ML20078B419

Submits Preliminary Results of Core Shroud Insps & Preliminary Evaluation Results,Per Insp Plans Provided in 940916 & 26 Ltrs for Pbaps,Unit 2

ML20078B419
Person / Time
Site:	Peach Bottom
Issue date:	10/17/1994
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-94-03, GL-94-3, NUDOCS 9410250221
Download: ML20078B419 (2)

Text

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Station Support Department

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PECO ENERGY r=Tr==6 965 Chesterbrook Boulevard i

, Wayne PA 19007-5691 l

October 17,1994 Docket No. 50-277 License No. DPR-44 l U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Peach Bottom Atomic Power Station, Unit 2 Summary of Core Shroud Inspection Preliminary Results

Dear Sir:

In our letters from G. A. Hunger, Jr. (PECO Energy Company) to U. S. Nuclear Regulatory Commission (USNRC), dated September 16,1994 and September 26,1994, PECO Energy Company provided inspection plans for the Peach ,

Bottom Atomic Power Station (PBAPS), Unit 2 core shroud. These plans were  ;

submitted in accordance with Generic Letter (GL) 94-03, "Intergranular Stress l Corrosion Cracking of Core Shrouds in Boiling Water Reactors." A final summary report, as requested by the GL, will be provided by November 7, 1994. The purpose of this letter is to voluntarily submit the preliminary results of the inspections and our preliminary evaluation of the results.

A baseline ultrasonic examination was performed on all accessible portions of welds H-1 through H-7 utilizing the General Electriu OD Tracker and the General Electric Suction Cup Scanners. The accessible portions of weld length for inspection exceeded our initial plan with the exception of the H-1 weld.

Approximately 200 degrees of the H-1 weld circumference was accessible versus the expected 280 degrees due to physical obstructions in the reactor pressure vessel annulus.

The overall results of the inspection revealed a minimal amount of flaws. Less than 5% of the examined weld length was found to contain flaws.

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October 17,1994 Page 2 The evaluation of results was performed following the approach outlined in the "BWR' Core Shroud Inspection and Evaluation Guidelines," GENE-523-113-0894, dated September 1994. This evaluation, based on the examination data, concludes that there is a substantial margin for each of these welds under conservative, bounding conditions to allow for continued operation of PBAPS, Unit 2. The analyses performed included limit load techniques under bounding design basis conditions, and linear elastic fracture mechanics (LEFM) techniques for the postulated highest fluence welds.

Since the evaluation of inspection results satisfactorily demonstrates structural integrity of the core shroud, a repair will not be performed on PBAPS, Unit 2.

If you have any questions, please contact us.

Very truly yours,

. . e  !-

G. A. Hunger, Jr.,

Director - Ucensing cc: T. T. Martin, Administrator, Region I, USNRC W. L. Schmidt, USNRC Senior Resident inspector, PBAPS i 1 . .  :