ML16141A865
| ML16141A865 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 01/12/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16141A864 | List: |
| References | |
| NUDOCS 9502030169 | |
| Download: ML16141A865 (5) | |
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0 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE SECOND TEN YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUEST FOR RELIEF NO. 92-14 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 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 Title 10 of the Code of Federal Regulations (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). Section 50.55a(a)(3) of 10 CFR 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 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 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) on the date 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 the Oconee Nuclear Station, Units 1, 2, and 3, second 10-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 and subject to Commission approval.
9502030169 950112 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 November 24, 1992, Duke Power Company submitted to the NRC its second 10-year interval inservice inspection program plan Request for Relief No. 92-14 for the Oconee Nuclear Station, Units 1, 2, and 3.
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 its second 10-year interval inservice inspection program plan Request for Relief No. 92-14 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 Evaluation Letter Report attached.
For Request for Relief No. 92-14, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i). This 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, given due consideration to the burden that could result if the requirements were imposed on your facility. The Code requires for the same nozzle a volumetric examination of the associated nozzle-to-vessel weld. This examination of the associated nozzle-to-vessel weld will provide a reasonable assurance that the structural integrity will be maintained for the HPI letdown cooler nozzle.
Principal Contributor: T. McLellan Date:
January 12, 1995
TECHNICAL EVALUATION LETTER REPORT OF THE SECOND TEN-YEAR INTERVAL INSERVICE INSPECTION REQUEST FOR RELIEF NO. 92-14 FOR 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 November 24, 1992, the licensee, Duke Power Company, submitted Request for Relief No. 92-14 requesting relief from the requirements of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section XI. The Idaho National Engineering Laboratory (INEL) staff has evaluated the information provided by the licensee in support of these requests for relief in the following section.
2.0 EVALUATION The information provided by the licensee in support of Request for Relief No. 92-14 has been evaluated and is documented below. The Code of record for the Oconee Nuclear Station, Units 1, 2, and 3, second 10-year inservice inspection (ISI) interval is the 1980 Edition through Winter 1980 Addenda of Section XI of the ASME Code.
A.
Reauest for Relief No. 92-14, Examination Category B-D, Item B3.160.
High Pressure Injection (HPI) Letdown Cooler Nozzle Inside Radius Sections Code Requirement: Table IWB-2500-1, Examination Category B-D, Item B3.160, requires a 100% volumetric examination, as defined by Figure IWB-2500-7, for all nozzle inside radius sections on the primary side of Class 1 heat exchangers.
Attachment
-2 Licensee's Code Relief Request: The licensee requested relief from performing the Code-required volumetric examination of the following HPI letdown cooler nozzle inside radius sections.
Attachment Unit 1 Unit 2 Unit 3 B03.160.001 B03.160.001 B03.160.001 B03.160.002 B03.160.002 B03.160.002 B03.160.003 B03.160.003 B03.160.003 B03.160.004 B03.160.004 B03.160.004 Licensee's Basis for Requesting Relief (as stated):
"Due to the size and geometry of the nozzle inside radius on the Letdown Coolers, we have been unable to perform a meaningful, (i.e., unable to get sound into the area of interest) volumetric examination.
"The alternate proposed inservice testing will provide an acceptable level of quality and safety and ensures the level of public health and safety is not reduced."
A drawing of the subject area was provided with the request. The licensee also stated in the cover letter that existing technology is inadequate to perform the inside radius examination of the HPI letdown coolers.
Licensee's Proposed Alternative Examination:
No alternatives to the Code-required examination were proposed. Volumetric examination of the HPI Letdown Cooler nozzle-to-vessel welds will be performed as required by the Code.
Evaluation: The Code requires 100% volumetric examination of nozzle-to vessel and nozzle inside radius sections for Class 1 heat exchangers.
However, as stated by the licensee, the size and geometry preclude volumetric examination of the HPI letdown cooler nozzle inside radius sections. It is apparent from the licensee's drawing that the design of
-3 the subject nozzle's inside radius section is not conducive to ultrasonic examination. The nozzles consist of a pipe welded into a larger pipe, both are of the same material, and appear to be more similar (in design) to a branch connection than a vessel nozzle.
Therefore, the design makes the Code-required volumetric examination of the subject nozzle's inside.radius section impractical to perform. To meet the Code requirement, the HPI letdown cooler nozzles would have to be redesigned and replaced. This would represent a considerable burden on the licensee.
Although no alternative to the Code requirement has been proposed, the Code requires a volumetric examination of the associated nozzle-to vessel weld for the same nozzle. Significant inservice degradation that may occur should be detected by performance of the Code-required volumetric examination of the associated nozzle-to-vessel weld. The Code required volumetric examination of the associated nozzle-to-vessel weld will provide reasonable assurance of the structural integrity of the subject nozzles. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).
3.0 CONCLUSION
The INEL staff has reviewed the licensee's submittal and concludes that, pursuant to 10 CFR 50.55a(g)(6)(i), the requirements of the Code are impractical and recommends that relief be granted for Request for Relief No. 92-14. The volumetric examination of the associated nozzle-to-vessel weld will provide reasonable assurance that the structural integrity will be maintained for the HPI letdown cooler nozzle inside radius sections.