ML25322A536
| ML25322A536 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 12/05/2025 |
| From: | Undine Shoop Plant Licensing Branch 1 |
| To: | Casulli E Susquehanna |
| Klett A | |
| References | |
| EPID L-2024-LLR-0056 | |
| Download: ML25322A536 (0) | |
Text
December 5, 2025 Mr. Edward Casulli Senior Vice President Susquehanna Nuclear, LLC President and Chief Nuclear Officer Susquehanna Nuclear LLC 769 Salem Boulevard Berwick, PA 60555
SUBJECT:
SUSQUEHANNA STEAM ELECTRIC STATION, UNITS 1 AND 2 - RELIEF REQUEST 4RR-12, INSERVICE INSPECTION IMPRACTICALITY DURING THE FOURTH 10-YEAR INTERVAL (EPID L-2024-LLR-0056)
Dear Mr. Casulli:
By letter dated May 20, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25140A973), Susquehanna Nuclear, LLC (the licensee), submitted Relief Request 4RR-12 pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g)(5)(iii), requesting relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, for the Susquehanna Steam Electric Station (SSES), Units 1 and 2. The request pertains to volumetric and/or surface examinations of specific reactor pressure vessel (RPV) and associated component welds during the fourth 10-year inservice inspection (ISI) interval, which concluded on May 31, 2024.
Specifically, pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the essentially 100 percent volumetric and/or surface examination coverage requirements of ASME Code,Section XI, for reactor pressure vessel (RPV) welds and reactor core isolation cooling pump attachment welds on the basis that compliance with the requirement is impractical.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that SSES has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(5)(iii). The NRC staff further concludes 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 giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Therefore, the NRC staff grants relief pursuant to 10 CFR 50.55a(g)(6)(i) for the examinations of the subject components and welds contained in 4RR-12 for the fourth 10-year ISI interval at SSES.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved remain applicable, including the third-party review by the Authorized Nuclear lnservice Inspector.
E. Casulli If you have any questions, please contact the Project Manager, Thomas Buffone, at 301-415-1136 or by email to Thomas.Buffone@nrc.gov.
Sincerely,
/RA/
Undine Shoop, Acting Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-387 and 50-388
Enclosure:
Safety Evaluation cc: Listserv
ML25322A536 OFFICE NRR/DORL/LPL1/PM NRR/DORL/LPL1/PM NRR/DORL/LPL1/LA NAME TBuffone RGuzman KEntz DATE 11/18/2025 11/20/2025 11/20/2025 OFFICE NRR/DNRL/NVIB/BC(A)
NRR/DORL/LPL1/BC(A)
NRR/DORL/LPL1/PM NAME JTsao UShoop TBuffone DATE 11/17/2025 12/4/2025 12/5/2025
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST 4RR-12, REVISION 0 LIMITED EXAMINATION COVERAGE FOURTH TEN-YEAR INSERVICE INSPECTION INTERVAL SUSQUEHANNA NUCLEAR, LLC SUSQUEHANNA STEAM ELECTRIC PLANT, UNITS NO. 1 AND NO. 2 DOCKET NO. 50-387 AND 50-388
1.0 INTRODUCTION
By letter dated May 20, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25140A973), Susquehanna Nuclear, LLC (the licensee) submitted request relief 4RR-12, Revision 0, to the U.S. Nuclear Regulatory Commission (NRC or the Commission), requesting relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Rules for Inservice Inspection [ISI] of Nuclear Power Plant Components, for the fourth ISI interval at Susquehanna Steam Electric Station (SSES), Units 1 and 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 and/or surface examination coverage requirements of ASME Code,Section XI, for reactor pressure vessel (RPV) welds and reactor core isolation cooling (RCIC) pump attachment welds on the basis that compliance with the requirement is impractical.
2.0 REGULATORY EVALUATION
Section 50.55a(g)(4) to 10 CFR states that ASME 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 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 Code, which was incorporated by reference in 10 CFR 50.55a(b) 18 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
Section 50.55a(g)(5)(iii) to 10 CFR states, in part, that licensees may determine that conformance with certain ASME 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 experience when attempting to comply with the code requirements during the ISI interval for which the request is being submitted. The relief requests (RRs) made in accordance with this section must be submitted to the NRC 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.
Section 50.55a(g)(6)(i) to 10 CFR states that 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.
3.0 TECHNICAL EVALUATION
3.1 Licensees Relief Request ASME Code Components Affected Code Class:
Class 1 and 2 Examination Categories: B-A, Pressure Retaining Welds in Reactor Vessels B-D, Full Penetration Welded Nozzles in Vessels C-C, Welded Attachments for Pressure Vessels, Piping, Pumps, and Valves Item Numbers:
B1.12, Longitudinal Shell Welds in reactor vessel B1.30, Shell-to-flange weld in reactor vessel B1.40, Head-to-flange weld in reactor vessel B3.90, Nozzle-to-Vessel Welds in reactor vessel C3.30, Welded Attachments in pumps Component IDs:
See Tables 3.1.1 and 3.1.2 of this safety evaluation ASME Code Edition and Addenda The licensee stated that the fourth 10-year ISI interval for SSES, Units 1 and 2, that concluded on May 31, 2024, was based on the ASME Code,Section XI, 2007 Edition with the 2008 Addenda. The license also stated that the ASME Code,Section XI, Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems, was implemented as required by 10 CFR 50.55a. Ultrasonic procedures and personnel were qualified to the Performance Demonstration Initiative (PDI) which satisfies the requirements of the 2007 Edition with 2008 Addenda of the ASME Code,Section XI, Appendix VIII, as modified by 10 CFR 50.55a.
ASME Code Requirements IWA-2200(c) requires that All nondestructive examinations of the required examination surface or volume shall be conducted to the maximum extent practical. When performing VT-1, surface, radiographic, or ultrasonic examination on a component with defined surface or volume, essentially 100 percent of the required surface or volume shall be examined. Essentially 100 percent coverage is achieved when the applicable examination coverage is greater than 90 percent; however, in no case shall the examination be terminated when greater than 90 percent coverage is achieved, if additional coverage of the required examination surface or volume is practical.
Table IWB-2500-1,Section XI, Examination Category B-A, Item No. B1.12, requires a volumetric examination of the RPV longitudinal shell welds in accordance with Figure IWB-2500-2. The extent of examination is essentially 100 percent of the required examination volume, as specified in IWA-2200(c).
Table IWB-2500-1,Section XI, Examination Category B-A, Item No. B1.30, requires a volumetric examination of the RPV shell-to-flange weld in accordance with Figure IWB-2500-4.
The extent of examination is essentially 100 percent of the required examination volume, as specified in IWA-2200(c).
Table IWB-2500-1,Section XI, Examination Category B-A, Item No. B1.40, requires a volumetric and surface examination of the RPV head-to-flange weld in accordance with Figure IWB-2500-5. The extent of examination is essentially 100 percent of the required examination volume, as specified in IWA-2200(c).
Table IWB-2500-1, Examination Category B-D, Item Number B3.90, requires a volumetric examination of the RPV nozzle-to-vessel welds in accordance with Figure IWB-2500-7. The extent of examination is essentially 100 percent of the required examination volume, as specified in IWA-2200(c).
Table IWB-2500-1, Examination Category C-C, Item Number C3.30, requires a surface examination of welded attachments to pressure vessels in accordance with Figure IWC-2500-5.
The extent of examination is essentially 100 percent of the length of the attachment weld, as specified in IWA-2200(c).
Relief Request The licensee listed the examination coverages achieved in Tables A and B in Enclosure 1 to the submittal, as summarized in Tables 3.1.1 and 3.1.2 of this safety evaluation, for the subject Examination Category B-A, B-D, and C-C welds. The licensee stated that in accordance with 10 CFR 50.55a(g)(5)(iii), relief is requested on the basis that conformance with the ASME 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 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 B-A, B-D, and C-C welds in Tables A and B in Enclosure 1 to the submittal and included corresponding details in Enclosures 2 and 3 to the submittal.
Table 3.1.1 ASME Code,Section XI, Examination Coverages (Unit 1)
ASME Code Item Component ID Weld Description Percent Coverage Achieved Examination Category B-A B1.12 BK & BM RPV Longitudinal Weld 81.4 volumetric B1.30 AF (0-360) Shell RPV Shell-to-Flange Weld 74 volumetric B1.40 AG (0-360)
RPV Head-to-Flange Weld 78.6 volumetric 100 surface Examination Category B-D B3.90 N4A Feedwater Nozzle-to-Vessel Weld 86.3 volumetric B3.90 N4D Feedwater Nozzle-to-Vessel Weld 86.3 volumetric Examination Category C-C C3.30 1P203-HW-2 RCIC Pump Mounting Foot Weld 83.3 surface Table 3.1.2 ASME Code,Section XI, Examination Coverages (Unit 2)
ASME Code Item Component ID Weld Description Percent Coverage Achieved Examination Category B-A B1.12 BK RPV Longitudinal Weld 72.1 volumetric B1.12 BM RPV Longitudinal Weld 70.1 volumetric B1.30 AF (0-360) Shell RPV Shell-to-Flange Weld 74 volumetric B1.40 AG (0-360)
RPV Head-to-Flange Weld 79.7 volumetric
> 90 surface Basis for Relief Request In Section 5 of 4RR-12, the licensee stated that the examinations required by ASME Code,Section XI, were performed to the maximum extent practical, or best effort, which are documented in Tables A and B in Enclosure 1 to the submittal. Due to physical interferences or component geometry, the licensee stated that there were no other examination techniques available to increase examination coverage, and no cases in any of the listed examinations where the components outside diameter surface features could have been conditioned to obtain the required coverage without major modification to the components.
The licensee also stated that during the fourth ISI Interval, periodic system pressure tests that include VT-2 visual examinations were performed in accordance with ASME Code, Section Xl, Table IWB-2500-1, Examination Category B-P for Class 1 pressure retaining welds and components and Table IWC-2500-1, Examination Category C-H for Class 2 pressure retaining welds and components, during each inspection period. The licensee stated that these periodic system pressure tests and VT-2 examinations provided additional assurance that the structural and leak-tight integrity of the subject components was maintained throughout the fourth ISI Interval. The licensee stated that the volumetric and/or surface examinations were performed to the maximum extent practicable on the components in 4RR-12, as required by the ASME Section XI ISI Program.
3.2
NRC Staff Evaluation
For the subject Examination Category B-A and B-D welds, the licensee obtained the volumetric examination coverages summarized in Tables 3.1.1 and 3.1.2 of this safety evaluation using procedures, equipment, and personnel qualified using ASME Code,Section XI, Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems. For the subject Examination Category C-C weld (i.e., C3.30 weld) and Examination Category B-A welds (i.e., B1.40 welds) that require surface examination, the licensee performed surface examinations specified in ASME Code,Section XI. The licensee achieved less than the required examination coverage due to physical interferences or component configuration that would entail extensive structural modifications to the associated components or surrounding structure if the required coverage were to be obtained. The NRC staff confirmed from the examination diagrams included in Enclosures 2 and 3 to the submittal that the examination coverages obtained (i.e., achieved) included regions near the inside surface where service-induced degradation could occur. The NRC staff also reviewed and verified the examination coverages achieved. The NRC staff finds the stated limitations to be an acceptable basis for impracticality of conforming to the requirements and finds the modifications necessary to achieve the required coverage constitute a burden upon the licensee.
For the subject Examination Category B-A welds at both SSES units, the volumetric and surface examinations were limited due to component configuration (for example, insulation support ring for the B1.12 welds), as indicated in Tables A and B in Enclosure 1 to the submittal. The licensee did not detect any recordable indications in the B-A welds.
For the subject Examination Category B-D welds at SSES, Unit 1, the volumetric examinations were limited due to the weld build up area of adjacent nozzles, as indicated in Table A in to the submittal. The licensee did not detect any recordable indications in the B-D welds.
For the subject Examination Category C-C welded attachment at SSES, Unit 1, the surface examination was limited due to the configuration of the reactor core isolation cooling pump, as indicated in Table A in Enclosure 1 to the submittal. The licensee did not detect any recordable indications in the C-C weld.
Based on the discussion above, the NRC staff finds that it is impractical to meet the ASME Code-required examination coverage for the subject Examination Category B-A welds at both SSES units, and for the Examination Categories B-D and C-C welds at SSES, Unit 1, because the design configurations, proximity of other nozzles, and proximity of integral vessel appurtenances (e.g., insulation support ring) that limited the examination coverage of the welds would need extensive modifications to obtain the required coverage. Furthermore, given the volumetric and surface examination coverages achieved, the NRC staff determined that if significant service-induced degradation had occurred in the subject welds, evidence of it would have been detected by the examinations that were performed because the examined volume or surface includes degradation-susceptible regions, is the same material as the unexamined volume or unexamined surface, is under the same loading conditions, and is exposed to the same environment. Accordingly, the NRC staff determined that the examination coverages that were achieved provide reasonable assurance of structural integrity of the subject welds.
4.0 CONCLUSION
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 relief request 4RR-12, Revision 0, for the fourth 10-year ISI interval at SSES, Units 1 and 2.
All other ASME 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: D. Dijamco, NRR Date: December 5, 2025