ML15218A145
| ML15218A145 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/28/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML15218A144 | List: |
| References | |
| NUDOCS 9508300356 | |
| Download: ML15218A145 (5) | |
Text
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. 94-07 FOR DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNIT 3 DOCKET NO.:
50-287
1.0 INTRODUCTION
The Technical Specifications for Oconee Nuclear Station, Unit 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 b6en 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 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) 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, Unit 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.
9508300356 950828 PDR ADOCK 05000287 G
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 July 14, 1994, Duke Power Company submitted to the NRC its second 10-year interval inservice inspection program plan, Request for Relief No. 94-07 for the Oconee Nuclear Station, Unit 3. Additional information was provided by the licensee in its letter dated April 27, 1995.
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 ReliefVNo. 94-07 for the Oconee Nuclear Station, Unit 3.
Based on the information submitted, the staff adopts the contractor's conclusions and recommendations presented in the attached Technical Letter Report. The staff concludes that the Code requirement is impractical, the Code requirement is a burden on the licensee, and the proposed alternative testing would provide a reasonable assurance of operational readiness of the 3A High Pressure Injection Letdown Cooler. Therefore, relief is granted for Request for Relief No. 94-07, pursuant to 10 CFR 50.55a(g)(6)(i).
Attachment:
Technical Letter Report Principal Contributor: T. McLellan Date:
August 28, 1995
e TECHNICAL LETTER REPORT ON THE SECOND 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR RELIEF 94-07 FOR OCONEE NUCLEAR STATION, UNIT 3 DUKE POWER COMPANY DOCKET NUMBER:
50-287
1.0 INTRODUCTION
By letter dated July 14, 1994, Duke Power Company (Duke Power) submitted Request for Relief 94-07. For this request for relief, the Nuclear Regulatory Commission (NRC) granted interim relief to the end of the next outage in a Safety Evaluation Report dated August 11, 1994.
Interim relief was given to provide the NRC the opportunity to perform a more detailed review of the preservice ultrasonic examinations (UT) limitations for weld examinations associated with the High Pressure Injection Letdown Cooler.
Based on the INEL staff's detailed review of the request for relief, a request for additional information was conveyed by the project manager to the licensee in a phone conversation on April 10, 1995. The licensee responded with the additional information in a letter dated April 27, 1995.
ThT Idalo Natlonal Engineering Laboratory
( INEL)
Staff has evaluated Request for Relief 94-07 in the following section.
2.0 EVALUATION The Code of record for the Oconee Nuclear Station, Unit 3, second 10-year inservice inspection interval, which ended December 1994, was the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 1980 Edition with addenda through the Winter 1980. The information provided by the licensee in support of the request for relief from impractical requirements has been evaluated and the basis for granting relief from those requirements is documented below.
Attachment
2 Request for Relief 94-07: Table IWB-2500-1. Examination Category B-B, Item B2.60, Tubesheet-to-Shell Welds and Examination Category B-D.
Item B3.150, Nozzle-to-Vessel Welds, High Pressure Injection Letdown Cooler Code Requirement: Table IWB-2500-1, Examination Category B-B, Item B2.60 requires 100% volumetric examination of the tubesheet-to-shell welds as defined in Figure IWB-2500-6.
Examination Category, B-D, Item B3.150 requires 100% volumetric examination of the nozzle-to-vessel welds as defined in Figure IWB-2500-7.
In the case of the tubesheet-to-shell welds, the examination may be limited to one of a series of vessels, similar in design, size, and service.
Licensee's Code Relief Request:
The licensee requested relief from the Code-required 100% volumetric examination of the 3A High Pressure Injection (HPI)
Letdown Cooler, primary side inlet and outlet tubesheet-to-shell Welds B02.060.001 and B02.060.002 and nozzle-to-vessel Welds 803.150.001 and B03.150.002.
Licensee's Basis for Requesting Relief (as stated):
"Conformance with the ASME Section XI requirements for examination coverage for the four welds addressed by this relief request is impractical.
During the replacement of the Unit 3 'A' HPI Letdown Cooler, the Tiihehet and Nozzle welds for the primary side inlet and outlet were ultrasonically examined to satisfy the preservice examination requirements of ASME Section XI.
Due to part geometry, joint configuration, and interferences, 90%
examination coverage could not be obtained on these welds.
The examination coverage obtained on the Channel Nozzle weld on the inlet and outlet was 38%. The examination coverage for the Tubesheet to Tube Side Channel Body welds were 80.9% for the inlet and 84.09% for the outlet.
The joint and part configuration for these four welds are such that Radiographic examination can not be used to supplement the Ultrasonic examination to increase the examination coverage.
These welds received a Liquid Penetrant Examination of the root and final weld by the manufacturer. The primary side of the cooler was hydrostatically tested by the manufacturer at 3750 PSIG."
Licensee's Proposed Alternative Examination (as stated):
"The NDE hydrostatic test performed by the Manufacturer and the Limited Ultrasonic Examinations performed by Duke Power."
g 3
Evaluation:
By letter dated August 11, 1994, the NRC granted Duke Power Company, interim relief for Request for Relief 94-07. Interim relief was given to provide the NRC the opportunity to perform a more detailed review of the preservice UT examinations of the subject replacement welds associated with the High Pressure Injection Letdown Cooler.
As part of the evaluation of the relief request, the INEL staff reviewed the component drawings and UT limitation data. Based on this review, it has been determined that part geometry, joint configuration, and interferences preclude full volumetric coverage of the subject welds.
Therefore, obtaining the Code-required preservice examination coverage is impractical.
To obtain Code-required coverage, design modifications would be necessary to eliminate the coverage limitations.
Imposition of this requirement would cause a considerable burden on the licensee.
The licensee performed the required fabrication nondestructive examinations associated with the replacement welds.
In addition, the manufacturer performed a hydrostatic test on the heat exchanger.
The preservice volumetric examination coverage obtained included 38% coverage on each of the nozzle-to-vessel welds and, 80% and 84% coverage, on the tubesheet welds. Based on the examinations and tests performed, it is reasonable to conclude that flaws, if present, should have been detected. As a result, reasonable assurance of structural integrity has been provided.
3.0
Conclusion:
The INEL staff has reviewed the Oconee Nuclear Station, Unit 3, Request for Relief 94-07.
Based on this evaluation, it is concluded that obtaining the preservice Code-required volumetric coverage for the subject High Pressure Injection Letdown Cooler nozzle and tubesheet welds is impractical for Oconee Nuclear Station, Unit 3. Therefore, it is recommended that relief be granted pursuant to 10 CFR 50.55a(g)(6)(i).