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Category:Meeting Agenda
MONTHYEARPMNS20250070, Meeting with Tennessee Valley Authority to Discuss Changes to Organization and Impacts on the Nuclear Quality Assurance Program Under Review2025-01-27027 January 2025 Meeting with Tennessee Valley Authority to Discuss Changes to Organization and Impacts on the Nuclear Quality Assurance Program Under Review PMNS20241519, Meeting with Tennessee Valley Authority to Discuss a Potential Second Round Request for Additional Information for a License Amendment Request Under Review2025-01-14014 January 2025 Meeting with Tennessee Valley Authority to Discuss a Potential Second Round Request for Additional Information for a License Amendment Request Under Review PMNS20241514, Meeting with the Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, License Amendment Request to Revise Technical Specification Surveillance Requirements 3.6.12.2 and 3.6.12.3 Related to Ice Mass2024-12-19019 December 2024 Meeting with the Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, License Amendment Request to Revise Technical Specification Surveillance Requirements 3.6.12.2 and 3.6.12.3 Related to Ice Mass PMNS20241350, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Fitness for Duty Exemption2024-11-19019 November 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Fitness for Duty Exemption PMNS20241312, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specification 3.4.14 Related to Reactor Coolant System Pressure Isolation Valve Leakage2024-11-0606 November 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specification 3.4.14 Related to Reactor Coolant System Pressure Isolation Valve Leakage PMNS20241229, Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 22024-10-0303 October 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2 PMNS20241083, Pre-submittal Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Alternative Related to Main Steam Safety Valve Surveillance Requirement 3.7.1.12024-08-27027 August 2024 Pre-submittal Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Alternative Related to Main Steam Safety Valve Surveillance Requirement 3.7.1.1 PMNS20241102, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specs 3.3.6 and 3.9.4 Related to Containment Isolation/Penetrations and the Fuel Handling a2024-08-21021 August 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specs 3.3.6 and 3.9.4 Related to Containment Isolation/Penetrations and the Fuel Handling a ML24228A2312024-08-15015 August 2024 TVA Meeting Slides for August 19 Public Meeting Re QAPD Supplement ML24225A2542024-08-14014 August 2024 August 14, 2024 - TVA Pre-Sub Meeting Presentation - Sequoyah, Units 1 and 2; Watts Bar, Units 1 and 2 - License Amendment Request to Revise TS 3.5.2 ECCS - Operating PMNS20240978, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant and Watts Bar Nuclear Plant License Amendment Request to Revise Technical Specs 3.5.2, Note 1 Related to the Residual Heat Removal System2024-08-13013 August 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant and Watts Bar Nuclear Plant License Amendment Request to Revise Technical Specs 3.5.2, Note 1 Related to the Residual Heat Removal System PMNS20241006, Pre-submittal Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Alternative Related to Inservice Testing of Thermal Relief Valves2024-08-0606 August 2024 Pre-submittal Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Unit 2, Alternative Related to Inservice Testing of Thermal Relief Valves PMNS20241000, Meeting with Tennessee Valley Authority to Discuss Proposed Changes to the Nuclear Quality Assurance Program2024-08-0606 August 2024 Meeting with Tennessee Valley Authority to Discuss Proposed Changes to the Nuclear Quality Assurance Program ML24191A0642024-07-16016 July 2024 TVA Pre-Submittal Conference Presentation for Proposed LAR Regarding a Revision to Sequoyah Fuel Handling Accident Analysis, Deletion of TS 3.9.4 and Modification of TS 3.3.6 - July 16, 2024 PMNS20240795, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specs 3.3.6 and 3.9.4 Related to Containment Isolation/Penetrations and the Fuel Handling Accident Analys2024-06-26026 June 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant License Amendment Request to Revise Technical Specs 3.3.6 and 3.9.4 Related to Containment Isolation/Penetrations and the Fuel Handling Accident Analysis PMNS20240831, Meeting with Tennessee Valley Authority to Discuss Proposed Changes to the Nuclear Quality Assurance Program2024-06-24024 June 2024 Meeting with Tennessee Valley Authority to Discuss Proposed Changes to the Nuclear Quality Assurance Program ML24117A0352024-05-0202 May 2024 TVA Sequoyah Nuclear Plant - 1B Emergency Diesel Generator Regulatory Conference May 02, 2024 -Presentation Slides PMNS20240551, Regulatory Conference with Tennessee Valley Authority (TVA) - Sequoyah Nuclear Plant2024-04-17017 April 2024 Regulatory Conference with Tennessee Valley Authority (TVA) - Sequoyah Nuclear Plant PMNS20240298, Meeting with Tennessee Valley Authority to Discuss the Meteorological Aspects of a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Revise the Fuel Handling Accident Analysis and Outage Related Fuel Decay Tim2024-03-13013 March 2024 Meeting with Tennessee Valley Authority to Discuss the Meteorological Aspects of a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Revise the Fuel Handling Accident Analysis and Outage Related Fuel Decay Time PMNS20240350, Annual Assessment Virtual Public Meeting2024-03-11011 March 2024 Annual Assessment Virtual Public Meeting PMNS20240344, Annual Assessment Public Poster Session and Open House Meeting2024-03-0707 March 2024 Annual Assessment Public Poster Session and Open House Meeting PMNS20240113, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Revise the Fuel Handling Accident Analysis and Outage Related Fuel Decay Time2024-02-21021 February 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Revise the Fuel Handling Accident Analysis and Outage Related Fuel Decay Time PMNS20240067, Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Delete Surveillance Requirement 3.8.1.8 from the Technical Specifications2024-02-0606 February 2024 Meeting with Tennessee Valley Authority to Discuss a Proposed Sequoyah Nuclear Plant, Units 1 and 2, License Amendment Request to Delete Surveillance Requirement 3.8.1.8 from the Technical Specifications ML23345A1662023-12-13013 December 2023 Tennessee Valley Authority - Pre-submittal Meeting for Conversion of Nuclear Quality Assurance Plan from ANSI N45.2-1971 to ASME NQA-1-2015 (EPID L-2023-LRM-0103) - Slides PMNS20231329, Meeting with Tennessee Valley Authority to Discuss Proposed License Amendment Request for the Browns Ferry, Sequoyah, and Watts Bar Nuclear Plants2023-11-28028 November 2023 Meeting with Tennessee Valley Authority to Discuss Proposed License Amendment Request for the Browns Ferry, Sequoyah, and Watts Bar Nuclear Plants ML23291A1562023-10-18018 October 2023 NRC Pre-Submittal Meeting Watts Bar & Sequoyah LAR, TVA Presentation Slides PMNS20231126, Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 22023-10-18018 October 2023 Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah Nuclear Plant, Units 1 and 2, and Watts Bar Nuclear Plant, Units 1 and 2 PMNS20230712, Meeting with Tennessee Valley Authority to Discuss Proposed License Amendment Request for the Browns Ferry, Sequoyah, and Watts Bar Nuclear Plants2023-06-12012 June 2023 Meeting with Tennessee Valley Authority to Discuss Proposed License Amendment Request for the Browns Ferry, Sequoyah, and Watts Bar Nuclear Plants PMNS20230549, Annual Assessment Virtual Meeting for the 2022 Assessment Period2023-04-25025 April 2023 Annual Assessment Virtual Meeting for the 2022 Assessment Period PMNS20230446, Annual Assessment Public Poster Session and Openhouse Meeting2023-04-17017 April 2023 Annual Assessment Public Poster Session and Openhouse Meeting ML22201A0292022-07-20020 July 2022 Pre-Submittal Teleconference Meeting with the Tennessee Valley Authority to Discuss Planned Alternative Request for Sequoyah Nuclear Plant, Unit 1 PMNS20220531, Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah and Watts Bar Nuclear Plants2022-05-19019 May 2022 Meeting with Tennessee Valley Authority to Discuss a Proposed License Amendment Request for Sequoyah and Watts Bar Nuclear Plants PMNS20220314, Meeting with Tennessee Valley Authority to Discuss a Proposed Alternative Request for Sequoyah and Watts Bar Nuclear Plants2022-03-31031 March 2022 Meeting with Tennessee Valley Authority to Discuss a Proposed Alternative Request for Sequoyah and Watts Bar Nuclear Plants PMNS20220285, Annual Assessment Meeting2022-03-29029 March 2022 Annual Assessment Meeting PMNS20220079, Public Meeting with the Tennessee Valley Authority (TVA)2022-02-0404 February 2022 Public Meeting with the Tennessee Valley Authority (TVA) PMNS20211347, Notice of Meeting with the Tennessee Valley Authority (TVA) Regarding a Potential Future Sequoyah Nuclear Plant, Units 1 and 2 License Amendment Request for Modifications to the Approved 10 CFR 50.69 Categorization Process2021-10-27027 October 2021 Notice of Meeting with the Tennessee Valley Authority (TVA) Regarding a Potential Future Sequoyah Nuclear Plant, Units 1 and 2 License Amendment Request for Modifications to the Approved 10 CFR 50.69 Categorization Process ML21281A2282021-10-13013 October 2021 Tennessee Valley Authority Fleet Pre-Submittal Meeting for License Amendment Request to Change Emergency Action Level Scheme Presentation - October 13, 2021 (EPID L-2021-LRM-0096) (Slides) PMNS20211308, Notice of Meeting with the Tennessee Valley Authority (TVA) Regarding a Potential Future Sequoyah Nuclear Plant Unit 2 Alternative Method for the Repair of a through-wall Defect in a Reactor Coolant Pump2021-10-0606 October 2021 Notice of Meeting with the Tennessee Valley Authority (TVA) Regarding a Potential Future Sequoyah Nuclear Plant Unit 2 Alternative Method for the Repair of a through-wall Defect in a Reactor Coolant Pump PMNS20211154, Meeting with Tennessee Valley Authority Regarding a Proposed Fleet Amendment Request2021-09-21021 September 2021 Meeting with Tennessee Valley Authority Regarding a Proposed Fleet Amendment Request PMNS20211085, Notice of Meeting with the Tennessee Valley Authority (TVA) - pre-application Meeting Regarding a Future Sequoyah Nuclear Plant License Amendment Request Regarding Elimination of the High Negative Flux Rate Trip2021-09-0303 September 2021 Notice of Meeting with the Tennessee Valley Authority (TVA) - pre-application Meeting Regarding a Future Sequoyah Nuclear Plant License Amendment Request Regarding Elimination of the High Negative Flux Rate Trip PMNS20210950, Notice of Meeting with TVA - pre-application Meeting Regarding a Sequoyah Nuclear Plant, Unit No. 2 Potential N-729-6 Relief Request2021-07-21021 July 2021 Notice of Meeting with TVA - pre-application Meeting Regarding a Sequoyah Nuclear Plant, Unit No. 2 Potential N-729-6 Relief Request PMNS20210702, Closed Meeting with Representatives from the Tennessee Valley Authority to Discuss a Planned Request for Exemption2021-05-25025 May 2021 Closed Meeting with Representatives from the Tennessee Valley Authority to Discuss a Planned Request for Exemption PMNS20210392, Annual Assessment Meeting2021-04-12012 April 2021 Annual Assessment Meeting ML21098A0422021-04-0808 April 2021 Teleconference Call to Discuss a Planned License Amendment Request for Sequoyah Nuclear Plant, Units 1 and 2 ML21055A5502021-02-24024 February 2021 Teleconference with the Tennessee Valley Authority to Discuss a Planned Request Regarding the Use of American Society of Mechanical Engineers Code Case N-504-4 at Sequoyah Nuclear Plant, Units 1 and 2 PMNS20201157, Meeting with Tennessee Valley Authority to Discuss Response to Requests for Additional Information Regarding Request to Revise Updated Final Safety Analysis Report Hydrologic Analysis for Sequoyah Nuclear Plant, Units 1 and 22020-09-29029 September 2020 Meeting with Tennessee Valley Authority to Discuss Response to Requests for Additional Information Regarding Request to Revise Updated Final Safety Analysis Report Hydrologic Analysis for Sequoyah Nuclear Plant, Units 1 and 2 ML20203M0572020-07-16016 July 2020 Updated TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20196L7922020-07-16016 July 2020 Corrected TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20196L6892020-07-16016 July 2020 TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20167A1202020-06-30030 June 2020 Public Meeting Notice - Notice of Predecisional Enforcement Conference (Pec) Between U.S. Nuclear Regulatory Commission (NRC) and Tennessee Valley Authority (TVA) (EA-20-006, EA-20-007) 2025-01-27
[Table view] Category:Meeting Briefing Package/Handouts
MONTHYEARML25010A2522025-01-14014 January 2025 January 14, 2025, Pre-Submittal Meeting Presentation License Amendment Request to Extend Ice Mass Surveillance Requirements 3.6.12.2 and 3.6.12.3 on a One-Time Basis ML24320A1062024-11-20020 November 2024 Pre-Submittal Meeting Presentation, November 20, 2024, Pmns 20241350 ML24284A0042024-10-16016 October 2024 Application to Use Online Monitoring Methodology for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant Session Slides ML24228A2312024-08-15015 August 2024 TVA Meeting Slides for August 19 Public Meeting Re QAPD Supplement ML24225A2542024-08-14014 August 2024 August 14, 2024 - TVA Pre-Sub Meeting Presentation - Sequoyah, Units 1 and 2; Watts Bar, Units 1 and 2 - License Amendment Request to Revise TS 3.5.2 ECCS - Operating ML24191A0642024-07-16016 July 2024 TVA Pre-Submittal Conference Presentation for Proposed LAR Regarding a Revision to Sequoyah Fuel Handling Accident Analysis, Deletion of TS 3.9.4 and Modification of TS 3.3.6 - July 16, 2024 ML24117A0352024-05-0202 May 2024 TVA Sequoyah Nuclear Plant - 1B Emergency Diesel Generator Regulatory Conference May 02, 2024 -Presentation Slides ML24067A2832024-03-27027 March 2024 2023 Browns Ferry, Sequoyah and Watts Bar Annual Assessment Public Meeting Presentation Slides ML24082A2532024-03-26026 March 2024 Summary of March 18, 2024, Public Preapplication Meeting with Tennessee Valley Authority Regarding a Future License Amendment Request Related to Fuel Handling and Fuel Decay Time ML24037A0252024-02-0808 February 2024 Pre-Submittal Presentation - 02/08/2024 - Proposed License Amendment Request Change to the Sequoyah Nuclear Plant Technical Specifications 3.8.1 and 3.8.2 ML23345A1662023-12-13013 December 2023 Tennessee Valley Authority - Pre-submittal Meeting for Conversion of Nuclear Quality Assurance Plan from ANSI N45.2-1971 to ASME NQA-1-2015 (EPID L-2023-LRM-0103) - Slides ML23291A1562023-10-18018 October 2023 NRC Pre-Submittal Meeting Watts Bar & Sequoyah LAR, TVA Presentation Slides ML23128A2882023-05-0808 May 2023 TVA Nuclear Plants -2022 EOC Media Slides ML22157A4132022-06-0606 June 2022 Plants - Pre-Submittal Teleconference for Proposed Amendment Request Regarding the Change for the Sequoyah and Watts Bar Nuclear Plants Technical Specification 3.4.12 Meeting Slides ML22080A1662022-03-21021 March 2022 TVA Nuclear Plants -2021 EOC Media Loop Slides for Automatic Play ML21308A4932021-11-0808 November 2021 Pre-submittal Meeting Presentation - License Amendment Request to Revise Sequoyah Operating License to Use Fire and Seismic PRA Models for 10 CFR 50.69 Risk-Informed Categorizations (EPID L-2021-LRM-0109) (Slides) ML21281A2282021-10-13013 October 2021 Tennessee Valley Authority Fleet Pre-Submittal Meeting for License Amendment Request to Change Emergency Action Level Scheme Presentation - October 13, 2021 (EPID L-2021-LRM-0096) (Slides) ML21252A3632021-09-15015 September 2021 Pre-Submittal Meeting for License Amendment Request to Eliminate the High Negative Flux Rate Trip ML21061A0892021-03-0202 March 2021 TVA Presentation Slides for March 2, 2021, Public Meeting to Discuss Sequoyah Alternative Request ML20196L6892020-07-16016 July 2020 TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20196L7922020-07-16016 July 2020 Corrected TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20203M0572020-07-16016 July 2020 Updated TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20175A0552020-06-23023 June 2020 TVA Slides for June 23, 2020, Emergency Plan Change Presubmittal Meeting ML20163A6952020-06-12012 June 2020 Bpg Presentation on TVA SCWE Final 2 ML20108E9082020-04-16016 April 2020 Presentation Slides for Sequoyah Nuclear Plant, Unit 2 - Exigent License Amendment Request TS 4.2.2, Control Rod Assemblies, Pre-Submittal Conference Call - April 16, 2020 ML20050C8662020-02-20020 February 2020 February 20, 2020 - Pre-Submittal Meeting Presentation - Permanent Operation with Control Rod H8 Removed ML20049G1822020-02-18018 February 2020 February 20, 2020 - Pre-submittal Meeting Presentation - Transition to Westinghouse Fuel ML20024D2112020-01-27027 January 2020 Pre-Submittal Meeting for License Amendment Request (LAR) Revised Steam Generator (SG) Inspection Intervals - January 27, 2020 ML19325C7142019-12-0202 December 2019 November 15,2019, Summary of Conference Call with Tennessee Valley Authority to Discuss Submittal of Exigent License Request (EPID L-2019-LLA-0239) for Sequoyah Nuclear Plant, Unit 1 ML19323D8882019-11-15015 November 2019 TVA Pre-submittal Presentation Slides - Exigent Amendment ML19161A2392019-06-10010 June 2019 Plants Pre-Submittal Meeting for Proposed License Amendments Hydrological Analysis Updates June 10, 2019 ML19142A2772019-05-21021 May 2019 Summary of Public Meeting - Sequoyah Nuclear Plant ML18312A3502018-11-14014 November 2018 Meeting to Discuss Proposed Technical Specification Changes Needed of Associated with the Use of Westinghouse Robust Fuel Assemblies at Sequoyah Nuclear Plant Units 1 & 2 - November 14, 2018 ML18164A3092018-06-13013 June 2018 June 6, 2018 Summary of Public Meeting - Sequoyah Nuclear Plant - Docket Nos. 50-327 and 50-328 ML18043B0592018-02-13013 February 2018 Pre-Submittal Meeting with NRC Regarding UFSAR Change to Clarify Separation Requirements for ERCW Electrical Load Groups - February 13, 2018 ML17342A3932017-12-0808 December 2017 Enclosure 3, Reactor Oversight Process Task Force FAQ Log of November 16, 2017 Working Group Meeting ML17342A3392017-12-0808 December 2017 Summary of Reactor Oversight Process (ROP) Working Group Meeting with Nuclear Energy Institutes ROP Task Force and Other Industry Representatives NEI 09-07, Enclosure 2, Handouts and Presentations Discussed During the November 16, 2017 ROP Working Group Public Meeting2017-12-0808 December 2017 Enclosure 2, Handouts and Presentations Discussed During the November 16, 2017 ROP Working Group Public Meeting ML17342A3642017-12-0808 December 2017 Enclosure 2, Handouts and Presentations Discussed During the November 16, 2017 ROP Working Group Public Meeting ML17271A0162017-09-28028 September 2017 Meeting Slide for Tennessee Valley Authority (TVA) Hydrology Precipitation Model Topical Report Review Status ML17212A8432017-08-0101 August 2017 Meeting Slides for Pre-submittal Meeting with Tennessee Valley Authority on Unbalanced Voltage License Amendment Request for TVA Nuclear Plants ML17053A0232017-02-22022 February 2017 Slides for Meeting with Tennessee Valley Authority to Discuss HEC-RAS Flood Model Project: Seismic Dam Failure Methodology ML16102A3302016-04-0404 April 2016 Presentation Slides for 04042016 Public Meeting on Resolution of TVA Flood Model Issue ML13108A1352015-04-0808 April 2015 Enclosure 2 - Sequoyah Scoping Public Meeting Handouts ML14259A1662014-09-17017 September 2014 Meeting Slides for the September 17, 2014 Public Meeting to Discuss the Dseis for License Renewal of Sequoyah Units 1 and 2 ML14262A3302014-09-16016 September 2014 9/16/2014 Meeting Slide for Sequoyah Nuclear Plant, Units 1 and 2 Regarding AST Presentation ML14191A0462014-07-10010 July 2014 7/10/2014, Meeting Slide for Sequoyah Nuclear Plant 5th Quarterly Update for the Flood Mitigation System ML14191A0442014-07-10010 July 2014 7/10/2014, Meeting Slide for Tennessee Valley Authority Browns Ferry, Sequoyah, Watts Bar, Near-Term Task Force Recommendation 2.1 Flooding Hazard Reevaluation Report Status Update ML14178B3362014-06-25025 June 2014 6/25/2014, Meeting Slide for Sequoyah Nuclear Plant, Units 1 and 2 Electrical Tech Specs ML14107A3352014-04-16016 April 2014 Summary of Meeting with Tennessee Valley Authority to Discuss NRCs Reactor Oversight Process (ROP) and NRCs Annual Assessment of Plant Safety Performance for Period of January 1, 2013, to December 31, 2013 for Sequoyah Bar Nuclear Plant 2025-01-14
[Table view] Category:Slides and Viewgraphs
MONTHYEARML25010A2522025-01-14014 January 2025 January 14, 2025, Pre-Submittal Meeting Presentation License Amendment Request to Extend Ice Mass Surveillance Requirements 3.6.12.2 and 3.6.12.3 on a One-Time Basis ML24320A1062024-11-20020 November 2024 Pre-Submittal Meeting Presentation, November 20, 2024, Pmns 20241350 ML24311A0332024-11-0707 November 2024 TVA Pre-Submittal Meeting Presentation on License Amendment Request to Revise SR 3.4.14.1 Reactor Coolant System Pressure Isolation Valves Leakage Testing Frequency on November 7, 2024 ML24284A0042024-10-16016 October 2024 Application to Use Online Monitoring Methodology for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant Session Slides ML24228A2312024-08-15015 August 2024 TVA Meeting Slides for August 19 Public Meeting Re QAPD Supplement ML24225A2542024-08-14014 August 2024 August 14, 2024 - TVA Pre-Sub Meeting Presentation - Sequoyah, Units 1 and 2; Watts Bar, Units 1 and 2 - License Amendment Request to Revise TS 3.5.2 ECCS - Operating ML24191A0642024-07-16016 July 2024 TVA Pre-Submittal Conference Presentation for Proposed LAR Regarding a Revision to Sequoyah Fuel Handling Accident Analysis, Deletion of TS 3.9.4 and Modification of TS 3.3.6 - July 16, 2024 ML24184B9162024-07-10010 July 2024 U.S. NRC Meeting Slides for Meeting with Tennessee Valley Authority Regarding NRC Questions Regarding Scope of Nuclear Quality Assurance Program ML24117A0352024-05-0202 May 2024 TVA Sequoyah Nuclear Plant - 1B Emergency Diesel Generator Regulatory Conference May 02, 2024 -Presentation Slides ML24067A2832024-03-27027 March 2024 2023 Browns Ferry, Sequoyah and Watts Bar Annual Assessment Public Meeting Presentation Slides ML24051A2042024-02-20020 February 2024 Tennessee Valley Authority Pre-Sub Meeting Presentation 2-22-2024 Pmns 20240113 ML24037A0252024-02-0808 February 2024 Pre-Submittal Presentation - 02/08/2024 - Proposed License Amendment Request Change to the Sequoyah Nuclear Plant Technical Specifications 3.8.1 and 3.8.2 ML23345A1662023-12-13013 December 2023 Tennessee Valley Authority - Pre-submittal Meeting for Conversion of Nuclear Quality Assurance Plan from ANSI N45.2-1971 to ASME NQA-1-2015 (EPID L-2023-LRM-0103) - Slides ML23291A1562023-10-18018 October 2023 NRC Pre-Submittal Meeting Watts Bar & Sequoyah LAR, TVA Presentation Slides ML23128A2882023-05-0808 May 2023 TVA Nuclear Plants -2022 EOC Media Slides ML22201A1262022-07-20020 July 2022 July 20, 2022 - Pre-submittal Meeting for Inservice Testing (IST) Program Request for Alternative for the Centrifugal Charging Pump 1B-B Testing Per ISTB-3310 (RP-12) ML22157A4132022-06-0606 June 2022 Plants - Pre-Submittal Teleconference for Proposed Amendment Request Regarding the Change for the Sequoyah and Watts Bar Nuclear Plants Technical Specification 3.4.12 Meeting Slides ML22103A0852022-04-14014 April 2022 And Watts Bar Plant Pre-submittal Meeting for Inservice Testing (IST) Program Request for Alternative for the Motor Driven Auxiliary Feedwater Pump Testing Following Maintenance During an Outage Per ISTB-3310 ML22080A1662022-03-21021 March 2022 TVA Nuclear Plants -2021 EOC Media Loop Slides for Automatic Play ML22046A2932022-02-15015 February 2022 Pre-submittal Meeting Presentation - Request for Alternative to ASME OM Code ISTC-3630 Regarding Leakage of Pressure Isolation Valves ML21308A4932021-11-0808 November 2021 Pre-submittal Meeting Presentation - License Amendment Request to Revise Sequoyah Operating License to Use Fire and Seismic PRA Models for 10 CFR 50.69 Risk-Informed Categorizations (EPID L-2021-LRM-0109) (Slides) ML21281A2282021-10-13013 October 2021 Tennessee Valley Authority Fleet Pre-Submittal Meeting for License Amendment Request to Change Emergency Action Level Scheme Presentation - October 13, 2021 (EPID L-2021-LRM-0096) (Slides) ML21252A3632021-09-15015 September 2021 Pre-Submittal Meeting for License Amendment Request to Eliminate the High Negative Flux Rate Trip ML21197A0022021-08-0505 August 2021 N-769-6 Relief Pre-Submittal TVA Presentation August 2021 ML21111A0202021-04-21021 April 2021 TVA Slides for April 21, 2021 Public Meeting to Discuss Planned Sequoyah Amendment Request ML21096A1002021-04-0606 April 2021 Annual Assessments ML21061A0892021-03-0202 March 2021 TVA Presentation Slides for March 2, 2021, Public Meeting to Discuss Sequoyah Alternative Request ML20196L6892020-07-16016 July 2020 TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20203M0572020-07-16016 July 2020 Updated TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20196L7922020-07-16016 July 2020 Corrected TVA Non-Proprietary Slides for Open Session of July 16, 2020, Partially Closed Public Meeting to Discuss Sequoyah License Amendment Request ML20175A0552020-06-23023 June 2020 TVA Slides for June 23, 2020, Emergency Plan Change Presubmittal Meeting ML20163A6952020-06-12012 June 2020 Bpg Presentation on TVA SCWE Final 2 ML20112F5302020-04-21021 April 2020 TVA Nuclear Plants -2019 EOC Media Loop Slides for Automatic Play (Final) ML20108E9082020-04-16016 April 2020 Presentation Slides for Sequoyah Nuclear Plant, Unit 2 - Exigent License Amendment Request TS 4.2.2, Control Rod Assemblies, Pre-Submittal Conference Call - April 16, 2020 ML20050C8662020-02-20020 February 2020 February 20, 2020 - Pre-Submittal Meeting Presentation - Permanent Operation with Control Rod H8 Removed ML20049G1822020-02-18018 February 2020 February 20, 2020 - Pre-submittal Meeting Presentation - Transition to Westinghouse Fuel ML20024D2112020-01-27027 January 2020 Pre-Submittal Meeting for License Amendment Request (LAR) Revised Steam Generator (SG) Inspection Intervals - January 27, 2020 ML19325C7142019-12-0202 December 2019 November 15,2019, Summary of Conference Call with Tennessee Valley Authority to Discuss Submittal of Exigent License Request (EPID L-2019-LLA-0239) for Sequoyah Nuclear Plant, Unit 1 ML19323D8882019-11-15015 November 2019 TVA Pre-submittal Presentation Slides - Exigent Amendment ML19161A2392019-06-10010 June 2019 Plants Pre-Submittal Meeting for Proposed License Amendments Hydrological Analysis Updates June 10, 2019 ML19164A2032019-05-30030 May 2019 OEDO-19-00288-TVA Sequoyah Leadership Forum Power Point ML19142A2772019-05-21021 May 2019 Summary of Public Meeting - Sequoyah Nuclear Plant ML18312A3502018-11-14014 November 2018 Meeting to Discuss Proposed Technical Specification Changes Needed of Associated with the Use of Westinghouse Robust Fuel Assemblies at Sequoyah Nuclear Plant Units 1 & 2 - November 14, 2018 ML18164A3092018-06-13013 June 2018 June 6, 2018 Summary of Public Meeting - Sequoyah Nuclear Plant - Docket Nos. 50-327 and 50-328 ML17347A1282017-12-14014 December 2017 Meeting Slide for Pre-Submittal Meeting with NRC Regarding License Amendment Request to Implement the Requirements of 10 CFR 50.69 for Sequoyah Nuclear Plant, Units 1 and 2 ML17271A0162017-09-28028 September 2017 Meeting Slide for Tennessee Valley Authority (TVA) Hydrology Precipitation Model Topical Report Review Status ML17212A8432017-08-0101 August 2017 Meeting Slides for Pre-submittal Meeting with Tennessee Valley Authority on Unbalanced Voltage License Amendment Request for TVA Nuclear Plants ML17053A0232017-02-22022 February 2017 Slides for Meeting with Tennessee Valley Authority to Discuss HEC-RAS Flood Model Project: Seismic Dam Failure Methodology ML16102A3302016-04-0404 April 2016 Presentation Slides for 04042016 Public Meeting on Resolution of TVA Flood Model Issue ML13108A1352015-04-0808 April 2015 Enclosure 2 - Sequoyah Scoping Public Meeting Handouts 2025-01-14
[Table view] |
Text
Sequoyah Nuclear Plant May 02, 2024 1B Emergency Diesel Generator Regulatory Conference
TVA Introductions and Meeting Agenda - Tom Marshall 2
- Purpose Tom Marshall, Site Vice President
- Background Information James Hodge, Director of Engineering
- Event and Immediate Actions Timeline John Tuite, Director of Maintenance
- Timeline Continued Beth Jenkins, Plant Manager
- Causal Product Results Brad Basham, Root Cause Lead
- Root Cause Review and Considerations Gary Thompson, Diesel Technical Expert, MPR
- Compliance Summary for Performance Deficiency Rick Medina, Site Licensing Manager
- Probabilistic Risk Evaluation Frank Hope, J-H Risk-Informed Engineering Mgr
- Closing Matt Rasmussen, TVA Senior Vice President
Purpose - Tom Marshall 3
Provide an overview of the event, timeline associated with the event, corrective actions, the root cause analysis and the safety significance of the event.
Provide Sequoyahs conclusion based on material analysis findings along with third party technical input.
Provide a detailed summary of the risk factors and inputs for the significance determination of the identified performance deficiency.
Background Information - James Hodge 4
- Valve lash is controlled through a combination of:
- Rocker Arm Adjusting Screw
- The hydraulic lash adjusters are incorporated into the tip of the valve bridge assembly that spans across two exhaust valves that interacts with a single rocker arm.
Background Information 5
- Fig. 2 Local lash - Is concentrated on either the inboard or outboard exhaust valves and the respective hydraulic lash adjuster.
- Fig. 1 Global lash - Involves both inboard and outboard exhaust valves, their respective hydraulic lash adjuster assemblies, and is ultimately impacting the whole valve bridge assembly.
Background Information 6
Exhaust valve bridge translates the action of a single rocker arm to a pair of exhaust valves.
Valve bridge spring seat rest in a corresponding semi-spherical seat in the cylinder head.
Each valve bridge contains two hydraulic lash adjuster assemblies.
During engine operation the hydraulic lash adjusters receive oil through oil gallies in the bridge assembly.
Event and Immediate Actions Timeline - John Tuite 7
1B diesel generator 24-hour run starts and after 4 hr. and 24 min run, diesel generator was emergency stopped 09/19/23 09/20/23 1B diesel generator investigation finds failed piston in cylinder #14 1B diesel generator restored with 32 new cylinder power pack assemblies 09/27/23 10/19/23 Successfully completed 12-year PM engine overhauls including power pack replacement on 1A, 2A, and 2B diesels SEP OCT NOV Equipment Apparent Cause Evaluation was completed to conclude an exhaust valve spring retainer failed resulting in damage to the engine 1B2 #14 powerpack.
No failure mode nor firm evidence have been attributed to maintenance activities related to 4-year PM. The vendor analysis of the damaged component was requested to identify causal factors.
11/02/23 11/06/23 Sequoyah confirmed receipt of failed material sent to ESI for a failure analysis report
Timeline Continued - Beth Jenkins 8
Sequoyah Initiated a Level 1 Root Cause Evaluation 01/02/24 12/22/23 Engineering Systems Inc.
(ESI) completed their failure analysis which concluded a loose rocker arm adjusting screw locknut.
Sequoyah Received the failed material back from ESI and sent to TVA Central Labs and Services for metallurgic analysis 12/21/23 01/08/24 Jensen Hughes begins Probabilistic Risk Analysis DEC JAN FEB MPR Engineers visit Central Labs and Services to inspect components 01/31/24 02/15/24 Sequoyah completed and provided an evaluation of risk impact for the DG failure NRC assessed the significance of the finding using the best information available at the time of the SERP 02/21/24 02/28/24 Sequoyah completes and provides Level 1 Root Cause Assessment
Root Cause Analysis Team Charter - Brad Basham 9
Root Cause Team Composition
- Team Leader - Root Cause SME
- Analyst - Corporate Root Cause analyst / SME
- Two Experienced Diesel Generator Engineers
- Experienced Licensing Engineer
- Mechanical Maintenance Supervisor
- Consultant from MPR, Gary Thompson Approach
- Validate the as found conditions
- Reviewed the previous level 2 evaluation
- Examine the ESI failure analysis
- Perform review of maintenance work practices, maintenance work history and training
- Document all potential equipment failure modes and build failure sequencing
- Conduct extensive OE search
- Then cross examine using metallurgical examination
Root Cause Investigation - Brad Basham 10 Maintenance Video Walk-through SQN Diesel Generator Maintenance Demo
Root Cause Investigation - Brad Basham 11 Failure Scenarios examined as correlated to similar industry Operating Experience:
Exhaust valve spring retaining ring failure ANO cracked retaining rings Turkey Point cracked retaining rings Rocker arm set screw loose locknut Davis Besse loose locknut Hydraulic lash adjuster failure Turkey Point lash adjuster failure We specifically mapped the loose locknut failure scenario using Industry precedent root cause findings based on the similarity of the ESI conclusion.
12 Davis Besse OE #219503 vs Sequoyah Fig. 3 Davis Besse Damaged Fig. 4 Sequoyah Event Bridge Stem Spherical Brass Seat (No Damage to Bridge Stem Spherical Brass Seat)
- Based on comparison to the Davis Besse OE, the Sequoyah initiating event did not cause excessive global lash.
Event Comparison Davis Besse Event:
Tapping noise was heard Damage to bridge stem brass seat Dislodging of the bridge stem Damaged cylinder head socket Sequoyah Event:
No noise heard in multiple opportunities No Bridge Stem brass seat damage Bridge stem not dislodged No damage to cylinder head socket
Davis Besse OE #219503 vs Sequoyah Figure 5 Davis Besse Damaged Bridge Stem Cylinder Head Socket with Brass Shavings from Bridge Stem Seat Figure 6 Sequoyah Bridge Stem Cylinder Head Socket (No Elongation Damage)
14 Central Labs Metallurgic Analysis
- Metallurgic analysis found a pre-existing fatigue crack on the plunger spring.
- The exhaust valve spring seats had a highly undesirable microstructure that would have made it more susceptible to fracture.
Figure 7 Exhaust Valve Bridge Internals
15 Material Flaw Figure 8 The rear outboard lash adjuster spring w as examined in a scanning electron microscope for fractographic analysis.
The fracture has a helicoidal shape that is indicative of fatigue in springs.
A fatigue crack initiation site w as found at the indicated location on the opposite, inside surface of the spring.
Figure 9 A small thumbnail region oriented 45° from the main spring axis w as found on the inside surface of the rear outboard lash adjuster spring.
Fig 9 is a backscattered electron (BSE) image of the fracture.
The contrast mechanism in BSE images is that of atomic number contrast w here lighter areas contain elements w ith higher atomic numbers and vice versa. In effect, the light areas on fracture are the spring material and the dark areas are typically carbonaceous deposits and/or oxides.
This fracture surface was sonicated in alcohol to remove any loose deposits on the surface.
How ever, oily deposits persisted around the fatigue initiation site.
This indicates that this fracture has been present for a long period of time, i.e., there is a good likelihood that this fatigue crack predated the fracture event.
Figure 8 Rear Outboard Lash Adjuster Spring Figure 9 Inside Surface of Adjuster Spring
Root Cause Investigation - Brad Basham 16 LASH ADJUSTER FAILURE SCENARIO
- 1. Lash Adjuster spring cracks
- 2. Lash Adjuster spring fails
- 3. Lash Adjuster Plunger collapses
- 4. Local Lash (gap) forms between exhaust valve stem and lash adjuster
- 5. Hammering effect on valve stem and valve bridge assembly
- 6. The magnitude of the vibrations and impact forces increases as the local lash increases. Excess vibrations and impact forces on the following:
i.
Exhaust valve ii.
Rocker arm adjusting screw iii.
Lash adjuster iv.
Rocking force on valve bridge stem
- 7. Global Lash (gap) forms between bridge assembly and rocker arm adjusting screw (after the locknut loosens sufficiently)
- 8. Retaining Ring failure, dropped exhaust valve, exhaust valve bridge stem fracture, inboard lash adjuster fails, etc
17 Diesel Failure Expert Perspective - Gary Thompson (MPR)
TVA engaged MPR Associates to provide technical support for the SQN RCA effort. Support was provided by Dr. Gary Thompson and other MPR engineers.
Scope of MPR Support
- Provide direct support to SQN RCA team (e.g., perform visual inspections, discuss key observations)
- Perform a separate, comprehensive review of relevant information - identify root and contributing cause based on support-refute matrix (11 potential causes considered)
Conclusions Most probable cause is lash adjuster failure due to fatigue fracture of internal spring Lash adjustment screw locknut loosening was a consequence Based on Central Labs evidence of spring fatigue fracture Dissimilarity between SQN and Davis-Besse failures Asymmetry of SQN failure damage Same TVA team used for all lash adjustments; all other locknuts > 80 ft-lbf after failure Number of starts and operating hours between lash adjustment and failure Lack of audible noise prior to failure event (was prominent during Davis-Besse event)
Potential for locknut loosening following valvetrain component failure
18 Valvetrain Operating Loads Assessment Conclusions Lash adjuster failure results in significant vibrational loading of valvetrain components Lash adjustment screw and locknut subjected to increased axial loading and additional lateral loading Loads are significant in magnitude and occur at relatively high frequency (900 rpm or 15 Hz)
Threaded fasteners are susceptible to self-loosening due to vibration, in particular from lateral loading Locknut @ 80 ft-lbf - adequate adjustment screw preload (normal conditions); marginal preload (w/ failed lash adjuster)
Locknut loosening as a consequence of a lash adjuster failure is plausible and should be expected Preload = 6,000 lbf (10,000 to 14,000 lbf is typical)
Elongation = 0.7 mil
< 5° counter-rotation of locknut results in full loss of preload Normal Condition Spring compression 300 to 700 lbf (axial)
Loads increase and decrease smoothly Failed Lash Adjuster Impact loading at high velocities Bending moment on valve bridge assembly Up to 1,900 lbf (axial)
Up to 600 lbf (lateral)
In addition to normal loads
19 Self-Loosening from Vibration Vibrational self-loosening of threaded fasteners is well-documented in technical literature G. Junker - performed pioneering research in late 1960s*; subject of numerous subsequent studies Junker vibration test - developed machine for studying phenomenon and testing effectiveness of solutions Junker, G.H. Video Click Here
- Junker, G.H., New Criteria for Self-Loosening of Fasteners Under Vibration, SAE Trans 78, 314-355 (1969).
20 Compliance Summary - Rick Medina No LER Submitted
- When the event occurred, Sequoyah entered our Past Operability Evaluation process.
- In accordance with NRC NUREG-1022 For the purpose of evaluating the reportability of a discrepancy found during surveillance testing that is required by the TS, licensees should do the following:
For testing that is conducted within the required time, it should be assumed that the discrepancy occurred at the time of its discovery unless there is firm evidence, based on a review of relevant information such as the equipment history and the cause of failure, to indicate that the discrepancy existed previously.
- Time of Discovery was September 19, 2023. It is not conclusive, and no firm evidence exists that the failure was attributed to Preventive Maintenance activities completed in January 2023 which performed checks and inspections on diesel generator 1B.
- The station remained in process and had no condition prohibited by Tech Spec or met any other conditions to report under §50.73, therefore, was not required to submit a Licensee Event Report (LER).
21 Compliance Summary Performance Deficiency Summary
- It is Sequoyahs conclusion that the 1B diesel generator failure occurred on September 19th and the engine was operable until that date.
- Based on the contrast in thoroughness and technical justification, it is more reasonable to conclude the cause of the 1B diesel cylinder failure was due to an equipment failure and therefore not a performance deficiency.
- A Self-Revealed AV of TS 5.4.1, Procedures, was identified. The licensees procedures for maintenance on the 1B diesel generator were not adequately prescribed and/or accomplished in accordance with documented instructions and procedures of a type appropriate to the circumstances.
- Sequoyah Procedure MMTP-104 requires that in part If no torque value can be determined for the specific application, Engineering is to provide specific written guidance or design output for tightening requirements.
Example 4.m states: The PD did not adversely affect the mitigating systems cornerstone objective because the inadequate proce dure would not have resulted in equipment damage. Specifically, although not required by the procedure, maintenance worker trainin g would have the worker set the torque switch to the prior setting.
- Sequoyah's RCE was completed and delivered one week after the NRC's SERP. We respectfully request that you consider our conclusion and results of the causal analysis, restoring compliance, and ensuring our continued safe operations.
PRA Analysis SQN uses RG 1.200 PRA Model for FPIE, Flood, Fire & Seismic Hazards Includes Level 2 Model Based on NUREG/CR-6595 Approved for 10 CFR 50.69 (ML22334A073)
Approved for RMTS (ML22210A118 & ML15236A351)
No Open Peer Review Findings RASP Handbook Methodology Used to Evaluate Risk Associated with DG 1B Failure
PRA Analysis SQN PRA Model Uses Static Event Trees to Evaluate Event Progression which Assume Run Failures During Mission Time Occur at t = 0 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> NRC RASP Methodology Assumes Variable 1B-B Diesel Run Capability During Exposure Time that Does Not Easily Fit into t = 0 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> Run Failure Assumption 0
4 8
12 16 20 24 0
60 120 180 240 Available EDG 1B-B Run TIme (hr)
Exposure Time (days)
PRA - Model Adjustments Model Updates were Performed Consistent with ASME/ANS RA-Sa-2009 to Accommodate Variable Diesel Run Failure Timing and Increase Realism:
High Pressure Fire Protection Credit for Steam Generator Feed Full Circuit Analysis for Permanently Installed 3MW FLEX Diesel Generators to Allow Credit in Additional Fire Areas RCP Seal LOCA Adjustment for Time Dependent Late EDG Failures Main Control Room Abandonment Adjustment for Late EDG Failures LERF Adjustment to Classify Late SBO Sequences As Non-Early Release Turbine Building Fire Modeling Refinement to Split Turbine-Generator Fire Scenarios into Catastrophic vs. Non-Catastrophic Model Updates Supported by Operations Interviews and MAAP Analysis
PRA - Model Conservatisms No Credit for FLEX High, Intermediate and Low Pressure Pumps FLEX 6.9kV and High Pressure Fire Protection Not Credited for Sequences with Assumed Immediate SBO Conditions These Conservatisms Significantly Affect the Results if RASP Handbook CCF Adjustment for Failure to Run During 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Mission Time is Conservatively Applied at Time Zero (i.e., increased probability of all diesels start but failing to run applied at t = 0 hr due to same cause)
Qualitative/Quantitative Consideration for FLEX/Fire Water Strategies Can Be Applied to Show Significance Determination Not Affected by CCF Adjustments Even if Conservative Diesel Failure Timing Assumptions are Applied
BDB Strategy Considerations SQN Beyond Design Basis Strategies More Robust than Industry Norms Two Installed 3MW 6.9kV FLEX DGs Either DG Can Support PRA Loads NEI 12-06 Timeline ~3 hr 30 min to Energize 6.9kV Shutdown Board Accelerated Non-ELAP Deployment if TDAFW fails; ~2 hr 20 min in Tabletop Exercise from SBO initiation SQN Uses INL DG Failure Data for FLEX Generators (FTS/FTL/FTR)
Data Treatment Accepted by NRC for RICT (ML22118A496, ML22210A118)
BDB Strategy Considerations High Pressure Fire Protection Has Permanent Connection to AFW Strategy Applicable to ECA-0.0 and FR-H.1 Quick Deployment - ~1 hr 50 min Following LOOP Initiator
BDB Strategy Considerations
- SQN Calculation MDN-000-999-2010-0221 3MW FLEX DG 3.5 hr Deployment Supports RCP Seal LOCA Mitigation Accelerated FLEX DG Deployment for Non-ELAP Procedure Path Results in Power Available Prior to Core Damage for Early TDAFW Failure Sequences Fire Water Credit for SG Feed Also Feasible to Mitigate AFW/FLEX Failures Insights Also Apply to Hydrogen Igniters for Level 2 Application MAAP Run*
AFW Available RCP Seal Leakage (per RCP)
RCS Cooldown Core Damage Time 3MW FLEX Deployment Time Fire Water Deployment Time SBO-02 Yes 21 gpm No
> Mission Time N/A N/A SBO-07 Yes 182 gpm No 6.43 hr 3.50 hr N/A SBO-12 Yes 480 gpm No 2.52 hr 3.50 hr N/A SBO-11 Yes 480 gpm Yes 5.05 hr 3.50 hr N/A SBO-05 Fails at 4 Hrs 21 gpm No 6.51 hr 3.50 hr 5.83 hr SBO-09 Fails at 4 Hrs 182 gpm No 5.65 hr 3.50 hr N/A SBO-05 No 21 gpm No 2.66 hr 2.33 hr 1.83 hr SBO-10 No 182 gpm No 2.43 hr 2.33 hr N/A
Conditional CCF Adjustment TVA Risk Results Based on No CCF Adjustment Because Section 5.0 of RASP Handbook is Not Appropriate for Fatigue Related Material Failures Sensitivity Performed Using Alpha Factor Method from RASP Handbook Timing of Maintenance Related Run Failures Cant Be Predicted Maintenance Related Run Failures Occurring at Same Time is Not Realistic Run Failures with Maintenance Related Proximate Cause Can Be Assumed to Occur with Uniform Distribution Throughout Surveillance Frequency Run Failures with Maintenance Related Proximate Cause Can Be Assumed to Occur with Uniform Distribution Throughout PRA Mission Time INL SPAR Data Framework - DG Run CCF Failure (EPS-EDG-FR) Requires At Minimum Successful Start, Load and One Hour Run of the DGs
Sensitivity Analysis for Conditional CCF Adjustment Sensitivity #1 NUREG/CR-6268 Timing Factors for Multiple Failures High (1.0) Failures Separated by No More Than the PRA Mission Time Medium (0.5) Failures Separated by 1-2 PRA Mission Times Low (0.1) Failures Separated by 2-3 PRA Mission Times Not CCF (0.0) Failures Separated by >3 times the PRA Mission Time Sensitivity #2 PM Frequency Weighting Factor for Multiple Failures CCF Multiplier Using Ratio of Exposure Time to PM Interval (4 year assumed)
Applied to All Common Cause Failure Groups Sensitivities Do Not Include Quantitative Credit for FLEX/Fire Water to Mitigate Time Zero Common Cause Failure of All Diesels to Run 24 Hours.
Early/Late Model Refinements Can Also Be Applied if CCF Events are Broken Up into Different Timing Bins Over the Mission Time.
Sensitivity Analysis for Conditional CCF Adjustment
PRA Results and Conclusion Combined internal events, internal flood, seismic PRA risk, and fire risk analysis results including the supplemental information for the identified deficiency and calculated exposure time:
o CDF calculated to be 5.14E-06/yr (Unit 1) and 9.31E-07/yr (Unit 2) o LERF calculated to be 4.08E-07/yr (Unit 1) and 9.53E-08/yr (Unit 2)
Results are well below the Yellow risk threshold of 1E-5/yr (CDF) and 1E-6/yr (LERF) for Unit 1.
Results are below the White risk threshold of 1E-6/yr (CDF) and 1E-7/yr (LERF) for Unit 2.
Closing - Matt Rasmussen 33 Impactful Event for the Sequoyah Nuclear Station and the TVA Fleet Lessons Learned Corrective Actions Summary of TVAs position An independent failure analysis provided technical justification for a most likely cause of the Diesel Generator failure.
It is Sequoyahs conclusion that the 1B diesel generator failure was due to a material flaw, and we did not have reasonable ability to foresee and prevent this event.
Based on our PRA insights and review of conservatisms, the significance of the event would be White on Unit 1 and Green on Unit 2.