ML17222A097

Transmittal of 10CFR50.46 Annual Report

ML17222A097
Person / Time
Site:	Peach Bottom
Issue date:	08/10/2017
From:	David Gudger Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML17222A097 (9)

Text

200 Exelon Way Exelon Gener-ation Kennett Square. PA 19348 www.exeloncorp.com August 10, 2017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 N RC Docket Nos. 50-277 and 50-278

Subject:

1 O CFR 50.46 Annual Report 10 CFR 50.46

Reference:

Letter from James Barstow (Exelon Generation Company, LLC) to the U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 10, 2016.

The purpose of this letter is to transmit the 1 O CFR 50.46 reporting information for Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3. The previous 50.46 report for PBAPS, Units 2 and 3, (Reference) provided the cumulative Peak Cladding Temperature (PCT) errors for the most recent fuel designs through August 10, 2016.

Since the last PBAPS 10 CFR 50.46 Report (Reference), two vendor notifications regarding Emergency Core Cooling System (ECCS) modeling changes/errors applicable to PBAPS have been issued (Notification 2017-01 and 2017-02). These notifications described issues related to the improper modelling of lower tie plate leakage for the GNF2 fuel design and changes to modeling of the fuel rod plenum for 1 Ox1 O fuel. Correction of these errors each resulted in a 0°F PCT change for GNF2 fuel.

Additionally, since the Reference report, the analytical limit for the Level 3 setpoint has been changed. The impact of this change on the Loss of Coolant Accident (LOCA) analysis was assessed in GNF Report 003N4534-RO, "Peach Bottom Level 3 Analytical Limit Reduction," dated May 25, 2016, which concluded that there is no impact on the licensing basis PCT for PBAPS, Units 2 and 3.

U.S. NRG Regulatory Commission Peach Bottom Atomic Power Station, Units 2 and 3 10 CFR 50.46 Report August 1 O, 2017 Page2 There are no regulatory commitments in this letter.

If you have any questions concerning this letter, please contact Richard Gropp at 610-765-5557.

Respectfully, J

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David T. Gudger Manager, Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments:

1. Peach Bottom Unit 2 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report

2. Peach Bottom Unit 3 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report

3. Assessment Notes cc:

USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, PBAPS USNRC Project Manager, PBAPS R. R. Janati, Bureau of Radiation Protection S. T. Gray, State of Maryland

ATTACHMENT 1 Peach Bottom Unit 2 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report

Peach Bottom Unit 2 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report PLANT NAME:

ECCS EVALUATION MODEL:

EVALUATION MODEL VENDOR:

REPORT REVISION DATE:

CURRENT OPERATING CYCLE:

Peach Bottom Unit 2 SAFER/PRIME GNF/GEH August10.2017 22 ANAL VSIS OF RECORD CALCULATIONS Page 1 of 1

1. 0000-0162-2354-RO, Revision 0, "Peach Bottom Atomic Power Station, Units 2 and 3 MELLLA+ Task T0407: ECCS-LOCA Performance," December 2013.

Fuels Analyzed in Calculations and in Operation:

GNF2 Limiting Fuel Type:

GNF2 Limiting Single Failure:

Battery Failure Limiting Break Size/Location:

0.05 ft2 Small Break in a Recirculation Discharge Pipe Reference PCT:

1920 °F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS:

Annual 1 O CFR 50.46 Report dated August 15, 2014 b.PCT=5 °F (See Note 1)

Annual 1 O CFR 50.46 Report dated August 10, 2016 b.PCT=0 °F (See Note 2)

Net PCT 1925 °F B. CURRENT LOCA MODEL ASSESSMENTS:

GNF2 Lower Tie Plate Leakage (See Note 3) b.PCT=0°F Level 3 Analytical Limit Change (See Note 4) b.PCT=0°F Fuel Rod Plenum Temperature Update (See Note 3) b.PCT=0°F Total PCT change from current assessments I:b.PCT=0°F Cumulative PCT change from current assessments I:lb.PCTl=0°F Net PCT 1925 °F

ATTACHMENT 2 Peach Bottom Unit 3 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report

Peach Bottom Unit 3 I SAFER/PRIME I GNF2 Fuel 10 CFR 50.46 Report PLANT NAME:

ECCS EVALUATION MODEL:

EVALUATION MODEL VENDOR:

REPORT REVISION DATE:

CURRENT OPERATING CYCLE:

Peach Bottom Unit 3 SAFER/PRIME GNF/GEH August 1 o. 2017

£1 ANALYSIS OF RECORD CALCULATIONS Page 1 of 1

1. 0000-0162-2354-RO, Revision 0, "Peach Bottom Atomic Power Station, Units 2 and 3 MELLLA+ Task T0407: ECCS-LOCA Performance," December 2013.

Fuels Analyzed in Calculations and in Operation:

GNF2 Limiting Fuel Type:

GNF2 Limiting Single Failure:

Battery Failure Limiting Break Size/Location:

0.05 ft2 Small Break in a Recirculation Discharge Pipe Reference PCT:

1920 °F MARGIN ALLOCATION A. PRIOR LOCA MODEL ASSESSMENTS:

Annual 1 O CFR 50.46 Report dated August 15, 2014 LlPCT=5 °F (See Note 1)

Annual 1 O CFR 50.46 Report dated August 10, 2016 LlPCT=0°F (See Note 2)

Net PCT 1925 °F B. CURRENT LOCA MODEL ASSESSMENTS:

GNF2 Lower Tie Plate Leakage (See Note 3)

LlPCT=0°F Level 3 Analytical Limit Change (See Note 4)

LlPCT=0°F Fuel Rod Plenum Temperature Update (See Note 3)

LlPCT=0°F Total PCT change from current assessments LLlPCT=0°F Cumulative PCT change from current assessments LILlPCTl=0°F Net PCT 1925 °F

ATTACHMENT 3 Assessment Notes 10 CFR 50.46 Report

Assessment Notes 10 CFR 50.46 Report

1. Prior LOCA Assessment Page 1 of 2 The referenced letter reported four vendor notifications that were received. The first notification addressed several accumulated updates to the SAFER04A model. The code maintenance changes had an individually and collectively insignificant effect on calculated peak cladding temperature. The second notification was for a correction to a logic error that was isolated, occurring with an indication that the expected systems mass diverged from the calculated actual system mass. This error affected the Emergency Core Cooling System (ECCS) flow credited as reaching the core. Correction of this error resulted in a 10°F Peak Cladding Temperature (PCT) change for GNF2 fuel.

The third notification addressed an error with the imposed minimum Pressure Differential (Lip) for droplet flow above a two-phase level in the core. This error could have offered an inappropriate steam cooling benefit above the core two phase level. To correct this error an explicit core Lip calculation was applied without regard to droplet condition resulting in a PCT of -10°F for GNF2 fuel. The forth notification addressed an incorrect pressure head representation when defining the Counter Current Flow Limitation (CCFL). Correction of this error resulted in a 5°F PCT change for GNF2 fuel. Note that the 1 O CFR 50.46 notifications discussed in the referenced report are applicable to the Unit 2 and Unit 3 MELLLA+ LOCA analysis.

[

Reference:

Letter from James Barstow (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 15, 2014.]

2. Prior LOCA Assessment The referenced letter reported that Peach Bottom Unit 2 and Unit 3 implemented Maximum Extended Load Line Limit Analysis Plus (MELLLA+) for which a new LOCA analysis was performed. Unit 2 and Unit 3 transitioned to MELLLA+ operation mid-cycle in April 2016 and May 2016, respectively. The error notifications reported in Assessment Note 1 are applicable to the Peach Bottom 2 and 3 MELLLA+ LOCA analysis. The notifications were issued subsequent to the performance of the MELLLA+

LOCA analysis, but prior to its implementation.

[

Reference:

Letter from James Barstow (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "10 CFR 50.46 Annual Report," dated August 10, 2016.]

3. Current LOCA Assessment Since the last Peach Bottom 1 O CFR 50.46 Report, two vendor notifications regarding Emergency Core Cooling System (ECCS) modeling changes/errors applicable to Peach Bottom have been issued (Notification 2017-01 and 2017-02). These notifications described issues related to the improper modelling of lower tie plate leakage for the GNF2 fuel design and changes to modeling of the fuel rod plenum for 1 Ox1 O fuel.

Correction of these errors each resulted in a 0°F PCT change for GNF2 fuel.

Assessment Notes 10 CFR 50.46 Report

4. Current LOCA Assessment Page 2 of 2 Since the last Peach Bottom 1 O CFR 50.46 Report, the analytical limit for the Level 3 setpoint has been changed. The impact of this change on the Loss of Coolant Accident (LOCA) analysis was assessed in GNF Report 003N4534-RO, "Peach Bottom Level 3 Analytical Limit Reduction," dated May 25, 2016, which concluded that there is no impact on the licensing basis PCT for Peach Bottom.