ML16148B152
| ML16148B152 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/11/1992 |
| From: | Matthews D Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16148B151 | List: |
| References | |
| NUDOCS 9206170247 | |
| Download: ML16148B152 (3) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE SECOND TEN-YEAR INTERVAL INSERVICE INSPECTION RELIEF REQUEST NO. 91-02 FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1. 2 AND 3 DOCKET NUMBERS 50-269, -270, AND -271
1.0 INTRODUCTION
Technical Specification 4.2.1 for the Oconee Nuclear Station states that inservice inspection of American Society of Mechanical 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 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used if (1) the proposed alternatives would provide an acceptable level of quality or safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulties 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 second ten-year interval 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) on the date twelve months prior to the start of the 120-month inspection interval, subject to the limitations and modifications listed therein. The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein.
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 his 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 or 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.
9206170247 920611 PDR ADOCK 05000269 P
_PDR
-2 In a letter dated January 31, 1991, the Licensee, Duke Power Company, submitted Request for Relief No. 91-02 askingfor relief from performing the examination of the nozzle-to-vessel welds during the first period of the Third Ten-Year Inservice Inspection (ISI) Interval at Oconee Nuclear Station.
However, the licensee is currently in its third period of the second ten-year interval and will not begin the third ten-year interval until March 1994.
The staff, with technical assistance from its Contractor, the Idaho National Engineering Laboratory (INEL), has evaluated Request for Relief No. 91-02 in the sections that follow.
2.0 EVALUATION The information provided by the Licensee in support of the request for relief has been evaluated and documented below.
Request for Relief No. 91-02, Examination Category B-D. Items B3.90 and B3.100. Units 1. 2 and 3 Reactor Pressure Vessel 36 inch Outlet Nozzle to-Vessel and Outlet Nozzle Inner Radius Sections Code Requirement:
For third ten-year inspection interval: No edition or addenda has been assigned to the third ten-year inspection interval.
For second ten-year inspection interval: ASME Boiler and Pressure Vessel Code Section XI, 1980 Edition with Addenda through Winter 1980 Article IWB-2000, Table IWB-2500-1 and Subsection IWB-2420(a) which require the following:
Section XI, Table IWB-2500-1, Examination Category B-D, Items B3.90 and B3.100 require 100% volumetric examination of the nozzle-to-vessel welds and nozzle inside radius sections as defined by Figure IWB-2500-7. Note 3 requires that at least 25%, but not more than 50% of the nozzles be inspected by the end of the first inspection period and the remainder by the end of third inspection period of each 10-year inspection interval.
Subsection IWB-2420(a) requires that the sequence of component examination established during the first inspection interval shall be repeated during each successive inspection interval to the extent practical.
Licensee's Code Relief Request:
Relief is requested from performing the Code-required minimum examination of 25% of the nozzles [per note (3)]
during the first inspection period of the third inspection interval at Oconee Nuclear Station, Units 1, 2 and 3.
Licensee's Proposed Alternative Examination:
The Licensee states that automated re-examination of the nozzle-to-vessel welds, including the nozzle inner radius sections, will be deferred to the last period of the third ten-year inspection interval.
-3 Licensee's Basis for Requesting Relief:
During the first period of the second ten-year inspection interval of Oconee Nuclear Station, the reactor vessel 36" outlet nozzle-to-vessel welds, including nozzle-to pipe welds were examined using Babcock & Wilcox's Automated Reactor Inspection Tool (ARIS). The two nozzle welds examined met the 25%
requirement of Table IWB-2500-1. No recordable indications were detected.
During the third period of the second ten-year inspection interval all reactor vessel nozzle-to-vessel and respective nozzle-to-pipe welds will be examined using automated inspection equipment. Included in this examination will be the 36" outlet nozzles-to-vessel and nozzle-to-pipe welds examined during the first period. The re-examination of these 36" outlet nozzles will be performed meeting the requirements of the ASME Section XI Code. Credit will be applied to the third interval, first period requirement for the 36" outlet nozzle-to-vessel welds. Category B-D, items B3.90 and B3.100. These examinations will not be performed during the first period of the third inspection interval.
Staff Evaluation: The proposed inspection sequence for the second ten year inspection interval meets the Code scheduling inspection requirements for the subject RPV outlet nozzle-to-vessel and outlet nuzzle inner radius sections at Oconee Nuclear Station, therefore relief is not required during the second 10-year inspection interval.
In response to the Licensee's request to defer the nozzle examinations for the third inspection interval, the examination schedule change for the third inspection interval must be evaluated to future editions and addenda of the ASME Code as defined by 10 CFR 50.55a(g)(4) and 10 CFR 50.55a(b).
Furthermore, based on current editions of the Code, applying credit into another inspection interval defeats the intent of the Code, which provides for a sampling of RPV examinations at less than 10-year intervals. Since the requirements for the third ten-year inspection interval have not been determined, the request for relief is premature and does not demonstrate the impracticality of such future requirements. Therefore, the relief cannot be evaluated and is denied.
When the appropriate Code edition and addenda are identified for the third inspection interval, the licensee may, at that time, request relief. That request should address the basis for the impracticality or hardship caused by the inspection requirement and also address why the proposed alternative schedule does not defeat the intent of the Code.
3.0 CONCLUSION
The staff concludes that Request for Relief 91-02 is not required for Oconee Nuclear Station Units 1, 2, and 3 Second 10-Year ISI Interval as the Code requirements will have been met. In addition, the staff denies the request for relief for the third inspection interval as discussed above.