ML20199J623
| ML20199J623 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 11/25/1997 |
| From: | Graham P NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS970154, NUDOCS 9711280177 | |
| Download: ML20199J623 (4) | |
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' November 25,1997 U.S. Nuclear Regulatory Commission Attention: Document Control De4 Washington, D.C. 20555-0001 Gentletu99:
Subject:
Reinspection of the Core Shroud Welds Cooper Nuclear Station, NRC Docket No. 50-298, DPR-46
References:
- 1. Letter (No. NLS950238) to USNRC Document Control Desk from G. R. Horn (NPPD) dated December 8,1995,"Results of Core Shroud Inspection"
- 2. Letter to G. R. Ilorn (NPPD) from D. L. Wigginton (USNRC) dated June 27, 1996," Cooper ' Nuclear Station Core Shroud Inspection and Flaw Evaluation -
(TAC No. M94401)."
- 3. Letter (No. NLS960195) to USNRC Document Control Desk from P. D. Graham (NPPD) dated October 22,1996," Reinspection of the Core Shroud Welds"
- 4. Letter to G. R. Horn (NPPD) from D. L. Wigginton (USNRC) dated January 24, 1997," Request for Deferral of Second Core Shroud Inspection (TAC No.
M96954)."
- 5. Letter to Carl Terry, BWRVIP Chairman, from G. C. Lainas (USNRC) dated September 15,1997," Transmittal ofNRC Staff's Safety Evaluation of the BWR Vessel and Internals Project BWRVIP-07 Report (TAC No. M94959)."
The purpose of this letter is to request deferral of the Core Shroud reinspection at Cooper Nuclear /
Station (CNS) tyntil Refueling Outage 19 (RFO-19, currently scheduled for Spring 2000). In
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Reference 1, Nebraska Public Power District (District) submitted the results of the Core Shroud
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inspections performed during the Fall 1995 refueling outage. All evaluated welds met the applicable Limit Load and/or Linear Elastic Fracture Mechanics screening criteria, and no further evaluation or non-destructive examination characterization was necessary. In Reference 3, the Cf 1)r District requested a deferral of the shroud reinspection until the 1998 refueling outage based,in part, on the guidance in EPRI TR-105747,"BWR Vessel n'nd Internals Project Guidelines for Reinspection of BWR Core Shrouds (BWRVIP-07)." This request was granted by the Nuclear
~ Regulatory Commission (NRC) as documented in Reference
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NLS970154
' November 25,1997 Page 2 of 2 A'lthough the NRC staff has not completed their review of BWRVIP-07, it recently provided comments to the BWRVIP (reference 5). Since the criteria for reinspection of the shroud welds is still unresolved, the District is requesting another deferral of the Core Shroud reinspection until RFO 19. Application of the 13WRVIP-07 guidelines, as described in Reference 3, indicates that the Core Shroud does not require reinspection for eight calendar years (Fall 2003). In Reference 4, the NRC stated that "on the basis of the large margin available between the actual and allowable crack lengths and allowing for crack growth at a bounding rate of 5x104 incMiour, the stafT finds that the structural integrity of the shroud is capable of being maintained for at least another fuel cycle."
The NRC's alternative to T@le 1 of the BWRVIP-07 Guidelines (Reference 5), would require reinspection of weld 113 oudng RFO 18. Reinspection of the other Core Shroud welds would not be required until RFO 19 or 20. The BWRVIP has not endorsed the NRC Safety Evaluation and is working to resolve the differences between the two documents. Although the NRC guidelines recommend reinspection of113 at RFO-18, it is the D: strict's position that there is sufficient margin based on the original flaw size and the crack rowth rate tojustify deferring the t
reinspection until RFO 19. It is the District's position that the staff's original conclusion in Reference 4, remains valid for RFO 19.
In order to etTectively plan for the RFO-18, the District requests NRC approval of this deferral by January 31,1998.
Should you have any questions concerning this matter, please contact me.
Sincerely, Don P. D. Graham Vice President-Nuclear
/dnm Attachment ec:
Regional Administrator Senior Resident Inspector USNRC - Region IV USNRC Senior Project Manager NPG Distribution USNRC - NRR Project Directorate IV-1
Attachment I to NLS970154
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Page1ofI Cooper Nuclear Station NRC Docket No. 50-298 License No. DPR-46 Attachment A The following table was originally submitted with Reference 3. It presents a summary of the 1995 Core Shroud inspection results in a h'ormat which allows determination of the reinspection frequency as presented in BWRVIP-07. It is resubmitted for convenience.
Weld Percentage Total Length of Percentage ofInspected Total Stress
- in B WRVIP-07 NdC.kiternative to Number Inspected Circumferential Weld Length Containing Faulted Condition Reinspection
- HWRVIP-07 Indications (in)
Indications (ksi)
Frequency (years)
Frequency 111.
66.9 17.48 4.4 1.31 8
5 yrs or 3 cycles 112 -
66.9, 0
0 1.43 10 6 yrs or 4 cycles 113-79.9 66.19 14.9 1.45 8'
4 yrs or 2 cycles -
114 78.5 0
0 1.7 10 6 yrs or 4 cycles -
115 76.1 2.73 0.6 2.5 8
. 5 yrs or 3 cycles II6A 73.4 2.14 0.5 2.91 9
5 yrs or 3 cycles II6B 73.4 0
0 3.33 10 6 yrs or 4 cycles
'117 68.6 0
0 4.24 10 6 yrs or 4 cycles
- Total stress calculated as the absolute' sum of axial force and bending moment stresses.
P
e ATTACHMENT 3 LIST OF NRC COMMITMENTS Corres,sondence No: ML9970154 The fol,owing table identifies those actions committed to by the District in this document.
Any othe r 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 regulatory commitme ts.
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 Reit.spect Core Shroud welds during RFO-19, contingent upon NRC apptsval.
RFO-19 l
PROCEDURE NUMBER 0.42 l
REVISION NUMBER 5 l
PAGE 9 OF 13 l
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