ML17235A905
| ML17235A905 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 08/21/2017 |
| From: | Simmons P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML17235A905 (10) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, TN 37402 August 21, 2017 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, Unit 1 Facility Operating License NPF-90 NRC Docket No. 50-390
Subject:
10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1
Reference:
TVA Letter to NRC, 10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and 2, dated March 8, 2017 (ML17067A079)
The purpose of this letter is to provide the 30-Day Report of changes or errors discovered in the emergency core cooling system (ECCS) evaluation model for Watts Bar Nuclear Plant (WBN)
Unit 1. This report is required in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.46, "Acceptance Criteria for ECCS for Light-Water Nuclear Power Reactors,"
paragraph (a)(3)(ii), which states that a holder of an operating license or construction permit is required to report significant changes and errors affecting an ECCS evaluation model to the NRC within 30 days. As defined in 10 CFR 50.46(a)(3)(i),a significant change or affecting an ECCS evaluation model includes the cumulative sum of the absolute magnitudes of resulting peak cladding temperature (PCT) changes exceeding 50°F. This report is the result of an increase in ECCS pump injection delay time and results in a 0°F change in PCT, but because the accumulated changes and errors from previous years are more than 50°F, a 30-day report is required in accordance with 10 CFR 50.46(a)(3)(ii).
The enclosure to this letter provides the 30-day report of significant changes to the WBN, Unit 1 and describes the nature and the estimated effect on the limiting ECCS analysis, of changes or errors discovered since the referenced letter for WBN Unit 1.
10 CFR 50.46(a)(3)(ii) also requires the licensee to provide 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. As shown 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
U.S. Nuclear Regulatory Commission Page 3 August 21, 2017 RDW Enclosure bcc (Enclosure)
G. P. Arent M. A. Balduzzi G. A. Boerschig J. M. Casner S. M. Connors D. M. Czufin R. A. Detwiler S. M. Douglas B. M. Duckett R. L. Gambone E. K. Henderson K. D. Hulvey B. A. Jenkins J. T. Polickoski E. D. Schrull R. Seipel J. W. Shea P. Simmons S. A. Vance K. T. Walsh R. D. Wells B. A. Wetzel A. L. Williams P. R. Wilson ECM CNL-17-080
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 1 of 7 In 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) large break LOCA (LBLOCA) Emergency Core Cooling System (ECCS) evaluation model for WBN Unit 1. This report estimates the change in the calculated peak cladding temperature (PCT) since the last analysis of record was submitted to the Nuclear Regulatory Commission (NRC) resulting from an increase in ECCS pump injection delay time.
TVA submitted the last 10 CFR 50.46 annual report for WBN Unit 1 to the NRC on March 8, 2017 (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 estimated effect on PCT. The increase in ECCS pump injection delay time was not previously identified in Reference 1 and is described in the note to Table 1. This change has no effect on the WBN Unit 1 small break LOCA (SBLOCA) analysis nor does it affect WBN Unit 2.
The updated (net) licensing basis PCT for the LBLOCA remains unchanged for WBN Unit 1 from the last annual report.
This report 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 significant changes and errors affecting an ECCS evaluation model to the NRC within 30 days. As defined in 10 CFR 50.46(a)(3)(i),a significant change or affecting an ECCS evaluation model includes the cumulative sum of the absolute magnitudes of resulting peak cladding temperature (PCT) changes exceeding 50°F. 10 CFR 50.46(a)(3)(ii) also requires the licensee to provide 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. The submitted change results in a 0°F change in PCT, but because the previous changes and errors result in more than 50°F change in PCT, a 30-day report is required.
As presented in this report, compliance with 10 CFR 50.46 requirements is demonstrated by the calculated PCT being below the 2200°F limit. Therefore, TVA has concluded that no proposed schedule for providing a reanalysis or other action is required.
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 2 of 7 Table 1 Watts Bar Unit 1 LBLOCA Year Description Reflood 1 Reflood 2 Note Reference PCT
(°F)
(°F)
(°F)
(°F) 1998 BE LBLOCA AOR PCT 1656 1892 2
1999 Vessel Channel DX Error 56 56
-4 4
3 2000 Increased Accumulator Room Temperature Evaluation 4
4 4
4 3
2000 1.4% Uprate Evaluation 12 12 12 12 3
2000 Accumulator Line/Pressurizer Surge Line Data Evaluation
-37 37
-131 131 3
2000 MONTECF Decay Heat Uncertainty Error 4
4 4
4 4
2001 WBN Specific LBLOCA Vessel Geometry Input Errors 0
0 0
0 5
2003 Input Error Resulting in Incomplete Solution Matrix 60 60 0
0 6
2003 Tavg Bias Error 8
8 8
8 6
2004 Increased Stroke Time for ECCS Valves 0
0 0
0 7
2004 Revised Blowdown Heatup Uncertainty Distribution 5
5 5
5 7
2006 Replacement Steam Generators (D3 to 68AXP)
-50 50
-10 10 8
2006 HOTSPOTTM Fuel Relocation Error 0
0 65 65 8
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 3 of 7 Table 1 Watts Bar Unit 1 LBLOCA Year Description Reflood 1 Reflood 2 Note Reference PCT
(°F)
(°F)
(°F)
(°F) 2012 PMID/PBOT Violation Evaluation 20 20 20 20 9, 10 2012 TCD and Peaking Factor Burndown 114 114 15 15 9, 10 2013 WCOBRA/TRACTM History File Dimension Error 0
0 0
0 11 2013 General Code Maintenance 0
0 0
0 12 2013 HOTSPOTTM Burst Temperature Calculation for ZIRLOTM Cladding 0
0 0
0 12 2013 HOTSPOTTM Iteration Algorithm for Calculation Initial Fuel Pellet Average Temperature 0
0 0
0 12 2013 WCOBRA/TRACTM Automated Restart Process Logic Error 0
0 0
0 12 2013 Rod Internal Pressure Calculation Error 0
0 0
0 12 2013 Elevations for Heat Slab Temperature Initialization 0
0 0
0 13 2013 Heat Transfer Model Error Corrections 0
0 0
0 13 2013 Correction to Heat Transfer Node Initialization 0
0 0
0 13 2013 Mass Conservation Error Fix 0
0 0
0 13 2013 Correction to Split Channel Momentum Equation 0
0 0
0 13
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 4 of 7 Table 1 Watts Bar Unit 1 LBLOCA Year Description Reflood 1 Reflood 2 Note Reference PCT
(°F)
(°F)
(°F)
(°F) 2013 Heat Transfer Logic Correction for Rod Burst Calculation 0
0 0
0 13 2013 Changes to Vessel Superheated Steam Properties 0
0 0
0 13 2013 Update to Metal Density Reference Temperatures 0
0 0
0 13 2013 Decay Heat Model Error Corrections 0
0 0
0 13 2013 Correction to the Pipe Exit Pressure Drop Error 0
0 0
0 13 2013 WCOBRA/TRAC File Dimension Error Correction 0
0 0
0 13 2013 Revised Heat Transfer Multiplier Distributions
-40 40
-85 85 13 2013 HOTSPOT Burst Strain Error 20 20 70 70 14 2014 General Computer Code Maintenance 0
0 0
0 15 2014 Revised Uncertainty in LBLOCA Monte Carl Simulations 0
0 0
0 15 2016 General Code Maintenance 0
0 0
0 1
2016 Clad Oxidation Calculation 0
0 0
0 1
2016 LOTIC2 Net Free Volume Direction of Conservatism and Ice Melt Condition 0
0 0
0 1
2016 LOTIC2 Calculation of the Thermodynamic Properties of Air 0
0 0
0 1
2016 Increased Safety Injection Time Delay with Offsite Power Available 0
0 0
0 1
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 5 of 7 Year Description Reflood 1 Reflood 2 Note Reference PCT
(°F)
(°F)
(°F)
(°F) 2017 Increase in ECCS pump injection delay time 0
0 0
0 1
Updated (net) licensing basis PCT AOR PCT + PCT 1832 1865 Cumulative sum of PCT changes PCT 430 433 Notes
- 1. The ECCS injection delay time is an input to the LBLOCA analysis that, in part, determines when injection to the reactor coolant system begins from the ECCS pumps. In the LBLOCA analysis, this time delay was increased to 40 seconds when offsite power is available and to 45 seconds when offsite power is not available to account for the additional time it may take for ECCS pump injection to begin when non-condensable gas is present in the ECCS pump discharge pipe. The resulting total delay time in ECCS injection remains small enough that the limiting LBLOCA scenario is not affected.
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 6 of 7
References:
- 1. TVA letter to NRC, 10 CFR 50.46 Day and Annual Report for Watts Bar, Units 1 and 2, dated March 8, 2017 (ML17067A079)
- 2. WCAP-14839, Revision 1, Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Watts Bar Nuclear Plant, September 1998
- 3. 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 (ML003764646)
- 4. 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)
- 5. 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 (ML021070404)
- 6. 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)
- 7. 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 (ML051120164)
- 8. 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)
- 9. TVA letter to NRC, Supplement to 10 CFR 50.46 Day Special Report, dated February 13, 2013 (ML13046A002)
- 10. TVA letter to NRC, 10 CFR 50.46 Day Special Report, dated October 18, 2012 (ML12296A254)
- 11. TVA letter to NRC, 10 CFR 50.46 Day Report for Watts Bar Unit 1, dated March 19, 2013 (ML13080A405)
- 12. TVA letter to NRC, 10 CFR 50.46 Day and Annual Report for 2012, dated April 25, 2013 (ML13120A005)
- 13. TVA letter to NRC, 10 CFR 50.46 - 30 day Report for Watts Bar, Unit 1, dated August 28, 2013 (ML13267A034)
ENCLOSURE TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT UNIT 1 DOCKET NO. 50-390 10 CFR 50.46 Day Report for Watts Bar Nuclear Plant Unit 1 E 7 of 7
- 14. 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. (ML14064A431)
- 15. 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 (ML15098A124)