Text

Transmittal of l0 CFR 50.46 Annual Report
	ML16081A248
Person / Time
Site:	Watts Bar
Issue date:	03/18/2016
From:	Walsh K; Tennessee Valley Authority
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	CNL-16-057
	Download: ML16081A248 (15)
	v • d • e

Tennessee Valley Authority, 1101 Market Street, Chattanooga, TN 37402 cNL-16-057 March 18, 2016 10 cFR s0.4 10 cFR 50 .46 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License NPF-90 NRC Docket No. 50-390 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

10 CFR 50.46 - Annual Report for Watts Bar Nuclear Plant Units 1 and 2

Reference:

1. TVA Letter to NRC, CNL-'I5-053, '10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and 2," dated March 30, 2015 [ML150984124]

The purpose of this letter is to provide the annual report of changes and errors to the calculated peak cladding temperature (PCT) for the Watts Bar Nuclear Plant (WBN) Units 1 and 2, Emergency Core Cooling System (ECCS) evaluation model. This report is required in accordance with Title 10 of the Code of Federal Regulafibns ('10 CFR) 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors,"

paragraph (a)(3Xii).

The Tennessee Valley Authority (TVA) submitted the last 10 CFR 50.46 annual report for WBN Units 1 and 2 to the Nuclear Regulatory Commission (NRC) in the referenced letter. As indicated in the enclosure, there are no changes to the current updated (net) licensing basis PCT for the WBN Unit 1 large break loss of coolant accident (LBLOCA) and the updated (net) licensing basis PCT for the WBN Unit 1 small break loss of coolant accident (SBLOCA).

Similarly, there are no changes to the current updated (net) licensing basis PCT for the WBN Unit 2 LBLOCA and the updated (net) licensing basis PCT for the WBN Unit 2 SBLOCA.

There are no new regulatory commitments in this letter. Please address any questions regarding this response to Mr. Gordon Arent at 423-365-2004.

U.S. Nuclear Regulatory Commission cNL-16-057 Page 2 March 18,2016 Respectfully, K. T. Walsh Site Vice President Watts Bar Nuclear Plant

Enclosure:

Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 cc (Enclosures):

NRC RegionalAdministrator - Region ll NRC Senior Resident lnspector - Watts Bar Nuclear Plant, Unit 1 NRC Senior Resident lnspector - Watts Bar Nuclear Plant, Unit 2 Division of Radiological Health - State of Tennessee

U.S. Nuclear Regulatory Commission cNL-16-057 Page 3 March 18, 2016 DCB Enclosures bcc (w/o Enclosures):

G. P. Arent M. A. Balduzzi G. A. Boerschig C. Carey J. M. Casner T. M. Conners S. M. Connors D. M. Czufin D. L. Daniels K. D. Dietrich S. M. Douglas B. M. Duckett B. M. Finn J. P. Grimes E. K. Henderson G. E. Pry E. D. Schrull J. W. Shea P. R. Simmons M. D. Skaggs S. A. Vance K. T. Walsh, Sr.

N. A. Welch B. A. Wetzel P. R. Wilson ECM

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS 1 ANd 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 ln accordance with the reporting requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.46(aX3)(ii), the Tennessee Valley Authority (TVA) is providing the following summary of the limiting design basis loss of coolant accident (LOCA) analysis results established using the current Watts Bar Nuclear Plant WBN) Emergency Core Cooling System evaluation models for WBN Units 1 and 2. This report describes the changes and errors affecting the calculated peak cladding temperatures (PCTs) since the last analysis of record was submitted to the Nuclear Regulatory Commission (NRC).

TVA submitted the last 1 0 CFR 50.46 annual report for WBN Units 1 and 2 to the NRC on March 30, 2015 (Reference 1).

Table 1 lists the changes and errors in the large break LOCA (LBLOCA) analysis for WBN Unit 1 since the last analysis of record (AOR) and the associated effect on PCT. For 2015, there were no new changes or errors to report for the LBLOCA analysis. Table 2 lists the changes and errors in the small break LOCA (SBLOCA) analyses for WBN Unit 1 since the last AOR and the associated effect on PCT. The changes that were not previously identified in Reference 1 are described in the notes to Tables 1and2.

Table 3 lists the changes and errors in the LBLOCA analysis for WBN Unit 2 since the last AOR and the associated effect on PCT. For 2015, there were no new changes or errors to report for the LBLOCA analysis. Table 4 lists the changes and errors in the SBLOCA analyses for WBN Unit 2 since the last AOR and the associated effect on PCT. The changes that were not previously identified in Reference 1 are described in the notes to Tables 3 and 4.

The updated (net) licensing basis PCT for the LBLOCA and SBLOCA remain unchanged for WBN Units l and2from the last annual report.

cNL-16-057 E1of12

ENCLOSURE TEN NESSEE VALLEY AUTHORIW WATTS BAR NUCLEAR PLANT UNITS 1 and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable 1 Watts Bar Unit 1 LBLOCA Reflood 1 Reflood 2 APCT Iancrl APCT lmcrl Note Reference Year Description ("F) ("F) ("F) ("F) 1 998 BE LBLOCA AOR PCT 1 656 1892 3 1 999 Vessel Channe! DX Error 56 56 -4 4 4 2000 ! ncreased Accumulator Room 4 4 4 4 4 Tem perature Evaluation 2000 1.4% Uprate Evaluation 12 12 12 12 4 2000 Accu m u lator Line/Pressu rizer

-37 37 -131 131 4 Surse Line Data Evaluation 2000 MONTECF Decay Heat 4 4 4 4 5 Uncertainty Error 2001 WBN Specific LBLOCA 0 0 0 0 6 Vessel Geometrv lnput Errors 2003 lnput Error Resulting in 60 60 0 0 7 lncomplete Solution Matrix 2003 Tavg Bias Error 8 I 8 8 7 2004 lncreased Stroke Time for ECCS Valves 0 0 0 0 I 2004 Revised Blowdown Heatup U ncertai nty Distri butio n 5 5 5 5 I 2006 Replacement Steam Generators (D3 to 68AXP)

-50 50 -10 10 I 2006 HOTSPOTTM Fuet Relocation 0 0 65 65 9 Error CNL-16-057 E2of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS 1 and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable I Watts Bar Unit I LBLOCA Reflood 1 Reflood 2 APCT Imcrl APCT lmcrl Note Reference Year Description ('F) ("F) ("F) ('F) 2012 PMID/PBOT Violation 20 20 20 20 10, 11 Evaluation 2012 TCD and Peaking Factor 114 114 15 15 10, 11 Burndown 2013 WCOBRA/TRACTM History 0 0 0 0 12 File Dimension Error 2013 General Code Maintenance 0 0 0 0 13 2013 HOTSPOTTM Burst Temperature Calculation for 0 0 0 0 13 ZIRLo'M Claddinq 2013 HOTSPOTTM lteration Algorithm for Calculation 0 0 0 0 13 lnitial Fuel Pellet Average Temperature 2013 WCO BRA/TRACTM Auto mate 0 0 0 0 13 d Restart Process Loqic Error 2013 Rod lnternal Pressure 0 0 0 0 13 Calculation Error 2013 Elevations for Heat Slab 0 0 0 0 14 Temperature I nitialization 2013 Heat Transfer Model Error 0 0 0 0 14 Corrections 2013 Correction to Heat Transfer 0 0 0 0 14 Node lnitialization 2013 Mass Conservation Error Fix 0 0 0 0 14 2013 Correction to Split Channel 0 0 0 0 14 Momentum Equation cNL-16-057 E3ot12

ENCLOSURE TEN NESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS 1 and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable 1 Watts Bar Unit I LBLOCA Reflood I Reflood 2 APCT Imcrl APCT lmcrl Note Reference Year Description ("F) ("F) ("F) ("F) 2013 Heat Transfer Logic Correction for Rod Burst 0 0 0 0 14 Calculation 2013 Changes to Vessel Superheated Steam 0 0 0 0 14 Properties 2013 Update to Metal Density 0 0 0 0 14 Reference Tem peratu res 2013 Decay Heat Model Error 0 0 0 0 14 Corrections 2013 Correction to the Pipe Exit 0 0 0 0 14 Pressure Drop Error 2013 WCOBRA/TRAC File 0 0 0 0 14 Dimension Error Correction 2013 Revised Heat Transfer

-40 40 -85 85 14 Mu ltiplier Distributions 2013 HOTSPOT Burst Strain Error 20 20 70 70 15 General Computer Code 2014 Maintenance 0 0 0 0 1 Revised Uncertainty in 2014 LBLOCA Monte Carl 0 0 0 0 1 Simulations Updated (net) Iicensing basis PCT 1832 I 865 AORPCT+fAPCT Gumulative sum of PCT changes 430 433 I !ancrl cNL-16-057 E4of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS I and 2 DOGKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable 2 Watts Bar Unit { SBLOCA SBLOCA SBLOCA Year Description APCT I APcr I Note Reference

("F) ("F) 2006 SBLOCA AOR PCT 1132 16 NOTRU M P-E MrM Evaluation 2013 0 0 13 of Fuel Pellet TCD General Computer Code 0 0 2014 Maintenance 1

Fuel Rod Gap Conductance 0 2014 0 1 Error Radiation Heat Transfer 0 0 2014 Model Error 1

SBLOCTA Pre-DNB Cladding Surface Heat 2014 0 0 1 Transfer Coefficient Calculation Evaluation of 8-inch Axial 0 2014 0 1 Blankets General Computer Code 0 0 2015 Maintenance 1

Auxiliary Feedwater (AFW)

Temperature lncrease 0 0 2 2015 During Cold Leg Recirculation Updated (net) Iicensing basis PCT 1132 AORPCT+fAPCT Cumulative sum of PCT changes 0 r lmcrl cNL-16-057 E5of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS 1 and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 GFR 50.46 Annual Report for 2015 Notes:

1. Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding.

2. The WBN Unit 1 and WBN Unit 2 AFW temperature during cold leg recirculation may reach a temperature of 130'F. This temperature is an increase in the AFW temperature modeled in the SBLOCA analyses of record. However, there is no effect on the SBLOCA analysis results.

cNL-16-057 E6of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS I and2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable 3 Watts Bar Untt2 LBLOCA Year Description LBLOCA LBLOCA Note Reference APCT

("F) lmcrl

('F) 17 2413 LBLOCA AOR PCT 1 766 2013 Elevations for Heat Slab 19 0 0 Temperatu re I n itialization 2013 Heat Transfer Model Error 19 0 0 Corrections 2013 Correction to Heat Transfer 19 0 0 Node lnitialization 2013 Mass Conservation Error Fix 0 0 19 2013 Correction to Split Channel 19 0 0 Momentum Equation 2013 Heat Transfer Logic 19 Correction for Rod Burst 0 0 Calculation 2013 Changes to Vessel 19 Superheated Steam 0 0 Properties 2013 Update to Metal Density 19 0 0 Reference Tem peratu res 2013 Decay Heat Model Error 19 0 0 Corrections 2013 Correction to the Pipe Exit 19 0 0 Pressure Drop Error 2013 WCOBRA/TRAC File 19 0 0 Dimension Error Correction 2013 Revised Heat Transfer 19

-55 55 Multiplier Distributions 2013 Initial Fuel Pellet Average 0 0 19 Tem perature U ncertainty Calculation 2013 HOTSPOT Burst Strain Error 0 0 15 CNL-16-057 ET of 12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUGLEAR PLANT UNITS 1 and2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Year Description LBLOCA LBLOCA Note Reference APCT lancrl

('F) ('F)

Cold Leg Accumulator 2014 Injection Lines Hydraulic 0 0 2 Resistance Chanqes General Computer Code 2014 Maintenance 0 0 1 Errors in Decay Group 2014 Uncertainty Factors 0 0 1 Treatment of Burnup Effects 2014 on Thermal Conductivity 0 0 1 Degradation Updated (net) Iicensing basis PCT (AORPCT+fAPCT) 1711 Cumulative sum of PCT changes 55 I lmcrl CNL-16-057 E8of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS 1 and2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Iable 4 Watts Bar Unit 2 SBLOCA Year Description SBLOCA SBLOCA Note Reference APGT

("F)

Imcrl

("F) 2010 SBLOCA AOR PCT 1184 18 Cold Leg Accumulator 2014 lnjection Lines Hydraulic 0 0 2 Resistance Changes General Computer Code 2014 Maintenance 0 0 1 Fuel Rod Gap Conductance 2014 Error 0 0 1 Radiation Heat Transfer 2014 Model Error 0 0 1 SBLOCTA Pre-DNB Cladding Surface Heat 2014 Transfer Coefficient 0 0 1 Calculation General Computer Code 2015 Maintenance 0 0 1 AFW Temperature I ncrease 2015 During Cold Leg 0 0 2 Recirculation Updated (net) Iicensing basis PCT (AORPCT+fAPCT) 1184 Cumulative sum of PCT changes 0 0 I lmcrl cNL-16-057 E9of12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS I and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015 Notes:

1. Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding.

2. The WBN Unit 1 and WBN Unit 2 AFW temperature during cold leg recirculation may reach a temperature of 130"F. This temperature is an increase in the AFW temperature modeled in the SBLOCA analyses of record. However, there is no effect on the SBLOCA analysis results.

cNL-16-057 E 10of12

ENCLOSURE TENNESSEE VALLEY AUTHORIW WATTS BAR NUCLEAR PLANT UNITS 1 and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 CFR 50.46 Annual Report for 2015

References:

1 . Letter from TVA to NRC, CNL-15-053, '10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and2," dated March 30,2015 [ML15098A124]

2. Letter from TVA to NRC, CNL-15-034, "10 CFR 50.46 Day Report for Watts Bar, Unit 2" dated February 6, 2015 [M115037A725]

3. WCAP-14839, Revision 1, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Watts Bar Nuclear Plant," September 1998

4. Letter from TVA to NRC, "Watts Bar Nuclear Plant WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes Day Report and Annual Notification and Reporting for 2000," dated October 26,2000 [ML003764646]

5. Letter from TVA to NRC, 'Watts Bar Nuclear Plant (VVBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes Day Report and Revised Annual Notification Report for 2000," dated September 7,2001 [ML012570290]

6. Letter from TVA to NRC, 'Watts Bar Nuclear Plant WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - Annua! Notification and Reporting for 2001,"

dated April 3, 20021MLO210704041

7. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes Day Report and Revised Annual Notification and Reporting for 2003," dated April 19, 2004 [M1041130196]

8. Letter from TVA to NRC, "Watts Bar Nuclear Plant WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - Annual Notification and Reporting for 2004,"

dated April 19, 2005 [M10511201641

9. Letter from TVA to NRC, 'Watts Bar Nuclear Plant WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes Day Report and Annual Notification and Reporting for 2006," dated July 3, 2007 [ML071860388]

10. Letter from TVA to NRC, "Supplement to 10 CFR 50.46 Day Special Report," dated February 13, 2013 [ML13046A002]

11 . Letter from TVA to NRC, '10 CFR 50.46 Day Special Report," dated October 18,2012 lML12296pc54l

12. Letter from TVA to NRC, '10 CFR 50.46 Day Report for Watts Bar Unit 1," dated March 19, 2013 [ML13080A405]

13. Letter from TVA to NRC, '10 CFR 50.46 Day and Annual Report for 2012," dated April 25, 2013 [M113120A005]

CNL-16-057 E 11 of 12

ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNITS I and 2 DOCKET Nos . 50-390 and 50-391 Watts Bar Nuclear Plant, 10 GFR 50.46 Annual Report for 2015

14. Letter from TVA to NRC, "10 CFR 50.46 - 30 day Report for Watts Bar, Unit 1," dated August 28, 2013 [MLl 32674034]

15. Letter from TVA to NRC, CNL-14-035, '10 CFR 50.46 - 30 day Report for Watts Bar, Units 1 and 2," dated February 28,2014. [ML14064A431]

16. WTV-RSG-06-015, "LOCA & Non-LOCA Analysis Summary for Replacement Steam Generator," February 2006

17. WCAP-I7093-P, Revision 1, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Watts Bar Unit 2 Nuclear Plant Using the ASTRUM Methodology," June 2013

18. WBT-D-1460, "Final Small Break LOCA Summary Report forWBN Unit 2," January 2010

19. Letter from TVA to NRC, 'Watts Bar Nuclear Plant, Unit 2 - Emergency Core Cooling System Evaluation Model Changes - 30 Day Report - 10 CFR 50.46 Notification," dated August 28, 2013. [ML132464076]

cNL-16-057 E 12of12