ML20044H390
| ML20044H390 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 06/03/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20044H389 | List: |
| References | |
| NUDOCS 9306080310 | |
| Download: ML20044H390 (4) | |
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E UNITED STATES 1
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NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 2055%o001 SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
OF FIRST-TEN-YEAR INSERVICE INSPECTION INTERVAL RE0 VEST FOR RELIEF FOR 1
DUKE POWER COMPANY MCGUIRE NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50-369 AND 50-370
1.0 INTRODUCTION
Technical Specification 4.0.5 for McGuire Nuclear Station Units 1 and 2 states that 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 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).
Section 10 CFR 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 compenents.
The regulations require that inservice examination of components and system pressure tests conducted during each 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 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 9306080310 930603 PDR ADDCK 03000369 p
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1 endanger life, property, or the common defense and security, and are otherwise i
in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
By letters dated May 18 and May 25, 1993, Duke Power Company (the licensee) submitted to the NRC a request for relief (Relief Request 93-02) from a i
pressure test requirement of Section XI of the.ASME Code. The licensee determined that to perform the specific requirement would be impractical during the First Ten-Year ISI interval for McGuire Units 1 and 2.
The staff has evaluated the licensee's request for relief from the Code requirement, and its evaluation and conclusions are discussed in the following sections.
2.0 RE0VIREMENTS AND SVPPORTING INFORMATION Code Reouirements:
The component for which the licensee is requesting relief is the Class B piping within containment penetrations M372 and M373, Item Number C07.021.045.
This piping is the supply and return glycol-water mixture lines for the ice condenser refrigerant system and is designated to be ASME Section XI Code Class 2.
The ASME Code Section XI requirement that the licensee has determined to be impractical is that contained in ASME Code Section XI,1980 Edition through Winter 1980 Addenda, Subsection IWC, Subarticle 2500, Table IWC-2500-1, Examination Category C-H (all pressure retaining components), Item Number C7.21.
The piping is required to be hydrostatically tested and visually examined.
Licensee's Basis for Reouestina Relief:
The examination specified by the code is a system hydrostatic test of the Class B piping for mechanical penetrations M372 and M373. These penetrations are part of the glycol-water mixture supply and return lines in the Ice Condenser Refrigeration System (NF). The lines are 4-inch carbon steel piping that is insulated. The examination method specified by the code is a VT-2 visual exam.
IWA-5242 delineates the requirements for performing a VT-2 visual examination of an insulated component.
Briefly, IWA-5242 states that a VT-2 visual exam may be performed without removing insulation provided that:
- 1) accessible and exposed surfaces and joints of insulation are examined;
- 2) vertical surfaces of insulation are examined at the lowest elevation; and
- 3) horizontal surfaces be examined at each insulation joint.
If the insulated surfaces are inaccessible for direct examinations, then only surrounding areas need be examined.
The piping in question for penetrations M372 and H373 is encapsulated with ice -
and frost.
Due to this layer of ice and frost, a VT-2 visual examination cannot be performed in accordance with the requirements specified within the ASME Section XI Code. The inspectors, during the examination, are not able to observe the appropriate areas for any signs of possible leakage. This layer of ice and frost on the piping is believed to be due to the nature of the fluid (glycol-water mixture) within the piping.
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a As such, to perform the code required VT-2 visual examination, the insulation around the piping will need to be removed.
The NF system would have to be shut down for an extended period of time in order to:
remove the insulation, drain the glycol-water mixture, perform the examination, re-install the insulation and charge the system with the glycol-water mixture.
Since these lines are in service at all times to maintain the weight of the ice baskets, the NF system cannot be shut down and the glycol-water mixture drained.
Doing so would result in the degradation of the safet3 related ice condenser system due to melting of the ice.
Further, the recovec ' rom such an incident would be a significant burden due to the need to re-weigh the ice baskets and the possible need to reload some.
Licensee's froposed Alternative Examination:
The basic intent of a hydrostatic test is to verify the overall integrity of the pressure retaining components of the system being examined.
The examination method specified by the ASME Code is a visual VT-2 exam. A VT-2 visual examination is performed in order to locate evidence of leakage or abnormal leakage from pressure retaining components.
The licensee proposes that in lieu of the system hydrostatic test, the Appendix J type C test of TS 4.6.1.2d.4) would be performed.
As stated within Appendix J, one of the purposes of the tests is to assure that leakage through components penetrating primary containment does not exceed allowable leakage rates, thus assuring leak-tight integrity of the primary containment.
For the particular penetrations in question (M372 and 373), the Appendix J type C test, performed in accordance with TS 4.6.1.2d.4), includes the class 8 piping of this relief request.
The acceptance criteria specified by TS 4.6.1.2d.4) is that a zero indicated leakage rate is measured.
Accordingly, the intent of the test and the examination method (verifying no leakage from the pressure i
retaining components) is accomplished.
3.0 STAiF EVALVATION AND CONCLUSION Pt. ;uant to 10 CFR 50.55a(g)(5)(iii), the licensee determined that conformance with certain Code requirements are impractical for its facility and submitted supporting information.
The staff has reviewed the licensee's submittal and agrees with the licensee that it is impractical to perform the Code required VT-2 visual examination. The staff notes that in order to do the visual examination, it would require removal of the ice and frost in c,rder to allow access and removal of the insulation around the pipe.
This would be followed by a draining of the glycol-water mixture, performing the Code required examination, re-installing the insulation, and charging the system with the j
glycol-water mixture.
The refrigerant system, although it is not a safety l
system, supports a safety system, the containment ice condenser system.
l Shutting down the refrigerant system will initiate degradation of the safety related ice condenser system.
The licensee contends that the proposed alternative would provide an acceptable level of quality and safety since the hydrostatic test and the surveillance test are intended to determine that no leakage exists in the system, thus, indicating the integrity of the system.
The staff agrees with the licensee's contention that the proposed alternative would provide an acceptable level of quality and safety.
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' i Pursuant to 10 CFR 50.55a(g)(6)(i), the staff concludes that the requirements of the Code ara impractical and relief may be granted for Relief Request 93-02.
Such relief is authorized by law and will not endanger life, property, or the common defense and security, and is otherwise in the public interest.
Relief has been granted giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Furthermore, the proposed alternative examinations should provide an acceptable level of quality and safety, and reasonable assurance that the structural integrity of the plant's systems, components, and supports will be maintained.
Principal Contributor:
Victor Nerses Dated:
June 3, 1993 l
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