Text

Submittal of 10 CFR 50.46 Annual Report
	ML16078A067
Person / Time
Site:	Calvert Cliffs
Issue date:	03/18/2016
From:	Jim Barstow; Exelon Generation Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	Download: ML16078A067 (11)
	v • d • e

Exelon Generation 200 Exelon Way Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.46 March 18, 2016 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-53 and DPR-69 NRC Docket Nos. 50-317 and 50-318

Subject:

10 CFR 50.46 Annual Report

References:

1) Letter from James Barstow (Exelon) to U.S. NRC, "Revised 2015 10 CFR 50.46 Annual Report," dated July 14, 2015.

2) Letter from Thomas Gardner (AREVA) to Tim Schearer (Exelon Generation Company, LLC) , "AREVA's 2015 50.46 Annual Reporting for Calvert Cliffs," dated February 9, 2016.

The purpose of this letter is to submit the 10 CFR 50.46 annual reporting information for Calvert Cliffs Nuclear Power Plant (CCNPP) Units 1 and 2. Reference 1 is the most recent annual 10 CFR 50.46 Report submitted to the U.S. NRC.

Since Reference 1 report was issued, a vendor notification for an error in application of power cutback ratios for once-burned gadolinia bearing rods was issued with 0°F PCT impact (Reference 2). This error only affected LBLOCA. No other EGGS-related changes or modifications have occurred at CCNPP that affect the assumptions of the Emergency Core Cooling System (ECCS).

Two attachments are included with this letter that provide the current CCNPP 10 CFR 50.46 status. Attachment 1 provides the Peak Cladding Temperature (PCT) and the "rack-up" sheets for the Unit 1 and Unit 2 Loss of Coolant Accident (LOCA) analyses. Attachment 2, "Assessment Notes," contains a detailed description of each model assessment and error reported.

There are no commitments contained in this letter. If you have any questions, please contact Ron Reynolds at 610-765-5247.

Respectfully, James Barstow Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

10 CFR 50.46 Annual Report March 18, 2016 Page 2 Attachments: 1) Peak Cladding Temperature Rack-Up Sheets for CCNPP, Units 1 and 2

2) Assessment Notes cc: USNRC Administrator, Region I USNRC Project Manager, CCNPP USNRC Senior Resident Inspector, CCNPP S. T. Gray, DNR

ATTACHMENT 1 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Peak Cladding Temperature Rack-Up Sheets for CCNPP, Units 1 and 2

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 1 of 4 PLANT NAME: Calvert Cliffs Unit 1 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 3/18/2016 CURRENT OPERATING CYCLE: 23 ANAL VSIS OF RECORD Evaluation Model: EMF-2328(P)(A)

Calculation: ANP-2871, November 2011 Fuel: HTP 14 x 14 M5 Limiting Fuel Type: HTP 14 x 14 M5 Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: 0.09 ft2 Break in the Cold Leg Pump Discharge Reference Peak Cladding Temperature (PCT) PCT= 1626.0°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR 50.46 report dated April 30, 2012 (Note 3) ~PCT= 69°F 10 CFR 50.46 report dated April 22, 2013 (Note 4) ~PCT= 0°F 10 CFR 50.46 report dated March 20, 2014 (Note 5) ~PCT= 0°F 10 CFR 50.46 report dated April 23, 2014 (Note 6) ~PCT= 63°F 10 CFR 50.46 report dated July 14, 2015 (Note 7) ~PCT= 0°F NET PCT PCT =1758.0°F B. CURRENT LOCA MODEL ASSESSMENTS None (Note 8) ~PCT= 0°F Total PCT change from current assessments L ~PCT= 0°F Cumulative PCT change from current assessments L I~PCT I= 0°F NET PCT PCT =1758.0°F

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 2 of 4 PLANT NAME: Calvert Cliffs Unit 1 ECCS EVALUATION MODEL: Realistic Large Break Loss of Coolant Accident (RLBLOCA)

REPORT REVISION DATE: 3/18/2016 CURRENT OPERATING CYCLE: 23 ANALYSIS OF RECORD Evaluation Model: EMF-2103(P)(A)

Calculation: ANP-3043(P), December 2011 Fuel: HTP 14 x 14 MS Limiting Fuel Type: HTP 14 x 14 MS Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: Guillotine break (4.S832 ft2/side) in Cold Leg Pump Discharge Reference PCT PCT = 1620.0°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 10 CFR S0.46 report dated March 20, 2014 (Note S) ~PCT= 14°F 10 CFR S0.46 dated April 23, 2014 (Note 6) ~PCT= 0°F 10 CFR S0.46 report dated July 14, 201 S (Note 7) ~PCT= 0°F NET PCT PCT =1634.0°F B. CURRENT LOCA MODEL ASSESSMENTS Error in Application of Power Cutback Ratios for Once-Burned ~PCT= 0°F Gadolinia Bearing Rods (Note 8)

Total PCT change from current assessments L ~PCT= 0°F Cumulative PCT change from current assessments L I ~PCT I= 0°F NET PCT PCT =1634.0°F

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 3 of 4 PLANT NAME: Calvert Cliffs Unit 2 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 03/18/16 CURRENT OPERATING CYCLE: 21 ANALYSIS OF RECORD Evaluation Model: EMF-2328(P)(A)

Calculation: ANP-2871, November 2011 Fuel: HTP 14 x 14 MS Limiting Fuel Type: HTP 14 x 14 MS Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: 0.09 ft 2 break in the Cold Leg Pump Discharge Reference PCT PCT= 1626.0°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR S0.46 report dated January 19, 2012 (Note 2) ~PCT= 69°F 10 CFR S0.46 report dated April 22, 2013 (Note 4) ~PCT= 0°F 10 CFR S0.46 report dated March 20, 2014 (Note S) ~PCT= 0°F 10 CFR S0.46 report dated April 23, 2014 (Note 6) ~PCT= 63°F 10 CFR S0.46 report dated July 14, 201 S (Note 7) ~PCT= 0°F NET PCT PCT =1758.0°F B. CURRENT LOCA MODEL ASSESSMENTS None (Note 8) ~PCT= 0°F Total PCT change from current assessments :L ~PCT= 0°F Cumulative PCT change from current assessments L I ~PCT I= 0°F NET PCT PCT =1758.0°F

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 4 of 4 PLANT NAME: Calvert Cliffs Unit 2 ECCS EVALUATION MODEL: Realistic Large Break Loss of Coolant Accident (RLBLOCA)

REPORT REVISION DATE: 03/18/16 CURRENT OPERATING CYCLE: 21 ANALYSIS OF RECORD Evaluation Model: EMF-2103(P)(A)

Calculation: ANP-3043(P), December 2011 Fuel: HTP 14 x 14 MS Limiting Fuel Type: HTP 14 x 14 MS Limiting Single Failure: Loss of one emergency diesel generator Limiting Break Size and Location: Guillotine break (4.S832 ft 2/side) in Cold Leg Pump Discharge Reference PCT PCT= 1620.0°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR S0.46 report dated April 22, 2013 (Note 4) LiPCT = 8°F 10 CFR S0.46 report dated March 20, 2014 (Note S) LiPCT = 6°F 10 CFR S0.46 report dated April 23, 2014 (Note 6) LiPCT = 0°F 10 CFR S0.46 report dated July 14, 201S (Note 7) LiPCT = 0°F NET PCT PCT =1634.0°F B. CURRENT LOCA MODEL ASSESSMENTS Error in Application of Power Cutback Ratios for Once-Burned LiPCT = 0°F Gadolinia Bearing Rods (Note 8)

Total PCT change from current assessments :L LiPCT = 0°F Cumulative PCT change from current assessments L ILiPCT I= 0°F NET PCT PCT =1634.0°F

ATTACHMENT 2 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Assessment Notes CCNPP, Units 1 and 2

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 2 Assessment Notes Page 1 of 3

1) Prior LOCA Model Assessment The 10 CFR 50.46 30-day report dated March 31, 2011 reported new analyses for (ANP-2834) RLBLOCA and (ANP-2871) SBLOCA applicable to Unit 2, Cycle 19. The licensing basis PCT value for Realistic Large Break LOCA (RLBLOCA) and Small Break (SBLOCA) reported was 1670°F and 1626°F, respectively. The analyses were done to support the transition from Westinghouse to AREVA-designed fuel. Unit 2 operation during 2014 uses the RLBLOCA Evaluation Model as summarized in ANP-3043(P). The PCT for RLBLOCA for Unit 2 is 1620°F.

2) Prior LOCA Model Assessment The 10 CFR 50.46 30-day report dated January 19, 2012, reported an error in the S-RELAP5 Sleicher-Rouse correlation used for predicting heat transfer to single-phase vapor heat transfer. Preliminary assessments of the potential impact of using the alternate Sleicher-Rouse correlation were performed. The SBLOCA assessment resulted in a 69°F PCT impact to Calvert Cliffs Unit 2 (ANP-2871) SBLOCA. (ANP-2834) RLBLOCA was impacted by this correction, however it did not reach the 30-day reporting threshold (50°F PCT impact); therefore, it was transmitted in the 2012 annual letter (See Note 3).

3) Prior LOCA Model Assessment The 10 CFR 50.46 combined 30-day and annual report dated April 30, 2012, reported a new licensing basis PCT for Calvert Cliffs Unit 1 and errors, respectively. The 30-day report changed the (ANP-2834) RLBLOCA and (ANP-2871) SBLOCA, applicable to Unit 1, Cycle 21, licensing basis PCT to 1670°F and 1626°F, respectively. The 10 CFR 50.46 annual report transmitted 3 errors. A steam generator tube liquid entrainment modeling error resulted in a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 (ANP-2834) RLBLOCA.

Liquid fallback from the upper plenum to the hot channel resulted in a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 (ANP-2834) RLBLOCA. Lastly, an error in the S-RELAP5 Sleicher-Rouse correlation used for predicting the heat transfer to single-phase vapor heat transfer, as reported for SBLOCA in the 10 CFR 50.46 30-day report dated January 19, 2012 (Note 2), resulted in a 69°F PCT impact in support of AREVA fuel transition for Calvert Cliffs Unit 1 (ANP-2871) SBLOCA and resulted in an 8°F PCT impact to Calvert Cliffs Unit 1 and 2 (ANP-2834) RLBLOCA. No new assessments were applicable to Calvert Cliffs Unit 2 (ANP-2871) SBLOCA.

4) Prior LOCA Model Assessment The 10 CFR 50.46 combined 30-day and annual report dated April 22, 2013, reported a new licensing basis PCT for Calvert Cliffs Unit 2 (ANP-3043) RLBLOCA applicable to once- and twice-burned fuel and a new error, respectively. The report changed the licensing basis to Calvert Cliffs Unit 2 RLBLOCA applicable to AREVA fuel to 1620°F PCT. The (ANP-2834)

RLBLOCA analysis applicable to Notes 1 through 4 assumed fresh fuel was limiting and applied a statistical treatment to the multiplier on decay heat. The inclusion of the burnup dependent RLBLOCA report satisfies the Technical Specification Appendix C license condition and allows for a full core of AREVA fuel in Calvert Cliffs Unit 2. The 10 CFR 50.46 report reported an error due to Cathcart-Pawel uncertainty implementation in RLBLOCA

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 2 Assessment Notes Page 2 of 3 application resulting in a 0°F PCT impact. An error in the S-RELAP5 Sleicher-Rouse correlation used for predicting the heat transfer to single-phase vapor heat transfer resulted in an 8°F PCT to Calvert Cliffs Unit 2 RLBLOCA. No impacts reported for SBLOCA.

5) Prior LOCA Model Assessment The 10 CFR 50.46 combined 30-day and annual report dated March 20, 2014, reported a new licensing basis PCT for Calvert Cliffs Unit 1 (ANP-3043) RLBLOCA applicable to once- and twice-burned fuel and a new error, respectively. The report changed the licensing basis to Calvert Cliffs Unit 1 RLBLOCA applicable to AREVA fuel to 1620°F PCT. The (ANP-2834) RLBLOCA analysis applicable to Notes 1 through 4 assumed fresh fuel was limiting and applied a statistical treatment to the multiplier on decay heat. The inclusion of the burnup dependent RLBLOCA report satisfies the Technical Specification Appendix C license condition and allows for a full core of AREVA fuel in Calvert Cliffs Unit 1. The 10 CFR 50.46 report reported an error due to an issue with S-RELAP5 routine associated with the RODEX3a fuel rod model resulting in a 6°F PCT impact to RLBLOCA.

The error in the S-RELAP5 Sleicher-Rouse correlation used for predicting the heat transfer to single-phase vapor heat transfer in combination with the error due to an issue with S-RELAP5 routine associated with the RODEX3A fuel rod model resulted in a 14 °F PCT impact. No impact reported for SBLOCA.

6) Prior LOCA Model Assessment The 10 CFR 50.46 30-day report dated April 23, 2014, reported an error in the correlation for vapor absorptivity use in S-RELAP5, applied outside of its intended range of applicability (no limit was imposed on the pressure at which the correlation was applied). The equation used for the absorption coefficient of vapor contains the term of the pressure which needs to be truncated in order to obtain the correct emissivity values for an optically thick steam.

Correction of this error is expected to result in a 63°F PCT change to Calvert Cliffs Unit 1 and 2 SBLOCA. The estimated impact of this change on the RLBLOCA analysis calculated PCT is 0°F.

7) Prior LOCA Model Assessment The revised 10 CFR 50.46 report dated July 14, 2015 reported an error in the modal decomposition method which led to a detailed examination of the actual axial shapes that were produced by the modal decomposition procedure and it was observed that some of these resulting shapes were significantly different from the 24-node shape that was generated by PWR Core Engineering. These shapes exhibit a super-imposed oscillation created by the modal decomposition that leads to non-physical artificial local peaks and valleys in the shape. When such shapes are generated and used in the LOCA analyses they tend to shift the PCT both in the positive and negative direction depending on application.

This led to the conclusion that in future application, the modal decomposition method will not be used and a linear interpolation will be used for the mapping. The linear interpolation provides a significantly better fit for the axial shapes. This evaluation led to a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 RLBLOCA analysis. This issue is not applicable to the SBLOCA analysis.

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2016 Attachment 2 Assessment Notes Page 3 of 3

8) Current LOCA Model Assessment Once-burned fuel, U02 and Gadolinia-bearing (Gad) rods, are generally modeled at a reduced peaking in comparison with the hot fresh U02 rod. The reduction is achieved by imposing a burnup-dependent multiplier, or cutback factor, specifying the radial peaking as a fraction of the hot rod radial peaking. A recent review indicated that cutback factor for once-burned Gad rods were instead applied as a fraction of the once-burned U02 rod resulting in the inadvertent once-burned GAD being modeled at a reduced power. This evaluation led to a 0°F PCT impact to Calvert Cliffs Unit 1 and 2 RLBLOCA analysis. This issue is not applicable to the SBLOCA analysis.

[Reference FAB16-00076, "AREVA's 2015 50.46 Annual Reporting for Calvert Cliffs,"

February 9, 2016]