ML090620158
| ML090620158 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/30/2009 |
| From: | Melanie Wong Division of Operating Reactor Licensing |
| To: | Baxter D Duke Energy Carolinas |
| Stang J, NRR/DORL, 415-1345 | |
| References | |
| TAC MD8666 | |
| Download: ML090620158 (12) | |
Text
March 30, 2009 Mr. Dave Baxter Vice President, Oconee Site Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
OCONEE NUCLEAR STATION, UNIT 2 - RELIEF REQUEST 08-ON-001, REGARDING LIMITED WELD EXAMINATION COVERAGE (TAC NO. MD8666)
Dear Mr. Baxter:
By letter dated April 29, 2008 (ADAMS Accession No. ML081260549), Duke Energy Carolinas, LLC (the licensee) submitted Relief Request 08-ON-001, requesting relief from the requirements of American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code,Section XI as it pertains to the volumetric coverage requirements for weld examination for Oconee Nuclear Station, Unit 2.
During ultrasonic examination conducted for the fourth 10-year inservice inspection interval, the licensee could not achieve 100-percent coverage of the ASME Boiler and Pressure Vessel Code,Section XI required examination volume for seven welds because of weld configurations. It was impractical for the licensee to achieve the required ultrasonic examination coverage of the seven welds due to existing piping/valve geometry, interferences, and existing examination technology.
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the licensee limited ultrasonic examination coverage of the welds, as complemented by additional examinations/observations, provides reasonable assurance of structural integrity.
Relief is granted pursuant to Title 10 of the Code of Federal Regulations, Section 50.55a(g)(6)(i) for the fourth 10-year inservice inspection interval of Oconee Nuclear Station, Unit 2 which is scheduled to end on September 9, 2014. This grant of relief 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 if the requirements were imposed on the facility.
Enclosed is the NRC safety evaluation.
D. Baxter If you have any questions, please call me at 301-415-1345.
Sincerely,
/RA/
Melanie C. Wong, Chief Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-270
Enclosure:
As stated cc w/encl: Distribution via Listserv
ML090620158 *via memo NRR-028 OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA CPNB/BC OGC NRR/LPL2-1/BC NRR/LPL2-1/PM NAME JStang MOBrien TChan* DRoth MWong JStang DATE 3/17/09 3/16/09 02/05/09 3/17/09 3/30/09 3/30/09
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR APPROVAL OF RELIEF 08-ON-001 REGARDING LIMITED WELD EXAMINATION COVERAGE OCONEE NUCLEAR STATION, UNIT 2 DUKE ENERGY CAROLINAS, LLC DOCKET NO. 50-270
1.0 INTRODUCTION
By letter dated April 29, 2008 (ADAMS Accession No. ML081260549), Duke Energy Corporation (Duke Energy or the licensee) requested pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(g)(5)(iii) approval of Relief Request (RR) 08-ON-001, which involved limited weld examination coverage at Oconee Nuclear Station, Unit 2 (Oconee 2).
Specifically, during ultrasonic examination conducted for the fourth 10-year inservice inspection (ISI) interval, the licensee could not achieve 100-percent coverage of the American Society for Mechanical Engineers (ASME), Boiler and Pressure Vessel Code,Section XI required examination volume for seven welds because of weld configurations.
2.0 REGULATORY EVALUATION
Section 50.55a(g) specifies that ISI of nuclear power plant components shall be performed in accordance with the requirements of ASME,Section XI, except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the U.S. Nuclear Regulatory Commission (NRC), if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Section 50.55a(g)(5)(iii) states that if the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the Commission and submit, as specified in Section 50.4, to support the determinations.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, to the extent practical within the limitations of design, geometry, and materials of construction of components. The regulations require that inservice examination of components and system pressure tests conducted during the first Enclosure
10-year interval and subsequent intervals comply with the requirements of the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable code of record for the third ISI interval for Oconee 2 is the ASME Code,Section XI, 1998 Edition through the 2000 Addenda. The proposed relief is sought for the fourth 10-year ISI interval which ends on September 9, 2014.
3.0 TECHNICAL EVALUATION
3.1 Components for Which Relief is Requested SYSTEM/COMPONENT ASME Weld ID ITEM NUMBER Class High Pressure Injection System 1 2-LDCA-IN-V1 B03.150.001 Letdown Cooler 2A Inlet Nozzle to Channel Body Weld High Pressure Injection System 1 2-LDCA-OUT-V2 B03.150.002 Letdown Cooler 2A Outlet Nozzle to Channel Body Weld Low Pressure Injection System 2 2LP-148-16 C05.011.001 Pipe to Valve 2LP-47 Weld High Pressure Injection System 2 2-51A-17-111 C05.021.026 Piping to Valve 2HP-128 Weld High Pressure Injection System 2 2HP-227-3 C05.021.027 Pipe to Valve 2HP-117 Weld High Pressure Injection System 2 2HP-227-7 C05.021.028 Pipe to Valve 2HP-148 Weld High Pressure Injection System 2 2-51A-28-67 C05.021.073 Tee to Pipe Weld 3.2 Code Requirements from Which Relief is Requested Relief Request 08-ON-001, requests relief from the requirements listed below:
Examination Weld ID ASME XI Examination Requirement Category Item No.
B-D 2-LDCA-IN-V1 B3.150 100-percent volumetric examination of examination volume A-B-C-D-E-F-G-H.
B-D 2-LDCA-OUT-V2 B3.150 100-percent volumetric examination of examination volume A-B-C-D-E-F-G-H.
C-F-1 2LP-148-16 C5.11 100-percent volumetric examination of examination volume C-D-E-F.
C-F-1 2-51A-17-111 C5.21 100-percent volumetric examination of examination volume C-D-E-F.
C-F-1 2HP-227-3 C5.21 100-percent volumetric examination of examination volume C-D-E-F.
C-F-1 2HP-227-7 C5.21 100-percent volumetric examination of
examination volume C-D-E-F.
C-F-1 2-51A-28-67 C5.21 100-percent volumetric examination of examination volume C-D-E-F.
3.3 Licensee Description of Impracticality Caused by Code Compliance Relief is requested from the requirement to examine essentially 100 percent (i.e., greater than 90 percent) of the required volume specified in the ASME Code,Section XI, 1998 Edition through the 2000 addenda. Due to existing piping/valve geometry, interferences, and existing examination technology, the ultrasonic examination coverage of the subject welds did not meet the 90-percent examination coverage requirements of Code Case N-460 as discussed below.
2-LDCA-IN-V1:
The Letdown Cooler Inlet Nozzle and Channel Head material is SA182 Grade T316L. The weld has a diameter of 3.0 inches and a wall thickness of 0.875 inches.
The licensee stated that during the ultrasonic examination of weld 2-LDCA-IN-V1, only 29.26 percent coverage of the required examination volume was obtained. The coverage reported represents the aggregate coverage of all scans performed. A 45º scan parallel to the weld covered 28.57 percent; a 60º scan perpendicular to the weld covered 29.95 percent. The licensee stated that the weld joint geometry, which is essentially a branch connection arrangement using a set-on nozzle, prevented scanning from both sides of the weld. In order to scan all of the required surfaces for the inspection of this weld, the inlet nozzle would have to be redesigned to allow scanning from both sides of the weld, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of the weld.
2-LDCA-OUT-V2:
The Letdown Cooler Outlet Nozzle and Channel Head material is SA182 Grade T316L.
The weld has a diameter of 3.0 inches and a wall thickness of 0.875 inches.
The licensee stated that during the ultrasonic examination of weld 2-LDCA-OUT-V2, only 29.26 percent coverage of the required examination volume was obtained. The coverage reported represents the aggregate coverage of all scans performed. A 45º scan parallel to the weld covered 28.57 percent; a 60º scan perpendicular to the weld covered 29.95 percent. The licensee stated that the weld joint geometry, which is essentially a branch connection arrangement using a set-on nozzle, prevented scanning from both sides of the weld. In order to scan all of the required surfaces for the inspection of this weld, the outlet nozzle would have to be redesigned to allow scanning from both sides of the weld, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of the weld.
The valve material is SA-351/CF8M cast stainless steel and the pipe material is SA-376/TP304 or TP316 stainless steel. This weld has a diameter of 10.0 inches and a wall thickness of 1.125 inches.
The licensee stated that during the ultrasonic examination of weld 2LP-148-16, 50-percent coverage of the required examination volume was obtained. The percentage of coverage
represents the aggregate coverage of all scans performed on the weld and adjacent base material. The 45º shear wave circumferential scans, both clockwise and counter-clockwise covered 80 percent of the examination volume and the 60º shear wave axial scan from the pipe side covered 40 percent of the weld and base material. A supplemental 60º refracted longitudinal wave scan covered 50 percent of the examination volume on the valve side from one axial direction, but is not included in the coverage calculations. The licensee stated that the limitation was caused by the taper on the valve side of the weld (which prevented scanning from that side) and the proximity of a 1 1/2 inch branch connection. In order to scan all of the required surfaces for the inspection of this weld, the tee would have to be redesigned to allow scanning from both sides of the weld, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of this weld.
2-51A-17-111:
The pipe material is SA-376/TP304 or TP316 stainless steel and the valve material is A182/F316 stainless steel. This weld has a diameter of 4.0 inches and a wall thickness of 0.531 inches.
The licensee stated that during the ultrasonic examination of weld 2-51A-17-111, 37.5-percent coverage of the required examination volume was obtained. The percentage of coverage represents the aggregate coverage of all scans performed on the weld and adjacent base material. The 45º shear wave circumferential scans, both clockwise and counter-clockwise covered 50 percent of the examination volume and the 60º shear wave axial scan covered 50 percent. A supplemental 60º refracted longitudinal wave scan covered 50 percent of the examination volume in one axial direction from the pipe side. The licensee stated that the limitations were caused by the taper on the valve side of the weld which prevented scanning from that side. In order to scan all of the required surfaces for the inspection of this weld, the valve would have to be redesigned to allow scanning from both sides of the weld, which is impractical.
In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of this weld.
The valve material is A182/F316 forged stainless steel and the pipe material is SA-376/TP304 or 316 stainless steel seamless pipe. This weld has a diameter of 4.0 inches and a wall thickness of 0.531 inches.
The licensee stated that during the ultrasonic examination of weld 2HP-227-3, 37.5-percent coverage of the required examination volume was obtained. The percentage of coverage represents the aggregate coverage of all scans performed on the weld and adjacent base material. The 45º shear wave circumferential scans, both clockwise and counter-clockwise covered 50 percent of the examination volume and the 60º shear wave axial scan covered 50 percent of the examination volume from one direction. A supplemental 60º refracted longitudinal wave scan covered 50 percent of the examination volume from one direction perpendicular to the weld. The licensee stated that the limitation was caused by the taper on the valve side of the weld which prevented scanning from that side. In order to scan all of the required surfaces for the inspection of this weld, the valve would have to be redesigned to allow scanning from both sides of the weld, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of this weld.
The valve material is A182/F316 forged stainless steel and the pipe material is SA-376/TP304 or 316 stainless steel seamless pipe. This weld has a diameter of 4.0 inches and a wall thickness of 0.531 inches. The licensee stated that during the ultrasonic examination of weld 2HP-227-7, 37.5-percent coverage of the required examination volume was obtained. The percentage of coverage represents the aggregate coverage of all scans performed on the weld and adjacent base material. The 45º shear wave circumferential scans, both clockwise and counter-clockwise covered 50 percent of the examination volume and the 60º shear wave axial scan covered 50 percent of the examination volume from the pipe side. A supplemental 60º refracted longitudinal wave scan covered 50 percent of the examination volume from one direction perpendicular to the weld. The licensee stated that the limitation was caused by the taper on the valve side of the weld which prevented scanning from that side. In order to scan all of the required surfaces for the inspection of this weld, the valve would have to be redesigned to allow scanning from both sides of the weld, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of this weld.
2-51A-28-67:
The tee material is SA 403/WP304 or WP316 and the pipe material is SA-376/TP304 or TP316 stainless steel seamless pipe. This weld has a diameter of 2.5 inches and a wall thickness of 0.375 inches.
The licensee stated that during the ultrasonic examination of weld 2-51A-28-67, 79.15-percent coverage of the required examination volume was obtained. The percentage of coverage represents the aggregate coverage of all scans performed on the weld and adjacent base material. The 45º shear wave circumferential, both clockwise and counter-clockwise covered 100 percent of the examination volume and the 60º shear wave axial scan covered 72.2 percent. A supplemental 70º shear wave scan covered 55.6 percent of the examination volume in one axial direction from the pipe side. The licensee stated that the limitation was caused by configuration of the tee which prevented scanning from that side in the 0° and 180° quadrants. In order to scan all of the required surfaces for the inspection of this weld, the tee would have to be redesigned to allow scanning from both sides of the weld around the full circumference, which is impractical. In the volume covered by the ultrasonic examination, there were no recordable indications found during the inspection of this weld.
3.4 Licensee Description of Proposed Alternative Examinations or Testing The scheduled 10-year code examinations were performed on the referenced welds and resulted in the noted limited-coverage of the required ultrasonic volume. The licensee states that radiography (RT) as an alternative to ultrasonic testing for welds 2-LDCA-IN-V1 and 2-LDCA-OUT-V2 is not feasible because access is not available for film placement.
For welds 2LP-148-16, 2-51A-17-111, 2HP-227-3, 2HP-227-7, and 2-51A-28-67, the licensee states that the use of RT to achieve more coverage was evaluated and discarded because RT is less sensitive to service induced cracking and has not been subjected to the performance demonstration requirements in a manner similar to the ultrasonic method. The licensee further states that, while RT could in most cases provide more coverage, the loss of sensitivity and lack of performance demonstration militates against its use.
ASME Code,Section XI Code Case N-460, which has been approved for use by NRC in Regulatory Guide (RG)1.147, Revision 15, allows credit for full volume coverage of welds if it can be shown that greater than 90-percent examination of the required volume has been examined.
The licensee stated that no alternate examinations or testing are planned for the areas/welds during the fourth inspection interval which is scheduled to end on September 9, 2014.
3.5 Licensee Description of Justification for Granting Relief ASME XI Item Number B3.150 The licensee stated that ultrasonic examination of areas/welds for ASME XI item number B3.150 (weld ID numbers 2-LDCA-IN-V1 and 2-LDCA-OUT-V2) were conducted using personnel qualified in accordance with ASME Code,Section XI, Appendix VII of the 1998 Edition with the 2000 Addenda. The ultrasonic procedures used complied with the requirements of ASME Code,Section V, Article 4, 1998 Edition through the 2000 addenda.
The licensee used Class 1, Examination Category B-P, pressure testing and VT-2 visual examination to complement the limited scan examinations. The Code requires that a pressure test be performed after each refueling outage for Class 1. These tests require a VT-2 visual examination for evidence of leakage. The licensee stated that this pressure testing provides adequate assurance of pressure boundary integrity.
In addition to the above Code required examinations (volumetric and pressure tests), the licensee performed other activities to provide a high level of confidence that, in the unlikely event that leakage did occur through one of these welds, it would be detected and proper action taken.
Specifically, system leak rate limitations imposed by Technical Specification 3.4.13, Reactor Coolant System Leakage, as well as reactor building normal sump rate monitoring, provided additional assurance that any leakage would be detected prior to gross failure of the component.
Lastly, the licensee stated that these welds/components were rigorously inspected by volumetric NDE methods during construction and verified to be free from unacceptable fabrication defects.
The licensee stated that it is their belief that the combination of examinations provides a reasonable assurance of quality and safety for areas/welds for ASME XI item number B3.150 (weld ID numbers 2-LDCA-IN-V1 and 2-LDCA-OUT-V2).
ASME XI Item Number C5.11 The licensee conducted ultrasonic examination of the area/weld for item number C5.11 (weld ID number 2LP-148-16) using personnel, equipment and procedures qualified in accordance with ASME Code,Section XI, Appendix VIII Supplement 2 of the 1998 Edition with the 2000 Addenda as administered by the Performance Demonstration Initiative (PDI). In addition to the volumetric examination with limited coverage, the licensee performed a surface examination (Code required) on the C5.11 item and achieved 100 percent coverage. The result of the surface examination was acceptable.
In addition to weld ID number 2LP-148-16, two other ASME Section XI Item No. C5.11 welds in the same system were examined using surface and volumetric techniques during the same outage. The examinations did not identify any recordable indications and 100-percent coverage was obtained on each of them. The examination and results of the two additional welds contributes to the reasonable assurance of pressure boundary integrity for this system.
The licensee did not claim credit for coverage of the far side of the austenitic weld when access is limited to one side only. The characteristics of austenitic weld metal attenuate and distort the sound beam when shear waves pass through the weld. Refracted longitudinal waves provide better penetration but cannot be used beyond the first sound path leg. The licensee uses a combination of shear waves and longitudinal waves to examine single sided austenitic welds when the nominal material thickness exceeds 0.5 inch. A 60º refracted longitudinal wave is used to interrogate the far side of the weld when the nominal material thickness is greater than 0.5 inch.
The licensee used Class 2, Examination Category C-H, pressure testing and VT-2 visual examination to complement the limited scan examinations. The Code requires that a pressure test be performed once each inspection period for Class 2 items. These tests require a VT-2 visual examination for evidence of leakage. The licensee stated that this pressure testing provides adequate assurance of pressure boundary integrity.
In addition to the above Code required examinations (volumetric, surface and pressure tests), the licensee will perform other activities which provide a high level of confidence that, in the unlikely event that leakage did occur through one of these welds, it would be detected and proper action taken. Specifically, reactor building normal sump rate monitoring provides additional assurance that any leakage would be detected prior to gross failure of the component.
Lastly, the licensee stated that this weld/component was rigorously inspected by volumetric NDE methods during construction and verified to be free from unacceptable fabrication defects. The licensee stated that it is their belief that the combination of examinations provides a reasonable assurance of quality and safety for area/weld for item number C5.11 (weld ID number 2LP-148-16).
ASME XI Item Number C5.21 The licensee conducted ultrasonic examinations of areas/welds for ASME XI item number C5.21 (weld ID numbers 2-51A-17-111, 2HP-227-3, 2HP-227-7 and 2-51A-28-67) using personnel, equipment and procedures qualified in accordance with ASME Code,Section XI, Appendix VIII Supplement 2 of the 1998 Edition through the 2000 Addenda as administered by the PDI. In addition to the volumetric examination with limited coverage, the licensee performed a surface examination (Code required) on each of the C5. 21 items and achieved 100 percent coverage.
The results from the surface examinations were acceptable.
In addition to the C5.21 welds that relief for limited scanning is being requested, twelve other C5.21 welds in the same system were examined using surface and volumetric techniques during the same outage. Eleven of the welds examined did not identify any recordable indications and 100 percent coverage was obtained on each of the 11 welds. One of the welds examined identified recordable indications (porosity & tungsten) during the volumetric examination that were acceptable per the 1998 Edition through the 2000 Addenda of the Section XI Code, Paragraph IWB-3514.3, Table IWB-3514-2. The weld that had recordable indications obtained 100-percent coverage. The examination and results of the twelve additional welds contributes to the reasonable assurance of pressure boundary integrity for this system.
The licensee did not claim credit for coverage of the far side of the austenitic weld. The characteristics of austenitic weld metal attenuate and distort the sound beam when shear waves
pass through the weld. Refracted longitudinal waves provide better penetration but cannot be used beyond the first sound path leg. The licensee used a combination of shear waves and longitudinal waves to examine single sided austenitic welds when the nominal material thickness exceeds 0.5 inch. A 70º shear wave angle beam is used to interrogate the far side of the weld when the nominal material thickness is equal to or less than 0.5 inch and a 60º refracted longitudinal wave is used to interrogate the far side of the weld when the nominal material thickness is greater than 0.5 inch.
The licensee used Class 2, Examination Category C-H, pressure testing and VT-2 visual examination to complement the limited examination coverage. The Code requires that a pressure test be performed once each period for Class 2 items. These tests require a VT-2 visual examination for evidence of leakage. The licensee stated that this pressure testing provides adequate assurance of pressure boundary integrity.
In addition to the above Code required examinations (volumetric, surface and pressure tests),
there are other activities which provide a high level of confidence that, in the unlikely event that leakage did occur through one of these welds, it would be detected and proper action taken.
Specifically, system leak rate limitations imposed by Technical Specification 3.4.13, Reactor Coolant System Leakage, as well as visual observations performed during operator rounds, provide additional assurance that any leakage would be detected prior to gross failure of the component.
Lastly, the licensee stated that these welds/components were rigorously inspected by volumetric NDE methods during construction and verified to be free from unacceptable fabrication defects.
The licensee believes that the combination of examinations provides a reasonable assurance of quality and safety for areas/welds for ASME XI item number C5.21 (weld ID numbers 2-51A-17-111, 2HP-227-3, 2HP-227-7 and 2-51A-28-67).
3.6 NRC Staffs Evaluation The NRC staff has evaluated the information provided by the licensee in support of the volumetric examinations of the subject welds performed during the fourth 10-year ISI interval. For the subject welds, ultrasonic scanning in the axial direction could be performed from only one side of the weld due to component configuration and geometries which prevented scanning from the other side of the weld. The licensees best effort examination with single sided access achieved volumetric examination coverages of the welds ranging from 29.26 percent to 79.15 percent.
The volume required to be examined and the nondestructive examination methods to be used for examination are described in IWB-2500 for the Class 1 welds and IWC-2500 for the Class 2 welds.
ASME Code Case N-460, which was approved for use by the NRC in RG 1.147, Revision 15, allows credit for full volume coverage if it can be shown that more than 90 percent of the required volume has been examined.
The NRC staff has determined that the examination coverage of the subject welds was reduced due to component configuration and geometries which restricted scanning to the ranges identified above. In addition to the volumetric examinations, the licensee performed surface examinations on all the welds. The results of the surface examinations were acceptable. For two of the welds, the licensee stated that they used Class 1, Examination Category B-P pressure testing and VT-2
visual examinations to complement the applicable limited examination coverage. The Code requires that a pressure test be performed after each refueling outage for these Class 1 welds.
For the other five welds, the licensee stated that they used Class 2, Examination Category C-H, pressure testing, and VT-2 visual examinations to complement the applicable limited examination coverage. The Code requires that a pressure test be performed once each inspection period for these Class 2 items. In addition to the ASME Section XI pressure testing, the licensee performed other activities such as reactor building normal sump rate monitoring and visual observations during operator rounds, which provide additional assurance that any leakage would be detected prior to gross failure of the components. Therefore, the NRC staff has determined that the licensees limited ultrasonic examination coverage of the welds, as complemented by additional examinations/observations, provide reasonable assurance of structural integrity. In order to meet the code requirements, the components would have to be redesigned, fabricated, and installed in the systems, which would be impractical. Based on the access limitations, it is impractical for the licensee to meet the Code coverage requirements.
4.0 CONCLUSION
The NRC staff has reviewed the licensees submittal and has concluded that compliance with the Code requirements for volumetric coverage of the subject welds is impractical due to component configuration. The NRC staff has also determined that if the Code requirements were to be imposed on the licensee, the components must be redesigned, which would impose significant burden on the licensee. The NRC staff finds the examination coverage of the accessible weld volume as complemented by the additional examinations performed by the licensee provide reasonable assurance of structural integrity of the subject welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the fourth 10-year ISI inspection interval of Oconee 2, which is scheduled to end on September 9, 2014. This grant of relief 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 if the requirements were imposed on the facility.
All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: K. Hoffman, DCI/NRR Date: March 30, 2009