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 J Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13196A248 (5)

Text

DUKE Michael J. Ainacone526 South Church StreetCharlotte, NC 28202Mailing Address:Mail Code EC07H / P.O. Box 1006Charlotte, NC 28201-1006 Office: 980-373-2544 Fax: 704-382-6056 Michae/,Annacone@duke-energy.com 10 CFR 50.410 CFR 50.46July 11, 2013U. S. Nuclear Regulatory Commission Attn: Document Control DeskWashington, DC 20555-0001 Oconee Nuclear Station, Unit 1, 2 and 3Docket 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 DayReport 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 -Responseto 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 -Responseto 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 CoreCooling (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 ECCSevaluation model. The ECCS bypass calculation model contained the first error, which whencorrected, shortened the lower plenum refill time and thus decreased the peak cladding U.S. Nuclear Regulatory Commission July 11,2013Page 2temperature (PCT) in both the ruptured and unruptured segments.

An 80°F decrease in theruptured segment PCT and a 40°F decrease in the unruptured segment PCT were assigned tothe correction of this error. This error was only applicable to the Large-Break Loss of CoolantAccident (LBLOCA) model. The second error involved enhanced modeling of the upper plenumcolumn weldment over the hot channel which reduced cooling during portions of the blowdownphase and resulted in increases in the ruptured and unruptured segment PCTs. An 80°Fincrease in the ruptured segment PCT and a 40°F increase in the unruptured segment PCTfollowing a LBLOCA were conservatively assigned to the correction of this error. Whencorrecting for both errors, the net result for a LBLOCA is a 0'F change in both segments.

Theimpact of the second error on the Small-Break LOCA results was estimated to be 0°F. Theseerrors 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 providedresponses 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 AffairsAttachment Table 1: Mk-B-HTP Full Core Peak Cladding Temperature Summary -Oconee Units 1, 2, and 3 U.S. Nuclear Regulatory Commission July 11,2013Page 3xc (with attachment):

V. M. McCree, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower245 Peachtree Center Avenue NE, Suite 1200Atlanta, GA 30303-1257 J. P. Boska, Senior Project Manager (ONS)U. S. Nuclear Regulatory Commission 11555 Rockville PikeMail Stop 0-8G9ARockville, MD 20852-2738 E. L. CroweNRC Senior Resident Inspector Oconee Nuclear Station ATTACHMENT Table 1: Mk-B-HTP Full Core Peak Cladding Temperature SummaryOconee Units 1, 2, and 3References for Table 1A) 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, Changesto 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 Reportof Two EM Error Corrections (AREVA CR 20120165:

ECCS Bypass Mathematical Error andAREVA 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 -Responseto 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. [ADAMSML12348A055]

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

Subject:

Oconee Nuclear Station -Responseto 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 ML1 3102A033]

Page 1 of 2 Table 1: Mk-B-HTP Full Core Peak Cladding Temperature Summary -Oconee Units 1, 2 & 3LBLOCA PCT(°F) CommentsEvaluation model: RELAP5/MOD2-B&W Analysis of record PCT 1913 References A, B, CPrior errors (APCT)1. None 0Prior evaluation model changes (APCT)1. None 0Errors (APCT) References D, E, F, G1. Error in ECCS Bypass Calculation

-80Evaluation model changes (APCT) References D, E, F, G1. Upper Plenum Column Weldment Modeling

+80Absolute value of errors/changes for this report (APCT) 0Net change in PCT for this report 0Final PCT 1913SBLOCA Full Power -100% FP PCT(°F) CommentsEvaluation model: RELAP5/MOD2-B&W Analysis of record PCT 1598 References A, B, C(2 HPI Case) 0.15 ft2 breakPrior errors (APCT)1. None 0Prior evaluation model changes (APCT)1. None 0Errors (APCT)1. None 0Evaluation model changes (APCT) References D, E, F, G1. Upper Plenum Column Weldment Modeling 0Absolute value of errors/changes for this report (APCT) 0Net change in PCT for this report 0Final PCT 1598SBLOCA Reduced Power- 50% FP [1] PCT(°F) CommentsAnalysis of record PCT N/A Will be reported under aseparate LAR(References A, B, C)Prior errors (APCT) N/APrior evaluation model changes (APCT) N/AErrors (APCT) N/AEvaluation model changes (APCT) References D, E, F, G1. Upper Plenum Column Weldment Modeling 0Absolute value of errors/changes for this report (APCT) N/ANet change in PCT for this report N/AFinal PCT N/A Operation Not Justified

[2]Notes1. Partial power SBLOCA analysis with one HPI pump out of service, supports 30 day LCOfor 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