ML20035F548
| ML20035F548 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/16/1993 |
| From: | Mccoy C GEORGIA POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| MSV-01415, MSV-1415, NUDOCS 9304220018 | |
| Download: ML20035F548 (4) | |
Text
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Georga Peaer Compaq 3
I 40 trivemers Cew Pawn Peu O"ce Bas '295 8 r%rpan Amo4ma 3T01 Teu hor.e 235 877-71E2 m
Georgia Power C. K. McCoy yyy '"
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April 16, 1993 MSV-01415
- 5368 Docket No. 50-424 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C.
20555 Gentlemen:
V0GTLE ELECTRIC GENERATING PLANT TEMPORARY RELIEF FROM ASME SECTION XI RE0VIREMENTS During the course of performing routine outage activities during the maintenance / refueling outage currently in progress at Georgia Power Company's (GPC) Vogtle Electric Generating Plant (VEGP), Unit 1, a pinhole leak was identified in the base material of one of the tubes in containment cooler 1-1501-A7-001-000 while the subject cooler was pressurized. The tubing in question is 90/10 copper / nickel material, 5/8" diameter, with a wall thickness of 0.035".
A leak was visually observed from the pinhole which is of such a size that it cannot be observed even when liquid penetrant tested. The subject containment cooler was manufactured to the requirements of the 1977 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section III with addenda through Winter 1977 and is a Class 2 component.
Section XI of the ASME Boiler and Pressure Vessel Code, which governs repair and replacement activities in service, requires corrective measures for components with unacceptable flaws. Acceptable corrective measures as determined by GPC would constitute either repair or replacement of the affected cooler tubing.
The repair or replacement must meet the original design specification and construction code. Acceptable means of satisfying the original construction criteria and/or ASME Section XI repair requirements would include:
- 1) replacement of the flawed tubing with acceptable materials, or 2) removal of the defect and plugging the tube by either thermal or mechanical processes such as brazed or mechanical plugs, or 3) removal of the flaw and base metal repair with a Code-compliant welding or brazing procedure.
The burden and problems associated with meeting these requirements are documented in the following paragraph.
In each case, the Code-acceptable options are either impract' cal or introduce the likelihood of creating a larger problem than currently exists.
A qualified brazing procedure is not available at VEGP for repairing the affected tubing at this time.
Even if a qualified brazing procedure was available, its use could adversely affect other brazed joints in proximity 930422OOiB 930416 PDR ADOCK 05000424 9
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GeorgiaPower n U. S. Nuclear Regulatory Commission MSV-01415 Page Two of the pinhole because of the high heat input involved in the brazing process. Therefore, because of these concerns with brazing the copper / nickel tubing, the pinhole was sealed using a lead / tin solder. The existing solder sealing the pinhole leak will be removed from the surface of the affected tubing and a split sleeve or coupling will be installed to reinforce the tubing.
The split sleeve or coupling will be soldered along its longitudinal joint and at each circumferential end using a silver / tin solder.
The enclosed figure depicts the corrective actions to be performed. While the corrective actions to be performed are acknowledged as not being in strict compliance with the repair and replacement requirements of ASME Section XI, they are the most practical in this particular case. Other corrective actions were considered such as plugging of the tubing which would require cutting the cubing and capping it with either a brazed plug or a compression fitting as allowed in ASME Section III. The foregoing corrective actions, while Code compliant, were not considered practical at this time and could adversely affect othPr tubing.
Therefore, a Code repair of the affected tubing is not an option at this time.
It is our opinion that sealing of the pinhole with solder and reinforcement of the affected tubing is the most desirable corrective action at this time. Should the corrective actions to be taken not be sufficient and the tubing leak, no adverse condition would exist except that the tubing would leak. The leakage of Nuclear Service Cooling Water (NSCW) would drain to a leakage measuring system associated with the containment cooler or to the sump and would be monitored. Any leakage will be monitored in accordance with the appropriate plant procedure (s) and Technical Specification requirements.
In the event of a design basis event (Loss of Coolant Accident with loss of off-site power), the sealed and reinforced tubing should prevent direct leakage of containment atmosphere to the outside atmosphere.
Georgia Power Company requests temporary relief from the requirements of Article IWA-4000 of ASME Section XI with respect o corrective actions to be taken to remedy leakage from the containment r;oler tubing.
Relief is requested to be granted by the NRC as allowed by 10 CFR 50.55a(g)(6)(i) because of the impracticality of imposing the ASME Section XI Code requirements.
GPC commits to either perform a Code repair or other long-term resolution during the next maintenance / refueling outage currently scheduled for Fall 1994. We request your prompt consideration of this relief request due to the outage activities currently in progress.
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Georgia Power n U. S. Nuclear Regulatory Commission MSV-01415 Page Three Should there be any questions in this regard, please contact this office at your earliest convenience.
Sincerely, C. K. McCo CKM/JAE/jae
Enclosure:
Figure depicting re-worked tubing xc: Georaia Power Company Mr. S. H. Chesnut (w/ encl.)
Mr. M. Sheibani (w/ encl.)
Mr. W. B. Shipman (w/ encl.)
NORMS (w/ encl.)
U. S. Nuclear Reaulatory Commission Mr. S. D. Ebneter, Regional Administrator (w/ encl.)
Mr. D. S. Hood, Licensing Project Manager, NRR (w/ encl.)
Mr. B. R. Bonser, Senior Resident inspector, Vogtle (w/ encl.)
700775
i r-CCPPER TUBING
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