ML20081J647
| ML20081J647 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/20/1995 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9503280089 | |
| Download: ML20081J647 (2) | |
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23 PARKER STREET IRVINE, CAUFOnNIA 92718 MAP 4AGEM OF L M EQULA Y AFFABRB (71 4S 403 March 20, 1995 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555
Subject:
Docket No. 50-361 Special Report Inservice Inspection of Steam Generator Tubes San Onofre Nuclear Generating Station, Unit 2
References:
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 Specifications to Facility Operating License NPF-10, this report is being submitted to the Commission following the completion of an inservice inspection of steam generator tubes at San Onofre Unit 2.
t Eddy current inspection of the steam generator tubing was completed on March 5, 1995. A total of 18,054 tubes (100% of the tubes in service) in two steam generators were inspected full length and 45 tubes were removed from service by mechanical plugging. This inspection significantly exceeded the amount of tubing required to be inspected per Surveillance Requirements 4.4.4.0 through 4.4.4.2.
The inspection programs for both steam generators were fully consistent with industry recommendations in the "PWR Steam Generator Examination Guidelines" (Reference 1). The programs included inspection of the full length of all tubes with the bobbin probe, and inspection of all tubes with a motorized rotating pancake coil (MRPC) at the inlet top-of-tubesheet location..The programs also ir,cluded inspection of seven percent of the tubing with an MRPC probe at the outlet top-of-tubesheet location.
In Steam Generator E-088, 9073 tubes were inspected full length. Fourteen tubes were found with the MRPC probe to have circumferential indications at the inlet top-of-tubesheet location and were plugged. One tube was found with the MRPC probe to have both circumferential and axial indications at the inlet top-of-tubesheet, and was plugged. One tube was found with the MRPC probe to have. a volumetric indication (i.e., no specific axial or circumferential aspect) at the inlet top-of-tubesheet, and was plugged. One tube was found with the bobbin probe to have a distorted indication at the outlet top-of-tubesheet, and was plugged. MRPC probe testing of this indication revealed that it was a volumetric indication. One tube was preventively plugged due to tie-rod denting.
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N Document Control Desk One tube in' E-088 was found to be defective, due to a 84% throughwall indica' tion within the explosively expanded region within the tubesheet, and was plugged.
An additional tube was found with a non-quantifiable bobbin probe indication within the explosively expanded region within the tubesheet, and was plugged. MRPC probe testing of both of these tubes within the tubesheet revealed that the indications are oriented axially.
One tube in E-088 was found with a distorted support indication by bobbin probe at the seventh eggcrate support on the inlet side of the tube, and was plugged. One other tube in E-088 had a non-quantifiable indication by bobbin probe at the sixth eggcrate support on the inlet side of the tube, and was plugged. MRPC probe testing of the indications in these two tubes, revealed an axial orientation of each of these indications.
In Steam Generator E-089, 8981 tubes were inspected full length. Twelve tubes were found with the MRPC probe to have circumferential indications at the inlet top-of-tubesheet location and were plugged.
Two tubes were found with the MRPC probe to have axial indications at the inlet top-of-tubesheet, and were plugged.
Four tubes were found with the MRPC probe to have a volumetric indication (i.e., no specific axial or circumferential aspect) at the inlet top-of-tubesheet, and were plugged. Also, in E-089 one tube was preventively plugged due to degradation at a vertical strap support.
Two tubes in E-089 were found to be defective, due to greater than 90%
throughwall indications within the explosively expanded region within the tubesheet, and were plugged. MRPC probe testing of these two tubes within the tubesheet revealed that the indications are oriented axially.
One tube in E-089 was found with a distorted support indication by bobbin probe at the sixth eggcrate support on the inlet side of the tube, and was plugged. One other tube in E-089 had a non-quantifiable indication by bobbin probe at the seventh eggcrate support on the inlet side of the tube, and was plugged. MRPC probe testing of the indications in these two tubes, revealed an axial orientation of each of these indications.
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 March 5, 1996.
If you require any additional information, please so advise.
Sincerely, cc:
L. J. Callan, Regional Administrator, NRC Region IV A. B. Beach, 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 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 Institute of Nuclear Power Operations (INP0) i i