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Category:Letter
MONTHYEARML23319A2452024-01-29029 January 2024 Issuance of Amendment Nos. 366 and 360; 164 and 71 Regarding the Adoption of TSTF-567, Revision 1, Add Containment Sump TS to Address GSI-191 Issues ML24008A2462024-01-18018 January 2024 Revision to the Reactor Vessel Material Surveillance Capsule Withdrawal Schedule CNL-24-017, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions2024-01-17017 January 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions CNL-24-016, Supplement to Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14)2024-01-10010 January 2024 Supplement to Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14) CNL-23-052, Application to Adopt TSTF-427-A, Revision 2, Allowance for Non-Technical Specification Barrier Degradation on Supported System Operability2024-01-0909 January 2024 Application to Adopt TSTF-427-A, Revision 2, Allowance for Non-Technical Specification Barrier Degradation on Supported System Operability CNL-23-062, Application to Revise the Technical Specifications Section 3.8.2, AC Sources-Shutdown, to Remove Reference to the C-S Diesel Generator (WBN-TS-23-018)2024-01-0808 January 2024 Application to Revise the Technical Specifications Section 3.8.2, AC Sources-Shutdown, to Remove Reference to the C-S Diesel Generator (WBN-TS-23-018) ML23346A1382024-01-0303 January 2024 Regulatory Audit Summary Related to Request to Increase the Number of Tritium Producing Burnable Absorber Rods CNL-23-069, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-21021 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation IR 05000390/20234412023-12-21021 December 2023 Plantfinal Significance Determination for a Security-Related Greater than Green Finding, Nov, and Assessment Follow-up, 05000390-2023441 and 05000391-2023441-Public CNL-23-036, Application to Revise Function 5 of Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant (SQN-TS-23-02 and WBN-TS-23-08)2023-12-18018 December 2023 Application to Revise Function 5 of Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant (SQN-TS-23-02 and WBN-TS-23-08) IR 05000390/20234042023-12-14014 December 2023 Security Baseline Inspection Report 05000390/2023404 and 05000391/2023404 CNL-23-001, Rebaseline of Sections 3.1 and 3.2 of the Technical Specifications (WBN-TS-23-01)2023-12-13013 December 2023 Rebaseline of Sections 3.1 and 3.2 of the Technical Specifications (WBN-TS-23-01) ML23293A0572023-12-0606 December 2023 Issuance of Amendment Nos. 163 and 70 Regarding Adoption of TSTF-501-A, Revision 1, Relocate Stored Fuel Oil and Lube Oil Volume Values to Licensee Control IR 05000390/20230102023-11-30030 November 2023 RE-Issue Watts Bar Nuclear Plant - Biennial Problem Identification and Resolution Inspection Report 050000390/2023010 and 05000391/2023010 and Apparent Violation CNL-23-067, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2023-11-27027 November 2023 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions IR 05000390/20230032023-11-13013 November 2023 Integrated Inspection Report 05000390/2023003 and 05000391/2023003 and Apparent Violation ML23312A1432023-11-0808 November 2023 Submittal of Dual Unit Updated Final Safety Analysis Report (UFSAR) Amendment 5 CNL-23-059, Supplement to Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-2023-09-20020 September 2023 Supplement to Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-03 CNL-23-061, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revision2023-09-20020 September 2023 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revision ML23251A2002023-09-11011 September 2023 Request for Withholding Information from Public Disclosure for Watts Bar Nuclear Plant, Units 1 and 2 CNL-23-057, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions. Includes CECC-EPIP-1, Revision 76 and CECC-EPIP-9, Revision 642023-09-0505 September 2023 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions. Includes CECC-EPIP-1, Revision 76 and CECC-EPIP-9, Revision 64 IR 05000390/20230052023-08-30030 August 2023 Updated Inspection Plan for Watts Bar Nuclear Plant, Units 1 and 2 - Report 05000390/2023005 and 05000391/2023005 ML23233A0042023-08-28028 August 2023 Proposed Alternative to the Requirements of the ASME Boiler and Pressure Vessel Code for Upper Head Injection Dissimilar Metal Butt Welds IR 05000390/20230022023-08-16016 August 2023 Reissue - Watts Bar Nuclear Plant - Integrated Inspection Report 05000390/2023002 and 05000391/2023002 ML23220A1582023-08-0909 August 2023 Integrated Inspection Report 05000390/2023002 and 05000391/2023002 CNL-23-045, License Amendment Request to Revise Technical Specification Table 1.1-1 Regarding the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Bolts (WBN-TS-23-010)2023-08-0707 August 2023 License Amendment Request to Revise Technical Specification Table 1.1-1 Regarding the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Bolts (WBN-TS-23-010) CNL-23-028, Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-03 and WBN-TS-23-06)2023-08-0202 August 2023 Application to Revise Technical Specifications to Adopt TSTF-567-A, Revision 1, Add Containment Sump TS to Address GSI-191 Issues (SQN-TS-23-03 and WBN-TS-23-06) ML23192A4472023-07-31031 July 2023 Staff Assessment of Updated Seismic Hazards at TVA Sites Following the NRC Process for the Ongoing Assessment of Natural Hazards Information CNL-23-055, Tennessee Valley Authority - Emergency Preparedness Department Procedure Revision. Includes EPDP-3, Revision 3, Emergency Plan Exercises and Preparedness Drills2023-07-25025 July 2023 Tennessee Valley Authority - Emergency Preparedness Department Procedure Revision. Includes EPDP-3, Revision 3, Emergency Plan Exercises and Preparedness Drills IR 05000390/20230112023-07-24024 July 2023 Quadrennial Focused Engineering Inspection (FEI) Commercial Grade Dedication Report 05000390 2023011 and 05000391 2023011 CNL-23-053, Tennessee Valley Authority - Radiological Emergency Plan Revisions2023-07-18018 July 2023 Tennessee Valley Authority - Radiological Emergency Plan Revisions CNL-23-020, Application to Revise Technical Specifications to Adopt TSTF-501-A, Revision 1, Relocate Stored Fuel Oil and Lube Oil Volume Values to Licensee Control (WBN-TS-22-06)2023-06-28028 June 2023 Application to Revise Technical Specifications to Adopt TSTF-501-A, Revision 1, Relocate Stored Fuel Oil and Lube Oil Volume Values to Licensee Control (WBN-TS-22-06) CNL-23-049, Tennessee Valley Authority - Radiological Emergency Plan and Central Emergency Control Center Emergency Plan .2023-06-26026 June 2023 Tennessee Valley Authority - Radiological Emergency Plan and Central Emergency Control Center Emergency Plan . ML23122A2322023-06-0707 June 2023 Issuance of Amendment Nos. 162 and 69 Regarding Change to Date in Footnotes for Technical Specification 3.7.11, Control Room Emergency Air Temperature Control System (Creatcs) CNL-23-044, Transmittal of Revision 3 to WCAP-18774-P and WCAP-18774-NP, Addendum to the Rotterdam Dockyard Company Final Stress Report for 173 P.W.R. Vessels TVA III & IV (Report No. 30749-B-030, Rev. 3) - Evaluation of One Closure Stud Out2023-06-0101 June 2023 Transmittal of Revision 3 to WCAP-18774-P and WCAP-18774-NP, Addendum to the Rotterdam Dockyard Company Final Stress Report for 173 P.W.R. Vessels TVA III & IV (Report No. 30749-B-030, Rev. 3) - Evaluation of One Closure Stud Out IR 05000390/20234032023-05-30030 May 2023 Cyber Security Inspection Report 05000390/2023403 and 05000391/2023403 ML23131A1812023-05-23023 May 2023 Correction to Amendment No. 161 to Facility Operating License No. NPF-90 CNL-23-042, Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2023-05-16016 May 2023 Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revisions IR 05000390/20220032023-05-0909 May 2023 Reissue Watts Bar Nuclear Plant - Integrated Inspection Report 05000390/2022003 and 05000391/2022003 ML23125A2202023-05-0505 May 2023 Issuance of Amendment No. 161 Regarding a Change to Footnotes for Technical Specification Table 1.1-1 Modes (Emergency Circumstances) IR 05000390/20230012023-05-0404 May 2023 Integrated Inspection Report 05000390/2023001 and 05000391/2023001 CNL-23-043, Emergency License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1.1-1, Modes (WBN-TS-23-09)2023-05-0404 May 2023 Emergency License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1.1-1, Modes (WBN-TS-23-09) CNL-23-032, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 412023-04-27027 April 2023 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 41 CNL-23-030, Tennessee Valley Authority - Hydrologic Engineering Center River Analysis System Project Milestone Status Update2023-04-27027 April 2023 Tennessee Valley Authority - Hydrologic Engineering Center River Analysis System Project Milestone Status Update CNL-23-033, Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revision2023-04-24024 April 2023 Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revision CNL-23-029, Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2023-04-11011 April 2023 Radiological Emergency Plan and Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML23072A0652023-04-0505 April 2023 Units 1 and 2 Issuance of Amendment Nos. 364 and 358; 160 and 68 Regarding a Revision to Technical Specification 3.4.12 ML23073A2762023-04-0303 April 2023 Individual Notice of Consideration of Issuance of Amendments to Facility Operating Licenses, Proposed No Significant Hazards Consideration Determination, and Opportunity for a Hearing (EPID L-2023-LLA-0029) (Letter) CNL-23-023, Annual Insurance Status Report2023-03-30030 March 2023 Annual Insurance Status Report CNL-23-024, TVA Guarantee of Payment of Deferred Premiums - 2022 Annual Report2023-03-29029 March 2023 TVA Guarantee of Payment of Deferred Premiums - 2022 Annual Report 2024-01-09
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Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 February 13, 2013 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 No. NPF-90 NRC Docket No. 50-390
Subject:
Supplement to 10 CFR 50.46 Day Special Report
Reference:
- 1. TVA Letter to NRC, "10 CFR 50.46 Day Special Report," dated October 18, 2012 [ML12296A254]
- 2. NRC Information Notice 2011-21, "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting from Nuclear Fuel Thermal Conductivity Degradation," dated December 13, 2011 [ML113430785]
The purpose of this letter is to provide a supplement to the 30-day special report submitted on October 18, 2012 (Reference 1) for Watts Bar Nuclear Plant (WBN) Unit 1. This supplement revises the summary of changes and calculated peak cladding temperature (PCT) previously reported for the WBN Unit 1 Emergency Core Cooling System (ECCS) Large Break Loss of Coolant Accident (LBLOCA) evaluation model. This supplement was necessitated based on a letter received from the Westinghouse Electric Company (WEC) on January 17, 2013 informing the Tennessee Valley Authority (TVA) of an error in the 10 CFR 50.46 report provided by WEC to TVA on September 20, 2012. The error involved the inappropriate double crediting of the PCT benefit for the change from WEC Fuel Rod Performance and Design (PAD) computer model Version 3.4 to PAD Version 4.0.
The Reference 1 submittal provided a 30-day special report of the impact of fuel pellet thermal conductivity degradation (TCD) and peaking factor burndown on the calculated PCT for the WBN Unit 1 ECCS evaluation model as required by 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)(3)(ii). United States Nuclear Regulatory Commission (NRC) Information Notice 2011-21 (Reference 2) notified addressees of the potential for this A D phenomenon to cause errors in realistic ECCS evaluation models. Fuel pellet TCD and peaking factor burndown had not been explicitly considered in the WBN Unit 1 ECCS LBLOCA evaluation analysis of record (AOR). As reported in Reference 1, the subsequent review by Printed onrecycled paper
U.S. Nuclear Regulatory Commission Page 2 February 13, 2013 WEC of the impact of the fuel pellet TCD and peaking factor burndown phenomenon resulted in an estimated 60 degree Fahrenheit (OF) reduction in the net licensing basis PCT for the LBLOCA. This change in net LBLOCA PCT included a 75°F beneficial reduction that was attributed to the upgrade to PAD Version 4.0 for the fuel rod design inputs into the WBN Unit 1 LBLOCA evaluation model AOR.
This supplement revises the Reference 1 submittal to delete the references to the 75 0 F reduction in LBLOCA PCT and the associated discussion in response to the discovery by WEC that the PAD 4.0 benefit had already been credited in the 1998 Best Estimate LBLOCA (BE LBLOCA) evaluation AOR. As described in the report provided in Reference 1, the 1998 BE LBLOCA AOR established the baseline PCT of 1892 0 F. The enclosed Revision 1 report provides an updated summary of the changes to the calculated PCT for the limiting ECCS analyses accounting for the deletion of the previously credited 75 0 F reduction in LBLOCA PCT.
Note that the 1998 BE LBLOCA evaluation continues to be the LBLOCA AOR for WBN Unit 1 as indicated in the enclosed Revision 1 report.
Furthermore, as presented in the enclosed Revision 1 report, there is an estimated 75 0 F increase in the net licensing basis PCT for the LBLOCA relative to the previous (Reference 1) report, resulting in an updated (net) licensing basis LBLOCA PCT of 1880 0 F. The updated (net) licensing basis Small Break Loss of Coolant Accident (SBLOCA) PCT remains at 11 32 0 F.
Accordingly, the LBLOCA and SBLOCA evaluation models for WBN Unit 1 continue to demonstrate compliance with the 10 CFR 50.46 requirements since the calculated PCTs for WBN Unit 1 remain below the 2200°F limit.
This issue was discussed with the NRC Project Manager for WBN on January 31, 2013 and it was agreed that this correction submittal would be provided by February 19, 2013.
There are no regulatory commitments in this letter. Please direct questions concerning this report to Clyde Mackaman at (423) 751-2834.
R esp ully, J. . SheaA Vi'e resident, Nuclear Licensing
Enclosure:
10 CFR 50.46 30-Day Report, Revision 1, for Watts Bar Nuclear Plant Unit 1 cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant
ENCLOSURE 10 CFR 50.46 30-DAY REPORT, REVISION 1, FOR WATTS BAR NUCLEAR PLANT, UNIT I The Watts Bar Nuclear Plant (WBN), Unit 1, reactor core currently contains only the Westinghouse Electric Company (WEC) Robust Fuel Assembly (RFA-2TM) fuel design.
Description of Changes or Errors Relative to the Previous 30-Day Report Removal of PAD 4.0 Benefit I
The most recent 10 CFR 50.46 Annual Report for WBN Unit 1 (Reference 1) was submitted to the United States Nuclear Regulatory Commission (NRC) on April 25, 2012. The previous 10 CFR 50.46 Day Special Report for WBN Unit 1 (Reference 2) was submitted to the NRC on October 18, 2012. As indicated in this report, WEC WCAP-14839, Revision 1, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for the Unit 1 Watts Bar Nuclear Plant" (Reference 3), is the current analysis of record (AOR) for the Best Estimate Large Break Loss of Coolant Analysis (BE LBLOCA), with a baseline Peak Cladding Temperature (PCT) of 1892 degrees Fahrenheit (OF). The indicated AOR for the Small Break Loss of Coolant Accident (SBLOCA) is WTV-RSG-06-015, "LOCA & Non-LOCA Analysis Summary for Replacement Steam Generator for WBN Unit 1" (Reference 4), with a baseline PCT of 1132°F.
On January 17, 2013, WEC notified the Tennessee Valley Authority (TVA) of a revision to the Unit 1 Cycle 12 ECCS PCT report. Specifically, WEC notified TVA that during an evaluation of fuel pellet thermal conductivity degradation (TCD) completed for WBN Unit 1, a benefit in ECCS PCT associated with an upgrade to the Westinghouse Improved Performance Analysis and Design (PAD) computer model from Version 3.4 to Version 4.0 had been doubly accounted.
This ECCS PCT benefit had been previously credited in the evaluation for the use of WEC RFA-2 fuel assemblies at WBN Unit 1. As a result, WEC revised the ECCS PCT report to remove the credit. Accordingly, this report revises the PCT value previously reported in the most recent 30-day report for WBN Unit 1 (Reference 1) consistent with WEC's revised ECCS PCT report.
The following Table details the accumulated PCT impact resulting from the changes or errors in the LBLOCA and SBLOCA analyses since each of the respective AORs (References 3 and 4) was established. The composite values are provided for the effects on the LBLOCA analysis because they represent the worst case PCT impact from either the Reflood 1 or the Reflood 2 accident scenario sequence. As indicated in the Table, the change to the LBLOCA limiting composite PCT has decreased by 12°F relative to the BE LBLOCA AOR Baseline PCT. This represents a 75 0 F increase over the most recent estimated net ECCS PCT value (Reference 2).
In accordance with 10 CFR 50.46(a)(3)(i), this change is considered significant for reporting purposes because the absolute magnitudes of the accumulated changes and errors to the calculated PCT since the baseline BE LBLOCA AOR analysis (Reference 3) was performed exceeds 50'F.
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ENCLOSURE 10 CFR 50.46 30-DAY REPORT, REVISION 1, FOR WATTS BAR NUCLEAR PLANT, UNIT I TABLE (Sheet I of 2)
Summary of Changes to WBN Unit I PCT for LBLOCA and SBLOCA Year Description LBLOCA LBLOCA SBLOCA SBLOCA Reference APCT IAPCT! APCT IAPCTI (OF) (OF) (F) (OF) 1998 BE LBLOCA AOR Baseline PCT 1892 3 3--
2006 SBLOCA AOR Baseline PCT --- --- 1132 --- 4 1999 Vessel Channel DX Error -4 4 .... 5 2000 Increased Accumulator Room 4 4 -- - - -- 5 Temperature Evaluation 2000 1.4% Uprate Evaluation 12 12 --- --- 5 2000 Accumulator Line/Pressurizer -131 131 --- --- 5 Surge Line Data Evaluation 2000 MONTECF Decay Heat 4 4 --- --- 6 Uncertainty Error 2001 WBN Specific LBLOCA Vessel 0 0 --- --- 7 Geometry Input Errors 2003 Input Error Resulting in 0 0 -- 8 Incomplete Solution Matrix 2003 Tavg Bias Error 8 8 ...... 8 2004 Increased Stroke Time for ECCS 0 0 --- --- 9 Valves 2004 Revised Blowdown Heatup 5 5 --- --- 9 Uncertainty Distribution 2006 Replacement Steam Generators -10 10 0 0 10 (D3 to 68AXP) 2006 HOTSPOT Fuel Relocation Error 65 65 0 0 10 E-2 of 4
ENCLOSURE 10 CFR 50.46 30-DAY REPORT, REVISION 1, FOR WATTS BAR NUCLEAR PLANT, UNIT I TABLE (Sheet 2 of 2)
Summary of Changes to WBN Unit I PCT for LBLOCA and SBLOCA Year Description LBLOCA LBLOCA SBLOCA SBLOCA Reference APCT IAPCTI APCT IAPCTI (OF) °(F) (OF) (OF) 2012 PMID/ PBOT Violation Evaluation 20 20 0 0 2 2012 TCD and Peaking Factor 15 15 --- 2 Burndown Updated (net) licensing basis PCT 1880 --- 1132 --- ---
AOR PCT + ) APCT Cumulative sum of PCT --- 278 --- 0 changes
- I I APCTI E-3 of 4
ENCLOSURE 10 CFR 50.46 30-DAY REPORT, REVISION 1, FOR WATTS BAR NUCLEAR PLANT, UNIT I REFERENCES
- 1. Letter from TVA to NRC, "10 CFR 50.46 Annual Report for Model Year 2011," dated April 25, 2012 [ML12117A261]
- 2. Letter from TVA to NRC, "10 CFR 50.46 - 30 Day Special Report," dated October 18, 2012 [ML12296A254]
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. WTV-RSG-06-015, "LOCA & Non-LOCA Analysis Summary for Replacement Steam Generator," February 2006
- 5. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - 30 Day Report and Annual Notification and Reporting for 2000," dated October 26, 2000 [ML003764646]
- 6. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - 30 Day Report and Revised Annual Notification Report for 2000," dated September 7, 2001 [ML012570290]
- 7. 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 2001," dated April 3, 2002 [ML021070404]
- 8. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - 30 Day Report and Revised Annual Notification and Reporting for 2003," dated April 19, 2004 [ML041130196]
- 9. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - 30 Day Annual Notification and Reporting for 2004," dated April 19, 2005 [ML051120164]
- 10. Letter from TVA to NRC, "Watts Bar Nuclear Plant (WBN) Unit 1 - Emergency Core Cooling System (ECCS) Evaluation Model Changes - 30 Day Report and Annual Notification and Reporting for 2006," dated July 3, 2007 [ML071860388]
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