ML20095C295

Forwards Rev 0 to NPPD Design Calculation Nedc 95-191, Evaluation of Core Shroud Insp Results, as Requested by Generic Ltr 94-03, IGSCC of Core Shrouds in Bwrs

ML20095C295
Person / Time
Site:	Cooper
Issue date:	12/08/1995
From:	Horn G NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20095C297	List: ML20095C295 ML20095C299
References
GL-94-03, GL-94-3, NLS950238, NUDOCS 9512110452
Download: ML20095C295 (4)

Text

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GENERAL OFFICE M Nebraska Public Power District P.O. DOX 499, COLUMBUS, NEBRASKA 68602-0499

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NLS950238 December 8,1995 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 4555

Subject:

Results of Core Shroud Inspection Cooper Nuclear Station NRC Docket No. 50-298, DPR-46

References:

1) NRC Generic Letter 94-03 dated July 25,1994, "Intergranular Stress Corrosion Cracking of Core Shrouds In Boiling Water Reactors"

2) letter from G. R. Horn (NPPD) to NRC dated August 26,1994, " Response to Generic Letter 94 Core Shroud Crackiag"

3) GENE-523-113-0894 dated March 1995, "BWR Core Shroud Inspection and Flaw Evaluation Guidelines"

4) Letter from G. R. Horn (NFPD) to NRC dated July 14,1995, " Core Shroud Inspection Plan" Gentlemen:

As requested by NRC Generic Letter 94-03 (Reference 1), the Nebraska Public Power District i

(District) has completed inspection and evaluation of the Cooper Nuclear Stadon (CNS) core shroud, and is providing the results for NRC review.

Ultrasonic examination of eight (8) circumferential (horizontal) welds (H1, H2, H3, H4, H5, H6a, H6b and H7) was performed by General Eleciric Nuclear Energy during the period of October 25, 1995, through November 4,1995. NPPD Calculation NEDC 95-191, " Evaluation of Core Shroud Inspection Results," (attached) provides the inspection results iucluding flaws detected and actual mspection coverages.

Indications found during the inspection were evaluated in accordance with GENE-52.0174-1293, Revision 2, " Evaluation and Screening Criteria for the Cooper Shroud," (Attachment 2.4 to NEDC 95-191). This General Electric document is consistent with the flaw evaluation criteria presented in Reference 3.

In summary, while evidence of IGSCC or IASCC cracking was recorded in welds H1, H3, H5 and H6a, all evaluated welds meet the applicable Limit Load and/or Linear Elastic Fracture Mechanics (LEFM) screening criteria and no further evaluation or NDE characterization is necessary.

Currently, CNS is assessing these results to determine the appropriate reinspection frequency to assure the ongoing structural and functional integrity of the core shroud.

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i Should you have any questions or require any additional information, please contact me.

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USNRC - Region IV Senior Project Manager USNRC-NRR Project Directorate IV-1 Senior Resident Inspector USNRC NPG Distribution I

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NLS950238 December 8,1995 Page 3 of 3 STATE OF NEBRASKA

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G. R. Horn, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of Nebraska; that he is duly authorized to st.bmit this response on behalf of Nebraska Public Power Distri { and that the statements contained herein are true to the best of his knowledge and belief.

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I n-G. R. Horn Subscribed in my presence and sworn to before me this k

day of b*f/mh,1995.

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LIST OF NRC COMMITMENTS ATTACHMENT 3 l

Correspondence No: NLS950238 The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's information and are not regulltory commitments.

Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITTED DATE COMMITMENT OR OUTAGE None.

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