ML15238A341
| ML15238A341 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/13/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML15238A340 | List: |
| References | |
| NUDOCS 9612160308 | |
| Download: ML15238A341 (7) | |
Text
C1-0pkREG(It UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION THIRD TEN-YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUEST FOR RELIEF NO. 96-01 FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1. 2. AND 3 DOCKET NOS. 50-269, 50-270, AND 50-287
1.0 INTRODUCTION
The Technical Specifications for Oconee Nuclear Station, Units 1, 2, and 3 state that the inservice inspection of the American Society of Technical Engineers (ASME) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable Addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), 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 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.
Pursuant to 10 CFR 50.55a(g)(4), 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, "Rules for Inservice Inspection of Nuclear Power Plant Components," 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 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. The applicable edition of Section XI of the ASME Code for Oconee Nuclear Station, Units 1, 2, and 3 third 10-year inservice inspection (ISI) interval is the 1989 Edition.
9 612160308 961213 PDR ADOCK 05000269 P
-2 Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
In a letter dated February 27, 1996, Duke Power Company (the licensee) submitted to the NRC Request for Relief No. 96-01 for Oconee Nuclear Station, Units 1, 2, and 3. Additional information was provided by the licensee in its letter dated September 5, 1996.
2.0 EVALUATION AND CONCLUSIONS The staff, with technical assistance from its contractor, the Idaho National Engineering Laboratory (INEL), has evaluated the information provided by the licensee in support of Request for Relief No. 96-01 for Oconee Nuclear Station, Units 1, 2, and 3. Based on the information submitted, the staff adopts the contractor's conclusions and recommendations presented in the Technical Letter Report (Enclosure 2).
The welds and components listed in this request for relief parts 1 and 2, for all configurations, including interferences, are considered identical for Units 1, 2, and 3. The current interval examinations have been performed on Unit 1 only, and the licensee expects that similar coverage limitations will be observed on the same components in Units 2 and 3 and requested that its relief be applied to Units 1, 2, and 3.
The staff concluded for Request for Relief No. 96-01 (Part 1) that the taper on the nozzle side of the weld restricts scanning, and prevents complete volumetric coverage of pressurizer nozzle-to-vessel Welds 1-PZR-WP34, 1-PZR-WP33-2, and 1-PZR-WP33-3. For Request for Relief No. 96-01 (Part 2),
the staff concluded that the five restraints on the tubesheet side of the weld restrict scanning of the examination volume, preventing complete examination of steam generator Weld 1-SGA-WG60. Therefore, the 100 percent volumetric examinations are impractical for the above subject welds in parts 1 and 2 of the relief request. To meet the Code examination coverage requirements, design modifications to the subject components would be necessary to allow complete volumetric coverage. Therefore, Request for Relief No. 96-01 Parts 1 and 2 are granted pursuant to 10 CFR 50.55a(g)(6)(i) for Unit 1. Relief pursuant to 10 CFR 50.55a(g)(6)(i) is also granted for Units 2 and 3, provided that actual examination coverages for the same component welds in Units 2 and 3 are equal to, or greater than those described by the licensee for Unit 1.
This relief and the alternative requirements imposed are authorized by law, will not endanger life, property, or the common defense and security, and are 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.
Principal Contributor: Thomas K. McLellan Date:
December 13, 1996
TECHNICAL LETTER REPORT ON THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR RELIEF 96-01 DUKE POWER COMPANY OCONEE NUCLEAR STATION. UNITS 1. 2. AND 3 DOCKET NUMBERS: 50-269, 50-270, AND 50-287
1.0 INTRODUCTION
By letter dated February 27, 1996, Duke Power Company submitted Request for Relief 96-01. The Nuclear Regulatory Commission requested additional information concerning the subject request in a letter dated August 9, 1996. The licensee provided the requested information in a letter dated September 5, 1996. The Idaho National Engineering Laboratory (INEL) staff has evaluated this request in the following section.
2.0 EVALUATION The Code of record for the Oconee Nuclear Station, Units 1, 2, and 3, third 10-year inservice inspection interval is the 1989 Edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI.
The information provided by the licensee in support of the request for relief from Code requirements has been evaluated and the basis for disposition is documented below.
It should be noted that for welds and components listed in this request for relief, all configurations, including interferences, are considered identical for Units 1, 2, and 3. Although the current interval examinations have been performed on Unit 1 only, it is expected that similar coverage limitations will be observed on the same components in Units 2 and 3.
A. Request for Relief 96-01, Part 1. Examination Category B-D, Item B3.110, Full Penetration Pressurizer Nozzle-to-Vessel Welds Code Requirement: Examination Category B-D, Item B3.110 requires 100%
volumetric examination of all pressurizer nozzle-to-vessel welds as defined by Figure IWB-2500-7.
Licensee's Code Relief Request:
The licensee requested relief from performing 100% of the Code-required volumetric examinations of the following pressurizer nozzle-to-vessel welds:
-2 WELD NUMBER ITEM NUMBER 1-PZR-WP34 B03.110.002 1-PZR-WP33-2 B03.110.004 1-PZR-WP33-3 B03.110.003 2-PZR-WP34 B03.110.002 2-PZR-WP33-2 B03.110.004 2-PZR-WP33-3 B03.110.003 3-PZR-WP34 B03.110.002 3-PZR-WP33-2 B03.110.004 3-PZR-WP33-3 B03.110.003 Licensee's Basis for Requesting Relief (as stated):
Pressurizer Nozzle-to-Shell Weld 1-PZR-WP34 (Item Number B03.110.002) was examined to the maximum extent practical using ultrasonic techniques in accordance with the requirements of ASME Section V, Article 4, and ASME Section XI, Appendix I, 1989 Edition.
This weld is limited to 70.75% coverage of the required volume because of the nozzle configuration.
Pressurizer Nozzle-to-Shell Welds 1-PZR-WP33-3 and 1-PZR-WP33-2 (Item Numbers B03.110.003 and B03.110.004 respectively) were examined to the maximum extent practical using ultrasonic techniques in accordance with the requirements of ASME Section V, Article 4, and ASME Section XI, Appendix I, 1989 Edition.
These welds are limited to 66.5% coverage of the required volume because of the nozzle configuration.
Duke Power Company will continue to ultrasonically examine the welds, including inside radii, to the extent practical within the limits of original design and construction. This will provide reasonable assurance of weld/component integrity. Thus, an acceptable level of quality and safety will have been achieved and public health and safety will not be endangered by allowing relief from the aforementioned Code requirements.
In the licensee's September 5, 1996, response to the NRC's RAI, the licensee provided copies of the ultrasonic examination sheets and sketches showing the coverages obtained and the limitations associated with each examination. The licensee also stated that "Duke is not seeking relief for the examinations of the nozzle inside radius sections."
'Not included in this Technical Letter Report.
-3 Licensee's Proposed Alternative (as stated):
Duke Power company will continue to perform ultrasonic examination of all welds identified in Section 1 of this request (for all units) to the maximum extent practical, within the limits of original design and construction, in accordance with the requirements of ASME Section V, Article 4 and ASME Section XI, Appendix I, 1989 Edition.
If for some reason, the actual examination coverage of the welds referenced in this request for relief for Units 2 and 3 are less than those listed for Unit 1, additional requests for relief will be submitted on a case-by-case basis.
Evaluation:
The Code requires 100% volumetric examination of all pressurizer nozzle-to-vessel welds. However, the taper on the nozzle side of the weld restricts scanning, and prevents complete volumetric coverage of pressurizer nozzle-to-vessel Welds 1-PZR-WP34, 1-PZR-WP33-2, and 1-PZR-WP33-3.
Therefore, the 100% volumetric examinations are impractical for these nozzle-to-vessel welds. To meet the Code examination coverage requirements, design modifications to the nozzles would be necessary to allow complete volumetric coverage. Imposition of this requirement would create a considerable burden on the licensee.
The licensee obtained 70.75%, 66.5%, and 66.5% coverage of pressurizer nozzle-to-vessel Welds 1-PZR-WP34, 1-PZR-WP33-2, and 1-PZR-WP33-3, respectively.
Based on the significant portions of the required volumetric examinations that have been completed, any existing patterns of degradation would have been detected. The partial volumetric examinations provide reasonable assurance of the continued structural integrity of the subject nozzle-to-vessel welds. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i) for Unit 1. Relief should also be granted for Units 2 and 3, provided that actual examination coverages for the same component welds in Units 2 and 3 are equal to, or greater than, those described in this request.
B. Request for Relief 96-01, Part 2. Examination Cateqory C-A, Item C1.30, Tubesheet-to-Shell Weld Code Requirement: Examination Category C-A, Item C1.30 requires 100%
volumetric examination of tubesheet-to-shell welds as defined by Figure IWC-2500-2. In the case of multiple vessels of similar design, size, and service, the required examination may be limited to one vessel or distributed among the vessels.
Licensee's Code Relief Request: The licensee requested relief from performing 100% of the Code-required volumetric examinations of steam generator tubesheet-to-shell Welds 1-SGA-WG60, 2-SGA-WG60,.and 3-SGA-WG60, Item C01.030.001.
-4 Licensee's Basis for Requesting Relief (as stated):
Steam Generator Tubesheet-to-Shell Weld 1-SGA-WG60(Item Number CO1.030.001) was examined to the maximum extent practical using ultrasonic techniques in accordance with the requirements of ASME Section V, Article 4, and ASME Section XI, Appendix I, 1989 Edition.
This weld was limited to 73.8% coverage of the required volume because of the proximity of five restraints which prevent scanning the required weld volume and near surface volume from the tube sheet side.
Duke Power Company will continue to ultrasonically examine the welds, to the extent practical within the limits of original design and construction. This will provide reasonable assurance of weld/component integrity. Thus, an acceptable level of quality and safety will have been achieved and public health and safety will not be endangered by allowing relief from the aforementioned Code requirements.
In the licensee's September 5, 1996, response to the NRC's RAI, the licensee provided copies of the ultrasonic examination sheetS2 and sketches showing the coverage obtained and the limitations associated with each examination.
Licensee's Proposed Alternative Examination (as stated):
Duke Power company will continue to perform ultrasonic examination of all welds identified in Section 1 of this request (for all units) to the maximum extent practical, within the limits of original design and construction, in accordance with the requirements of ASME Section V, Article 4 and ASME Section XI, Appendix I, 1989 Edition.
If for some reason, the actual examination coverage of the welds referenced in this request for relief for Units 2 and 3 are less than those listed for Unit 1, additional requests for relief will be submitted on a case-by-case basis.
Evaluation: The Code requires 100% volumetric examination of one steam generator tubesheet-to-shell weld. However, five restraints on the tubesheet side of the weld restrict scanning of the examination volume, preventing complete examination of steam generator Weld 1-SGA-WG60.
Therefore, the 100% volumetric examination is impractical for the subject weld. To meet the Code examination coverage requirements, design modifications to the steam generator would be necessary to allow complete volumetric examination coverage. Imposition of this requirement would create a considerable burden on the licensee.
2Not included in this Technical Letter Report.
-5 The licensee obtained 73.8% coverage of steam generator tubesheet-to shell Weld 1-SGA-WG60. Based on the significant portion of the required volumetric examination that has been completed, existing patterns of degradation would have detected. The partial volumetric examination provides reasonable assurance of the continued structural integrity of the subject tubesheet-to-shell weld. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i) for Unit 1. Relief should also be granted for Units 2 and 3, provided that actual examination coverages for the same component welds in Units 2 and 3 are equal to, or greater than, those described in this request.
3.0 CONCLUSION
The INEL staff has reviewed the licensee's submittals and concludes that the Code examination requirements are impractical for the welds evaluated in Request for Relief 96-01, Parts 1 and 2, for Oconee Units 1, 2, and 3. The examinations performed to the extent possible will provide reasonable assurance of structural integrity. Therefore, it is recommended that relief be granted, pursuant to 10 CFR 50.55a (g)(6)(i), for Unit 1. Relief should similarly be granted for Units 2 and 3, provided that actual examination coverages for the same component welds in Units 2 and 3 are equal to, or greater than, those described in this request.
Date:
December 13, 1996