ML20043B491

Submits Rept:On 900507,eddy Current Insp of Steam Generator Tubing Completed.Of 2,106 Tubes Inspected in Steam Generator E-088 No Tubes Found Defective.One Tube in Steam Generator E-089 Found Defective & Plugged

ML20043B491
Person / Time
Site:	San Onofre
Issue date:	05/22/1990
From:	Morgan H SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9005300100
Download: ML20043B491 (2)

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Southern California Edison Company SAN ONorRE NUCLEAR GENERATING GT AllON P O isOX 128 SAN CLEMENTE, C ALIFORNIA fs2672 STATHbHMANAQR q7 9 6$ 1

(:< 1 U. S.. Nuclear Regulatory Commission 1 Document = Control Desk L Washington, D. C. 20555 h -

Subject:

- Docket No. 50-362

. Special Report ,

Inservice Inspection of Steam Generator Tubes i San Onofre Nuclear Generating Station, Unit 3  ;

References:

'A. PWR Steam Generator Examination Guidelines, Revision 2, Electric Power Research Institute (EPRI) Report Number NP-6201, dated December 1988.

B.. Letter from M. O. Medford (SCE) to Mr. G. W. Knighton

'(USNRC) dated April 5, 1985.

l Pursuant to Surveillance Requirement 4.4.4.5(a) of Appendix A, Technical

-Specifications -to' Facility Operating License NPF-15, this report .is being 2 submitted' to the' Commission'following the completion of inservice inspection

, of steam' generator tubes at San Onofre Unit 3.

Eddy current inspection of the steam generator tubing was completed on May 7, 1990. A total _ of 4191 tubes (23% of the tube; in service) in two steam

. generators were. inspected full-length and 18 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 including all- prospective .C-2 expansions '[i.e., a 3% sample plus a 6%

-(2S).and a'12% (4S) expansion in each steam generator].

The planned. inspection programs for both steam' generators were fully y

consistent with recent industry recommendations in the "PWR Steam Generator Examination Guidelines" (Reference A). The programs included-inspection of

• the fullLlength of 100% of the tubing in the area of the tube bundle where the '

. batwing-wear mechanism previously described in Reference B is active. The .

programs included tubes adjacent to tie rods where denting was anticipated l based on experience from similar steam generators at San Onofre Unit 2 in October 1989. The-programs also included general surveillance of-the full length of 20% of the remainder of the tubing. The programs were expanded to-

. include tubes adjacent to, or associated with tubes exhibiting new eddy current' indications.

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Document Control Desk In Steam Generator E-088, 2106 tubes were inspected. No tubes were found to be defective. Eight tubes were preventively plugged due to the wear mechanism

)reviously described in- Reference B. In addition, three tubes at the tube-aundle periphery were preventively plugged due to degradation at diagonal strap supports.

In Steam Generator E-089, 2085 tubes were inspected. One tube was found to be defective at its intersection with a vertical strap sup) ort and was )1ugged.

Two tubes were preventively plugged due to the wear meclanism descriaed in Reference B, three tubes were preventively plugged due to degradation at vertical strap supports, and one tube was preventively plugged due to tie-rod denting.

As- required by Surveillance Requirement 4.4.4.5(b), complete results of the recently completed inservice inspection will be submitted to the Commission by May 7, 1991.

'If you require any additional information, please so advise.

Sincerely, Mk "'

o _

e cc: J. B. Martin (Regional Administrator, USNRC Region V)

C. W. Caldwell (USNRC Senior Resident Inspector, Units 1, 2 & 3)

L. Kokajko (Project Manager, SONGS 2/3, USNRC, NRR)

Institute of Nuclear Power Operations (INPO) 1 a