ML20058F258
| ML20058F258 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/02/1993 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9312080048 | |
| Download: ML20058F258 (3) | |
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l December 2, 1993 j
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U. S. Nuclear Regulatory Commission j
Document Control Desk Washington, D. C. 20555
Subject:
Docket No. 50-362 i
Special Report, Inservice Insptction of Steam Generator Tubes San Onofre Nuclear Generating Station,. Unit 3
References:
A.
PWR Steam Generator Examination Guidelines, Revision 3, Electric Power Research Institute (EPRI.) Report
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Number NP-6201, dated November 1992.
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B.
Letter from W. C. Marsh (SCE) to Document Control Desk (USNRC) dated November 8.-1993.
Pursuant to Surveillance Requirement 4.4.4.5(a) of Appendix A, Technical Specifications to Facility Operating License NPF-15, this report is being i
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 l
November 18,-1993. A total of 13,594 tubes (72.6% of the tubes in service) in two steam generators were inspected full length and 59 tubes were removed from j
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, including all prospective C-2 expansions [i.e., a 3%
sample plus a 64 (2S) and a 12% (4S) expansion in each steam generator].
The planned insp:ction programs for both steam generators were consistent with l
industry recommendations in the "PWR Steam Generator Examination Guidelines" (Reference A).
The planned programs were previously described in Reference B.
l The inspection programs for.both steam generators were expanded. The i
expansions' included local bounding of tubes to be plugged, local bounding of 3
all tubes indicating the presence of foreign material, and inspection of ali tubes vithin 5 tubes of the periphery of the tube bundle dee to the potential
'l for presence of foreign material.
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i Document Control Desk 2
In Steam Generator E-088, 1020 tubes were inspected full length.
Two tubes
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were found to be defective due to a 54% throughwall indication and a 51%
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throughwall indication, respectively, at vertical strap support locations.
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Two tubes were found to be defective due to a 100% throughwall. indication and a 44% throughwall indication, respectively, just above the secondary face of the tubesheet on the outlet end of the tubes.
The indications in these two tubes resulted from the presence of foreign material. Also,'one tube was found to be defective due to a 74% throughwall indication at 11.75 inches-
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above the secondary face of the tubesheet on the outlet end of the tube.
This indication initiated on the outer tube wall.
Inspection of this indication by l
the motorized rotating pancake coil (14RPC) probe revealed a volumetric indication (i.e., no specific axial or circumferential aspect). All five of the defective tubes described in this paragraph were plugged.
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Also in Steam Generator E-088, the following number of tubes were preventively
-l plugged for the indicated reason.
Seventeen tubes were preventively,nlugged due to the presence of foreign material.
Eight tubes were preventively-plugged due to degradation at a batwing support. Six tubes were preventively plugged due to degradation at a vertical strap support. Two tubes were i
preventively plugged due to non-quantifiabh indications at locations not i
associated with supports (i.e., in freespan tubing). These two non-i quantifiable indications were volumetric. Two tubes were preventively plugged due to quantified indications (23% throughwall and 27% throughwall, respectively) at locations not associated with supports.
These two quantified indications were volumetric (i.e., no specific axial or circumferential aspect). One tube was preventively plugged due to wear induced degradation at the lowest eggcrate support on the inlet end of the tube. One tube was j
preventively plugged due to tie-rod denting.
In Steam Generator E-089, 6574 tubes were inspected. The following number of tubes were preventively plugged for the indicated reason. Seven tubes were l
preventively plugged due to tie-rod denting.
Four tubes were preventively plugged due to the presence of foreign material.
Three 'obes were
.i preventively plugged due to degradation at a vertical strap support. One tube was preventively plugged due to a non-quantifiable/singie volumetric indication at a location not associated with a support (i.e., in freespan tubing). One tube was preventively plugged due to a single volumetric indication at an eggcrate support on the outlet end of the tube.
One tube was preventively plugged due to wear induced degradation at an eggcrate support on the outlet end of the tube.
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' Document Contnil Desk 3
I As required by Surveillance Requirement 4.4.4.5(b), complete results of the i
recently completed inservice inspection will be submitted to the Commission by November 18, 1994.
If you require any additional informacion, please so advise.
Sincerely, f
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l B. H. Faulkenberry, Regional Administrator, NRC Region V.
1 cc:
M. B. Fields, NRC Project Manager, San Onofre tinits 2 and 3 i
NRC Resident Inspector Office, San Onofre Units 1, 2 & 3 Institute of Nuclear Power Operations (INPO) i l
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