07-13-2016 | On March 14, 2016, Watts Bar Nuclear Plant ( WBN) Unit 1 determined through engineering analysis that both trains of emergency gas treatment system ( EGTS) were inoperable for 8 minutes, 10 seconds during preoperational testing of Unit 2 EGTS. The inoperability of A and B trains of Unit 1 EGTS took place on October 22, 2015, while Unit 1 was in Mode 1 and two trains of EGTS were required to be operable in accordance with technical specification (TS) limiting condition for operation (LCO) 3.6.9, " Emergency Gas Treatment System ( EGTS)." At the time of the event, Unit 2 was in "no Mode," prior to initial fuel loading.
This condition is being reported pursuant to 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D), "Event or Condition That Could Have Prevented Fulfilment of a Safety Function. |
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Category:Letter
MONTHYEARCNL-24-060, Supplement to Request for Approval of the Tennessee Valley Authority Nuclear Quality Assurance Program Description2024-09-24024 September 2024 Supplement to Request for Approval of the Tennessee Valley Authority Nuclear Quality Assurance Program Description CNL-24-047, Decommitment of Flood Mode Mitigation Improvement Systems2024-09-24024 September 2024 Decommitment of Flood Mode Mitigation Improvement Systems ML24262A0602024-09-23023 September 2024 Summary of August 19, 2024, Meeting with Tennessee Valley Authority Regarding a Proposed Supplement to the Tennessee Valley Authority Nuclear Quality Assurance Plan CNL-24-065, Tennessee Valley Authority – Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-09-18018 September 2024 Tennessee Valley Authority – Central Emergency Control Center Emergency Plan Implementing Procedure Revisions 05000390/LER-2024-002, Automatic Reactor Trip Due to Main Generator Protection Relay Actuation2024-09-0505 September 2024 Automatic Reactor Trip Due to Main Generator Protection Relay Actuation IR 05000390/20240052024-08-28028 August 2024 Updated Inspection Plan and Assessment Follow-Up Letter for Watts Bar Nuclear Plant, Units 1 and 2 - Report 05000390-2024005 and 05000391-2024005 ML24218A1442024-08-27027 August 2024 Issuance of Amendment Nos. 169 and 75 Regarding Technical Specification Surveillance Requirement 3.9.5.1 to Reduce the Residual Heat Removal Flow Rate IR 05000390/20244022024-08-20020 August 2024 – Security Baseline Inspection Report 05000390-2024402 and 05000391/2024402 - Public CNL-24-061, Supplement to Application to Revise Function 5 of Technical Specification Table 3.3.2-1, ‘Engineered Safety Feature Actuation System Instrumentation,’ for the Sequoyah and Watts Bar (SQN-TS-23-02 and WBN-TS-23-08),2024-08-19019 August 2024 Supplement to Application to Revise Function 5 of Technical Specification Table 3.3.2-1, ‘Engineered Safety Feature Actuation System Instrumentation,’ for the Sequoyah and Watts Bar (SQN-TS-23-02 and WBN-TS-23-08), ML24219A0262024-08-12012 August 2024 Request for Withholding Information from Public Disclosure IR 05000390/20240022024-08-0707 August 2024 Integrated Inspection Report 05000390/2024002 and 05000391/2024002 Rev ML24204A2652024-07-25025 July 2024 Regulatory Audit Summary Related to Request to Revise Technical Specification Surveillance Requirement 3.9.5.1 to Reduce the Residual Heat Removal Flow Rate ML24199A0012024-07-22022 July 2024 Clarification and Correction to Exemption from Requirement of 10 CFR 37.11(c)(2) ML24172A1342024-07-15015 July 2024 Exemptions from 10 CFR 37.11(C)(2) (EPID L-2023-LLE-0024) - Letter ML24170A8002024-07-15015 July 2024 Issuance of Amendment Nos. 168 and 74 Regarding Revision to Technical Specification Table 1.1-1 for Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Bolts IR 05000390/20244402024-07-12012 July 2024 95001 Supplemental Inspection Supplemental Report 05000390-2024440 and 05000391-2024440 and Follow-Up Assessment Letter ML24131A0012024-07-0202 July 2024 Issuance of Amendment Nos. 167 and 73 Regarding Adoption of Technical Specification Task Force Traveler TSTF-427-A, Revision 2 CNL-24-052, Response to Request for Additional Information Regarding Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14)2024-06-27027 June 2024 Response to Request for Additional Information Regarding Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14) CNL-24-018, License Amendment Request for Adoption of Technical Specification Task Force Traveler TSTF-276-A, Revision 2, Regarding TS 3.8.1 AC Sources – Operating to Clarify Requirements for Diesel Generator Testing (WBN-TS2024-06-25025 June 2024 License Amendment Request for Adoption of Technical Specification Task Force Traveler TSTF-276-A, Revision 2, Regarding TS 3.8.1 AC Sources – Operating to Clarify Requirements for Diesel Generator Testing (WBN-TS ML24089A1152024-06-21021 June 2024 Transmittal Letter, Environmental Assessments and Findings of No Significant Impact Related to Exemption Requests from 10 CFR 37.11(c)(2) ML24141A0482024-05-17017 May 2024 EN 56958_1 Ametek Solidstate Controls, Inc ML24100A7642024-05-16016 May 2024 Issuance of Amendment No. 166 Regarding Revision to Technical Specification 3.8.2, AC Sources-Shutdown, to Remove Reference to C-S Diesel Generator (CNL-23-062) IR 05000390/20240012024-05-14014 May 2024 Integrated Inspection Report 05000390/2024001 and 05000391/2024001 CNL-24-040, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-05-0808 May 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions IR 05000391/20240072024-04-30030 April 2024 Assessment Follow-up Letter for Watts Bar Nuclear Plant, Unit 2 – Report 05000391/2024007 ML24120A1182024-04-29029 April 2024 – Notification of NRC Supplemental Inspection (95001) and Request for Information CNL-24-037, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 422024-04-22022 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 42 ML24087A1912024-04-18018 April 2024 Exemption from Select Requirements of 10 CFR Part 73, Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting CNL-24-010, License Amendment Request to Recapture Low-Power Testing Time (WBN-TS-23-19)2024-04-17017 April 2024 License Amendment Request to Recapture Low-Power Testing Time (WBN-TS-23-19) CNL-24-024, Hydrologic Engineering Center River Analysis System Project Milestone Status Update2024-04-17017 April 2024 Hydrologic Engineering Center River Analysis System Project Milestone Status Update CNL-24-033, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-04-17017 April 2024 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions ML24072A0052024-04-15015 April 2024 Issuance of Amendment Nos. 165 and 72 Regarding Increase in the Maximum Number of Tritium Producing Burnable Absorber Rods and Supporting Changes, and Revision to the Updated Final Safety Analysis Report CNL-24-004, Application to Modify the Watts Bar Nuclear Plant, Unit 1 and Unit 2 Technical Specifications for Main Control Room Chiller Completion Time Extension (WBN-TS-23-13)2024-04-0404 April 2024 Application to Modify the Watts Bar Nuclear Plant, Unit 1 and Unit 2 Technical Specifications for Main Control Room Chiller Completion Time Extension (WBN-TS-23-13) IR 05000390/20244012024-04-0202 April 2024 – Security Baseline Inspection Report 05000390/2024401 and 05000391/2024401 - (Public) CNL-24-020, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements2024-04-0101 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements CNL-24-007, Annual Insurance Status Report2024-03-27027 March 2024 Annual Insurance Status Report CNL-24-008, Guarantee of Payment of Deferred Premiums - 2023 Annual Report2024-03-27027 March 2024 Guarantee of Payment of Deferred Premiums - 2023 Annual Report CNL-24-025, Notice of Intent to Pursue License Renewal for Watts Bar Nuclear Plant, Unit 1 - Submittal Schedule2024-03-25025 March 2024 Notice of Intent to Pursue License Renewal for Watts Bar Nuclear Plant, Unit 1 - Submittal Schedule ML24081A0262024-03-21021 March 2024 Emergency Plan Implementing Procedure Revisions ML24079A0312024-03-19019 March 2024 Wb 2024-301, Corporate Notification Letter (210-day Ltr) CNL-24-031, Supplement to Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance2024-03-18018 March 2024 Supplement to Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance CNL-24-028, Response to Request for Additional Information Regarding Watts Bar Nuclear Plant, Units 1 and 2, Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2024-03-14014 March 2024 Response to Request for Additional Information Regarding Watts Bar Nuclear Plant, Units 1 and 2, Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation CNL-24-029, Response to Request for Additional Information Regarding Tennessee Valley Authority - Request for Exemption from Specific Requirements of 10 CFR Part 372024-03-14014 March 2024 Response to Request for Additional Information Regarding Tennessee Valley Authority - Request for Exemption from Specific Requirements of 10 CFR Part 37 IR 05000390/20240102024-03-0808 March 2024 Age-Related Degradation Inspection Report 05000390/2024010 and 05000391/2024010 CNL-24-012, Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance2024-02-28028 February 2024 Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance IR 05000390/20230062024-02-28028 February 2024 Annual Assessment Letter for Watts Bar Nuclear Plant Units 1 and 2 - Report 05000390/2023006 and 05000391/2023006 CNL-24-023, Central Emergency Control Center Emergency Plan Implementing Procedure Revision. Includes CECC EPIP-17, Revision 252024-02-20020 February 2024 Central Emergency Control Center Emergency Plan Implementing Procedure Revision. Includes CECC EPIP-17, Revision 25 ML24009A1712024-02-16016 February 2024 Environmental Assessment and Finding of No Significant Impact Related to an Increase in the Maximum Number of Tritium Producing Burnable Absorber Rods (EPID L-2023-LLA-0039) - Letter ML24019A0722024-02-14014 February 2024 Request for Withholding Information from Public Disclosure IR 05000390/20230042024-02-13013 February 2024 Integrated Inspection Report 05000390/2023004 and 05000391/2023004 and Apparent Violation 2024-09-05
[Table view] Category:Licensee Event Report (LER)
MONTHYEAR05000390/LER-2024-002, Automatic Reactor Trip Due to Main Generator Protection Relay Actuation2024-09-0505 September 2024 Automatic Reactor Trip Due to Main Generator Protection Relay Actuation WBL-24-029, Inoperability of Both Trains of Unit 2 Low Head Safety Injection2024-07-11011 July 2024 Inoperability of Both Trains of Unit 2 Low Head Safety Injection WBL-24-017, Re Automatic Reactor Trip Due to Steam Generator 3 Level LO-LO2024-05-0606 May 2024 Re Automatic Reactor Trip Due to Steam Generator 3 Level LO-LO WBL-24-013, Automatic Reactor Trip Due to Main Generator Protection Relay Actuation2024-03-27027 March 2024 Automatic Reactor Trip Due to Main Generator Protection Relay Actuation WBL-24-006, Automatic Reactor Trip Due to Loss of Main Feedwater Regulating Valve Control2024-02-29029 February 2024 Automatic Reactor Trip Due to Loss of Main Feedwater Regulating Valve Control 05000391/LER-2017-0052018-01-25025 January 2018 Unplanned Emergency Core Cooling System Injection into the Reactor Coolant System due to Personnel Error, LER 17-005-00 for Watts Bar, Unit 2, Regarding Unplanned Emergency Core Cooling System Injection into the Reactor Coolant System due to Personnel Error 05000390/LER-2017-0152018-01-0808 January 2018 Failure to Enter Limiting Condition of Operation Action Statement Results in a Condition Prohibited by Technical Specifications, LER 17-015-00 for Watts Bar, Units 1 and 2, Regarding Failure to Enter Limiting Condition of Operation Action Statement Results in a Condition Prohibited by Technical Specifications 05000390/LER-2017-0142017-12-20020 December 2017 Main Control Room Boundary Door Left Open Leading to a Loss of Safety Function, LER 17-014-00 for Watts Bar, Unit 1, Regarding Main Control Room Boundary Door Left Open Leading to a Loss of Safety Function 05000390/LER-2017-0122017-10-23023 October 2017 Error in Plant Emergency Procedures Leads to a Condition Prohibited by the Technical Specifications, LER 17-012-00 for Watts Bar, Unit 1, Regarding Error in Plant Emergency Procedures Leads to a Condition Prohibited by the Technical Specifications 05000390/LER-2017-0112017-10-23023 October 2017 Failure to Enter Technical Specification 3.6.3 for Containment Isolation Valve, LER 17-011-00 for Watts Bar, Unit 1, Regarding Failure to Enter Technical Specification 3.6.3 for Containment lsolation Valve 05000390/LER-2017-0102017-10-10010 October 2017 Actuation of Turbine Driven Auxiliary Feedwater Pump Due to Loss of 6.9kV Shutdown Board, LER 17-010-00 for Watts Bar Nuclear Plant, Unit 1 Regarding Actuation of Turbine Driven Auxiliary Feedwater Pump Due to Loss of 6.9kV Shutdown Board 05000391/LER-2017-0042017-09-25025 September 2017 Manual Reactor Trip Due to Inoperable Rod Position Indication, LER 17-004-00 for Watts Bar Nuclear Plant, Unit 2 Regarding Manual Reactor Trip Due to Inoperable Rod Position Indication 05000390/LER-2017-0042017-08-31031 August 2017 Manual Reactor Trips Due to Failed Reactor Coolant Pump Power Transfer During Plant Startup, LER 17-004-01 for Watts Bar, Unit 1, Regarding Manual Reactor Trips Due to Failed Reactor Coolant Pump Power Transfer During Plant Startup 05000390/LER-2017-0082017-08-14014 August 2017 Shield Building Inoperability and Potential Loss of Safety Function Resulting from Spurious Equipment Operation, LER 17-008-00 for Watts Bar, Unit 1, Regarding Shield Building Inoperability and Potential Loss of Safety Function Resulting from Spurious Equipment Operation 05000390/LER-2017-0072017-08-0808 August 2017 Multiple Unreported Potential Loss of Safety Function Events Associated with Inoperable Single Train Systems Due to Misinterpretation of Reporting Guidance, LER 17-007-00 for Watts Bar, Unit 1, Regarding Multiple Unreported Potential Loss of Safety Function Events Associated with Inoperable Single Train Systems Due to Misinterpretation of Reporting Guidance 05000390/LER-2017-0062017-07-31031 July 2017 Structural Degradation of 161 kV Line Pole Leads to a Condition Prohibited by Technical Specifications, LER 17-006-00 for Watts Bar, Unit 1, Regarding Structural Degradation of 161 kV Line Pole Leads to a Condition Prohibited by Technical Specifications 05000390/LER-2017-0052017-07-10010 July 2017 Isolation of the 1 B-B Safety Injection Pump Leads to Condition Prohibited by Technical Specifications, LER 17-005-00 for Watts Bar re Isolation of the 1B-B Safety Injection Pump Leads to a Condition Prohibited by Technical Specifications 05000391/LER-2017-0032017-05-22022 May 2017 Automatic Start of Auxiliary Feedwater System Due to Main Condenser Failure, LER 17-003-00 for Watts Bar, Unit 2, Regarding Automatic Start of Auxiliary Feedwater System Due to Main Condenser Failure 05000391/LER-2017-0022017-05-12012 May 2017 Manual Reactor Trip as a Result of a Secondary Plant Transient, LER 17-002-00 for Watts Bar, Unit 2, Regarding Manual Reactor Trip as a Result of a Secondary Plant Transient 05000391/LER-2017-0012017-05-0303 May 2017 Containment Airlock Function Lost Due to Equalizing Valve Not Closing, LER 17-001-00 for Watts Bar, Unit 2, Regarding Containment Airlock Function Lost Due to Equalizing Valve Not Closing 05000390/LER-2017-0032017-03-0303 March 2017 Inadequate Operability Determination Leads to a Condition Prohibited by the Technical Specifications, LER 17-003-00 for Watts Bar, Unit 1, Regarding Inadequate Operability Determination Leads to a Condition Prohibited by the Technical Specifications 05000390/LER-2017-0022017-02-22022 February 2017 Incorrectly Hung Clearance Leads to a Condition Prohibited by the Technical Specifications, LER 17-002-00 for Watts Bar Nuclear Plant, Unit 1, Regarding: Incorrectly Hung Clearance Leads to a Condition Prohibited by the Technical Specifications 05000390/LER-2016-0112016-12-0909 December 2016 Loss of Centrifugal Charging Pump Due to Repeat Failure of Associated Room Cooler, LER 16-011-01 for Watts Bar Nuclear Plant, Unit 1 Regarding Loss of Centrifugal Charging Pump Due to Repeat Failure of Associated Room Cooler 05000391/LER-2016-0082016-10-28028 October 2016 Reactor Trip Resulting from Failure of 2B Main Bank Transformer, LER 16-008-00 for Watts Bar, Unit 2, Regarding Reactor Trip Resulting from Failure of 2B Main Bank Transformer 05000391/LER-2016-0052016-08-19019 August 2016 Main Feedwater Pump Trip on Loss of Condenser Vacuum Leads to Turbine Trip and Reactor Trip, LER 16-005-00 for Watts Bar, Unit 2, Regarding Main Feedwater Pump Trip on Loss of Condenser Vacuum Leads to Turbine Trip and Reactor Trip 05000390/LER-2016-0102016-08-0808 August 2016 Emergency Diesel Generator Crankcase Pressure Switches Not Analyzed to Withstand the Effects of a Tornado, LER-16-010-00 for Watts Bar Nuclear Plant, Units 1 and 2 Regarding Emergency Diesel Generator Crankcase Pressure Switches Not Analyzed to Withstand the Effects of a Tornado 05000391/LER-2016-0042016-08-0404 August 2016 Reactor Trip and Safety Injection Actuation Caused by Turbine Governor Valve Failure, LER 16-004-00 for Watts Bar, Unit 2, Regarding Reactor Trip and Safety Injection Actuation Caused by Turbine Governor Valve Failure 05000391/LER-2016-0032016-07-27027 July 2016 Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer than Allowable Outage Time due to Governor Valve Spring Over-Tensioning, LER 16-003-00 for Watts Bar, Unit 2, Regarding Turbine Driven Auxiliary Feedwater Pump lnoperable for Longer Than Allowable Outage Time Due to Governor Valve Spring Over-Tensioning 05000390/LER-2016-0082016-07-15015 July 2016 Emergency Diesel Generator Manual Start Due to Loss of Voltage on the 6.9kV Shutdown Board 1B-B, LER 16-008-00 for Watts Bar, Unit 1, Regarding Emergency Diesel Generator Manual Start Due to Loss of Voltage on the 6.9kV Shutdown Board 1B-B 05000390/LER-2016-0092016-07-15015 July 2016 Failure to Complete Surveillance Requirements Causes a Condition Prohibited by the Technical Specifications, LER 16-009-00 for Watts Bar, Unit 1, Regarding Failure to Complete Surveillance Requirements Causes Conditions Prohibited by the Technical Specifications 05000391/LER-2016-0022016-07-11011 July 2016 Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer than Allowable Outage Time due to Turbine Speed Control Failure, LER 16-002-00 for Watts Bar, Unit 2, Regarding Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer Than Allowable Outage Time Due to Turbine Speed Control Failure 05000390/LER-2016-0062016-06-30030 June 2016 Undersized Room Cooler Fan Shaft Results in Loss of Centrifugal Charging Pump, LER 16-006-00 for Watts Bar, Unit 1, Regarding Undersized Room Cooler Fan Shaft Results in Loss of Centrifugal Charging Pump 05000390/LER-2016-0072016-06-20020 June 2016 Technical Specification Action Not Met for Rod Position Indication, LER 16-007-00 for Watts Bar Nuclear Plant, Unit 1 Regarding Technical Specification Action Not Met for Rod Position Indication 05000391/LER-2016-0012016-06-13013 June 2016 Loss of Automatic Containment Isolation for the Steam Generator Blowdown Sampling Lines, LER 16-001-00 for Watts Bar, Unit 2, Regarding Loss of Automatic Containment Isolation for the Steam Generator Blowdown Sampling Lines 05000390/LER-2016-0042016-05-23023 May 2016 Automatic Reactor Trip Due to Actuation of Over Temperature Delta Temperature Bistables, LER 16-004-00 for Watts Bar, Unit 1, Regarding Automatic Reactor Trip Due to Actuation of Over Temperature Delta Temperature Bistables 05000390/LER-2016-0052016-05-13013 May 2016 Both Trains of Unit 1 Emergency Gas Treatment System Inoperable During Unit 2 Testing, LER 16-005-00 for Watts Bar, Unit 1, Regarding Both Trains of Unit 1, Emergency Gas Treatment System Inoperable During Unit 2, Testing 05000390/LER-2016-0032016-05-10010 May 2016 Technical Specification Surveillance Requirement Not Met During Emergency Core Cooling System Venting, LER 16-003-00 for Watts Bar, Unit 1, Regarding Technical Specification Surveillance Requirement Not Met During Emergency Core Cooling System Venting 05000390/LER-2016-0022016-05-0404 May 2016 Technical Specification Action Not Met for Inoperable Containment Isolation Valve, LER 16-002-00 for Watts Bar, Unit 1, Regarding Technical Specification Action Not Met for Inoperable Containment Isolation Valve 05000390/LER-2016-0012016-03-0909 March 2016 Channel Mode Switch in Incorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor Inoperable, LER 16-001-00 for Watts Bar, Unit 1, Regarding Channel Mode Switch in Incorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor Inoperable ML1134703432011-12-13013 December 2011 Withdrawal of License Event Report 390/2011-003, Mode Change Without Meeting Limiting Condition for Operation (LCO) 3.7.5 2024-09-05
[Table view] |
comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
I. PLANT OPERATING CONDITIONS BEFORE THE EVENT
Watts Bar Nuclear Plant (WBN) Unit 1 was in Mode 1 at 14 percent rated thermal power (RTP). WBN Unit 2 was in "no Mode" prior to initial fuel loading.
II. DESCRIPTION OF EVENT
A. Event
On March 14, 2016, Watts Bar Nuclear Plant (WBN) Unit 1 determined through engineering analysis that both trains of emergency gas treatment system (EGTS) [EMS: BH] were inoperable for 8 minutes, 10 seconds during preoperational testing of Unit 2 EGTS. The inoperability of A and B trains of Unit 1 EGTS took place on October 22, 2015, while Unit 1 was in Mode 1 and two trains of EGTS were required to be operable in accordance with technical specification (TS) limiting condition for operation (LCO) 3.6.9, "Emergency Gas Treatment System (EGTS)." At the time of the event, Unit 2 was in "no Mode," prior to initial fuel loading. This condition is being reported pursuant to 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D), "Event or Condition That Could Have Prevented Fulfilment of a Safety Function.
B. Inoperable Structures, Components, or Systems that Contributed to the Event Train A and train B EGTS were concurrently inoperable for 8 minutes, 10 seconds on October 22, 2015.
C. Dates and Approximate Times of Occurrences Date Time Event 10/17/15 1007 EDT WBN Unit 1 entered Mode 4 coming out of refueling outage 13 10/22/15 0118 EDT Both trains Unit 1 EGTS inoperable due to Unit 2 test configuration 10/22/15 0126 EDT Unit 2 EGTS train A suction dampers closed.
D. Manufacturer and Model Number of Components that Failed There were no failed components associated with this event.
E. Other Systems or Secondary Functions Affected
There were no systems or secondary functions affected by this event.
F. Method of discovery of each Component or System Failure or Procedural Error This issue was identified during the incorporation of Unit 2 EGTS system testing requirements into WBN engineering documents.
G. Failure Mode and Effect of Each Failed Component There were no component failures associated with this event.
comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to Infocollects.Resource@nrc,gov, and to the Desk Officer, Office of Information and Regulatory Affairs, used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3. LER NUMBER
2016 - 01
H. Operator Actions
There was no actual event requiring operator actions.
I. Automatically and Manually Initiated Safety System Responses There were no automatic or manual system responses associated with this event.
III. CAUSE OF THE EVENT
A. The cause of each component or system failure or personnel error, if known.
There was no component or system failure associated with this event.
B. The cause(s) and circumstances for each human performance related root cause.
The cause of this event was that engineers were assigned tasks without the requisite knowledge and experience to fully understand all issues that needed to be addressed for a first of a kind testing on a complex shared system. This resulted in inadequate special requirements to maintain Unit 1 EGTS operable during the Unit 2 preoperational testing.
IV. ANALYSIS OF THE EVENT
On October 22, 2015, both trains of Unit 1 EGTS were inoperable for 8 minutes, 10 seconds due to inadequate special requirements to maintain Unit 1 EGTS operable during Unit 2 EGTS testing. The specified safety functions of EGTS are:
1. To keep the air pressure within each Shield Building annulus below atmospheric pressure at all times in which the integrity of that particular containment is required.
2. To reduce the concentration of radioactive nuclides in annulus air that is released to the environs during a loss of coolant accident (LOCA) in either reactor unit to levels sufficiently low to keep the site boundary and low population zone (LPZ) dose rates below the 10 CFR 100 values.
3. To withstand the safe shutdown earthquake.
4. To provide for initial and periodic testing of the system capability to function as designed.
EGTS is a dual unit system. TS LCO 3.6.9 requires both trains of EGTS be Operable in Modes 1, 2, 3, and 4 and TS 3.6.15 requires that the Shield Building shall be Operable in Modes 1, 2, 3, and 4. The EGTS must be capable of producing the correct flow and pressure requirements relative to the annulus, which ensures that the EGTS is capable of performing Specified Safety Function 2 described above to keep annulus releases below the 10 CFR 100 limits. A single train of EGTS is capable of drawing suction on the annulus of the unit undergoing a LOCA such that the specified safety functions of EGTS are met.
Annulus in-leakage for the suction path in service is assumed to meet surveillance requirement (SR) 3.6.15.4 in-leakage limit of 5. 250 scfm.
Because in-leakage from the Unit 2 annulus was unknown, and both EGTS trains were aligned to the Unit 2 annulus for 8 minutes, 10 seconds, both trains should have been declared inoperable on Unit 1 which would have required that Unit 1 enter TS LCO 3.0.3.
comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3. LER NUMBER
A demand for EGTS did not exist during this timeframe. During times where individual trains of EGTS were inoperable, the conditions existed for less than the TS LCO 3.6.9 required action completion times. In addition, LCO 3.0.3 required action completion times were not exceeded when both trains of EGTS were inoperable.
V. ASSESSMENT OF SAFETY CONSEQUENCES
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event The WBN probabilistic risk model does not consider EGTS in core damage and large early release frequencies. As a result, any risk increase associated with a short-duration misalignment of EGTS EGTS test for operators to close dampers to isolate Unit 2 from the suction path of EGTS, should it become necessary to prevent Unit 2 testing from adversely impacting Unit 1 operation.
See discussion below regarding safety system functional failure reporting in accordance with NEI 99-02.
B. For events that occurred when the reactor was shut down, availability of systems or components needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident Not applicable. Watts Bar Unit 1 was in Mode 1 at the time of this event.
C. For failure that rendered a train of a safety system inoperable, an estimate of the elapsed time from the discovery of the failure until the train was returned to service There was not an actual failure associated with this event. In the engineering evaluation performed subsequent to the event, WBN demonstrated that both trains of Unit 1 EGTS were inoperable for 8 minutes, 10 seconds.
VI. CORRECTIVE ACTIONS
This event was entered into the Tennessee Valley Authority Corrective Action Program and is being tracked under condition report 1143076.
A. Immediate Corrective Actions
This issue was identified subsequent to the inoperability of both trains of Unit 1 EGTS. Condition report 1143076 was initiated, and a past operability evaluation performed.
B. Corrective Actions to Prevent Recurrence
Watts Bar Unit 2 EGTS has been turned over to plant operations, and is controlled under the WBN Unit 2 TS. Testing requirements for EGTS were revised to support dual unit operation, including appropriate controls to ensure that EGTS on the unit not undergoing testing will remain operable.
CONTINUATION SHEET
2016 - 01 APPROVED BY OMB: NO. 3150.0104 EXPIRES: 10131/2018 comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
VII. ADDITIONAL INFORMATION
A. Previous similar events at the same plant
None.
B. Additional Information
None.
C. Safety System Functional Failure Consideration
This event is considered a safety system functional failure in accordance with NEI 99-02.
The Emergency Gas Treatment System (EGTS) is a common system capable of drawing suction from the containment annulus of either Unit 1 or Unit 2 following an accident. While the system is capable of responding to an accident while testing the other unit, annulus in-leakage is assumed to meet Technical Specification 3.6.15, "Shield Building," requirements for both units.
During preoperational testing of the Unit 2 EGTS, Unit 2 annulus in-leakage did not meet Technical Specifications requirements during times when EGTS was required to be operable for Unit 1. Unit 2 EGTS was not required to be operable during this time. In order to compensate for the Unit 2 annulus in-leakage during Unit 2 preoperational testing, specific operator actions were developed to isolate the Unit 2 annulus and place the EGTS system into an alignment which would support the response to an accident on Unit 1.
In the 10 CFR 50.59 evaluation to support the Unit 2 EGTS testing, TVA concluded that the actions required to isolate Unit 2 EGTS in the event of a Unit 1 accident were reliable and achievable and could be implemented without prior NRC approval assuming only one train was tested at a time. For the period of concern, however, both trains of EGTS had been placed in the test configuration and were inoperable, and therefore outside the scope of the 10 CFR 50.59 evaluation. The actions required in the event of a Unit 1 loss of coolant accident were the closure of open Unit 2 EGTS dampers by a dedicated operator. The dampers met stroke time testing prior to the event described in LER 390/2016005 and were demonstrated to function properly from the main control room. In addition, TVA confirmed through review of testing documents and operator logs that the operator actions were in place during this event.
Given the above, there is high confidence that the EGTS safety functions were maintained.
D. Scrams with Complications Consideration None.
VIII. COMMITMENTS
None.
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05000390/LER-2016-010 | Emergency Diesel Generator Crankcase Pressure Switches Not Analyzed to Withstand the Effects of a Tornado LER-16-010-00 for Watts Bar Nuclear Plant, Units 1 and 2 Regarding Emergency Diesel Generator Crankcase Pressure Switches Not Analyzed to Withstand the Effects of a Tornado | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition | 05000390/LER-2016-001 | Channel Mode Switch in Incorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor Inoperable LER 16-001-00 for Watts Bar, Unit 1, Regarding Channel Mode Switch in Incorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor Inoperable | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000390/LER-2016-011 | Loss of Centrifugal Charging Pump Due to Repeat Failure of Associated Room Cooler LER 16-011-01 for Watts Bar Nuclear Plant, Unit 1 Regarding Loss of Centrifugal Charging Pump Due to Repeat Failure of Associated Room Cooler | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000391/LER-2016-001 | Loss of Automatic Containment Isolation for the Steam Generator Blowdown Sampling Lines LER 16-001-00 for Watts Bar, Unit 2, Regarding Loss of Automatic Containment Isolation for the Steam Generator Blowdown Sampling Lines | 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000391/LER-2016-002 | Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer than Allowable Outage Time due to Turbine Speed Control Failure LER 16-002-00 for Watts Bar, Unit 2, Regarding Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer Than Allowable Outage Time Due to Turbine Speed Control Failure | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000390/LER-2016-002 | Technical Specification Action Not Met for Inoperable Containment Isolation Valve LER 16-002-00 for Watts Bar, Unit 1, Regarding Technical Specification Action Not Met for Inoperable Containment Isolation Valve | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000391/LER-2016-003 | Turbine Driven Auxiliary Feedwater Pump Inoperable for Longer than Allowable Outage Time due to Governor Valve Spring Over-Tensioning LER 16-003-00 for Watts Bar, Unit 2, Regarding Turbine Driven Auxiliary Feedwater Pump lnoperable for Longer Than Allowable Outage Time Due to Governor Valve Spring Over-Tensioning | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000390/LER-2016-003 | Technical Specification Surveillance Requirement Not Met During Emergency Core Cooling System Venting LER 16-003-00 for Watts Bar, Unit 1, Regarding Technical Specification Surveillance Requirement Not Met During Emergency Core Cooling System Venting | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000391/LER-2016-004 | Reactor Trip and Safety Injection Actuation Caused by Turbine Governor Valve Failure LER 16-004-00 for Watts Bar, Unit 2, Regarding Reactor Trip and Safety Injection Actuation Caused by Turbine Governor Valve Failure | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000390/LER-2016-004 | Automatic Reactor Trip Due to Actuation of Over Temperature Delta Temperature Bistables LER 16-004-00 for Watts Bar, Unit 1, Regarding Automatic Reactor Trip Due to Actuation of Over Temperature Delta Temperature Bistables | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000391/LER-2016-005 | Main Feedwater Pump Trip on Loss of Condenser Vacuum Leads to Turbine Trip and Reactor Trip LER 16-005-00 for Watts Bar, Unit 2, Regarding Main Feedwater Pump Trip on Loss of Condenser Vacuum Leads to Turbine Trip and Reactor Trip | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000390/LER-2016-005 | Both Trains of Unit 1 Emergency Gas Treatment System Inoperable During Unit 2 Testing LER 16-005-00 for Watts Bar, Unit 1, Regarding Both Trains of Unit 1, Emergency Gas Treatment System Inoperable During Unit 2, Testing | 10 CFR 50.73(a)(2)(v)(C), Loss of Safety Function - Release of Radioactive Material 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | 05000391/LER-2016-006 | Turbine Driven Auxiliary Feedwater Pump Auto Start on Lo-Lo Steam Generator Level Following Planned Unit Trip | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000390/LER-2016-006 | Undersized Room Cooler Fan Shaft Results in Loss of Centrifugal Charging Pump LER 16-006-00 for Watts Bar, Unit 1, Regarding Undersized Room Cooler Fan Shaft Results in Loss of Centrifugal Charging Pump | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000391/LER-2016-007 | Manual Reactor Trip Due to Loss of Main Feedwater | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000390/LER-2016-007 | Technical Specification Action Not Met for Rod Position Indication LER 16-007-00 for Watts Bar Nuclear Plant, Unit 1 Regarding Technical Specification Action Not Met for Rod Position Indication | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications | 05000390/LER-2016-008 | Emergency Diesel Generator Manual Start Due to Loss of Voltage on the 6.9kV Shutdown Board 1B-B LER 16-008-00 for Watts Bar, Unit 1, Regarding Emergency Diesel Generator Manual Start Due to Loss of Voltage on the 6.9kV Shutdown Board 1B-B | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000391/LER-2016-008 | Reactor Trip Resulting from Failure of 2B Main Bank Transformer LER 16-008-00 for Watts Bar, Unit 2, Regarding Reactor Trip Resulting from Failure of 2B Main Bank Transformer | 10 CFR 50.73(a)(2)(iv)(A), System Actuation | 05000390/LER-2016-009 | Failure to Complete Surveillance Requirements Causes a Condition Prohibited by the Technical Specifications LER 16-009-00 for Watts Bar, Unit 1, Regarding Failure to Complete Surveillance Requirements Causes Conditions Prohibited by the Technical Specifications | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
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