L-19-019, Transmittal of 10 CFR 50.46 - 30-Day and Annual Report for Watts Bar Nuclear Plant, Units 1 and 2

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Transmittal of 10 CFR 50.46 - 30-Day and Annual Report for Watts Bar Nuclear Plant, Units 1 and 2
ML19066A046
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 03/07/2019
From: Anthony Williams
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
WBL-19-019
Download: ML19066A046 (14)
v • d • e


Text

Tennessee Valley Authority, 1 101 Market Street, Chattanooga, TN 37402 wBL-19-019 March 7, 2019 10 cFR 50.4 10 cFR 50.46 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Units 1 and2 Facility Operating License NPF-90 and NPF-96 NRC Docket Nos. 50-390 and 50-391

Subject:

10 CFR 50.46 Day and Annual Report for Watts Bar Nuclear Plant Units 1 and2

Reference:

TVA Letter to NRC, CNL-18-040, '10 CFR 50.46 Day and Annual Report for Watts Bar Nuclear Plant Units 1 and 2," dated March 7 , 2018 (ML18066A730)

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 Regulations (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.

The enclosure also serves as the 30-day report in accordance with 10 CFR 50.46(a)(3)(ii),

which states that a holder of an operating license or construction permit is required to report changes and errors affecting an ECCS evaluation modelto the NRC within 30 days when the cumulative sum of the absolute magnitudes of resulting PCT changes exceeds 50'F. The licensee is also required to include with the report, a proposed schedule for providing a

U.S. Nuclear Regulatory Commission wBL-19-019 Page 2 March 7,2019 reanalysis or taking other action as may be needed to show compliance with the 10 CFR 50.46 requirements. Westinghouse performs the LOCA analysis for WBN and Westinghouse submitted a list of changes and errors to the LOCA analysis to TVA on February 14,2019. All the submitted changes and errors result in a 0"F change in PCT, but because the accumulated changes and errors from previous years are more than 50'F (with the exception of the WBN Units 1 and2 SBLOCA analysis), a 30-day report is required.

As presented in this report, compliance with 10 CFR 50.46 requirements is demonstrated by the calculated PCT for both WBN units remaining below the 2200'F limit. Therefore, TVA has concluded that no proposed schedule for providing a reanalysis or other action is required. No further actions are needed to show compliance with 10 CFR 50.46 requirements.

Also, during the review of this report, TVA made a revision to the reporting years for the Vessel Channel DX Error and Accumulator Line/Pressurizer Surge Line Data Evaluation line items in Table 1 to the enclosure. These revisions are for consistency with the data used in the supporting Westinghouse data used to develop the enclosure.

There are no regulatory commitments in this letter. Please address any questions regarding this response to Kimberly Hulvey at(423) 365-7720.

y L. Williams lV Site Vice President Watts Bar Nuclear Plant

Enclosure:

Wafts Bar Nuclear Plant, 10 CFR 50.46 30-Day and Annual Report tor 2018 cc (Enclosures):

NRC RegionalAdministrator - Region !l NRC Senior Resident lnspector - Watts Bar Nuclear Plant Division of Radiological Health - State of Tennessee

ENCLOSURE Watts Bar Nuclear Plant, 10 CFR 50.46 30-Day and Annual Report for 2018 ln accordance with the reporting requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.46(a)(3)(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 (ECCS) 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 10 CFR 50.46 annual report for WBN Units 1 and2 to the NRC in Reference 1.

Table 1 lists the changes and errors in the large break LOCA (LBLOCA) analysis for WBN Unit 1 since the analysis of record (AOR) and the associated effect on PCT. Table 2 lists the changes and errors in the small break LOCA (SBLOCA) analyses for WBN Unit 1 since the AOR and the associated effect on PCT. The changes that were not previously identified in Reference 'l are described in the notes to Tables 1 and 2.

Table 3 lists the changes and errors in the LBLOCA analysis for WBN Unit 2 since the AOR and the associated effect on PCT. Table 4 lists the changes and errors in the SBLOCA analyses for WBN Unit 2 since the 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 1 and 2from the last annual report.

This report also serves as the 30-day report in accordance with 10 CFR 50.46(aX3)(ii), which states that a holder of an operating license or construction permit is required to report changes and errors affecting an ECCS evaluation model to the NRC within 30 days when the cumulative sum of the absolute magnitudes of resulting PCT changes exceeds 50'F. The licensee is also required to include with the report, a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with the 10 CFR 50.46 requirements. Westinghouse performs the LOCA analysis forWBN;Westinghouse submitted a list of changes and errors to the LOCA analysis to TVA on February 14,2019. All the submitted changes and errors result in a 0'F change in PCT, but because the accumulated changes and enors from previous years are more than 50"F, a 30-day report is required.

As presented in this report, compliance with 10 CFR 50.46 requirements is demonstrated by the calculated PCT for both WBN units remaining below the 2200"F limit. Therefore, TVA has concluded that no proposed schedule for providing a reanalysis or other action is required.

wBL-19-019 E1of12

ENCLOSURE Table 1 Watts Bar Unit 1 LBLO9A Reflood 1 Reflood 2 APCT lancrl APCT lrncrl Note Reference Year Description ('F) ("F) ('F) ('F) 1 998 BE LBLOCA AOR PCT { 656 I 892 3 1 998 Vessel Channel DX Error 56 56 -4 4 4 1 999 Accumulator Li ne/Pressu rizer Surge -37 37 -131 131 4 Line Data Evaluation 2000 lncreased Accumulator Room Temperature 4 4 4 4 4 Evaluation 2000 1 .4o/o Uprate Evaluation 12 12 12 12 4 2000 MONTECF Decay Heat 4 4 4 4 5 Uncertainty Error 2001 WBN Specific LBLOCA Vessel Geometry lnput 0 0 0 0 6 Errors 2003 lnput Error Resulting in lncomplete Solution 60 60 0 0 7 Matrix 2003 Tavg Bias Error I 8 I I 7 2004 lncreased Stroke Time for ECCS Valves 0 0 0 0 I 2004 Revised Blowdown Heatup Uncertainty 5 5 5 5 I Distribution 2006 Replacement Steam Generators (D3 to -50 50 -10 10 I 68AXP) 2006 HOTSPOTTM Fuel Relocation Error 0 0 65 65 I 2012 PMID/PBOT Violation 2A 2A 20 2A 10, 11 Evaluation 2012 TCD and Peaking Factor 114 114 15 15 10, 11 Burndown WBL-19-019 E2 of 12

ENCLOSURE Table 1 Watts Bar Unit I LBLOCA Reflood 1 Reflood 2 APCT laecrl APCT lancrl Note Reference Year Description ("F) ('F) ("F) ("F) 2013 wcoBRArrRACrM History File Dimension 0 0 0 0 12 Error 2013 General Code 0 0 0 0 13 Maintenance 2413 HOTSPOTTM Burst Tem peratu re Calcu lation 0 0 0 0 13 for ZIRLOTM Claddins 24rc HOTSPOTTM lteration Algorithm for Calculation 0 0 0 0 13 lnitial Fuel Pellet Average Temperature 2013 WCOBR/A/TRACTM Automated Restart 0 0 0 0 13 Process Logic Error 2013 Rod lnternal Pressure 0 0 0 0 13 Calculation Error 2013 Elevations for Heat Slab 0 0 0 0 14 Tem peratu re I n itialization 2013 Heat Transfer Model 0 0 0 0 14 Error Corrections 2413 Correction to Heat Transfer Node 0 0 0 0 14 lnitialization 2013 Mass Conservation Error 0 0 0 0 14 Fix 2013 Correction to Split Channe! Momentum 0 0 0 0 14 Equation Heat Transfer Logic 2013 Correction for Rod Burst 0 0 0 0 14 Calculation Changes to Vessel 2013 Superheated Steam 0 0 0 0 14 Properties WBL-19-019 E 3 of 12

ENCLOSURE Table I Watts Bar Unit I LBLOCA Reflood 1 Reflood 2 APCT lmcrl APCT laecrl Note Reference Year Description ("F) ('F) ("F) ("F)

Update to Metal Density 2A13 o 0 0 0 14 Reference Tem peratures Decay Heat Model Error 2013 0 0 0 0 14 Corrections Correction to the Pipe 2013 0 0 0 0 14 Exit Pressure Drop Error WCOBRA/TRAC File 2013 Dimension Error 0 0 0 0 14 Correction Revised Heat Transfer 2413 -40 40 -85 85 14 Multiplier Distributions HOTSPOT Burst Strain 2013 20 20 70 7A 15 Error General Computer Code 2014 0 0 0 0 20 Maintenance Revised Uncertainty in 2014 LBLOCA Monte Carl o 0 0 0 20 Simulations General Code 2016 0 0 0 0 22 Maintenance Clad Ox idation 2016 0 0 0 0 22 Calculat ion LOTIC2 Net Free Volume 2016 Direction of Conservatism 0 0 0 0 22 and lce Melt Condition LOTI C2 Calculation of the 2016 Thermodynamic 0 0 0 o 22 Properties of Air lncreased Safety lnjection 2416 Time Delay with Offsite 0 0 0 0 22 Power Available lncrease in ECCS pump 2417 0 0 0 0 23 iniection delay time General Code 2017 0 0 0 0 1 Maintenance Entrained Liquid / Vapor lnterfacial Drag 2017 0 0 0 0 1 Coefficient Calculation lnconsistency WBL-19-019 E4ot12

ENCLOSURE Table 1 Watts Bar Unitl LBLOCA Reflood 1 Reflood 2 APCT lnecrl APCT lmcrl Note Reference Year Description ('F) ("F) ("F) ("F)

Resetting of the 2A17 Transverse Liquid Mass 0 0 0 0 1 Flow Vapor Temperature 2018 0 0 0 0 1 Resetting Updated (net) licensing basis PCT 1832 { 865 AORPCT+IAPCT Cumulative sum of PCT changes 430 433 I lrncrl Notes:

1. !n the LBLOCA analysis when the vapor temperature is greater than the wall temperature, and several other conditions are met, the vapor temperature is set to the saturation temperature for heat transfer calculations. This vapor temperature logic results in an inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. 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.

WBL-19-019 E 5 of 12

ENCLOSURE Table 2 Watts Bar Unil I SBLOCA SBLOCA SBLOCA Year Description APCT I APCT I Note Reference

("F) ("F) 2006 SBLOCA AOR PCT 1132 16 NOTRUMP-EMrM Evaluation of Fuel 13 2013 0 0 Pellet TCD General Computer Code 0 0 20 2014 Maintenance 2014 Fuel Rod Gap Conductance Error 0 0 20 2014 Radiation Heat Transfer Model Error 0 0 20 SBLOCTA Pre-DNB Cladding 2014 Surface Heat Transfer Coefficient 0 0 20 Calculation 2014 Evaluation of 8-inch Axial Blankets 0 0 20 General Computer Code 0 0 21 2015 Maintenance Auxiliary Feedwater (AFW) 2015 Temperature lncrease During Cold 0 0 21 Leq Recirculation Plant-Specific Upper Head 22 2016 0 0 Geometric Data lncreased Containment Spray Flow 2016 Rate and Reduced RWST Useable 0 0 22 Volume 2017 General Code Maintenance 0 0 1 Upper Plenum Fluid Volume 2017 0 0 1 Reduction WBL-19-019 E 6 of 12

ENCLOSURE Table 2 Watts Bar Unit 1 SBLOCA SBLOCA SBLOCA Year Description APCT I APCr I Note Reference

("F) ("F) 2018 UO2 Fuel Pellet Heat Capacity 0 0 1 Updated (net) licensing basis PGT AORPCT+IAPCT 1132 Cumulative sum of PCT changes

lancrl 0 Notes:
1. A typographical error was discovered in the calculation of the UO2 fuel pellet heat capacity used in the fuel rod heat-up determination, which results in a maximum decrease in heat capacity of approximately 1 .2o/o. The small error in UO2 fuel pellet heat capacity has an estimated PCT impact of 0"F.

WBL-19-019 E7 of 12

ENCLOSURE Table 3 Watts Bar Unit 2 LBLOCA LBLOCA LBLOCA Year Description Note Reference APCT ("F) lpcrl ("F) 2013 LBLOCA AOR PCT 1 766 17 Elevations for Heat Slab 2013 0 0 19 Temperature I nitialization Heat Transfer Model Error 2013 0 0 19 Corrections Correction to Heat Transfer Node 2013 0 0 19 lnitialization 2013 Mass Conservation Error Fix 0 0 19 Correction to Split Channel 2013 0 0 19 Momentum Equation Heat Transfer Logic Correction for 2013 0 0 19 Rod Burst Calculation Changes to Vessel Superheated 2013 0 0 19 Steam Properties Update to Metal Density Reference 2013 0 0 19 Temperatures Decay Heat Model Error 2A13 0 0 19 Corrections Correction to the Pipe Exit 2A13 0 0 19 Pressure Drop Error WCOBRA/TRAC File Dimension 2013 0 0 19 Error Correction Revised Heat Transfer Multiplier 2013 -55 55 19 Distributions lnitial Fuel Pellet Average 2013 Tem perature U ncertai nty 0 0 19 Calculation 2013 HOTSPOT Burst Strain Error 0 0 15 Cold Leg Accumulator lnjection 2014 Lines Hydraulic Resistance 0 0 2 Chanqes General Computer Code 2014 0 0 2A Maintenance Errors in Decay Group Uncertainty 2014 0 0 20 Factors WBL-19-019 E 8 of 12

ENCLOSURE Table 3 Watts Bar Unit ?LBLOCA Year LBLOCA LBLOCA Description Note Reference APCT ('F) I lpcr I ("F)

Treatment of Burnup Effects on 2014 Thermal Conductivity Degradation 0 0 20 2016 General Code Maintenance 0 0 22 2016 Clad Oxidation Calculation 0 0 22 Use of Steam Tables in Upper 22 2416 Head Fluid Temperature 0 0 Calculations Lower Support Plate Heat 2016 0 0 22 Conductor Surface Area LOTIC2 Net Free Volume Direction 22 2016 of Conservatism and lce Melt 0 0 Condition LOTIC2 Calculation of the 2016 0 0 22 Thermodynamic Properties of Air 2017 General Code Maintenance 0 0 1 Entrained Liquid / Vapor Interfacial 2017 Drag Coefficient Calculation 0 0 1 lnconsistency Resetting of Transverse Liquid 2017 0 0 1 Mass Flow Steady State Fuel Temperature 2017 0 0 1 Calibration non-Conservatisms 2018 Vapor Temperature Resetting 0 0 1 Updated (net) licensing basis PCT 1711 (AORPCT+fAPCT)

Gumulative sum of PCT changes 55 I lrncrl Notes:

1. ln the LBLOCA analysis when the vapor temperature is greater than the wall temperature, and several other conditions are met, the vapor temperature is set to the saturation temperature for heat transfer calculations. This vapor temperature logic results in an inconsistency between the conduction solution and the hydraulic solution, such that energy is not conserved between the two solutions. Sensitivity calculations showed that correcting this error had minima! impact on LOCA transient calculations, leading to an estimated peak cladding temperature impact of 0'F.

WBL-19-019 E I of 12

ENCLOSURE Table 4 Watts Bar Unit 2 SBLOCA Year Description SBLOCA SBLOCA Note Reference APCT ("F) I lpcr I ("F) 201A SBLOCA AOR PCT 1184 18 Cold Leg Accumulator Injection 2014 Lines Hydraulic Resistance 0 0 2 Changes General Computer Code 2AM 0 0 20 MaintenanGe 2014 Fuel Rod Gap Conductance Error 0 0 20 Radiation Heat Transfer Model 2014 0 0 20 Error SBLOCTA Pre-DNB Cladding 2014 Surface Heat Transfer Coetficient 0 0 20 Calculation General Computer Code 2015 Maintenance 0 0 21 AFW Temperature lncrease During 2015 Cold Leg Recirculation 0 0 21 Plant-Specific Upper Head 22 2016 Geometric Data 0 0 2016 Reduced RWST Useable Volume 0 0 22 2017 lncreased Sl injection time delay 0 0 1 2017 General Code Maintenance 0 0 1 Upper Plenum Fluid Volume 2017 Reduction 0 0 1 2018 UOz Fuel Pellet Heat Capacity 0 0 1 Updated (net) Iicensing basis PCT 1184 (AORPCT+f^PCT)

Cumulative sum of PCT changes I lancrl 0 0 Notes:

1. A typographical error was discovered in the calculation of the UO2 fuel pellet heat capacity used in the fuel rod heat-up determination, which results in a maximum decrease in heat capacity of approximately 1 .2o/o. The smallerror in UO2 fuel pellet heat capacity has an estimated PCT impact of 0'F.

wBL-19-019 E10of12

ENCLOSURE

References:

1. TVA Letter to NRC, CNL-18-040, "10 CFR 50.46 Day and Annual Report forWatts Bar, Units 1 and 2," dated March 7, 2018 (ML180664730)
2. TVA letter to NRC, CNL-15-034, "10 CFR 50.46 Day Report for Watts Bar, Unit 2" dated February 6,2015 (ML150374725)
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. TVA letter 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 (M1003764646)
5. TVA letter to NRC, "Watts Bar Nuclear Plant WBN) 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. TVA letter to NRC, "Watts Bar Nuclear Plant WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - Annual Notification and Reporting for 2001," dated April 3, 2002 (M1021070404)
7. TVA letter 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 (ML041130196)
8. TVA letter 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 (M1051120164)
9. TVA letter 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. TVA letter to NRC, "Supplement to 10 CFR 50.46 Day Special Report," dated February 13, 2013 (ML130464002)
11. TVA letterto NRC,'10 CFR 50.46 Day Special Report," dated October 18,2012 (M112296A254)
12. TVA letterto NRC,'10 CFR 50.46 Day ReportforWatts Bar Unit 1," dated March 19,2013 (M1130804405)
13. TVA letter to NRC, '10 CFR 50.46 Day and Annual Report for 2A12," dated April 25, 2013 (M1131204005)
14. TVA letter to NRC, "10 CFR 50.46 - 30 day Report for Watts Bar, Unit 1," dated August 28,2413 (M113267A034)
15. TVA letter to NRC, CNL-14-035, "10 CFR 50.46 - 30 day Report for Watts Bar, Units 1 and 2,"

dated February 28, 2014 (ML140644431 )

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

February 2006

17. WCAP-17093-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 for WBN Unit 2," January 201 0 wBL-19-019 E11of12

ENCLOSURE

19. TVA letter 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 (M1132464076)
20. TVA letter to NRC, CNL-15-053, "10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and 2," dated March 30, 2015 (ML150984124) 21 . TVA letter to NRC, CNL-16-057, '10 CFR 50.46 - Annual Report for Watts Bar, Units 1 and 2,"

dated March 18,2016 (M1160814248) 22.'fVA Letter to NRC, '10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and2,"

dated March 8,2017 (M1170674079)

23. TVA Ietter to NRC, 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit '1," dated Aug ust 21, 2017 (ML17235A905) wBL-19-019 E 12of12
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