ML16131A425
| ML16131A425 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 01/12/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16131A426 | List: |
| References | |
| NUDOCS 9301190216 | |
| Download: ML16131A425 (3) | |
Text
~pR REGj 0
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. 92-15 FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNIT 1 DOCKET NO. 50-269
1.0 INTRODUCTION
Technical Specification 4.2.1 for the Oconee Nuclear Station, Unit 1, states that inservice inspection and testing 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 given granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Pursuant to 10 CFR 50.55a(a)(3), 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 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 applicable edition of Section XI of the ASME Code for Oconee Nuclear Station, Unit 1, Second Ten-Year Inservice Inspection (ISI) Interval, is the 1980 Edition through Winter 1980 Addenda. 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.
9301190216 930112 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, 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.
In a letter dated November 19, 1992, Duke Power Company (licensee) submitted Request for Relief No. 92-15 requesting relief from hydrostatic testing after replacing check valves 1FDW-39, 1FDW-232, 1FDW-233 and 1FDW-345 by welding.
These valves were in piping between the Emergency Feedwater System and the steam generators. The welds could not be isolated from the steam generators.
2.0 EVALUATION Code Requirement:
The licensee requests relief from ASME code requirement IWA-4400(a) "After repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWA-5000."
Licensee's Basis for Requesting Relief: The licensee stated that due to the inability to isolate any of these eight welds from the steam generators, performing a hydrostatic test would expose the steam generators to a needless cycle possibly shortening the life of the steam generators. In addition, this test would require filling some 600 feet of piping in the Feedwater, Emergency Feedwater and Main Steam systems with an average pipe size of 12 inches.
Therefore, the licensee determined that the Code-required hydrostatic testing is impractical.
Licensee's Proposed Alternative Examination:
The licensee proposed that the subject welds will receive a 100% radiograph (RT) and visual (VT-2) inspection at normal operating pressure.
Staff Evaluation: The Code requires that after repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed at a test pressure 1.25 times normal operating pressure. The staff has determined that the Code-required test would be an undue hardship on the licensee, because the steam generators are limited by design as to the number (35) of hydrostatic pressure tests that are allowed in the plant's operating life span. Furthermore, the hydrostatic testing would generate an excessive amount of potentially contaminated water and it would be difficult to ensure a slug of water would not be injected on the turbine blades when the stop valves were open during unit restart and cause damage to the turbine blades.
The licensee proposes as an alternative to the Code requirement to examine the welds by RT and to perform a VT-2 inspection at normal operation pressure.
Compliance with the Code would not provide a compensatory increase in safety.
The licensee's proposed alternative examination provides reasonable assurance
-3 of the structural integrity of the pressure boundary of the Emergency Feedwater System. The licensee should perform the Code-required hydrostatic test on these eight welds at the next regularly scheduled system hydrostatic test.
3.0 CONCLUSION
Paragraph 10 CFR 50.55a(g)(4) requires that components (including supports) that are classified as ASME Code Class 1, 2, and 3 meet the requirements, except the design and access provisions and preservice requirements, set forth in applicable editions of ASME Section XI to the extent practical within the limitation of design, geometry, and materials of construction of the components. The staff has determined that the hydrostatic testing requirements of the Code would be unusually difficult and do not increase the level of quality and safety for Oconee Nuclear Station, Unit 1. The licensee should perform a hydrostatic test at the next regularly scheduled system hydrostatic test.
Pursuant to 10 CFR 50.55a(3)(ii), the proposed alternative testing is authorized because compliance with the Code would result in hardship or unusual difficulty without a compensatory increase in the level of quality and safety.
Date: January 12, 1993