ML20141E385

Special Rept:On 851208-31,during Inservice Insp of Steam Generator tubing,63 Tubes Removed from Svc by Mechanical Plugging.Caused by Degradation in Cold Leg Near Top of Tubesheet.Imperfect Tubes Plugged

ML20141E385
Person / Time
Site:	San Onofre
Issue date:	02/11/1986
From:	Morgan H SOUTHERN CALIFORNIA EDISON CO.
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
TAC-59406, NUDOCS 8602250236
Download: ML20141E385 (2)

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>: a. s o RECEIVED f[5 ImC Southem Califomia Edison Companx SAN ONOFRE NUCLEAR GENERATING STATION P, O BOX 128 SAN CLEMENTE, CALIFORNIA 92672 gg ef y-H E. MORGAN TELE PHONE

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February 11, 1986 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596-5368 Attention:

Mr. J. B. Martin, Regional Administrator

Subject:

Docket No. 50-206 Special Report San Onofre Nuclear Generating Station Unit 1 Pursuant to Section 4.16.E.4, of the Appendix A Technical Specifications.to Provisional Operating License No. DPR-13 for San Onofre Unit 1, this submittal provides a report on conditions identified during Inservice Inspection of Steam Generator Tubing.

It is noted that Specification 4.16.E.4 requires providing a report to the Commission in accordance with Section 6.6, Reportable Event Action. Section 6.6 requires reporting in accordance with 10 CFR 50.73, however, the rule does noc require reporting the level of degradation or plugging of steam generator tubes experienced at San Onofre, Unit 1.

We therefore are submitting this report in accordance with Section'6.9.2, Special Reports. Approval of the remedial action taken and clarification of this reporting requirement will be the subject of separate correspondence with the NRC PWR Project Directorate in the near future.

The Inservice Inspection of Steam Generator tubes required by Technical Specification 4.16 was conducted between December 8, 1985 and December 31, 1985. A total of 2740 tubes (26 percent of the tubes in service) were inspected and 63 tubes were removed from service by mechanical plugging.

The inspection demonstrated that there has been no detectable progression of intergranular attack (IGA), denting, or antivibration bar (AV8) wear.

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Mr. J. B. Martin -

i The 63 tubes which required plugging h:d imperfections located near the top of the cold leg tubesheet (39), near the top of the hot leg tubesheet (1) and at the antivibration bars (23). However, more than. half of these showed no real growth since previous inspections and required plugging only because improved 4

inspection and analysis techniques were used.

Further only limited degradation has occurred since 1980 and only in the cold leg near the top of the tubesheet. All tubes having imperfections above the plugging limit have

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been plugged.

There was no impact on plant operation or the health and safety of plant personnel or the public as a result of the steam generator tube degradation and plugging. -The remedial actions taken are considered to be appropriate to resolve steam generator tube degradation identified during this inspection.

As previously stated, further details regarding the above described inspection 1

and repair will be provided to the NRC/NRR.

If there are any questions 1

regarding the above or attached, please contact me, i

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Sincerely, NY l

F. R. Huey (USNRC Senior Resident Inspector, Units 1, 2, and 3) cc:

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U.S. Nuclear Regulatory Commission Document Control Desk i

R. Dudley (USNRC Unit 1 Project Manager) 1 Institute of Nuclear Power Operations (INPO) i I

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