ML24109A066
| ML24109A066 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 05/02/2024 |
| From: | Jeffrey Whited Plant Licensing Branch III |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| Kuntz R | |
| References | |
| EPID L-2023-LLR-0047 | |
| Download: ML24109A066 (1) | |
Text
May 2, 2024
David P. Rhoades Senior Vice President Constellation Energy Generation, LLC President and Chief Nuclear Officer Constellation Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - RELIEF REQUEST I5R-26, REVISION 0 (EPID L-2023-LLR-0047)
Dear David P. Rhoades:
By letter dated August 28, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23240A390), as supplemented by letter dated January 3, 2024 (ML24003A690), Constellation Energy Generation, LLC (the licensee) submitted Request Relief (RR) I5R-26 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 Code),Section XI, Rules for Inservice Inspection [ISI] of Nuclear Power Plant Components, for the fifth ISI interval at Quad Cities Nuclear Power Station (Quad Cities),
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, RPV nozzle welds, and piping welds on the basis that compliance with the requirement is impractical.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, 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 li censee has adequately a ddressed 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 I5R-26, for the fifth 10-year ISI interval, which ended on May 17, 2023, at Quad Cities, 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.
D. Rhoades
If you have any questions, please contact me at 301-415-3733 or via e-mail at Robert.Kuntz@nrc.gov.
Sincerely,
Jeffrey A. Whited, Chief Plant Licensing Branch III Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Docket Nos. 50-254 and 50-265
Enclosure:
Safety Evaluation
cc: Listserv
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION
RELIEF REQUEST I5R-26
LIMITED EXAMINATION COVERAGE
FIFTH INSERVICE INSPECTION INTERVAL
CONSTELLATION ENERGY GENERATION, LLC
QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2
DOCKET NOS. 50-254 AND 50-265
1.0 INTRODUCTION
By letter dated August 28, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23240A390), as supplemented by letter dated January 3, 2024 (ML24003A690), Constellation Energy Generation, LLC (the licensee) submitted Request Relief (RR) I5R-26 to the U.S. Nuclear Regulatory Commission (NRC or Commission), requesting relief from the requirements of the Americ an 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 fifth ISI interval at Quad Cities Nuclear Power Station (Quad Cities), 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, RPV nozzle welds, and piping 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) 12 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
Enclosure
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. Any RR 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
The NRC staff evaluated RR I5R-26 according to ASME Code,Section XI, Examination Category, as documented below.
The licensee stated that the fifth 10-year ISI interval at Quad Cities, Units 1 and 2, ended on May 17, 2023, and was based on the ASME Code,Section XI, 2007 Edition with the 2008 Addenda.
3.1 ASME Code,Section XI, Examination Category B-A, Item Nos. B1.12, B1.40, and B1.51
3.1.1 Licensees Relief Request
ASME Code Components Affected
Code Class: Class 1
Examination Category: B-A, Pressure Retaining Welds in Reactor Vessels
Item Numbers: B1.12, Longitudinal Shell Welds B1.40, Head-to-flange Welds B1.51, Repair welds, Beltline Region
Component IDs: See Tables 3.1.1 and 3.1.2 of this safety evaluation.
ASME Code Requirement
Table IWB-2500-1 of ASME Code,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 of ASME Code,Section XI, Examination Category B-A, Item No. B1.40, requires a volumetric and surface examination of the RPV closure head-to-flange weld in accordance with Figure IWB-2500-5. The extent of examination is essentially 100 percent of the required examination volume and surface, as specified in IWA-2200(c).
Table IWB-2500-1 of ASME Code,Section XI, Examination Category B-A, Item No. B1.51, requires a volumetric examination of RPV repair welds within the beltline region in accordance with Figures IWB-2500-1 and IWB-2500-2 for base metal repairs where the repair depth exceeds 10 percent nominal of the vessel wall thickness. The extent of examination is essentially 100 percent of the required examination volume, as specified in IWA-2200(c).
Per IWA-2200(c), 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.
Relief Request
The licensee achieved the volumetric examination coverages shown in Tables 3.1.1 and 3.1.2 for the subject Examination Category B-A welds. For the one RPV head-to-flange weld (Item No.
B1.40) which requires both volumetric and surface examination, the licensee stated that the magnetic particle surface examination was acce ptable. 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 Code,Section XI, requirements is impractica l 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 weld in Tables A and B in Attachment 1 to the submittal and included corresponding details in Attachments 2 and 3 to the submittal.
Table 3.1.1 ASME Code,Section XI, Examination Category B-A (Unit 1)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B1.12 RPV-VSC1-55 RPV COURSE #1 55 DEG Vertical Shell Weld 83.73 B1.12 RPV-VSC1-197 RPV COURSE #1 197 DEG Vertical Shell Weld 38.20 B1.12 RPV-VSC2-22 RPV COURSE #2 22 DEG Vertical Shell Weld 57.07 B1.12 RPV-VSC3-77 RPV COURSE #3 77 DEG Vertical Shell Weld 75.21 B1.12 RPV-VSC3-197 RPV COURSE #3 197 DEG Vertical Shell Weld 73.59 B1.12 RPV-VSC3-317 RPV COURSE #3 317 DEG Vertical Shell Weld 78.58 B1.51 BMR-167-305 RPV Weld Beltline Repair Area at 167 degrees 66.40
Table 3.1.2 ASME Code,Section XI, Examination Category B-A (Unit 2)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B1.12 RPV-VSC1-77 RPV COURSE #1 77 DEG Vertical Shell Weld 89.3 B1.12 RPV-VSC-197 RPV COURSE #1 197 DEG Vertical Shell Weld 42.5 B1.12 RPV-VSC1-317 RPV COURSE #1 317 DEG Vertical Shell Weld 78.8 B1.12 RPV-VSC2-22 RPV COURSE #2 22 DEG Vertical Shell Weld 58.3
Table 3.1.2 ASME Code,Section XI, Examination Category B-A (Unit 2)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B1.12 RPV-VSC3-77 RPV COURSE #3 77 DEG Vertical Shell Weld 71.3 B1.12 RPV-VSC3-197 RPV COURSE #3 197 DEG Vertical Shell Weld 67.7 B1.12 RPV-VSC3-317 RPV COURSE #3 317 DEG Vertical Shell Weld 76.2 B1.12 RPV-VSC4-219 RPV COURSE #4 219 DEG Vertical Shell Weld 81.3 B1.40 RPV-THHF RPV Top Head-to-Flange Weld 76.3
Basis for Relief Request
The licensee stated that it performed the ASME Code,Section XI, required examinations to the maximum extent practical, or best effort, at Quad Cities, Units 1 and 2, which are documented in Tables A and B in Attachment 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 fifth 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 during each refueling outage. 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 fifth ISI interval.
3.1.2 NRC Staff Evaluation
For the subject Examination Category B-A welds, the licensee obtained the coverages summarized in Tables 3.1.1 and 3.1.2 using procedures, equipment, and personnel qualified using ASME Code,Section XI, Appendix VIII, P erformance 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 confirmed from the examination diagrams included in Attachments 2 and 3 to the submittal that the coverages obtained 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 modification necessary to achieve the required coverage constitutes a burden upon the licensee.
For the subject RPV longitudinal (i.e., vertical) shell welds at Quad Cities, Units 1 and 2, (Item No. B1.12), the volumetric examinations were limited due to the proximity of core shroud repair tie rods and bracket, sensing line clamps, baffle plate, diffuser, core spray and feedwater spargers, jet pump diffusers, the guide rod, and steam dryer support brackets, as applicable.
For some Item No. B1.12 welds, the licensee reported subsurface indications that were detected and stated that the indications were acceptable per the ASME Code,Section XI. The
NRC staff verified that the indications were acceptable per ASME Code,Section XI, IWB-3500, based on the dimensions of the subsurface indications that were provided. The licensee also reported one indication that was detected in a previous examination and that was determined as having no through-wall dimension, and therefore, was evaluated by the licensee as acceptable.
The licensee stated that the current examination identified that the indication did not change in flaw characteristics from the previous ex amination, and thus acceptable per ASME Code,Section XI. For the other Item No. B1.12 welds, the licensee stated that no recordable indications were observed during the volumetric examinations.
The volumetric examination of the Quad Cities, Unit 2, RPV head-to-flange weld RPV-THHF (Item No. B1.40) was limited due to flange configuration. The licensee obtained 76.3 percent of the required ASME Code volume, with five recordable indications detected. The licensee stated that the magnetic particle surface examination fo r this RPV head-to-flange weld was acceptable.
In the supplement the licensee provided additional cl arification on the five recordable indications detected. The licensee explained that initial evaluation of the five recordable indications deemed the indications unacceptable per the IWB-3000 criteria of the 2007 Edition (2008 Addenda) of ASME Code,Section XI. The licensee then correlated these indications to previous indications detected in 1989 and determined there was no new growth with respect to the 1989 indications.
The licensee stated that a 1990 IWB-3600 flaw evaluation (ML17202L231) of the 1989 indications deemed them acceptable. The NRC sta ff confirmed that the 1990 flaw evaluation was performed per the method of IWB-3600 of the ASME Code,Section XI, and appropriate for the material of the Quad Cities, Unit 2, RPV-THHF weld (low alloy steel). Based on this discussion, the NRC staff determined that the five recordable indications detected are acceptable because there was no new growth with respect to previous indications that were deemed acceptable per IWB-3600 of the ASME Code Section XI.
The volumetric examination of the Quad Cities, Unit 1, RPV beltline repair area weld (Item No. B1.51) was limited due to the proximity of the jet pump riser brackets and the core shroud repair tie rod. The licensee obtained 66.4 percent of the required ASME Code volume, with no recordable indications detected.
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 Quad Cities, Units 1 and 2, because the identified design geometries and proximity of integral RPV appurtenances that limited the examination coverage of the welds would need extensive modifications to obtain the required coverage. Furthermore, given the volumetric coverages obtained, the NRC staff determined that if sign ificant 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 weld volume includes the most susceptible regions, is the same material as the unexamined volume, is under the same loading conditions, and is exposed to the same environment. Accordingly, the NRC staff determined that the coverages obtained provide reasonable assurance of structural integrity of the subject welds.
3.2 ASME Code,Section XI, Examination Category B-D, Item No. B3.90
3.2.1 Licensees Relief Request
ASME Code Components Affected
Code Class: Class 1
Examination Category: B-D, Full Penetration Welded Nozzles in Vessels
Item Number: B3.90, Reactor Vessel Nozzle-to-Vessel Welds
Component IDs: See Tables 3.2.1 and 3.2.2 of this safety evaluation.
ASME Code Requirement
Table IWB-2500-1, Examination Category B-D, Item No. 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).
Per IWA-2200(c), 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.
Relief Request
The licensee achieved the volumetric examination coverages shown in Tables 3.2.1 and 3.2.2 for the subject Examination Category B-D 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 Code,Section XI, requirements is impractica l 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-D weld in Tables A and B in Attachment 1 to the submittal and included corresponding details in Attachments 2 and 3 to the submittal.
Table 3.2.1 ASME Code,Section XI, Examination Category B-D (Unit 1)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B3.90 N2C NOZ Recirculation Nozzle-to-Shell Weld 78.7 B3.90 N4A NOZ Feedwater Nozzle-to-Shell Weld on RPV 74.4 B3.90 N4B NOZ Feedwater Nozzle-to-Shell Weld on RPV 74.4 B3.90 N4C NOZ Feedwater Nozzle-to-Shell Weld on RPV 74.4 B3.90 N4D NOZ Feedwater Nozzle-to-Shell Weld on RPV 74.4
Table 3.2.2 ASME Code,Section XI, Examination Category B-D (Unit 2)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B3.90 N6ANOZ Head Spray Nozzle-to-RPV Head 59.1 B3.90 N2A NOZ Recirculation Nozzle-to-Vessel Weld on RPV 77.9
Table 3.2.2 ASME Code,Section XI, Examination Category B-D (Unit 2)
ASME Percent Code Component ID Weld Description Coverage Item Obtained B3.90 N2B NOZ Recirculation Nozzle-to-Vessel Weld on RPV 80.3 B3.90 N2D NOZ Recirculation Nozzle-to-Vessel Weld on RPV 77.9 B3.90 N2E NOZ Recirculation Nozzle-to-Vessel Weld on RPV 77.9 B3.90 N5A NOZ Core Spray Nozzle-to-Shell Weld 73.9 B3.90 N3A NOZ Main Steam Nozzle-to-Vessel Weld on RPV 77.7 B3.90 N4A NOZ Feedwater Nozzle-to-Shell Weld on RPV 77.4 B3.90 N4B NOZ Feedwater Nozzle-to-Shell Weld on RPV 77.4 B3.90 N4C NOZ Feedwater Nozzle-to-Shell Weld on RPV 77.4 B3.90 N4D NOZ Feedwater Nozzle-to-Shell Weld on RPV 77.4
Basis for Relief Request
The licensee stated that it performed the ASME Code,Section XI, required examinations to the maximum extent practical, or best effort, at Quad Cities, Units 1 and 2, which are documented in Tables A and B in Attachment 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 fifth 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 during each refueling outage. 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 fifth ISI interval.
3.2.2 NRC Staff Evaluation
For the subject Examination Category B-D welds, the licensee obtained the coverages summarized in Tables 3.2.1 and 3.2.2 using procedures, equipment, and personnel qualified using ASME Code,Section XI, Appendix VIII, P erformance 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 confirmed from the examination diagrams included in Attachments 2 and 3 to the submittal that the coverages obtained 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 modification necessary to achieve the required coverage constitutes a burden upon the licensee.
For the subject RPV nozzle-to-vessel shell welds at Quad Cities, Units 1 and 2, (Item No. B3.90), the volumetric examinations were limited due to the configuration of the nozzles.
The licensee did not detect any recordable indications in the welds.
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-D welds at Quad Cities, Units 1 and 2, because the nozzle configurations that limited the examination coverage of the welds would need extensive modifications to obtain the required coverage. Furthermore, given the volumetric coverages obtained, 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 weld volume includes the most susceptible regions, is the same material as the unexamined volume, is under the same loading conditions, and is exposed to the same environment. Accordingly, the NRC staff determined that the coverages obtained provide reasonable assurance of structural integrity of the subject welds.
3.3 ASME Code,Section XI, Examination Category R-A, Item No. R1.20
3.3.1 Licensees Relief Request
ASME Code Components Affected
Code Class: Class 1 and 2
Examination Category: R-A, Risk-Informed Piping Examinations
Item Number: R1.20, Elements not subject to a damage mechanism
Component IDs: See Table 3.3.1 of this safety evaluation.
ASME Code Requirement
Table 1 of ASME Code Case N-578-1, "Risk-Informed Requirements for Class 1, 2 or 3 Piping, Method B,Section XI, Division 1, assigns Examination Category R-A, Item R1.20, to piping inspection elements not subject to a known damage mechanism. This code case requires 100 percent of the examination location volume, as described in Figures IWB-2500-8(c), 9, 10, or 11, as applicable, including an additional one half on an inch of base metal adjacent to the ASME Code volume, be completed for selected Class 1 and 2 piping welds.
Relief Request
The licensee achieved the volumetric examination coverages shown in Table 3.3.1 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 Code,Section XI, requirements is impractica l 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 accompli shed 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 A in Attachment 1 to the submittal and
included corresponding details in Attachment 2 to the submittal. The licensee reported Examination Category R-A welds only for Quad Cities, Unit 1.
Table 3.3.1 ASME Code,Section XI, Examination Category R-A (Unit 1)
ASME Percent Code Component ID Weld Description Coverage Item Obtained R1.20 03-F1A Nozzle-to-Safe End Weld 89.7 R1.20 1015B-17R Elbow-to-Valve Weld in Residual Heat Removal (RHR) System 55.49 R1.20 1016C-2R Pipe-to-Valve Weld (RHR) 84.64 R1.20 1016C-3R Valve-to-Pipe Weld (RHR) 84.64 R1.20 1016D-1R Valve-to-Pipe Weld (RHR) 78.17
Basis for Relief Request
The licensee stated that it performed the ASME Code,Section XI, required examinations to the maximum extent practical, or best effort, at Quad Cities, Unit 1, which are documented in Tables A and B in Attachment 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 fifth 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 refueling outage. 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 fifth ISI interval.
3.3.2 NRC Staff Evaluation
For the subject Examination Category R-A welds, the licensee obtained the volumetric examination coverages summarized in Table 3.3.1 using procedures, equipment, and personnel qualified using ASME Code,Section XI, Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems. The licensee achieved less than the required volumetric examination coverage due to geometric, materi al, 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 and surface 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 both surface and volumetric pre-service inspections and satisfied the VT-2 system leakage test. The NRC staff finds the licensee's 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. Furthermore, the NRC staff determined that the examinations performed provide reasonable assurance of structural integrity of the subject welds.
The NRC staff also noted that the licensee assess ed the potential for additional or alternative welds for examination to supplement the reduced volumetric coverages, and that the licensee determined that no other welds could have been selected to achieve better coverage.
Based on the above discussion, the NRC staff determined that obtaining the ASME Code-required examination volume coverage for the subject Examination Category R-A welds Quad Cities, Unit 1, 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 provides reasonable assurance of the structural integrity of the weld because: (1) the licensee identified no recordable indications; and (2) evidence of significant service-induced degradation in the welds, if it were to occur, would likely have been detected by the volumetric examination coverage obtained by the licensee, because the examined weld volume includes the most susceptible regions, is the same material as the unexamined volume, is under the same loading conditions, and is exposed to the same environment.
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 t he 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 I5R-26, for the fifth 10-year ISI interval, which ended on May 17, 2023, at Quad Cities, Units 1 and 2.
All other ASME Code,Section XI, requirements fo r which relief was not specifically requested and approved in the subject requests for relief rema in applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors: Karen Sida, NRR David Dijamco, NRR
Date: May 2, 2024
ML24109A066 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DNRL/NPHP/BC NAME Rkuntz SRohrer MMitchell DATE 4/17/2024 4/18/2024 4/15/2024 OFFICE NRR/DNRL/NVIB/BC NRR/DORL/LPL3/BC NAME ABuford (OYee for) JWhited DATE 4/15/2024 5/2/2024