ML20236T999
| ML20236T999 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 07/20/1998 |
| From: | Swailes J NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-92-01, GL-92-1, NLS980113, TAC-MA1185, NUDOCS 9807290240 | |
| Download: ML20236T999 (7) | |
Text
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w NLS980113 July 20,1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Response to Request for Additional Information Regarding Reactor Pressure Vessel Integrity at Cooper Nuclear Station - (TAC No. mal 185)
References:
- 1) NRC Generic Letter 92-01, Revision 1, Supplement 1, " Reactor Vessel Structural Integrity," dated May 19,1995
- 2) Letter NLS950174 from G. R. Horn (NPPD) to USNRC dated August 17, 1995,"90-Day Response to Generic Letter 92-01, Revision 1, Supplement 1, Reactor Vessel Structural Integrity, Cooper Nuclear Station, NRC Docket 50-298, DPR-46"
- 3) Letter NLS950223 from G. R. Horn (NPPD) to USNRC dated November 20,1995, "Six Month Response to Gene i L ttr c e er 92-01, Revision 1, Supplement 1, Reactor Vessel Structural Integrity, Cooper Nuclear Station, NRC Docket 50-298, DPR-46"
- 4) Letter from D. L. Wigginton (USNRC) to G. R. Horn (NPPD) dated July 30,1996, "Closecut for Nebraska Public Power District Response to Generic Letter 92-01, Revision 1, Supplement I for the Cooper Nuclear Station (TAC No. M92666)"
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- 5) Letter NLS980040 from J. H. Swailes (NPPD) to USNRC dated March 9,1998, "BWR Vessel and Internals Project, Update of Bounding Assessment of BWR/2-6 Reactor Vessel Integrity Issues (BWRVIP-46), EPRI Report TR-109727, December 1997 02 V
" Request For Additional Information Regarding Reactor Pressure Vessel Integrity at Cooper Nuclear Station - (TAC No. mal 185)"
Per Generic Letter (GL) 92-01, Revision 1, Supplement 1 (Reference 1), the Nuclear Regulatory l
Commission (NRC) requested Licensees to:
L Perform a review of their reactor pressure vessel structural integrity assessments in order to identify, collect, and report any new data pertinent to the analysis of the stiactural integrity of their reactor pressure vessels (RPVs),
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NLS980113 July 20,1998 Page 2
' Asse'ss the impact of that data on their RPV integrity analyses relative to the requirements of10 CFR 50.60,10 CFR 50.61, and Appendices G and H to 10 CFR Part 50, and Assess any potential impact oflow temperature overpressure limits or pressure-temperature (P-T) limits.
Byletters dated August 17,1995, and November 20,1995 (References 2 and 3, respectively), the Nebraska Pubic Power District (District) responded to the subject GL and included a discussion on the Boiling Water Reactor Owners' Group (BWROG) activities relative to the supplement.
By letter dated July 30,1996 (Reference 4), the NRC assessed the District's responses and -
requested the District provide the NRC with the results of the Owners Groups' programs relative to Cooper Nuclear Station (CNS). The District provided this assessment per Reference 5.
By Reference 6 the NRC issued a request for additional information requesting a re-evaluation of the RPV weld chemistry values previously submitted. The Attachment to this submittal provides the requested information.
Sincerel O}\\
J. H. Swailes Vice President ofNuclear Energy
/nr cc:
Regional Administrator w/ enclosure l
- USNRC - Region IV i
Senior Project Manager w/ enclosure USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/ enclosure USNRC NPG Distribution w/o enclosure b
l
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l NLS980113 Attachment Page1of4 l
Response to Request for Additional Information f
Reactor Pressure Vessel Integrity at Cooper Nuclear Station i
The following discussion restates the questions raised in the Nuclear Regulatory Commission's Request For Additional Information (Reference 6) and provides the corresponding District response.
l Section 1.0: Assessment of Best-Estimate Chemistry The staffrecently received the BWRVIP report " Update ofBounding Assessment ofBW102-6 Reactor Pressure VesselIntegrityissues (BWRVIP-46)",
Based on this information, in accordance with the provisions of Generic Letter 92-01, Revision 1, Supplement 1, the NRC requests thefollowing:
1.
An evaluation of the bounding assessment in the reference above and its applicability to the determination of the best-estimate chemistryfor all ofyour RPV beltline welds. Based upon this reevaluation, supply the information necessary to completelyfill out the data requested in Table 1for each RPV beltline weld material. If the limiting materialfor your vessel's P-Tlimits evaluation is not a weld, include the information requested in Table Ifor the limiting material also.
District Response:
BWR Vessel and Internals Project BWRVIP-46 (Reference 5) provided an analysis of the impact on the BWR Upper Shelf Energy (USE) and P-T curve based on the use of the bounding chemistries. Weld heats in the irradiated beltline region were examined and chemistries of the beltline weld heats were determined. Bounding values were assumed for each weld heat to project embrittlement levels in the welds. These values were compared to the adjusted reference temperatures of the limiting beltline materials. The results demonstrated that there is insignificant impact on the current P-T curve due to chemistry variability.
BWRVIP-46 used the bounding approach for weld chemistries to evaluate the effects on the weld chemistry variability whereas General Electric (GE)'s report GE-NE-523-159-12921 used the results of Cooper's surveillance specimen testing. The irradiated material properties were
. compared to unirradiated specimen test results of the same materials. Predictions of the RTNDT and USE at 32 EFPY were made for comparison with allowable values in " Fracture Toughness
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Requirements," Appendix G to Part 50 of Title 10 of the Code of Federal Regulations, July 1983.
l
/1 NPPD Letter from G. R. Horn to the USNRC dated February 25,1993, " Submittal of Reactor Vessel Surveillance Test Results, Cooper Nuclear Station, NRC Docket 50-298, DPR-46 (GE-NE-523-159-1292)."
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NLS980113 Attachment j
Page 2 of4 Predictions of 32 EFPY properties were made based on Regulatory Guide 1.99, Revision 2, adjusted to account for surveillance data.
By comparison between the BWRVIP-46 and the GE report, the District concludes that GE's report provides an analysis with results based on surveillance specimen test results withdrawn from Cooper's Vessel. GE's report provides a detailed analysis for development of the Operating l
Limits Curves (P-T curves) per the guidelines of Appendix G to Part 50 of Title 10 of the Code of Federal Regulations, July 1983, and per the cases provided in the Meeting with Owners Group Representatives and NEI.2 The District provided the information necessary to completely fill out the data requested in Table I for each RPV beltline weld material and limiting plate beltline material. GE-NE-523-159-1292 provides the basis for the calculation of the values used in the Table 1.
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" Meeting Summary for November 12,1997, Meeting with Owners Group Representatives and NEI Regarding Review of Responses to Generic Letter 92-01, Revision 1, Supplement 1 Responses
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Attachment Page 4 of 4 i
Section 2.0: P-TLimit Evaluation 2.
If the limiting materialforyourplam changes or of the adjustedreference temperature for the limiting materialincreases as a result of the above evaluations, provide the revisedRTa valuefor the limiting material. In addition, if the adjustedRTuo7 value increased, provide a schedulefor revising the P-Tlimits. The schedule shouldensure that compliance with 10 CFR 50 Appemlix G is maintained.
1 District Response:
Based on the review of the current CNS Technical Specification's adjusted reference temperature (ART), the associated EFPYs and the results ofGE's analysis, the District concludes that the ARTS values did not increase. The GE analysis also validated the P-T curve for 32 EFPY of operation. Therefore compliance with Appendix G is maintained.
Tech Specs EFPY ART GE's Report EFPY ART 13 93 15 89 18 102 18 96 q
21 110 21 101 24 108 32 128 Note: CNS will update the P-T limits after the implementation ofImproved Technical Specifications to address operation beyond 21 EFPY.
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l ATTACHME!JT 3 LIST OF NRC COMMITMENTS l
Correspondence No:
NLS980113 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 l information and are not regulatory commitments.
Please notify the NL&S Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITTED DATE COMMITMENT OR OUTAGE CNS will update the P-T limits after implementation of N/A Improved Technical Specifications to address operation beyond 21 EFPY.
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l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 6 l
PAGE 9 OF 13 l
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