ML20035H125
| ML20035H125 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/26/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035H123 | List: |
| References | |
| NUDOCS 9305030174 | |
| Download: ML20035H125 (3) | |
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UNITED STATES
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D,j NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555-0001
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f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE RE0 VEST FOR RELIEF UNDER 10 CFR 50.55afa)(5)(iv)
TOLED0 EDISON COMPANY CENTERIOR SERVICE COMPANY bilQ THE CLEVELAND ELECTRIC ILLUMINATING COMPANY DAVIS-BESSE NUCLEAR POWER STATION. UNIT NO. 1 DOCKET NO. 50-346 INTRODUCTION By letter dated September 28, 1990, Toledo Edison Company (the licensee) requested relief from the ASME Boiler and Pressure Vessel Code,Section XI, requirements for visual examination of portions of Class 2 piping associated with containment penetration nos. 30, 31, 33, and 34 at the Davis-Besse Nuclear Power Station, Unit No.1 (DBNPS) for the first ten-year interval of the inservice inspection program. Guardpipes, rubber foam barriers, and rubber boots prevent access necessary to perform VT-2 visual examination of the containment purge piping associated with containment penetration nos. 33 and 34.
Similarly, guardpipes inhibit performance of a VT-2 visual examination of containment penetration nos. 30 and 31.
EVALUATION Relief Recuest. Examination Cateaorv C-H. Item C7.21. Pneumatic Test of Containment Purae Lines Code Recuirement:
Subsection IWC, Table IWC-2500-1 Examination Category C-P, item No. C7.21, ASME Section XI, 1977 Edition with Addenda through Summer 1978, requires a hydrostatic test per IWC-5222. A pneumatic test is allowed for the subject containment purge lines by IWC-5210(b).
Licensee's Code Relief Recuest: Relief is requested from performing the VT-2 visual examination to the extent required by the Code for the containment purge lines from valve CV5005 to valve CV5006 (line HBB-17) at containment penetration 33, and from valve CV5007 to valve CV5008 (line HBB-18) at containment penetraticn 34.
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Licensee's Basis for Recuestino Relief: Due to the configuration of the pipe, surrounding guardpipes, and penetration rubber foam barriers and rubber boots, it is not practical to use a soap bubble technique with the VT-2 visual examination along the entire length of the subject piping.
Even removal of the fire ' penetration barriers and rubber boots would not allow for a complete examination due to the length of the pipe and lack of clearance between the pipe and guardpipes. During pneumatic tests, the accessible welds will be examined by the soap bubble technique. The inaccessible welds are longitudinal welds, which will be evaluated during the Appendix J local leak rate tests. The system will be pressurized to 38 psig (design basis accident pressure) for the Appendix J local leak rate test.
l Licensee's Proposed Alternative Examination: The pneumatic test and associated VT-2 visual examination will be performed to the extent practical.-
I Inaccessible portions shall be deemed acceptable based on successful completion of the 10 CFR Part 50, Appendix J 1eak rate test.
Evaluation: The Code requirement for the subject piping includes system pressure tests as specified in IWC-5222.
Paragraph IWC-5210(b) states: "lhe contained fluid in the system shall serve as the pressurizing medium, except I
that in steam systems either water or air may be used. Where air is used, the l
test procedure shall permit the detection and location of through-wall leakages in components of the system tested."
The licensee will perform a pneumatic test using the soap bubble technique to enhance the VT-2 visual examination, in lieu of the pressure test requirements
-i of IWC-5222, as allowed by the Code. The extent of the Code-required examination is impractical due to the above described access limitations.
In order to perform the VT-2 visual examination to the extent required by the Code, the subject piping would require extensive design modifications.
Imposition of the requirement on the licensee would cause a burden that would not be compensated by an increase in safety above that provided by the limited examination.
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Conclusion:==
It is concluded that the VT-2 visual examination of the subject l
containment purge lines at DBNPS is impractical to perform, to the extant required by the Code.
Therefore, pursuant to 10 CFR 50.55a(g)(6)( % chte NRC staff finds that relief should be granted. The granting of relief will not endanger life, properb 9r the common defense and security, and is otherwise in the public interest, considering the burden on the licensee that woui result if the requirement were imposed on the facility.
l Relief Recuest. Examination Cateoory C-H. Item C7.21. Pressure Test of Emeroency SumD Recirculation Lines Enclosed by Guardoioe Code Reauirement: Subsaction IWC, Table IWC-2500-1 Examination Category C-H,
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Item No. C7.21, ASME G :!on XI, 1977 Edition with Addenda through Summer i
1978, requires a VT-2 w l examination during system hydrostatic tests (IWC-5222).
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. Licensee's Code Relief Recuest:
Relief is requested from performing the Code-required VT-2 visual examination during the Code-required system hydrostatic tests of emergency sump recirculation lines, and associated valves DH9A and i
DH9B (of Decay Heat Trains 1 and 2) within the guardpipe enclosure.
Licensee's Basic for Reauestino Relief: The licensee states that due to the guardpipe, it is not practical to visually examine the enclosed pipe and I
associated valves. However, the guardpipes contain a drain that is opened and observed for leakage.
Per the licensee's ASME Section XI pressure testing procedure, the examination shall consist of examining the enclosure drains for evidence of leakage; the presence of dampness (not active leakage) shall be acceptable based on successful completion of a 10 CFR Part 50, Appendix J pressure test of the guardpipe (e.g. local leak rate test).
Licensee's Proposed Alternative Examination: The subject piping will be pressurized to the test pressure and the enclosure drains will be examined for evidence of leakage. No active leakage, and a successful completion of the 10 CFR Part 50, Appendix J local leak rate test, will constitute an acceptable test.
r Evaluation: The licensee requests relief from the direct VT-2 visual examination during system hydrostatic tests for the subject piping and valves.
Paragraph IWA-5241(b) states: "For components whose external surfaces are i
inaccessible for direct visual examination (VT-2), only the examination of surrounding area (including areas or equipment surfaces located underneath the components) for evidence of leakage shall be required." Since the licensee will be examining the guardpipe drain for evidence of leakage, the intent of the Code will be met. Therefore, relief is not required.
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Conclusion:==
As stated in the above evaluation, the intent of the Code is being met by the licensee; therefore, the NRC staff finds that relief is not required.
Principal Contributor:
J. Hopkins Date: April 26, 1993 l