NL-24-0397, Response to Request for Additional Information Regarding Proposed Alternative to Use ASME Code Case N-752, Risk-Informed Categorization and Treatment for Repair/ Replacement
| ML24320A129 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Vogtle, Farley  |
| Issue date: | 11/15/2024 |
| From: | Coleman J Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NL-24-0397 | |
| Download: ML24320A129 (1) | |
Text
3535 Colonnade Parkway Birmingham, AL 35243 205 992 5000 tel Regulatory Affairs November 15, 2024 Docket Nos.: 50-424 50-348 50-321 NL-24-0397 50-425 50-364 50-366 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Edwin I. Hatch Nuclear Plant Units 1&2 Joseph M. Farley Nuclear Plant Units 1&2 Vogtle Electric Generating Plant Units 1&2 Response to Request for Additional Information Regarding Proposed Alternative to Use ASME Code Case N-752, Risk-Informed Categorization and Treatment for Repair/ Replacement Activities in Class 2 and 3 Systems,Section XI, Division 1 Ladies and Gentlemen:
By letter dated June 27, 2024 [ML24179A334], Southern Nuclear Operating Company (SNC) requested the Nuclear Regulatory Commissions (NRC) authorization of a proposed alternative GEN-ISI-ALT-2024-01 to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. The proposed alternative would allow the use the alternative requirements of Code Case N-752, Risk Informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 Systems,Section XI, Division 1, for determining the risk-informed categorization and for implementing alternative treatment for repair/replacement activities on moderate and high energy Class 2 and 3 items in lieu of certain ASME Boiler and Pressure Vessel Code,Section XI, IWA-1000, IWA-4000, and IWA-6000 requirements.
By email dated October 16, 2024, NRC staff sent SNC a request for additional information (RAI)
[ML24290A155] regarding the aforementioned alternative request. The enclosure to this letter provides a response to the NRC staffs RAI.
No regulatory commitments are contained in this submittal. If you have any questions, please contact Ryan Joyce at 205.992.6468.
U. S. Nuclear Regulatory Commission NL-24-0397 Page 2 of 2 Respectfully, Jamie M. Coleman Regulatory Affairs Director
Enclosure:
Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Cc:
Regional Administrator, Region ll NRR Project Manager - Farley, Hatch, Vogtle 1 & 2 Senior Resident Inspector - Farley, Hatch, Vogtle 1 & 2 RTYPE: CGA02.001
Edwin I. Hatch Nuclear Plant - Units 1 and 2 Joseph M. Farley Nuclear Plant - Units 1 and 2 Vogtle Electric Generating Plant - Units 1 and 2 Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 1 of 6 By letter dated June 27, 2024 [ML24179A334], Southern Nuclear Operating Company (SNC) requested the Nuclear Regulatory Commissions (NRC) authorization of a proposed alternative GEN-ISI-ALT-2024-01 to allow the use of American Society of Mechanical Engineers (ASME)
Code Case N-752 Risk-Informed Categorization and Treatment for Repair/Replacement Activities in Class 2 and 3 SystemsSection XI, Division 1. By email dated October 16, 2024,
[ML24290A155] NRC staff sent SNC requests for additional information (RAIs) regarding the aforementioned alternative request. Each RAI is repeated below in italicized font, followed by SNCs response to each RAI in plain font.
RAI-1
Section 5.1, Overview of Code Case N-752, the licensee states the following:
The categorization and treatment requirements of Code Case N-752 are consistent with those in 10 CFR 50.69.
The NRC regulations in 10 CFR 50.69 specifies requirements regarding the categorization and treatment of SSCs. For example, 10 CFR 50.69 includes the following:
10 CFR 50.69(c), SSC Categorization Process.
(1) SSCs must be categorized as RISC-1, RISC-2, RISC-3, or RISC-4 SSCs using a categorization process that determines if an SSC performs one or more safety significant functions and identifies those functions. The process must:
(v) Be performed for entire systems and structures, not for selected components within a system or structure.
10 CFR 50.69(d), Alternative treatment requirements.
(2) RISC-3 SSCs. The licensee or applicant shall ensure, with reasonable confidence, that RISC-3 SSCs remain capable of performing their safety related functions under design basis conditions, including seismic conditions and environmental conditions and effects throughout their service life. The treatment of RISC-3 SSCs must be consistent with the categorization process. Inspection and testing, and corrective action shall be provided for RISC-3 SSCs.
(i) Inspection and testing. Periodic inspection and testing activities must be conducted to determine that RISC-3 SSCs will remain capable of performing their safety-related functions under design basis conditions; and (ii) Corrective action. Conditions that would prevent a RISC-3 SSC from performing its safety-related functions under design basis conditions must be corrected in a timely manner. For significant conditions adverse to quality, measures must be taken to provide reasonable confidence that the cause of the condition is determined and corrective action taken to preclude repetition.
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 2 of 6 The licensee is requested to describe the following:
- a. the provisions of the SNC Fleet categorization process that are consistent with 10 CFR 50.69(c)(1)(v) recognizing that industry guidance cannot modify NRC regulations without rulemaking.
- b. the provisions of the SNC Fleet treatment process that are consistent with 10 CFR 50.69(d) with respect to inspection, testing, and corrective action for safety-related SSCs categorized as low safety significant (LSS) to provide a technically defensible method for the treatment of LSS safety-related SSCs as indicated by the Commission guidance in the Federal Register notice (69 FR 68008) describing acceptable implementation of 10 CFR 50.69 programs.
SNC Response to RAI-1
- a. The Code Case N-752 categorization process or methodology strictly applies to the passive or pressure retaining function of Class 2 and 3 components or items. The Code Case N-752 categorization process is the same as the process (i.e., the Arkansas Nuclear One, Unit 2 passive categorization methodology) used for passive component categorizations in the typical 50.69 applications approved by the NRC to date, including as incorporated into the approved 50.69 categorization process for SNC. The basis for applying this categorization process to individual items within a system is addressed in Section 5.2.A of the SNC alternative request. It does not apply to the active functions of components that have both passive and active functions such as pumps and valves.
The SNC alternative request is requesting approval to use Code Case N-752 including its categorization process. While Section 5.1 of the alternative request notes that the categorization requirements of Code Case N-752 are consistent with those used under 50.69, this alternative request is not proposing to comply with or seeking alternatives from the categorization requirements of 50.69.
- b. Under 50.69(d)(2), the licensee or applicant is responsible for establishing alternative treatment requirements that ensure with reasonable confidence that RISC-3 SSCs remain capable of performing their safety related functions under design basis conditions throughout their service life. Inspection, testing, and corrective actions must be performed. These alternative treatment requirements are not required to comply with various regulations including 10 CFR 50.55a(g) and 10 CFR 50 Appendix B.
Under Code Case N-752, the Owner is also responsible for establishing alternative treatment requirements that ensure with reasonable confidence that each LSS item remains capable of performing its safety related functions under design basis conditions.
However, unlike 50.69(d)(2) that does not specify explicit requirements or restrictions for controlling implementation of these alternative treatments, Code Case N-752 does.
According to Section -1420 of Code Case N-752, the Owner must specify or establish process requirements applicable to design control, procurement, installation, configuration control, corrective action, etc. to ensure that LSS items remain capable of performing their safety related functions under design basis conditions. These process
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 3 of 6 requirements must also comply with the treatment provisions of paragraphs -1420(a) through (h). Code Case N-752 requirements applicable to ISI, IST, and corrective action are described below and in Items 11 and 12 of Section 5.2.E of the SNC alternative request. Therefore, while the alternative treatment provisions of Code Case N-752 are consistent with 50.69 with respect to LSS items, they are also more conservative in that they include requirements and controls not specified in 50.69(d).
Code Case N-752 only applies to performance of repair/replacement activities on Class 2 and 3 items. Therefore, ISI and IST on Class 2 and 3 LSS items must continue to comply with the SNC ISI and IST programs implemented in accordance with 10 CFR 50.55a.
Code Case N-752, Section -1420 requires the Owner to establish requirements for corrective action. As stipulated in paragraph 5.2.E.12, SNC has committed to performing corrective action in accordance with its Corrective Action Program which complies with 10 CFR 50 Appendix B.
The SNC alternative request is requesting approval to use Code Case N-752 including its alternative treatment provisions for items categorized as LSS. While Section 5.1 of the alternative request notes that the treatment requirements of Code Case N-752 are consistent with those in 50.69, this alternative request is not proposing to comply with or seeking alternatives from the treatment requirements of 50.69.
RAI-2
The alternative request includes statements regarding treatment requirements established by the Owner such as the following:
treatment requirements established by the Owner Owner to define alternative treatment requirements SNC will develop and/or revise existing procedures and documents to define treatment requirements Owners Requirements shall be met requirements shall be established by the Owner SNC will define alternative treatment requirements Owner-defined administrative requirements on LSS items Further, Item 14 of Paragraph E, Treatment Requirements for LSS Items, of the alternative request states the following:
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 4 of 6 For SNC nuclear sites having received NRC authorization to use the alternative repair/replacement categorization and treatment requirements of ASME Code Case N-752 in lieu of the corresponding sections of ASME Section XI, as referenced in 10 CFR 50.55a Codes and Standards, treatment of safety-related structures, systems, and components identified as low safety significant (LSS) Class 2 and 3 SSCs in accordance with ASME Code Case N-752 is not required to meet the requirements of this manual
[SNC Quality Assurance Topical Report (QATR)]. Instead, treatment of these LSS SSCs is performed in accordance with existing QA Program procedures and processes which include supplemental controls to ensure the capability and reliability of the SSCs design basis function.
The licensee is requested to clarify these statements because QA and treatment activities for LSS safety-related SSCs remain within the scope of 10 CFR Part 50, Appendix B, when implementing Code Case N-752, with risk-informed relaxation of specific activities allowed by the NRC when authorizing N-752 requests, with the design, licensing basis, and regulatory enforcement remaining subject to 10 CFR Part 50, Appendix B, regardless of the change to the SNC QATR.
SNC Response to RAI-2 SNC intends to implement the QATR change described in Section 5.2.E.14 as permitted in 10 CFR 50.54(a)(3)(ii). Under this proposed change, the SNC QATR will allow repair/replacement activities on items categorized as LSS to be in accordance with Code Case N-752 provided treatment of these LSS SSCs is performed in accordance with existing QA Program procedures and processes which include supplemental controls to ensure capability and reliability of the SSC design basis function. These supplemental controls include conducting receipt inspections using qualified inspection personnel consistent with SNC's procurement requirements and prohibiting suppliers of Class 2 and 3 SSCs and subparts from making design changes or changes to the procurement order without prior SNC approval. SNC believes that implementation of this QATR change will provide reasonable assurance that Class 2 and 3 LSS SSCs will remain capable of performing their safety related functions under design basis conditions.
SNC agrees that the treatment provisions of Code Case N-752 on Class 2 and 3 LSS items are required to comply with 10 CFR 50 Appendix B. However, SNC is not proposing an alternative to 10 CFR 50 Appendix B. Rather, SNC is proposing to implement a change to its QATR that would allow use of Code Case N-752 for plants that are authorized to use the Code Case. The proposed QATR change is the same as that which was initially approved by the NRC for Entergys Quality Assurance Program Manual (QAPM) in accordance with 10 CFR 50.54(a)(4) as documented in a safety evaluation dated May 19, 2021 [ML21132A279]. Since the approval of Entergys Code Case N-752 alternative and associated QAPM change, the NRC has approved three additional Code Case N-752 alternative requests for thirteen plants, all of which implemented the approved Entergy QAPM change as permitted in 10 CFR 50.54(a)(3)(ii).
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 5 of 6
RAI-3
An alternative request under 10 CFR 50.55a(z) cannot grant an exemption to 10 CFR Part 50, Appendix B, requirements. The NRC staff approved the Arkansas Nuclear One (ANO) precedent, referenced in the SNC Fleet request, on the basis that the QA Manual changes were acceptable for meeting 10 CFR Part 50, Appendix B, for LSS safety-related SSCs when implementing Code Case N-752. In its evaluation of the ANO request, the NRC staff determined that the relaxed requirements did not constitute a reduction in the effectiveness for the LSS items and continue to meet 10 CFR Part 50, Appendix B.
The SNC Fleet alternative request includes statements regarding exemptions such as the following:
LSS components are exempt from ASME Section XI repair/replacement requirements In light of these statements and the above discussion, the licensee is requested to clarify the statements in the SNC Fleet alternative request regarding:
(1) the applicability of 10 CFR Part 50, Appendix B, during the use of Code Case N-752, (2) the submittals reference to the use of Code Case N-752 without exception although Appendix B will continue to apply, (3) meeting reasonable confidence vs. reasonable assurance to confirm that Appendix B will continue to be met, and (4) updates to the QATR regarding Class 2 and 3 LSS items in that these items are not exempt from Appendix B.
Also, please discuss whether these clarifications will result in changes to the SNC plans for updating the QATR under 10 CFR 50.54.
SNC Response to RAI-3 (1) As discussed in the response to RAI-2 above, SNC is not proposing an exemption from 10 CFR 50 Appendix B. Rather, the proposed alternative would allow for altering the treatment of LSS components under the provisions of 10 CFR 50 Appendix B. To facilitate this, SNC is proposing to implement a change to its QATR that was initially approved by the NRC for Entergy in accordance with 10 CFR 50.54(a)(4) as discussed in the response to RAI-2 above. SNC intends to update the QATR as stated in Item 14 of Paragraph 5.2.E of the alternative request dated June 27, 2024 [ML24179A334] in accordance with the provisions of 10 CFR 50.54(a)(3)(ii).
(2) Although Code Case N-752 takes exception to IWA-1400(o) (IWA-1400(n) of the ASME Section XI Code of record for the applicable SNC sites), footnote 1 in Code Case N-752 states that if compliance with 10 CFR 50 Appendix B or NQA-1 is required at the Owners facility, IWA-1400(o) is not exempt.
Enclosure to NL-24-0397 Response to Request for Additional Information Regarding Proposed Alternative GEN-ISI-ALT-2024-01 Page 6 of 6 (3) Under Code Case N-752, SNC is responsible for confirming with reasonable confidence that LSS items remain capable of performing their safety related functions under design basis conditions. This is a requirement of Code Case N-752, Section -1400. In addition, SNCs application of the Appendix B controls as outlined in Section 5.2 of the alternative request provide reasonable assurance that LSS items remain capable of performing their safety function under design basis conditions.
(4) See item (1) above.