pressure Vessel Code (hereafter called the code) specifies code-acceptable repair methods for flaws that exceed code acceptance limits in piping that is in service. A code repair is required to restore the structural integrity of flawed ASME Code piping, independent of the operational mode of the plant when the flaw is detected
- This guideline applies when a flaw is detected during plant operation Non-code repair in GL 90-05 means temporary acceptance of leak, note the enclosure in ML031140590 If there was no OL regulatory requirement to perform an ASME Code repair in accordance with 10 CFR 50.55a(g) there would be no need for this GL GL 90-05 found to have no backfit 10
Communications - Reedy Letters (1 of 3)
- In a 02/20/1996 response to Mr. Reedy, the NRR OD, with approval by the Chairman, EDO and OGC, responded to the following question -
- Mr. Reedys question: The NRC staff has not provided any legal or regulatory basis for not permitting leakage in Code piping during operation
- NRC Response (ML20006H278)
- Section 50.55a, paragraph (g)(4) states, in part, that "[t]hroughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) which are classified as ASME Code Class 1, Class 2 and Class 3 must meet the requirements, except design and access provisions and preservice examination requirements, set forth in Section XI..." As such, the regulations would not be satisfied if deterioration has caused a breach (i.e., leakage) in the wall of components within the scope of Section 50.55a.
11
Communications - Reedy Letters (2 of 3)
- NRC Response (ML20006H278)
- That is, if a pipe has a through-wall defect that causes a leak, then the pipe obviously has a flaw in it and a licensee could not demonstrate that the structural integrity of the component meets the flaw acceptance criteria of Section XI, IWX-3000 (See 3[a]
response).
- Arguments that Code references do not specifically require the defect causing a leak to be characterized and flaw evaluation to be performed are insufficient for determining operability.
- Part 50, Appendix B, Criterion XVI, " Corrective Measures," would require further evaluation of the deterioration to ascertain if the system, subsystem, or component has sufficient safety margin and to ensure that other design basis and regulatory requirements are met (e.g., Appendix A, General Criteria 14, 15, 31, 36, 37, 45, 46, and 51, plant SARs, plant technical specifications, etc.).
12
Communications - Reedy Letters (3 of 3)
- In a 06/12/1996 follow-up response to Mr. Reedy, the EDO, with the Chairmans concurrence, reaffirmed that the previous position was unchanged. (ML20112K084)
- Further the EDO confirmed,
- The NRC has made those editions and addenda of the ASME Code that it has endorsed in 10 CFR 50.55a a part of its regulations
- ASME Interpretations are not a part of the regulations
- The NRC regulations permit the use of alternatives, including those that may be based on engineering judgement
- However, the NRC has the responsibility for assuring that the Code of Federal Regulations is effectively implemented and that alternatives to the regulations are reviewed and approved by the NRC staff prior to use by a licensee 13
Section XI Assessment of Potential New Requirements Question 3 - Please describe staff response to these industry positions.
A.
Section XI methods are useful but should not be the exclusive method B.
Section XI methods are not available and/or applicable to every situation C.
Industry would prefer to use Section XI approved methods if they are available and applicable Staff Response 3 -
A.
In order to be in compliance with TS and 50.55a, these are the only options currently available 1)
NRC authorized alternatives; Construction code, GL 90-05, Appendix W of Section XI, ASME Code Cases N-513 and N-705 2) 50.55a(z) can be used B.
Repair/replacement is an option for any type of component for any ASME Class 1, 2 or 3 SSC with a through-wall defect C.
Industry must use Section XI approved methods, and they are available 14
Section XI Assessment of Potential New Requirements Question 3a -
- Related to question 3, for conditions that are not addressed by the code, have we taken a position that approved methods do not need to be used in other processes, such as operability determinations? Industrys position is that the GL we referenced relates to repairs, not operability.
Staff Response 3a -
- Yes, we have taken a position that approved methods do not need to be used in some other processes for operability determinations outside of operational leakage. See Section 08.04, Use of Alternative Analytical Methods in Operability Determinations, of IMC 0326 (ML19273A878)
- Again, as clarified in GL 90-05 and GL 91-18, the only option available was repair to verify structural integrity to ensure the safety function of the component. See Section 08.13, Operational Leakage from ASME Code Class 1, 2, and 3 Components, of IMC 0326 for the special case for operational leakage because of ASME Code requirements.
15
Section XI Assessment of Potential New Requirements Question 4 - Describe staff response to these industry comments A.
This is a new requirement B.
Pointed to our regulations that indicate if we intend to differ from an ASME position, we must justify that through rulemaking Staff Response 4 A.
This is not a new requirement (50.55a in combination with TS)
B.
Staff does not differ from requirements of ASME Section XI. The NRC differs from the ASME interpretation of Section XI, which we have consistently stated.
In a December 24, 1996, NRC Memorandum, Summary of Meeting with ASME Executives on November 12, 1996, (ML20133Q130), the NRC staff discussed with ASME this issue and came to a resolution. Quotes are on the next slide.
16
Section XI Assessment of Potential New Requirements December 24, 1996, NRC Memorandum, Summary of Meeting with ASME Executives on November 12, 1996, (ML20133Q130)
The NRC and ASME staff identified in the attached attendance list met to discuss several issues regarding the requirements of 10CFR50.55a in implementing the ASME Code. The discussions during the meeting centered on the NRC Inspection Manual Part 9900 guidance on ASME Sections III and XI. This document provides guidance on use of ASME Code Interpretations, engineering judgement and timeliness of flaw evaluations.
ISSUE: Code Interpretations ASME representatives stated that the guidance in the Inspection Manual chapter is consistent with ASME's understanding of the relationship between the ASME Code and NRC regulations. There were discussions regarding the mechanism for NRC informing ASME of code interpretations that NRC takes exception to. It was agreed that the NRC should not establish a formal method for reviewing ASME code interpretations for acceptance. This conclusion was based primarily on the understanding that it would be tantamount to NRC becoming the interpreter of the Code. It was agreed that any concerns NRC has regarding specific ASME code interpretations would be brought to the codes attention through the NRC staff's normal interaction with the Code. Situations in which NRC disagrees with an ASME Code interpretation or how it is being implemented will also be identified and dealt with through the inspection process. Finally, it was noted that, considering the large number of ASME interpretations that are issued, there have been very few cases where NRC has taken exception to ASME interpretations and that interpretations have been of great benefit. The NRC representative to Section XI will inform Section XI of the guidance in the Inspection Manual.
17
Section XI Assessment of Potential New Requirements Question 4 - Describe staff response to these industry comment C.
Pointed also to a 2015 letter Staff Response 4 (cont) -
C.
In 2006, NRR wrote a letter to ASME and said the NRC believes the ASME Code needs to address operational leakage. The ASME Executive committee said they agreed and formed a committee to evaluate the operational leakage. After 7 years and the issuance of some code cases that would allow a licensee to deal with operational leakage, and a verification that no pressure boundary leakage is allowed on Class 1 components, the ASME Code said operational leakage is outside the scope of the code. In the 2015 letter, the NRC wrote ASME and thanked them for their efforts and stated we would evaluate regulatory action.
This RIS is the culmination of that action.
18
Section XI Assessment of Potential New Requirements Question 4 - Describe staff response to these industry comments D.
Indicates that the NRC has allowed alternative methods to evaluation operability and recognized that licensees may have to rely on alternative methods beyond the approved licensing basis. Industry points to IMC 0326 as supportive (see slide 29 of their presentation).
Staff Response 4 (cont) -
D. The quote on slide 29 of the NEI presentation is from Section 08.04, Use of Alternative Analytical Methods in Operability Determinations, of IMC 0326 (ML19273A878), however it does not cover the special case of Section 08.13 Operational Leakage from ASME Code Class 1, 2 and 3 Components, which states, 10 CFR 50.55a requires that the structural integrity of ASME Code Class 1, 2, and 3 components be maintained in accordance with the ASME Code or construction code acceptance standards.
This quote is from the 2019 edition of IMC 0326 19
Section XI Assessment of Potential New Requirements Question 4 - Describe staff response to these industry comments Special case section for operational leakage under Part 9900 issued by GL 91-18.
Furthermore, the regulations and TS require that the structural integrity of ASME Code Class 1, 2, and 3 components be maintained according to Section XI of the ASME Code. If a leak is discovered in a Class 1, 2, or 3 component in the conduct of inservice inspections, maintenance activities, or during plant operation, IWA-5250 of Section XI requires corrective measures be taken based on repair or replacement in accordance with Section XI. In addition, a through-wall flaw does not meet the acceptance criteria in IWB-3600.
Upon discovery of leakage from a Class 1, 2, or 3 component pressure boundary (i.e., pipe wall, valve body, pump casing, etc.) the licensee should declare the component inoperable. The only exception is for Class 3 moderate energy piping as discussed in Generic Letter 90-05.
NRC staff finds our position consistent for operational leakage and alternative methods in IMC 0326 and through the history of this item.
20
Section XI Assessment of Potential New Requirements Question 4a -
- Why did we not condition 50.55a like we do in other cases to deviate from the ASME code?
- Are there other areas where our regulations go beyond what is required in the ASME code without a specific condition in the regulations?
Staff Response 4a -
- Different interpretation of the ASME Code regarding implementation under 50.55a(g)
- 50.55a(g) requires the use of Section XI throughout the service life of a facility to provide reasonable assurance of the structural integrity of safety components
- We have communicated this difference of interpretation through a significant number of guidance documents, generic communications, and even rulemaking for the incorporation of ASME Code Case N-513. (ML993280389)
The reason for incorporating the Code cases in the proposed rule was that § 50.55a(g)(4) requires the application of Section XI during all phases of plant operation. Under Section XI structural and operability requirements, piping containing indications greater than 75 percent of the pipe thickness are deemed unsatisfactory for continued service. A limitation must be included in the rulemaking to modify the above mentioned Section XI regulatory requirements.
21
Section XI Assessment of Potential New Requirements ASME Code Case N-513
- Alternative to IWA-4000 repair/replacement activity; applies only if the Code mandates repair/replacement
- Flaw geometry - volumetric inspection or physical measurement and classified as planar or non-planar
- Flaw evaluation - max allowable flaw calculated as a bounding planar or non-planar flaw size
- Measure flaws at least every 30 days or 90 days (with flaw growth-rate analysis) to track growth
- Daily leakage monitoring
- NDE on at least five of the most susceptible and accessible locations, or, if fewer than five, all susceptible and accessible locations within 30 days N-513 goes well beyond just an engineering judgement evaluation 22
Section XI Assessment of Potential New Requirements
- Question 4b -
- if there is a reason to permit the use of different methods for other operability assessments but not for operational leakage, what is the safety basis for this position?
- Staff Response 4b -
- Operational leakage is a safety concern due to the unknown condition of the component when leakage is identified
- An SSC exhibiting operational leakage could be vulnerable to structural concerns
- 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 23
Section XI Assessment of Potential New Requirements Staff Response 4b - (cont)
- In other TS, for example, a pump failing or a relief valve sticking open, the impact on operability (i.e., the capability of the SSC to perform its specified safety function) is readily evaluated
- In contrast, leakage from ASME BPV Code Class 1, 2, and 3 SSCs does not provide a clear indication for understanding the impact on the systems operability
- Operational experience has shown that a small leak may be the first and only indication of a significant degradation issue that could challenge the structural integrity of a component
- Several degradation mechanisms, such as stress corrosion cracking, thermal fatigue, flow accelerated corrosion, and general corrosion, can lead to a system being vulnerable to structural concerns while exhibiting only limited indication of leakage
- The NRC staff relies on operational leakage detection as a key defense in depth measure to identify potential degradation concerns in these SSCs 24
25 NEA Component Operational Experience, Degradation and Ageing Programme (CODAP): Second Term (2015-2017) Status Report, November 2018 - Unclassified English Text April 2019
Small Leak is Not a Small Problem 26
Section XI Assessment of Potential New Requirements Question 4c -
- did we do a backfit when we wrote 50.55(a)(g) since we deviated from the code?
Staff Response 4c -
- No, the Backfit rule was not applicable to inspection requirements when 50.55a(g) was issued (1971 and 1976)
- Additionally, 50.55a(g) established the requirement to implement Section XI of the ASME Code, which as agreed by NEI, requires IWA-4000 to be used to address defects in ASME Class 1, 2 and 3 SSCs
- It is a difference in interpretation of the impact of 50.55a(g) to require Section XI of the ASME Code as most clearly stated in the Reedy Letters
- As stated in the Reedy Letters, ASME Interpretations are not a part of the regulations 27
Operability Determinations vs Corrective Actions Question 5 -
- Industry spent some time distinguishing between and among operability determinations and repair/replacement activities. What is staff perspective on this distinction?
Staff Response 5 -
- There is no requirement for them to be separate
- Specifically, in the special case of operational leakage, corrective actions may be the only option to verify structural integrity of a TS SSC experiencing operational leakage, therefore actions to verify or restore structural integrity (i.e., corrective actions) would need to be completed within a TS specified timeframe 28
Operability Determinations vs Corrective Actions Question 5a -
- The industry stated that there was a discrepancy between IMC 0326 and the RIS. Does staff agree or disagree with this statement from industry?
Staff Response 5a -
- The NRC staff disagrees with this comment
- Section 08 of IMC 0326 is entitled, Specific Operability Issues
- Specific guidance for operational leakage is contained in Section 08.13, Operational Leakage from ASME Class 1, 2 and 3 Components
- The information provided in Section 08.13 of IMC 0326 is consistent with the clarification of options allowed to verify structural integrity as stated in the RIS 29
Operability Determinations vs Corrective Actions Question 6 -
- Industry seemed to say that they have been using various methods to support operability determinations all along. Thus this new interpretation will have a significant impact on their programs, processes, procedures. Please provide staff perspective.
Staff Response 6 -
- This has been the consistent position of the NRC and not a new interpretation
- Regional and NRC Headquarters staff have interacted on numerous operational leakage issues when licensees do not follow the generic guidance of IMC 0326. As provided in the draft public comment response there are numerous relief requests and a few violations over the years.
We can go into those examples, if desired.
- The latest change in industrys position was NEI 18-03 which states the option to use engineering judgement to evaluate leakage. NEI 18-03 itself recognizes that NEI 18-03 is not consistent with IMC 0326.
30
Operability Determinations vs Corrective Actions Question 7 -
- How have Tech Specs changed over time with respect to this issue?
- Does that history support staff position?
Staff Response 7 -
- The first revisions of the standard technical specifications (STS) contained limiting conditions for operations (LCOs) that addressed structural integrity. The structural integrity LCOs, as adopted in plant-specific technical specifications (TS), required licensees to maintain structural integrity for ASME Code Class 1, 2 and 3 components. This specification supported assurance that structural integrity and operational readiness of these components would be maintained at an acceptable level throughout the life of the facility. The specification was applicable in all operational modes. Throughout the years, licensees requested, and the NRC authorized, the removal or relocation of this specification, in part, because it eliminated the redundancy of structural integrity requirements already covered under 10 CFR 50.55a.
31
Operability Determinations vs Corrective Actions Staff Response 7 -
- Another justification for removing the structural integrity LCO from the TS was because the definition of OPERABLE - OPERABILITY in the STS (and adopted in plant-specific TS) describes a structure, systems and components (SSCs) as being OPERABLE or have OPERABILITY when the SSC is capable of performing its specified safety function(s). TS SSCs that do not have structural integrity are not capable of performing their specified safety functions. Therefore, the definition of OPERABLE - OPERABILITY incorporates the requirements of 10 CFR 50.55a and provides a direct relationship between operability and structural integrity.
Consequently, while the content of the TS may have changed, the way the requirements are implemented has not: an SSC that does not maintain structural integrity is inoperable.
- Also, TS are independent of ASME code requirements in 50.55a. TS can only implement more restrictive requirements that are compliant with the code. For this reason, licensees must use Code methodologies to assess operability for conditions addressed by the ASME code. Operational leakage, by definition, does not meet ASME Code acceptance criteria: through-wall leakage does not need further evaluation to determine that Section XI requires repair/replacement activities.
32
Operability Determinations vs Corrective Actions
- Staff Response 7 -
- Additionally, an April 22, 1993, memorandum from NRR/ORS to NRR/DE, Structural Integrity Technical Specifications, clarified the Technical Specifications Branchs position regarding the treatment of structural integrity in TS and the relocation of the structural integrity TS outside of TS
- The memo clarified that the basis for removal was, in part, because an Inservice Inspection Program for ASME Code Class 1, 2, and 3 components meets the requirements of Section XI of the ASME B&PV Code and 10 CFR 50.55a (ML20236K883)
- The enclosure to the memo stated that the position had been reviewed by legal staff, the Office of Enforcement, Technical Specification Branch and Director, DET (ML19339G863) 33
Operability Determinations vs Corrective Actions Question 8 -
- Page 7 of the staffs response to comments on the RIS states, to evaluate the structural integrity of the leaking component, the licensee may use the criteria in Section XI of the ASME code, the construction code, or any applicable ASME Code case approved by the NRC. This seems to imply that methods other than those specified in ASME Section XI may be used to evaluate operational leakage. How does the staff interpret this language?
Staff Response 8 -
- The NRC staff was not intending to restrict the options available to licensees through the RIS. The RIS clarifies the various NRC approved options of Section XI or the construction code, which is always available, or any approved ASME Code case approved by the NRC. For example, ASME Code case N-752 has not yet been approved for use by the NRC in 50.55a, but it could be an option for licensees to address operational leakage requirements in the future based on a risk informed approach.
34
Repair and Replacement Question 9a -
- Industry agreed that repair/replacement must conform to Code requirements throughout service life (and it is not just limited to preservice or inservice inspection activities). Industry spent some time on differentiating between corrective actions and operability determinations.
Please provide staff perspective.
Staff Response 9a -
- It is the longstanding, consistent NRC position that the special case of operational leakage renders a component inoperable until an ASME code repair/replacement or NRC approved alternative is performed
- ASME Case N-513 is an example of an NRC approved, ASME Code alternative to repair/replacement that provides a methodology to evaluate leakage, perform NDE, expand examinations to similar locations and provides monitoring requirements
- Other alternatives may be approved by the NRC as an alternative or as relief from the requirements of repair/replacement 35
Repair and Replacement Question 9b -
- Please also provide information on what information in GL 90-05 provides the staff interpretation that methods specified in the code be used for operability determinations related to operational leakage Staff Response 9b -
GL 90-05, at its time of issuance, was the only option other than ASME Code repair/replacement to address operational leakage.
- of GL 90-05 provides guidelines for the staff to accept relief requests for enhanced surveillance as a non-code repair, but only if a code repair would cause a shutdown of the plant Section XI of the ASME Boiler and Pressure Vessel Code (hereafter called the code) specifies code-acceptable repair methods for flaws that exceed code acceptance limits in piping that is in service. [a through-wall flaw exceeds those limits] A code repair is required to restore the structural integrity of flawed ASME Code piping, independent of the operational mode of the plant when the flaw is detected. Those repairs not in compliance with Section XI of the ASME Code are non-code repairs. [Hence, they are not allowed as an option.] However, the required code repair may be impractical for a flaw detected during plant operation unless the facility is shut down.
36
Repair and Replacement Staff Response 9b (cont)
- The staff continues [notice we continue] to find temporary non-code repairs of code Class 1, 2 and 3 piping unacceptable without specific written relief granted by the NRC. However, this generic letter provides guidance that will be considered by the NRC staff in evaluating relief requests submitted by licensees for temporary non-code repairs [again the GL 90-05 option is a flaw evaluation, sampling and leakage monitoring program] of code Class 3 piping.
- So, if a licensee had the option to use any engineering judgement to evaluate operational leakage, why would they ever be in a position to need to use GL 90-05?
- If the leakage is minor, as allowed by GL 90-05, why would a licensee ever make the engineering judgement assessment that they have to shut down the plant and repair the component, unless it was a regulatory requirement?
37
Repair and Replacement Staff Response 9b (cont)
- Additional discussion of GL 90-05 implementation is provided in an August 16, 1990, memorandum from NRR/DE Director to all regional DRS Directors (ML20059A928)
- Additional information can be provided for GL 90-05 specifically in a Memo to address TIA 92-09. (ML18153D060)
- These documents again substantiates the NRC position on options available to address operational leakage, specifically GL 90-05 and operability options for the time period each addresses.
38
Repair and Replacement Question 10a -
- Industry disagrees with the notion that approved Section XI methods must be the exclusive approach when determining operability. ASME does not have the answer to all techniques/methods/materials/configurations. This would mean that NRC approval will be needed for all operability determinations if there is no ASME-approved approach. It would mean that if there isnt an approved ASME method, an SSC will have to be declared inoperable when there isnt a safety issue (e.g., pinhole leak too small to cause concern) and lead to unnecessary plant shutdowns. Please provide staff perspective.
Staff Response 10a -
- Section XIs repair/replacement is available for all situations
- NEI 18-03 took the position that engineering judgement can be used when ASME alternatives to repair/replacement are not available
- The issue for industry is that TS may mandate structural integrity be verified on a potentially faster timeline than what may be feasible for repair/replacement to avoid shutdown
- The issue for NRC staff is that without an appropriate evaluation, it is not safe to determine that a leak isnt an indication of a more severe safety problem 39
Repair and Replacement Staff Response 10a (cont)
- Additionally, in the draft public comment response, the NRC staff noted the NEI comment on leakage from drain lines or branch connections whose complete failure could not challenge the structural integrity of the main piping line which is required to maintain its safety function by TS.
- Therefore, NRC staff are proposing additional clarification to be included.
40
Repair and Replacement Question 10b -
- In the staffs response to Comments on the RIS, page 8, we point to IMC 0326 Section 8.12 which states if flaws are found in components for which ASME Section XI has no acceptance standards, then the construction codes is to be used. Does this mean that the staff agrees that if a condition other than those in Section XI exists, that methods other than those used in Section XI of the code may be used?
Staff Response 10b -
- Section XI, Repair/Replacement is always an option for any SSC
- But yes, other NRC approved methods may be used, such as the construction code
- A licensee may also use a proposed alternative under 10 CFR 50.55a(z) 41
Requirements for Structural Integrity Initial license identifies SSC necessary for safety Design of SSC by Construction Code is based on maintaining structural integrity for license duration Technical specifications
- Specify the SSC required for safe operation
- Operability requirements for safety
- Structural integrity fundamental basis for performing intended function of SSC 10 CFR 50.55a(g) mandates the use of Section XI for inservice requirements to provide reasonable assurance of structural integrity 42
Inspection Manual Chapter 0326, Revision 2, 2019 43 10 CFR 50.55a requires that the structural integrity of ASME Code Class 1, 2, and 3 components be maintained in accordance with the ASME Code or construction code acceptance standards.
If a leak is discovered in a Class 1, 2, or 3 component while conducting an in-service inspection, maintenance activity, refueling outage, or during facility operation, appropriate corrective measures to repair or replace the leaking component must be performed in accordance with IWA-4000 of Section XI.
Options to Address Operational Leakage
- Draft RIS language
- Recognizes ASME Code interpretation issue
- Clarifies that §50.55a(g) requires operational leakage must be addressed in the same manner as leakage detected during an ASME BPV Code,Section XI, pressure test
- Applies to the same scope
- Allows the same options to address leakage
- Repair/Replacement is an option for any SSC
- Clarifies proposed alternative options to the regulations through §50.55a(z)
- One goal of draft RIS clarification is for development of additional options beyond repair/replacement activities 44
Discussion 45