ML25128A271
| ML25128A271 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 05/20/2025 |
| From: | David Wrona Plant Licensing Branch II |
| To: | Coffey B Florida Power & Light Co |
| Jordan N | |
| References | |
| EPID L-2024-LLR-0052 | |
| Download: ML25128A271 (9) | |
Text
May 20, 2025 Mr. Bob Coffey Executive Vice President, Nuclear and Chief Nuclear Officer Florida Power & Light Company 700 Universe Blvd.
Mail Stop: EX/JB Juno Beach, FL 33408
SUBJECT:
ST. LUCIE PLANT, UNIT NO. 2 - RELIEF REQUEST #14 - LIMITED EXAMINATION COVERAGE FOURTH INSERVICE INSPECTION INTERVAL (EPID L-2024-LLR-0052)
Dear Mr. Coffey:
By letter dated August 7, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24220A148), Florida Power and Light Company (the licensee) submitted Relief Request (RR) #14 to the U.S. Nuclear Regulatory Commission (NRC),
requesting relief from certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME B&PV Code),Section XI, Rules for Inservice Inspection [ISI] of Nuclear Power Plant Components, for the fourth ISI interval at St. Lucie Nuclear Plant, Unit 2 (St. Lucie Unit 2).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii),
the licensee requested relief from the essentially 100 percent volumetric examination coverage requirements of ASME B&PV Code,Section XI on the basis that the required examination coverage is impractical due to physical obstructions and limitations imposed by the design, geometry, and materials of construction of the subject components.
As set forth in the enclosed safety evaluation, the NRC staff has determined that granting the licensees request for relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Furthermore, the staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii) and grants relief pursuant to 10 CFR 50.55a(g)(6)(i) for the examinations of the subject components contained in RR#14, for the fourth 10-year ISI interval at St. Lucie Unit 2.
All other ASME B&PV Code,Section XI, requirements for which an alternative was not specifically requested and authorized remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
If you have any questions, please contact the Project Manager, Natreon (Nate) Jordan at (301) 415-7410 or by email at Natreon.Jordan@nrc.gov.
Sincerely, David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-389
Enclosure:
Safety Evaluation cc: Listserv DAVID WRONA Digitally signed by DAVID WRONA Date: 2025.05.20 13:18:14 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST RR#14 LIMITED EXAMINATION COVERAGE FOURTH INSERVICE INSPECTION INTERVAL FLORIDA POWER AND LIGHT COMPANY ST. LUCIE NUCLEAR PLANT, UNIT 2 DOCKET NO. 50-389 EPID NO. L-2024-LLR-0052
1.0 INTRODUCTION
By letter dated August 7, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24220A148), Florida Power and Light Company (the licensee) submitted Relief Request (RR) #14 to the U.S. Nuclear Regulatory Commission (NRC),
requesting relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME B&PV Code),Section XI, Rules for Inservice Inspection [ISI]
of Nuclear Power Plant Components, for the fourth ISI interval at St. Lucie Nuclear Plant, Unit 2 (St. Lucie Unit 2).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii),
the licensee requested relief from the essentially 100 percent volumetric examination coverage requirements of ASME B&PV Code,Section XI on the basis that the required examination coverage is impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the subject components.
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(g)(4) state that ASME B&PV Code, Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME B&PV Code,Section XI to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME B&PV Code, which was incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
Pursuant to 10 CFR 50.55a(g)(5)(iii), a licensee may determine that conformance with certain ASME B&PV Code requirements is impractical, and that the licensee shall notify the Commission and submit information in support of the determination. Determination of impracticality in accordance with this section must be based on the demonstrated limitations experienced when attempting to comply with the code requirements during the ISI interval for which the request is being submitted. The RRs made in accordance with this section must be submitted to the U.S. Nuclear Regulatory Commission (NRC or the Commission) no later than 12 months after the expiration of the initial 120-month inspection interval or subsequent 120-month inspection interval for which relief is sought.
Pursuant to 10 CFR 50.55a(g)(6)(i), the NRC will evaluate determinations under paragraph (g)(5) of this section that code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the NRC to grant the relief requested by the licensee.
3.0 TECHNICAL EVALUATION
3.1 ASME B&PV Code Components Affected Code Class:
Class 1 and 2 Examination Category:
R-A, Risk-Informed Piping Examinations Item Number: R1.11, R1.16, R1.20 Components: Pressure retaining piping welds 3.2 ASME B&PV Code Edition and Addenda The licensee stated that the fourth 10-year ISI interval of St. Lucie Unit 2 ended on August 7, 2023, and was based on the ASME Code,Section XI, 2007 Edition with the 2008 Addenda.
3.3 ASME B&PV Code Requirement The examination requirements for the subject piping welds at St Lucie Unit 2, are governed by a risk-informed inservice inspection (RI-ISI) program that was approved by the NRC in a safety evaluation, dated August 10, 2015 (ML15196A623). The licensee RI-ISI program was developed in accordance with the NRC-approved methodology of Electric Power Research Institute Topical Report-112657, Revision B-A, Revised Risk-Informed lnservice Inspection Evaluation Procedure (ML013470102).
Additionally, ASME B&PV Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1, which defines greater than 90 percent coverage of an examination volume or a surface area, as applicable, as essentially 100 percent. ASME
B&PV Code Case N-460 is an NRC-approved alternative that can be used by licensees, as referenced in Regulatory Guide 1.147, Revision 20, Inservice Inspection Code Case Acceptability (ML16321A336).
In addition, pursuant to 10 CFR 50.55a(b)(2)(xv)(A)(1) and 10 CFR 50.55a(b)(2)(xv)(A)(2), full coverage credit from a single side of an austenitic weld may be claimed only after completing a successful single-sided ASME B&PV Code,Section XI, Appendix VIII demonstration using flaws on the opposite side of the weld. To date, no examination procedure has successfully passed ASME B&PV Code,Section XI, Appendix VIII, Supplement 2 demonstration testing from a single side of an austenitic weld, limiting single-sided examinations to 50 percent coverage.
3.4 Reason for Relief Request The licensee achieved the volumetric examination coverages shown in Table 1 for the subject Examination Category R-A welds. The licensee stated that in accordance with 10 CFR 50.55a(g)(5)(iii), relief is requested on the basis that conformance with these ASME B&PV Code,Section XI requirements is impractical since conformance would require extensive structural modifications to the component or the surrounding structure. The licensee also stated that compliance with the applicable ASME B&PV Code,Section XI volumetric and surface examination requirements can only be accomplished by redesigning and refabricating the subject and/or surrounding components. The licensee summarized the limitations for each subject Examination Category R-A weld in Table U2-I4-PSI and Table U2-I4-ISI in Attachment 1 to the submittal and included corresponding details in Attachment 2 to the submittal. The licensees Examination Category R-A welds with limited examination coverage St. Lucie Unit 2, are summarized below, along with the achieved examination coverage for each of the welds for which relief was needed.
Table 1 ASME B&PV Code,Section XI, Examination Category R-A ASME B&PV Code Item Component ID Weld Description Percent Coverage Obtained R1.20 Sl-151-FW-4-R Pipe to Valve 50 R1.20 RC-153-FW-1-R Pipe to Valve 50 R1.20 Sl-181-FW-14 Valve to Pipe 50 R1.16 Sl-191-FW-1 Pipe to Valve 50 R1.11 Sl-191-FW-2000 Pipe to Valve 50 R1.11 Sl-191-FW-2001 Pipe to Valve 50 R1.20 Sl-191-FW-2003 Pipe to Pipe 50 R1.20 Sl-515-FW-2001 Valve to Pipe 50 R1.20 Sl-113-FW-2000 Pipe to Pipe 50 R1.20 Sl-113-FW-2001 Pipe to Valve 50 R1.20 RC-151-FW-2 Elbow to Safe End 86 R1.20 RC-152-FW-2 Elbow to Safe End 85 R1.20 RC-153-FW-2 Elbow to Safe End 83 R1.20 RC-154-FW-2 Elbow to Safe End 86
Table 1 ASME B&PV Code,Section XI, Examination Category R-A ASME B&PV Code Item Component ID Weld Description Percent Coverage Obtained R1.11 RC-103-FW-2003 Reducer to Tee 84 R1.11 CH-148-FW-20 Valve to Pipe 50 3.5 Proposed alternative and Basis for Relief Request The licensee stated that St. Lucie Unit 2 performed the ASME B&PV Code, Section XI-required examinations to the maximum extent practical, which are documented in Table U2-I4-PSI and Figures 1 through 15 of the submittal. Due to physical interferences or component geometry, the licensee stated that there were no other examination techniques available to increase examination coverage without major modification to the components.
The licensee determined that the ASME B&PV Code-required volumes of the subject welds were examined to the maximum extent possible using Performance Demonstration Initiative (PDI)-qualified ultrasonic testing (UT) techniques. Additionally, the licensee stated that no alternative methods or advanced technologies were considered capable of obtaining complete coverage of the examination volume. Based on the weld configurations, the examinations were limited to single-sided access, and relief was requested from complying with the essentially 100 percent required examination coverage.
At present, no PDI-qualified single-sided examination procedures have demonstrated equivalency to two-sided examinations for austenitic piping welds. None of the current technology is capable of reliably detecting or sizing flaws on the opposite side of an austenitic weld. Therefore, the licensee requested relief from complying with the ASME B&PV Code-required volumetric examinations of the subject components.
In lieu of meeting the examination coverage requirements of ASME B&PV Code,Section XI, the licensee has proposed an alternative examination coverage for the subject welds, as detailed in Table 1. The basis of this proposed alternative is that the licensee has performed the ASME B&PV Code, Section XI-required examinations to the maximum extent practical, utilizing PDI-qualified personnel, techniques, and equipment. Additionally, the licensee stated that the volumetric examination coverage obtained, along with a visual examination (VT-2) conducted during each inspection period, provides adequate monitoring.
3.6 Duration of Relief Request The licensee submitted RR#14 for the fourth 10-year ISI interval at St. Lucie Unit 2, which began on August 8, 2013, and ended on August 7, 2023.
3.7
NRC Staff Evaluation
For the subject Examination Category R-A welds, the licensee obtained the volumetric examination coverages from 50 to 86 percent with no recordable indications, using procedures, equipment, and personnel qualified using ASME B&PV Code,Section XI, Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems. The licensee achieved less than the required volumetric examination coverage due to geometric, material, and physical
limitations that would entail modification of the associated components if the required coverage were to be obtained. The NRC staff finds the stated limitations to be an acceptable basis for impracticality of conforming to the requirements and finds the modification necessary to achieve the required coverage constitutes a burden upon the licensee.
The licensee examined the subject welds to the maximum extent practical using volumetric examination. However, due to the noted limitations, the licensee was not able to achieve the required examination volumes for the subject welds. The NRC staff reviewed and verified the examination coverages achieved. The NRC staff determined that subject welds had acceptable results for volumetric pre-service inspections and satisfied the VT-2 examination. The NRC staff finds the licensees achieved coverages acceptable, given the noted limitations.
Given the examination results and coverage obtained, the NRC staff concludes that, if significant service-induced degradation had occurred in the subject welds, evidence of it would have been detected by the examinations performed. Therefore, the NRC staff determined that the examinations performed provide reasonable assurance of structural integrity of the subject welds.
Based on the above discussion, the NRC staff determined that obtaining the ASME B&PV Code-required examination volume coverage for the subject Examination Category R-A welds at St. Lucie Unit 2 is impractical because of the stated limitations and that the modifications necessary to obtain the required coverage would impose a burden upon the licensee. The NRC staff also determined that the volumetric examination performed to the maximum extent practical provide reasonable assurance of the structural integrity of the weld because: (1) the coverage was calculated in a reasonable manner; (2) the personnel and UT procedures utilized for the volumetric examination were qualified as required by the regulation; (3) the coverage was limited by physical limitations or access, and (4) no unacceptable indications were identified.
As shown in the figures and technical descriptions included in the licensees submittal, the subject welds in RR #14 are all austenitic stainless steel piping welds with geometric limitations that restricted performing ultrasonic scanning from both sides of the welds. However, volumetric examinations on the subject welds were conducted with equipment, procedures, and personnel that were qualified to a performance demonstration process outlined in the ASME B&PV Code,Section XI, Appendix VIII. These techniques have been qualified through the PDI, which meets the intent of the ASME B&PV Code,Section XI, Appendix VIII requirements for flaws located on the near side of the welds. Far-side detection of flaws is considered to be a best effort. The NRC staff finds that the licensees achieved examination coverage constitutes a best effort and is considered justified.
Although the ASME B&PV Code-required coverage could not be obtained, the ultrasonic techniques employed by the licensee provided nearly full volumetric coverage for the near side of the welds. Based on the volumetric coverage achieved for the subject welds on the near side of the weld and the best efforts done for the far side of these welds, had significant flaws been present on the far side, the licensee would have been able to detect them. Additionally, considering the aggregate coverage obtained for the subject austenitic stainless steel welds, the extent of the examinations, and considering the licensees performance of essentially 100 percent examination coverage for the accessible portions of these welds, it is reasonable to conclude that had significant flaws been present in these welds, they would have been detected by the licensee.
4.0 CONCLUSION
S As set forth above, the NRC staff has determined that granting relief pursuant to 10 CFR 50.55a(g)(6)(i) is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise in the public interest given due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Furthermore, the NRC staff concluded that the examinations performed to the extent practical provide reasonable assurance of structural integrity of the subject components.
Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii) and grants relief pursuant to 10 CFR 50.55a(g)(6)(i) for the examinations of the subject components contained in RR#14, for the fourth 10-year ISI interval at St. Lucie Unit 2.
All other ASME B&PV Code,Section XI requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: K. Sida Date: May 20, 2025
- via eConcurrence NRR-028 OFFICE NRR/DORL/LPL2-2/PM*
NRR/DORL/LPL2-2/LAiT NRR/DNRL/NPHP/BC*
NAME NJordan CAdams (SL)
MMitchell DATE 5/8/2025 5/13/2025 3/18/2025 OFFICE NRR/DORL/LPL2-2/BC*
NAME DWrona DATE 5/20/2025