ML15218A150
| ML15218A150 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/28/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML15218A149 | List: |
| References | |
| NUDOCS 9709020130 | |
| Download: ML15218A150 (3) | |
Text
%$r *.jP.IREGtu, UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ON HIGH PRESSURE INJECTION RECIRCULATION LINE WELD REPAIR THIRD 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR RELIEF NO. 97-03 OCONEE NUCLEAR STATION, UNIT NO. 3 DOCKET NO. 50-287
1.0 INTRODUCTION
The Technical Specifications for Oconee Nuclear Station, Unit No. 3, state that the inservice inspection and testing 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 (ASME 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 (1) 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.
ursuant to 1 5
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 Oconee Nuclear Station, Unit No. 3, for the current inservice inspection (ISI) interval is the 1989 Edition. 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.
9709020130 970628 PDR ADOCK 05000287 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.
By letter dated June 17, 1997, Duke Power Company (licensee) requested relief from compliance with the 1992 Edition of ASME Code,Section III, paragraph NC-5222, which was invoked under the rules of Code Case N-416-1. The licensee proposes the use of ultrasonic and liquid penetrant examinations as an alternative to Code-required radiographic examination for acceptance of a weld on the High Pressure Injection System 3A recirculation orifice.
The staff has reviewed and evaluated the licensee's request and supporting information on the proposed altemative to the Code requirements for Oconee Unit 3, pursuant to the provisions of 10 CFR 50.55a(a)(3)(1).
2.0 DISCUSSION Component:
High Pressure Injection Pump (HPI) 3A Minimum Recirculation Orifice Assembly.
Licensee's Request for Code Relief:
The licensee has requested relief from the requirement of the ASME Code,Section III, 1992 Edition, to perform a 100 percent radiographic examination of an orifice assembly shell weld identified as 3-HPI-262-45 on the High Pressure Injection Pump 3A minimum recirculation line due to partial masking from an adjacent weld.
Licensee's Basis for Relief Request: (As stated)
Duke Power Company has determined that the requirements of a 100%
radiography examination is impractical for the 3 inch weld 3-HPI-262-45 per 10 CFR 50.55a section (g)(5)(iii). Weld 3-HPI-262-45 is the circumferential butt weld which reconnects the orifice shell. This weld resulted from cutting open the orifice assembly to repair the orifice internals. Radiography coverage of this weld reconnecting the orifice shell was incomplete due to the partial masking from an adjacent internal structural weld and the first orifice plate,
-3 resulting in a limited examination. This geometric configuration resulted from cutting open the orifice assembly shell too close to the internal structural weld.
Although only a limited examination of the weld was achieved, a majority of the weld including the root was acceptable per the radiographic sensitivity requirements.
Licensee's Proposed Alternate Examination: (As stated)
Duke Power Company proposes use of ultrasonic and liquid penetrant examinations in addition to the limited radiography examination. For a similar weld configuration, ultrasonic and liquid penetrant examinations are used to meet the requirements of ASME Section III, Paragraph NC-5279. These additional examinations along with the limited radiography examination will provide an acceptable level of quality and safety in lieu of the required ASME Section Ill 100% radiography examination and the health and safety of the general public will not be diminished.
Additionally, the actual weld thickness (0.65 inch) is more than twice the minimum calculated (0.30 inch) for system design pressure and temperature.
Therefore, a significant safety margin exists with the construction of the weld.
3.0 EVALUATION The staff has evaluated the licensee's request for relief from performing a 100 percent radiographic examination of the subject weld on the orifice assembly as required by the ASME Code,Section III, due to the configuration of the weld.
The licensee's proposed alternative of an ultrasonic examination of the weld is a reliable volumetric examination but suffers from a drawback of missing shallow surface flaws due to the near-field effect of the ultrasonic transducer. However, the licensee has also proposed to perform a surface examination using liquid penetrant. The combination of ultrasonic and liquid penetrant examinations of the weld are adequate to detect weld integrity and thus will provide an acceptable level of quality and safety.
4.0 CONCLUSION
Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee's Request for Relief No.97-03, proposing ultrasonic and liquid penetrant examinations in lieu of the Code-required radiographic examination of Weld No. 3-HPI-262-45 on the orifice assembly, is authorized in that it provides an acceptable level of quality and safety.
Principal Contributor: Prakash Patnaik Date: August 28, 1997