ML13196A248

Duke Energy Carolinas, LLC (Duke Energy): Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model

ML13196A248
Person / Time
Site:	Oconee
Issue date:	07/11/2013
From:	Annacone M Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13196A248 (5)

Text

DUKE Michael J. Ainacone 526 South Church Street Charlotte, NC 28202 Mailing Address: Mail Code EC07H / P.O. Box 1006 Charlotte, NC 28201-1006 Office: 980-373-2544 Fax: 704-382-6056 Michae/,Annacone@duke-energy.com 10 CFR 50.4 10 CFR 50.46 July 11, 2013 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Oconee Nuclear Station, Unit 1, 2 and 3 Docket Numbers 50-269, 50-270, and 50-287/Renewed License Numbers DPR-38, DPR-47, and DPR-55

Subject:

Duke Energy Carolinas, LLC (Duke Energy): Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model

Reference:

1) Letter, D. C. Culp (Duke Energy) to USNRC,

Subject:

Oconee Nuclear Station Day Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model, March 9, 2012. [ADAMS Accession No. ML12073A354]

2) Letter, G. D. Miller (Duke Energy) to USNRC,

Subject:

Oconee Nuclear Station -Response to NRC RAI regarding 10 CFR 50.46 Notification of Change in Peak Cladding Temperature for Large Break Loss of Coolant Accident Analysis, December 7, 2012. [ADAMS Accession No. ML12348A055]

3) Letter, G. D. Miller (Duke Energy) to USNRC,

Subject:

Oconee Nuclear Station -Response to NRC RAI regarding 10 CFR 50.46 Notification of Change in Peak Cladding Temperature for Large Break Loss of Coolant Accident Analysis, April 4, 2013. [ADAMS Accession No.ML13102A033]

10 CFR 50.46 (a)(3)(ii) requires the reporting of changes to or errors in Emergency Core Cooling (ECCS) evaluation models (EMs). This report covers the time period from January 1, 2012 to December 31, 2012 for the Oconee Nuclear Station (ONS).On February 23, 2012, AREVA notified Duke Energy of two offsetting errors in the ONS ECCS evaluation model. The ECCS bypass calculation model contained the first error, which when corrected, shortened the lower plenum refill time and thus decreased the peak cladding U.S. Nuclear Regulatory Commission July 11,2013 Page 2 temperature (PCT) in both the ruptured and unruptured segments.

An 80°F decrease in the ruptured segment PCT and a 40°F decrease in the unruptured segment PCT were assigned to the correction of this error. This error was only applicable to the Large-Break Loss of Coolant Accident (LBLOCA) model. The second error involved enhanced modeling of the upper plenum column weldment over the hot channel which reduced cooling during portions of the blowdown phase and resulted in increases in the ruptured and unruptured segment PCTs. An 80°F increase in the ruptured segment PCT and a 40°F increase in the unruptured segment PCT following a LBLOCA were conservatively assigned to the correction of this error. When correcting for both errors, the net result for a LBLOCA is a 0'F change in both segments.

The impact of the second error on the Small-Break LOCA results was estimated to be 0°F. These errors were reported to the NRC in Reference

1. The NRC has issued requests for additional information related to the errors described above. Duke Energy and AREVA have provided responses to these requests in References 2 and 3.There were no other errors in, or changes to, the ONS LOCA analyses during this reporting period. Included in this report are LOCA PCT summary tables for Oconee Units 1, 2, and 3.There are no regulatory commitments contained in this letter.Please address any comments or questions regarding this matter to Paul Guill at (704) 382-4753 (paul.guill@duke-energy.

corn).Sincerely, Michael J. Annacone, Vice President

-Organizational Effectiveness

&Regulatory Affairs Attachment Table 1: Mk-B-HTP Full Core Peak Cladding Temperature Summary -Oconee Units 1, 2, and 3 U.S. Nuclear Regulatory Commission July 11,2013 Page 3 xc (with attachment):

V. M. McCree, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, GA 30303-1257 J. P. Boska, Senior Project Manager (ONS)U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8G9A Rockville, MD 20852-2738 E. L. Crowe NRC Senior Resident Inspector Oconee Nuclear Station ATTACHMENT Table 1: Mk-B-HTP Full Core Peak Cladding Temperature Summary Oconee Units 1, 2, and 3 References for Table 1 A) Letter, R. M. Glover (Duke Energy) to USNRC, "30-Day Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model", December 8, 2011. [ADAMS MI1 1347A1 93]B) Letter, B. C. Waldrep (Duke Energy) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model", July 5, 2012. [ADAMS ML121910319]

C) Letter, B. C. Waldrep (Duke Energy) to USNRC, "30-Day Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model", December 20, 2012.D) Letter, G. J. St.Clair (AREVA) to S. B. Thomas (Duke Energy), "10 CFR 50.46 LOCA Report of Two EM Error Corrections (AREVA CR 20120165:

ECCS Bypass Mathematical Error and AREVA CR 2012-757:

Upper Plenum Column Weldment EM Change)", Dated February 23, 2012, AREVA Letter FAB12-120.

E) Letter, D. C. Culp (Duke Energy) to USNRC, "30-Day Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model", March 9, 2012. [ADAMS ML12073A354]

F) Letter, G. D. Miller (Duke Energy) to USNRC,

Subject:

Oconee Nuclear Station -Response to NRC RAI regarding 10 CFR 50.46 Notification of Change in Peak Cladding Temperature for Large Break Loss of Coolant Accident Analysis, December 7, 2012. [ADAMS ML12348A055]

G) Letter, G. D. Miller (Duke Energy) to USNRC,

Subject:

Oconee Nuclear Station -Response to NRC RAI regarding 10 CFR 50.46 Notification of Change in Peak Cladding Temperature for Large Break Loss of Coolant Accident Analysis, April 4, 2013. [ADAMS ML13102A033]Page 1 of 2 Table 1: Mk-B-HTP Full Core Peak Cladding Temperature Summary -Oconee Units 1, 2 & 3 LBLOCA PCT(°F) Comments Evaluation model: RELAP5/MOD2-B&W Analysis of record PCT 1913 References A, B, C Prior errors (APCT)1. None 0 Prior evaluation model changes (APCT)1. None 0 Errors (APCT) References D, E, F, G 1. Error in ECCS Bypass Calculation

-80 Evaluation model changes (APCT) References D, E, F, G 1. Upper Plenum Column Weldment Modeling +80 Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0 Final PCT 1913 SBLOCA Full Power -100% FP PCT(°F) Comments Evaluation model: RELAP5/MOD2-B&W Analysis of record PCT 1598 References A, B, C (2 HPI Case) 0.15 ft 2 break Prior errors (APCT)1. None 0 Prior evaluation model changes (APCT)1. None 0 Errors (APCT)1. None 0 Evaluation model changes (APCT) References D, E, F, G 1. Upper Plenum Column Weldment Modeling 0 Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0 Final PCT 1598 SBLOCA Reduced Power- 50% FP [1] PCT(°F) Comments Analysis of record PCT N/A Will be reported under a separate LAR (References A, B, C)Prior errors (APCT) N/A Prior evaluation model changes (APCT) N/A Errors (APCT) N/A Evaluation model changes (APCT) References D, E, F, G 1. Upper Plenum Column Weldment Modeling 0 Absolute value of errors/changes for this report (APCT) N/A Net change in PCT for this report N/A Final PCT N/A Operation Not Justified

[2]Notes 1. Partial power SBLOCA analysis with one HPI pump out of service, supports 30 day LCO for TS 3.5.2 Condition B. Also supports TS 3.5.2 Condition Cl and C2.2. Pending review and approval of separate LAR. Refer to Reference A for additional details.Page 2 of 2