ML16341E882

Forwards Proprietary WCAP-12064, Diablo Canyon 1 & 2 Evaluation for Tube Vibration Induced Fatigue. All Five Tubes Requiring Corrective Action Removed from Svc During Unit 2 Refueling Outage.Rept Withheld (Ref 10CFR2.790)

ML16341E882
Person / Time
Site:	Diablo Canyon
Issue date:	11/30/1988
From:	Shiffer J PACIFIC GAS & ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML16341E883	List: ML16341E882
References
DCL-88-290, IEB-88-002, IEB-88-2, NUDOCS 8812060094
Download: ML16341E882 (6)

Text

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8812060094 DOC.DATE: 88/11/30 NOTARIZED: NO DOCKET 4 FACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275 50-323 Diablo Canyon Nuclear Power Plant, Unit 2, Pacific Ga 05000323 AUTH. NAME AUTHOR AFFILIATION SHIFFER,J.D. Pacific Gas & Electric Co.

RECIP.NAME RECIPIENT AFFILIATION jp~DY Document Control Branch (Document Control Desk' R

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SUBJECT:

Forwards proprietary WCAP-12064, "Diablo Canyon 1 & 2 Evaluation for Tube Vibration Induced Fatigue."

DISTRIBUTION CODE: IE13D COPIES RECEIVED LTR ENCL SIZE:

TITLE: Bulletin Response, 88-02 Rapidly Propaga ing Fatigue Crac s s NOTES:

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<'2 "-!2'rLYs0 ~fgrtssr Pc'r Geo November 30, 1988 PGhE Letter No. DCL-88-290 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

<8 Re: Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Evaluation of Steam Generator Tubing at DCPP for Susceptibility to Fatigue Induced Cracking-NRC Bulletin 88-02, "Rapidly Propagating Fatigue Cracks in Steam Generator Tubes" Gentlemen:

As committed to in PGhE letters DCL-88-064 and DCL-88-262, dated March 24 and November 2, 1988, respectively, enclosed are the results from the PG&E/Westinghouse evaluation of the steam generator tubing at Diablo Canyon Power Plant for the susceptibility to fatigue-induced'cracking of the type experienced at North Anna Unit 1. Based on the results of the tube fatigue evaluation it l-l was concluded that for Unit 1 three tubes located in steam generator (R9C41, R10C47 and R11C47) exceed the threshold stress ratio value of 1.0. None of these three tubes showed the presence of crevice corrosion or magnetite based on an 1988 eddy current inspection.

However, it has been conservatively determined that these tubes should be removed from service at the next scheduled outage to preclude any question on tube fatigue. For Unit 2 the tube fatigue evaluation identified five tubes in steam generator 2-3 (R9C37, R10C37, R10C43, R11C43 and R12C43) that would require corrective action under dented or clamped tube/tube support plate interface conditions. No denting was found in these tubes. However, R9C37, R10C43 and R11C43 showed evidence of crevice magnetite by eddy current inspection. As a preventative measure relative to potential future crevi ce corrosion, all five of these tubes were removed from service 'during the current Unit 2 refueling outage as noted in PGhE letter DCL-88-262.

In support of PGLE's response, the enclosure provides a copy of WCAP-12064 (proprietary), "Diablo Canyon and 2 Evaluation For Tube 1

Vibration Induced Fatigue". The WCAP contains information proprietary to Westinghouse Electric Corporation. It is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.790 of the Commission's regulations.

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Document Control Desk 1 PG&E Letter No. DCL-88-290 Novdm&er 30, 1988 In order not to delay this submittal of information to the Commission in connection with the review of evaluation of the steam generator tubing at DCPP for susceptibility to fatigue induced cracking PGhE will comply with the requirements of 10 CFR 2.790 to provide proprietary and non-proprietary versions together with an affidavit as soon as the proprietary information contained in the submittal has been specifically identified and the proprietary and non-proprietary versions have been prepared. PGhE will submit the total required numbered of copies of the proprietary and non-proprietary versions of the information and the required affidavit at that time.

In the meantime, we have provided sufficient copies for you to initiate your review. E. Shomaker, Esq., of the NRC Office of the General Counsel has advised Westinghouse that he concurs with this procedure.

We expect to be able to fully comply with the requirements for the propri etary and non-propri etary versions of the information and an accompanying affidavi t within two weeks.

Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelope.

Sincerely, J. D. S ffer cc w/enc.: J. B. Hartin H. H. Hendonca P. P. Narbut H. Rood B. H. Vogler cc w/o enc.: B. Norton E. Shomaker R. A. Wiesemann CPUC Diablo Distribution 2425S/0065K/DJH/1968