ML19077A129

10 CFR 50.46 Annual Report

ML19077A129
Person / Time
Site:	Calvert Cliffs
Issue date:	03/18/2019
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML19077A129 (14)

Text

Exelon Generation 200 Exelon Way Kennett Square. PA 19348 www.exeloncorp.com 10 CFR 50.46 March 18, 2019 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, "1 O CFR 50.46 Annual Report," dated March 16, 2018.

2) FS 1-0042569-1.0, "Framatome's 2018 50.46 Annual Reporting for Calvert Cliffs," dated February 18, 2019.

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. Reference 2 documents Framatome's annual summary deliverable to Exelon to support the upcoming 10 CFR 50.46 annual report.

Unit 1 and Unit 2 Small Break Loss fo Coolant Accident (SBLOCA) Evaluation Model used to establish the Analysis of Record (AOR) Peak Cladding Temperature (PCT) was changed in 2018. There were no new changes or errors reported against the previous SBLOCA evaluation model and there are no changes or errors reported against the current SBLOCA Evaluation Model. Since Reference 1, there were no changes or errors reported against the Realistic Large Break Loss of Coolant Accident (RLBLOCA) Evaluation Model during the previous reporting period. No other EGGS-related changes or modifications have occurred at CCNPP that affect the assumptions of the ECCS system.

Two attachments are included with this letter that provide the current CCNPP 10 CFR 50.46 status. Attachment 1 provides the PCT "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.

10 CFR 50.46 Annual Report March 18, 2019 Page 2 There are no commitments contained in this letter. If you have any questions, please contact Ron Reynolds at 610-765-5247.

Respectfully, AJc.--_:J -r .A- Jr iJ_._

James Barstow Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC 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 D. A. Tancabel, DNA

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, 2019 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, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 1 of 6 PLANT NAME: Calvert Cliffs Unit 1 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 3/18/2019 CURRENT OPERATING CYCLE: 24 ANALYSIS OF RECORD Evaluation Model: EMF-2328(P)(A), Revision 0, Supplement 1(P)(A),

Revision O Calculation: ANP-3641, March 2018 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: 0.34 ft 2 Break in the Cold Leg Pump Discharge Reference Peak Cladding Temperature (PCT) PCT= 1648°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS N/A- Note 12 NET PCT PCT= 1648°F B. CURRENT LOCA MODEL ASSESSMENTS EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision O ~PCT= 0°F Total PCT change from current assessments L ~PCT= 0°F Cumulative PCT change from current assessments L !~PCT i=0°F NET PCT PCT=1648°F

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 2 of 6 PLANT NAME: Calvert Cliffs Unit 1 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 3/18/2019 CURRENT OPERATING CYCLE: 24 ANAL VSIS 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 Peak Cladding Temperature (PCT) PCT= 1626°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR 50.46 report dated April 30, 2012 (Note 3) APCT = 69°F 10 CFR 50.46 report dated April 23, 2014 (Note 6) APCT = 63°F 10 CFR 50.46 report dated March 16, 2018 (Note 10) APCT = 0°F 10 CFR 50.46 report dated March 16, 2018 (Note 11) APCT = +6°F NET PCT PCT=1764°F B. CURRENT LOCA MODEL ASSESSMENTS None APCT = 0°F Total PCT change from current assessments I APCT= 0°F Cumulative PCT change from current assessments I IAPCT l=0°F NET PCT PCT=1764°F

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 3 of 6 PLANT NAME: Calvert Cliffs Unit 1 ECCS EVALUATION MODEL: Realistic Large Break Loss of Coolant Accident (RLBLOCA)

REPORT REVISION DATE: 3/18/2019 CURRENT OPERATING CYCLE: 24 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°F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS 1o CFR S0.46 report dated March 20, 2014 (Note S) ~PCT= 14°F 10 CFR 50.46 report dated April 23, 2014 (Note 6) ~PCT= 0°F 10 CFR 50.46 report dated July 14, 2015 (Note 7) ~PCT= 0°F 1o CFR 50.46 report dated March 18, 2016 (Note 8) ~PCT= 0°F NET PCT PCT =1634°F B. CURRENT LOCA MODEL ASSESSMENTS None ~PCT= 0°F Total PCT change from current assessments I ~PCT= 0°F Cumulative PCT change from current assessments I l~PCT I= 0°F NET PCT PCT =1634°f

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 4 of 6 PLANT NAME: Calvert Cliffs Unit 2 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 3/18/19 CURRENT OPERATING CYCLE: 23*

ANALYSIS OF RECORD Evaluation Model: EMF-2328(P)(A), Revision 0, Supplement 1(P)(A),

Revision O Calculation: ANP-3641, March 2018 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: 0.34 ft 2 Break in the Cold Leg Pump Discharge Reference Peak Cladding Temperature (PCT) PCT= 1648°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS N/A- Note 12 NET PCT PCT= 1648°F B. CURRENT LOCA MODEL ASSESSMENTS EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision O LlPCT = 0°F Total PCT change from current assessments I LlPCT = 0°F Cumulative PCT change from current assessments L ILlPCT I= 0°F NET PCT PCT =1648°F

• CCNPP Unit 2 is currently in a refueling outage. CCNPP Unit 2 Cycle 23 Mode 4 entry is scheduled to occur March, 2019.

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page S of 6 PLANT NAME: Calvert Cliffs Unit 2 ECCS EVALUATION MODEL: Small Break Loss of Coolant Accident (SBLOCA)

REPORT REVISION DATE: 3/18/2019 CURRENT OPERATING CYCLE: 23*

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 Peak Cladding Temperature (PCT) PCT= 1626°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR 50.46 report dated April 30, 2012 (Note 3) APCT = 69°F 10 CFR 50.46 report dated April 23, 2014 (Note 6) APCT = 63°F 10 CFR 50.46 report dated March 16, 2018 (Note 10) APCT = 0°F 10 CFR 50.46 report dated March 16, 2018 (Note 11) APCT = +6°F NET PCT PCT =1764°F B. CURRENTLOCAMODELASSESSMENTS None APCT = 0°F Total PCT change from current assessments L APCT= 0°F Cumulative PCT change from current assessments L \APCT l=0°F NET PCT PCT =1764°F

• CCNPP Unit 2 is currently in a refueling outage. CCNPP Unit 2 Cycle 23 Mode 4 entry is scheduled to occur March, 2019. EMF-2328(P)(A) is not used in Unit 2 Cycle 23.

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 1 Peak Cladding Temperature Rack-Up Sheet for CCNPP Page 6 of 6 PLANT NAME: Calvert Cliffs Unit 2 ECCS EVALUATION MODEL: Realistic Large Break Loss of Coolant Accident (RLBLOCA)

REPORT REVISION DATE: 3/18/19 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 ft 2/side) in Cold Leg Pump Discharge Reference PCT PCT = 1620°F MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS 10 CFR S0.46 report dated April 22, 2013 (Note 4) APCT = 8°F 10 CFR S0.46 report dated March 20, 2014 (Note S) APCT = 6°F 10 CFR S0.46 report dated April 23, 2014 (Note 6) APCT = 0°F 10 CFR S0.46 report dated July 14, 201 S (Note 7) APCT= 0°F 10 CFR S0.46 report dated March 18, 2016 (Note 8) APCT = 0°F NET PCT PCT =1634°F B. CURRENT LOCA MODEL ASSESSMENTS None APCT = 0°F Total PCT change from current assessments IAPCT= 0°F Cumulative PCT change from current assessments I IAPCT I= 0°F NET PCT PCT=1634°F

• CCNPP Unit 2 is currently in a refueling outage. CCNPP Unit 2 Cycle 23 Mode 4 entry is scheduled to occur March, 2019.

ATTACHMENT2 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, 2019 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, 2019 Attachment 2 Assessment Notes Page 1 of 4

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. An error in the S-RELAPS 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 application resulting in a 0°F PCT impact. An error in the S-RELAP5 Sleicher-Rouse correlation used for

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 2 Assessment Notes Page 2 of 4 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.

8) Prior LOCA Model Assessment The 10 CFR 50.46 report dated March 18, 2016, identified once-burned fuel, U02 and Gadolinia-bearing (GAD) rods, are generally modeled at a reduced peaking in comparison with

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 2 Assessment Notes Page 3 of 4 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 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.

9) Prior LOCA Model Assessment The 10 CFR 50.46 report dated March 17, 2017, reported no model changes or errors for both the RLBLOCA and SBLOCA analyses.

10) Prior LOCA Model Assessment CR 2017-3565 identified an update to the MS swelling and rupture mode (SRM) had the potential to impact Calvert Cliff's SBLOCA analysis.

MS SRM is used in several of AREVA LOCA methodologies and since approval of the MS SRM in the MS Licensing Topical Report, BAW-10227, Rev. 1 (P)(A) by the NRC in the early 2000s, additional MS cladding rupture test data was obtained. Following the same approach as the original model, an updated MS SRM was developed to consider the updated test data.

The model changes do not change the predicted occurrence or conditions at the time of rupture, but would impact the post-rupture cladding characteristics for certain rupture temperatures.

Calvert Cliffs Units 1 and 2 SBLOCA uses MS SRM. The analyses of record rupture temperatures were less than the range of the model changes, and therefore a 0°F PCT estimate was assigned. The Calvert Cliffs Units 1 and 2 RLBLOCA analysis was performed with a LOCA methodology which did not use the MS SRM and therefore is not affected.

Annual Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of March 18, 2019 Attachment 2 Assessment Notes Page 4 of 4

11) Prior LOCA Model Assessment CR 2017-5630 identified an error in the S-RELAP5 calculations of oxidation due to high temperature metal-water reaction. In a LOCA event, the cladding can swell (and potentially rupture) due to the difference in pressure between the fuel and the system. As the clad radius increases, the thickness decreases. It was discovered that the S-RELAP5 oxidation calculations used cold cladding dimensions and therefore, did not fully account for the swelling phenomena. The error can lead to an under-prediction of the oxidation and heat from the metal-water reaction.

Calvert Cliffs Units 1 and 2 SBLOCA analysis utilizes S-RELAP5 and it was determined that the estimated PCT effect is +6°F. The local oxidation and whole core hydrogen remain well within the 10 CFR 50.46 acceptance criteria with the correction. The Calvert Cliffs Units 1 and 2 RLBLOCA analysis was performed with a LOCA methodology which did not model swelling and therefore is not affected.

12) Current LOCA Model Assessment Calvert Cliffs Units 1 and 2 SBLOCA was re-analyzed using Evaluation Model EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision 0. The local oxidation and whole core hydrogen remain well within the 10 CFR 50.46 acceptance criteria. The analysis establishes an AOR PCT of 1648°F. No errors in or changes to the EMF-2328(P)(A), Revision 0, Supplement 1(P)(A), Revision O analysis have been reported.

There were no errors or changes reported against RL!3LOCA during this reporting period.