ML20092A631
| ML20092A631 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/30/1995 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9509110114 | |
| Download: ML20092A631 (2) | |
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Southem Califomia Edison Company P O ESOM 12n E. AN Clff ME NTE, C AL If ORNIA 92674-0128 August 30, 1995
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Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555
Subject:
Docket No. 50-362 Special Report, Steam Generator Tubes Inservice Inspection San Onofre Nuclear Generating Station, Unit 3
Reference:
PWR Steam Generator Examination Guidelines, Revision 3, Electric Power Research Institute (EPRI) Report Number NP-6201, dated November 1992.
Pursuant to Surveillance Requirement 4.4.4.5 (a) of Appendix A, Technical tpecifications to Facility Operating License NPF-15, this report is being submitted to the Commission following the completion of an inservice inspection of steam generator tubes at San Onofre Unit 3.
Eddy current inspection of the steam generator tubing was completed on August 17, 1995.
A total of 18,086 tubes (100% of the tubes in service) in two steam generators were inspected full length and 31 tubes were removed from service by mechanical plugging.
This inspection significantly exceeded the inspection requirements of Surveillance Requirements 4.4.4.0 through 4.4.4.2.
The planned inspection programs for both steam generators were fully consistent with industry recommendations in the "PWR Steam Generator Examination Guidelines." The programs included inspection of the full length of all tubes with the bobbin probe, and inspection of all tubes with a rotating probe at the inlet top-of-tubesheet location.
- Further, they included inspection of 20% of the tubing with a rotating probe at the outlet top-of-tubesheet location, and full length profilometry of all tubes adjacent to tie rods.
In Steam Generator E-088, 9047 tubes were inspected full length.
Fourteen tubes were preventively plugged due to degradation at a vertical strap support.
Two tubes were preventively plugged due to degradation at an eggerate support.
One tube was found to exhibit distortion of the eddy current signal at the tube expansion transition at the inlet top-of-tubesheet location anc was preventively plugged.
One tube in E-088 had a non-quantifiable indication by bobbin probe at the diagonal support on the inlet side of the tube, and was plugged.
Rotating probe testing of the indication in this tube indicated volumetric (i.e.,
no specific axial or circumferential aspect) degradation.
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DOCUMENT CONTROL DESK Also in E-088, two tubes had a non-quantifiable indicatier:, and one tube had a less than 20% indication, by bobbin probe, in the v ;inity of or between the ninth eggerate support and the diagonal suppt t on the inlet side of the tube.
In subsequent testing of these tubes and surrounding tubes, by a rotating probe, two additional tubes with a similar single volumetric indication at a similar location were identified.
All five of these tubes were plugged.
In Steam Generator E-089, 9039 tubes were inspected full length.
One tube was found with the MRPC probe to have a circumferential indication at the inlet top-of-tubesheet location and was plugged.
One tube was found to be defective due to a 49% throughwall indication above the lowest eggcrate support on the outlet side of the tube, and was plugged.
One tube was found to be defective due to a 44% throughwall indication at a diagonal support on the inlet side of the tube, and was plugged.
Two tubes were found by rotating probe to have a single volumetric indication at the outlet top-of-tubesheet and were plugged.
Three tubes were preventively plugged due to degradation at a vertical strap support.
As required by Surveillance Requirement 4.4.4.5 (b), complete results of the recently completed inservice inspection of steam generator tubing will be submitted to the Commission by August 17, 1996.
If you require any additional information, please so advise.
Sincerely, h '& 0 AA
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cc:
L. J. Callan, Regional Administrator, NRC Region IV J. E. Dyer, Director, Division of Reactor Projects, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident, San Onofre Units 1, 2& 3 M.
B. Fields, NRC Project Manager, San Onofre Units 2 and 3 Institute of Nuclear Power Operations (INPO)
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