ML19164A027

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2018 10CFR 50.46 LOCA Annual Report
ML19164A027
Person / Time
Site: Prairie Island  Xcel Energy icon.png
Issue date: 06/10/2019
From: Sharp S
Northern States Power Company, Minnesota, Xcel Energy
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-Pl-19-024
Download: ML19164A027 (17)
v • d • e


Text

fl Xcel Energy*

RESPONSIBLE BY NATURE 1717 Wakonade Drive Welch, MN 55089 June 10, 2019 L-Pl-19-024 10 CFR 50.46 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 2018 10 CFR 50.46 LOCA Annual Report Pursuant to 10 CFR 50.46(a)(3)(ii), Northern States Power Company, A Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submits the 2018 annual report of changes and errors associated with the Prairie Island Nuclear Generating Plant (PINGP) Units 1 and 2 Emergency Core Cooling System (ECCS) analyses (Enclosure 1).

The peak cladding temperature (PCT) for PINGP Unit 1 and Unit 2 were unchanged since the last annual report for the LOCA analyses. The plant specific changes and errors (absolute value) since the last annual report are summarized below:

LBLOCA Unit 1 None SBLOCA Unit 1 None LBLOCA Unit 2 None SBLOCA Unit 2 None There were no changes that resulted in more than O degrees Fahrenheit PCT penalty.

Enclosure 1 contains the 10 CFR 50.46 PCT Rack-up sheets addressed in the report.

If there is any question or if any additional information is needed, please contact Sarah Schwartz at 612-342-8971.

Document Control Desk Page 2 Summary of Commitments Enclosure (1) cc: Administrator, Region Ill, USNRC Project Manager, Prairie Island Nuclear Generating Plant, USNRC Resident Inspector, Prairie Island Nuclear Generating Plant, USNRC

Document Control Desk Page 3 ENCLOSURE 1 WESTINGHOUSE LETTER LTR-LIS-19-21 14 Pages Follow

Westinghouse Non-Proprietary Cla.ss 3

@Westinghouse Westinghouse Electric Company 1000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA Directtel: (412)374-5598 e-mail: mcmillh@westinghouse.com Our ref: LTR-LIS-19-21 February 13, 2019 Prairie Island Units 1 and 2 10 CFR 50.46 Annual Notification and Reporting for 2018

Dear Sir or Madam:

This is a notification of 10 CFR 50.46 reporting information pertaining to the Westinghouse Electric Company Evaluation Models/analyses. As committed to in WCAP-13451, Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting, Westinghouse is providing an Annual Report for Emergency Core Cooling System (ECCS)

Evaluation Model changes and errors for the 2018 model year. All necessary stanqardized reporting pages for any changes and errors for the Evaluation Models utilized for your plant(s) are enclosed, consistent with the commitment following the NUPIC audit in early _1999. Peak Clad Temperature (PCT) summary sheets are enclosed. All necessary revisions for any non-zero, non-discretionary PCT changes have been included. Changes with estimated PCT impacts of 0°F may not be presented on the PCT summary sheet. The Evaluation Model changes and errors ( except any plant-specific errors in the application of the model) have been provided to the NRC via Westinghouse letter.

Evaluations for Units 1 and Unit 2 were performed in 2015 to assess the impact of utilizing the Westinghouse integral fuel burnable absorber (IFBA) product in addition to the Gadolinia (Gad) burnable absorbers. Cycle 31 is the first Unit 1 cycle that will implement the ~se of IFBA in conjunction with Gadolinium; therefore, large and small break loss-of-coolant accident reporting text and a large break LOCA PCT summary sheet applicable to Unit 1 are included in the 2018 annual report. As requested in a meeting was held on March 19th, 2018 between Westinghouse and Xcel Energy to discuss how to handle the TCD, the original Pressurized Water Reactor Owners Group (PWROG) Thermal Conductivity Degradation (TCD) effect of 227°F is included on the IFBA/Gad PCT summary sheet.

© 2019 Westinghouse Electric Company LLC All Rights Resen*ed

"""This record was final approved on 2114/2019 4:14:25 PM. {This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 LTR-LIS-19-21 Page 2 of2 This information is for your use in making a determination relative to the reporting requirements of 10 CFR 50.46.

The information that is provided in this letter was prepared in accordance with Westinghouse's Quality Management System (QMS). Please contact your LOCA plant cognizant engineer (PCE), Danial Utley (412-374-6663), ifthere are any questions concerning this information.

Lead Author: (Electronically Approved)* Co-Author: (Electronically Approved)*

Heather McMillen Sean T. Kinnas LOCA Integrated Services II Containment and Radiological Analysis Scope: All, except for PCT Summary sheets in the Scope: PCT Summmy sheets in the attachment attachment

  • Verified: (Electronically Approved)* Approved: (Electronically Approved)*

Danial W. Utley Jason R. Beebe LOCA Integrated Services II Manager, LOCA Integrated Services II

Attachment:

10 CFR 50.46 Reporting Text and PCT Summary Sheets (12 Pages)

  • Electronica//y approved records are authenticated in the electronic document management system.

.... This record was final approved an 2114/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation)

Attachment to LTR-LIS-19-21 Page 1 of 12 U0 2 FUEL PELLET HEAT CAPA CITY Backg:rmmd A typographical error was discovered in the implementation of the U02 fuel pellet heat capacity as described by Equation C-4 of WCAP-8301 [l] for fuel rod heat-up calculations within the Appendix K Large Break and Small Break LOCA evaluation models. The erroneous formulation results in an over-prediction of heat capacity that increases with fuel temperature. The corrected formulation results in a maximum decrease in heat capacity on the order of approximately 1.2% for existing analyses of record.

This represents a Non-Discretionary Change in accordance with Section 4.1.2 ofWCAP-13451.

Affected Evaluation Model(s) 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The small over-prediction in U02 fuel pellet heat capacity has been evaluated to have a negligible effect on existing large and small break LOCA analysis results due to the small magnitude of the change, .

leading to an estimated PCT impact of 0°F.

Reference

1) WCAP-8301, "LOCTA-IV Program: Loss-of-Coolant Transient Analysis," June 1974.
      • This record was final approved on 2/14/2019 4:14:25 PM. (This statemenfwas added by the PRIME system upon its validation)

Attachment to LTR-LIS-19-21 Page 2 of 12 ERROR IN CCTF MODEL USED IN WCOBRA/TRAC VALIDATION FOR UPI PLANTS

Background

WCAP-14449-P-A, Revision 1 [1] documents the extension of the Best-Estimate Large-Break Loss-of-Coolant Accident methodology using WCOBRA/TRAC to 2-loop Westinghouse Pressurized .Water Reactors (PWRs) equipped with Upper Plenum Injection (UPI), and supports the. application of the A_STRUM methodology to 2-loop PWRs equipped with UPI. WCOBRA/TRAC calculations for two Cylindrical Core Test Facility (CCTF) upper plenum injection tests were performed !iS part of the code validation. The test report for these tests indicated that the accumulator and high pressure coolant injects into the lower plenum for some time, then ramps down to zero and injection switches entirely into the cold legs. In the WCOBRA./TRAC model for these tests, the accumulator and high pressure coolant flow into the lower plenum was not modeled consistent with the test conditions. _Therefore, the total amount of injected flow into the lower plenum was higher in the WCOBRA/TRAC calculations than in the tests.

This item represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Affected Evaluation Model(s) 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM Estimated Effect Calculations using the modified accumulator and high pressure coolant flow confirm that the error does not impact the conclusions made in Reference 1 relative to the simulations, leading to an estimated peak cladding temperature impact of 0°F.

Reference

1) WCAP-14449-P-A, Revision 1, "Application of Best Estimate Large Break LOCA Methodology to Westinghouse PWRs with Upper Plenum Injection," October 1999.
      • .This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation)

Attachment to LTR-LIS-19-21 Page 3 of 12 VAPOR TElVl:PERATURE RESETTING

Background

In the WCOBRA/TRAC and WCOBRA/TRAC-TF2 codes, when the vapor temperature is greater than the wall temperature, and several other conditions are met, the vapor temperature is reset to the saturation temperature for heat transfer calculations. It was discovered that this vapor* temperature resetting logic results in an inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. The correction of this error represents a Non-Discretionary Change in the Evaluation Model as described in Section 4.1.2 of WCAP-13451.

Affected Evaluation Model(s) 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM Estimated Effect Engineering judgement supported by sensitivity calculations showed that correcting this error had minimal impact on LOCA transient calculations, leading to an estimated peak cladding temperature impact of 0°F.

      • This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation)

Attachment to L TR-LlS-19-21 Page 4 of 12 IMPLEMENTATION OF FUE.L ASSEMBLIES CONTAINING ZrB 2 (IFBA) OR A COMBINATION OF IFBA AND Gd 2 O3 (GAD) FUEL RODS

Background

Xcel Energy is planning to transition from a Gd2 0 3 (Gad) burnable absorber to a ZrB 2 Integral Fuel Burnable Absorber (IFBA) or a combination ofIFBA and Gad fuel rods in each fuel assembly for Prairie Island Unit 1 (NSP). This item represents a change in plant configuration, distinguished from an evaluation model change in Section 4 ofWCAP-1345}.

Affected Evaluation Model(s) 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect Based on a qualitative evaluation, it was determined that implementation of fuel assemblies containing IFBA fuel rods or a combination of IFBA and Gad fuel rods is acceptable for the Prairie Island Unit 1 small break loss-of-coolant accident (SBLOCA) analysis, leading to an estimated PCT impact of 0°F for 10 CFR 50.46 reporting purposes.

      • This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation}

Attachment to LTR-LIS-19-21

  • Page 5 of 12 EVALUATION OF THE INTRODUCTION OF IFBA FUEL

Background

Prairie Island Unit 1 (PINGP) desire to employ an operating strategy utilizing the Westinghouse integral fuel burnable absorber (IFBA) product iri addition to the Gadolinia (Gad) burnable absorbers already in use at PlNGP. This change requires an evaluation for the Prairie Island Unit 1 large break loss-of-coolant accident (LBLOCA) analysis ofrecord (AOR). This evaluation represents a change in plant configuration or associated set point, distinguished from an evaluation model change in Section 4 of WCAP-13451.

Affected Evaluation Model(s) 2004 Westinghouse Realistic Large Break LOCA Evaluation Model Using ASTRUM Estimated Effect To establish the effect of IFBA fuel, the HOTSPOT code was executed with IFBA fuel performance data for all 124 runs for both feed and non-feed fuel. IFBA fuel was found to be bounded by rion-IFBA fuel, and was thus assigned an estimated PCT effect of 0°F.

      • This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation)

Attachment to LTR-LIS-19-21 Page 6 of 12 LOCA Peak Cladding Temperature (PCT) Summary Plant Name: PRAIRIE ISLAND 1*

Utility Name: Xcel Energy, Inc EM: NOTRUMP AOR

Description:

Appendix K Small Break Summary Sheet Status: Current

  • PCT(°F) Reference#
  • Note#

ANALYSIS-OF-RECORD 959. 1 AOR + ASSESSMENTS PCT= 959.0 °F REFERENCES 1 LTR-LIS-08-158, "Transmittal ofFuture Prairie Island Units 1 and 2 PCT Summaries," February 2008.

NOTES:

(a)' None Version: PRAIRIE ISLAND 1 NSP_LOCA-50.46~NSP_Base_Appendix_K_SBLOCA-1.2 V.V

© 2019 Westinghouse Electric Company LLC All Rights Reserved

-This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its.validation)

Aliachment to LTR-LIS-19-21 Page 7 of 12 LOCA Peak Cladding Temperature (PCT) Summary Plant Name: PRAIRIE ISLAND 1 Utility Name: Xcel Energy, foe EM: ASTRUM (2004)

AOR

Description:

Best Estimate Large Break Summary Sheet Status: Current PCT (°F) Reference# Note#

ANALYSIS-OF-RECORD 1765 1 Delta PCT Reporting ASSESSMENTS* (°AF) Reference# Note# Year**

1. Evaluation of Fuel Pellet 2012 Thermal Conductivity 227 2 (a)

Degradation and Peaking Factor Bumdown

2. Revised Heat Transfer 2013

-2 3 Multiplier Distributions

3. Error in Burst Strain Application 25 4 2013 AOR + ASSESSMENTS PCT= 2015.0 °F
  • The licensee should determine the reportability of these assessments pursuant to 10 CFR 50.46.
    • .The "ReportingYear" refers to the annual reporting year in which this assessment was included.

REFERENCES 1 WCAP-17783-P, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for Prairie Island Units 1 and 2 with Replacement Steam Generators Using ASTRUM Methodology," June 2013.

2 LTR-LIS-12-414, "Prairie Island Units 1 and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Bumdown, September 2012.

3 LTR-LIS-13-366, Revision 1, "Prairie Island Units 1 and 2 10 CFR 50.46 Report for Revised Heat Transfer Multiplier Distributions, August 2013.

4 LTR-LIS-14-50, "Prairie Island Units 1 and 2 lQ CFR 50.46 Report for the HOTSPOT Burst Strain Error

. CorrectioFI," January 2014.

NOTES:

(a) This evaluation credits peaking factor bumdown, see Reference 2.

Version: PRAIRIE ISLAND 1 NSP_LOCA-50.46_NSP__Base__:ASTRUM-1.1 V.V

© 2019 Westinghouse Electric Company LLC A 11 Rights Reserved

.... This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upon its validation)

  • Attachment to LTR-LIS-19-21 Page 8 of12 LOCAPeak Cladding Temperature (PCT) Summary
  • Plant Name: PRAJRIE ISLAND 1 Utility Name: Xcel Energy, Inc EM: ASTRUM (2004)

AOR

Description:

  • Best Estimate Large Break Summary Sheet Status: IFBA/Gad

. PCT (0 F) Reference# Note#

ANALYSIS-OF-RECORD 1765 i Delta.PCT Reporting ASSESSMENTS* {°AF) Reference# Note# Year**

1. Revised Heat Transfer 2013

-2 3 Multiplier Distributions

2. Error in Burst Strain Application 25 4 2013
3. Evaluation of the Introduction of 2018 0 2 IFBAFuel
4. Evaluation of Fuel Pellet 2012 Thermal Conductivity*
  • . 227 5 (a)

Degradation and Peaking Factor

.Bumdown AOR + ASSESSMENTS PCT= 2015.0 °F

  • * . The licensee should determine the reportability cifthese assessments pursuant to 10 CFR 50.46.
    • The "Reporting Year" refers to the annual reporting year in which this assessment was included.

REFERENCES 1 WCAP-17783-P, "Best-Estimate Analysis of the Large Break Loss-of-Coolant Accident for Prairie Island 0

Units 1 and 2 y.,ith Replacement Steam Generators Usirtg ASTRUM Methodology," June 2013.

2 LTR-LTS-15-287, Rev. 1, "Prairie Island Units 1 and 2, 10 CFR 50.46 Notification and Reporting for the Revised Fuel.Pellet Thermal Conductivity Degradation and Peaking Factor Burndown Ev'.11uation and the Introduction ofIFBA Fuel," September 2015.

3 LTR-LJS-13-366, Revision 1, "Prairie Island Units 1and210 CFR 50.46 Report for Revised Heat Transfer Multiplier Distributions," August :2013.

4 LTR-LJS-14-?0, "Prairie Island Units 1and210 CFR 50.46 Report for the HOTSPOT Burst Strain Error Correction," January 2014.

Version: PRAIRIE ISLAND 1 NSP_LOCA-50.46_NSP_IFBA_GAD_ASTRUM-1.3 V.V

© 2019 Westinghouse Electric Company LLC All Rights Reserved

  • . *- This record was final approved on 2/14/201.9 4:14:25 PM. (This stateril~ni was added by the PRIME; S¥Slem upon its validation)

. Attachment to L TR-LIS-19-21 Page 9 of 12

  • 5 LTR-LIS-12-414, ."Prairie Island Units.

1 and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet.

Thermal Conductivity Degradation and Peaking Factor Bumdown," September 2012.

NOTES:

(a) This evaluation credits peaking factor burndown, see Reference 5.

Version: ~RAIRIE ISLAND 1 NSP_LOCA..:50.46_NSP_IFBA_GAD_ASTRUN.I-1.3 V.V

© 2019 Westinghouse Electric Comp~y LLC .

. All Ri,ghts Reserved

-* This record was fiTJal approved on 2/14/2019 4:14:25 PM. (This staternerit was added by the PRIME system tipon its validation)

Attachment to LTR-LIS-19-21 Page 10 of 12 LOCAPeak Cladding Temperature (PCT) Summary Plant Name: PRAIRIE ISLAND 2 Utility Name: Xcel Energy, Inc.

EM: NOTRU:MP AOR

Description:

Appendix K Small Break Summary Sheet Status: _Current

. PCT {°F) Reference# Note#

ANALYSIS-OF-RECORD 959 1,2 a AOR + ASSESSMENTS

. . . PCT= 959.0 °F REFERENCES

  • 1 LTR-LIS-08-158, "Transmittal ofFuture Prairie Island Units 1 and 2 PCT Summaries," February 2008.

2 LTR-LIS-13-274, "Prairie Island Units 1 and 2, 10 CFR 50.46 Summary Sheets for the Evaluation to Support the Unit 2 Installation of AREVA Model 56/19 Replacement Steam Generators (RSGs)," June 2013.

NOTES:

(a) The Unit 1 AOR is applicable to Unit 2 with the RSGs installed.

Version: PRAIRIE ISLAND 2 NRP_LOCA-50.46_NRP_Base_Appendix_K_SBLOCA-1.2 V.V

© 2019 Westinghouse Electric Company LLC All Rights Reserved

      • This reco~d was final approved on 2/14/2019 4:~4:25 PM. (This statement ~as added by the PRIME system upon its validation)

Attachment to LTR-LIS-19-21 Page 11 of 12 LOCAPeak Cladding Temperature (PCT) Summary

  • Plant Name: PRAIRIE ISLAND 2 Utility Name: Xcel Energy, Inc EM: ASTRUM (2004)

AOR

Description:

Best Estimate Large Break Summary Sheet.Status: Current PCT {°F) Reference# Note#

ANALYSIS-OF-RECORD 1765 1 Delta PCT Reporting ASSESSMENTS* (°AF) Reference# Note# Year**

1. Evaluation of Fuel Pellet 2012 Thermal Conductivity 227 2 (a),(b)

Degradation and Peaking Factor Burndown

2. Revised Heat Transfer 2013

-2 3 Multiplier Distributions

3. Error in Burst Strain Application 25 4 2013 AOR + ASSESSMENTS PCT= 2015.0 °F
  • The licensee should determine the reportability of these assessments pursuant to 10 CFR 50.46.
    • The "Reporting Year refers to the annual reporting year in which this assessment was included.

REFERENCES 1

Large-Break Loss-of-Coolant Accident for Prairie Island Units 1 and 2 with Replacement Steam Generators Using ASTRUMMethodology," June 2013.

2 LTR-LIS-12-414, "Prairie Island Units 1 and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown," Septembet2012. .

3 LTR~LIS-13-366, Revision 1, Prairie Island Units 1 and 2 10 CFR 50.46 Report for Revised Heat Transfer Multiplier Distributions," August 2013.

4 LTR-LIS-14-50, "Prairie Island Units 1 and 2 10 CFR 50.46 Report for the HOTSPOT Burst Strain Error Correction," January 2014.

. NOTES:

(a) This evaluation credits peaking factor burndown, see Reference 2.

{b) The reporting text and line item originally identified for Unit 1 in Reference 2 is applicable to Unit 2 with RSGs.

Vers.ion: PRAIRIB ISLAND 2 NRP_LOCA-50.46_NRP_Base~ASTRUM-1.1 V.V

© 2019 Westinghouse Electric Company LLC All Rights Reserved

  • -*This record was final approved on 2/14/2019 4:14:25 PM. (This statement was added by the PRIME system upori its validation) .

Attachment to LTR-LIS-19-21 Page 12 ofl2 10 CFR 50.46 Reporting Sha:rePoi:rit Site Check: .

  • EMs applicabJe to Prairie Island:
  • Realistic Large Break -ASTRUM (Z004)
  • Appendix K Small Break- NOTRlJMP.

2018 Issues .

Transmittal Letter Issue Descri

  • tion
  • None None 20151ssues Imtp Iemented.m. 2018 Transmittal Letter Issue Description LTR-US-15-287, Rev. 1 10 CFR 50.46 Notification and Reporting for the Realistic Large Break Loe.A Evaluation of the Introduction ofIFBA Fuel.

. . ' . . ' . . ' .~ . .

  • - This record wa~ fina; approved on 2/1;/2019 4.:14:25 P~. (This ~~ternent was added by~~ PRIME system upon its validation)
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