01-24-2018 | On September 6, 2017, Watts Bar Nuclear Plant ( WBN) identified that the vacuum relief line airflows did not meet acceptance criteria for the Auxiliary Building Gas Treatment System ( ABGTS) for Train A during the performance of 0- SI-30-7-A, ABGTS Pressure Test Troubleshooting of the low airflows identified an Auxiliary Building Secondary Containment Enclosure ( ABSCE) Unit 2 General Ventilation intake damper 2-FC0-30-108 with approximately one inch gaps in the blade seals with the damper in the closed position Preliminary investigation found that the damper linkage appeared to not be adjusted correctly to allow full closure of the damper blades following maintenance in May of 2017 The low vacuum relief line airflows resulted in the Train A ABGTS being inoperable, based on identified open ABSCE breaches, from July 7, 2017 to September 5, 2017 This time period is longer than that allowed by Technical Specification (TS) 3 7 12 for ABGTS, and is therefore a condition prohibited by TS The cause of this event was an incorrectly adjusted damper linkage after replacement of the damper actuator A training needs analysis will be performed to evaluate training solutions for damper linkage adjustments Damper preventative maintenance activities will be revised to address smooth operation and absence of mechanical binding |
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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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Infocollects Resource@nrc gov, and to the Desk Officer, Office of Informahon 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
I PLANT OPERATING CONDITIONS BEFORE THE EVENT Watts Bar Nuclear Plant (WBN) Unit 1 was at 100 percent rated thermal power (RTP) WBN Unit 2 was also in Mode 1 at 100 percent power.
II DESCRIPTION OF EVENT
A Event Summary On September 6, 2017, Watts Bar Nuclear Plant (WBN) identified that the vacuum relief line airflows did not meet acceptance criteria for the Auxiliary Building Gas Treatment System (ABGTS){EIIS VF} for Train A during the performance of 0-S1-30-7-A, ABGTS Pressure Test Troubleshooting of the low airflows identified an Auxiliary Building Secondary Containment Enclosure (ABSCE) Unit 2 General Ventilation intake damper 2-FCO-30-108 {EllS:CDMP} with approximately one inch gaps in the blade seals with the damper in the closed position Preliminary investigation found that the damper linkage appeared to not be adjusted correctly to allow full closure of the damper blades following maintenance in May of 2017 The low vacuum relief line airflows resulted in the Train A ABGTS being inoperable, based on identified open ABSCE breaches, from July 7, 2017 at 2030 Eastern Daylight Time (EDT) to September 5, 2017 at 1645 EDT This time period is longer than that allowed by Technical Specification (TS) 3 7.12 for ABGTS, and is therefore a condition prohibited by TS This event is being reported to the Nuclear Regulatory Commission (NRC) under 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
B Inoperable Structures, Components, or Systems that Contributed to the Event No inoperable equipment contributed to this event C. Dates and Approximate Times of Occurrences Date Time Event 5/19/17 Actuator associated with damper 2-FCO-30-108 replaced to address air leaks. A visual inspection of the damper by inspecting the blade seals through the ventilation manway was not performed Only external checks were performed 7/07/17 2030 ABSCE breach exceeds 63.9 square inches for Train A.
9/05/17 1645 ABSCE breach is less than 63.9 square inches for Train A .
9/06/17 During performance of 0-S1-30-7-A, Auxiliary Building Gas Treatment System Pressure Test Train A, the vacuum relief line airflows obtained did not meet the required acceptance criteria of greater than or equal to 1370 cubic feet per minute (cfm) 9/19/07 1609 Damper issue corrected by Work Order 119015649 10/06/17 A Past Operability Evaluation (POE) performed for this event determined that the A Train of ABGTS was inoperable from July 7, 2017 at 2030 EDT until September 5, 2017 at 1645 EDT.
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3. LER NUMBER
2017 - 01 013 D Manufacturer and Model Number of Components that Failed During the Event The damper that failed was provided by Pacific Air Products, Part OB1001 E Other Systems or Secondary Functions Affected No other systems or secondary functions were affected F Method of discovery of each Component or System Failure or Procedural Error The issue was identified during periodic testing of the ABGTS required by TS.
G Failure Mode and Effect of Each Failed Component The cause of the equipment issue was an incorrectly adjusted damper linkage
H. Operator Actions
No actual event was ongoing related to this report.
I Automatically and Manually Initiated Safety System Responses Not applicable
III CAUSE OF THE EVENT
A. The cause of each component or system failure or personnel error, if known.
The cause of this event was an incorrectly adjusted damper linkage after replacement of the damper actuator in May 2017, which subsequently resulted in linkage slippage and incomplete damper closure.
B The cause(s) and circumstances for each human performance related root cause Individuals adjusting the damper linkage in May 2017 made a skill based error that resulted in linkage slippage due to linkage tightness during travel, and subsequent incomplete damper closure
IV ANALYSIS OF THE EVENT
The ABGTS and ABSCE serve a specified safety function when either WBN Unit 1 or Unit 2 are in Modes 1 through 4 by (1) providing a secondary containment barrier maintained under negative pressure during certain postulated accidents involving airborne radioactivity, and (2) providing contaminant removal sufficient to keep radioactivity levels in the air released to the environment low enough to assure compliance with the requirements of 10 CFR 100 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 The ABGTS consists of two 100 percent redundant air cleanup units (ACUs), located in separate rooms in the Auxiliary Building (AB) adjacent to each reactor building This system consists of two parallel ducts originating from exhaust ducting that normally serves the fuel handling and waste packaging areas Each of these ducts leads directly to an ABGTS ACU and fan combination, which then exhausts the building air directly to the shield building exhaust vent Following an accident, potential radioactivity releases within the AB are processed by the ABGTS units prior to release to the environment ABGTS performs the primary safety-related function of maintaining the AB at a minimum negative pressure of -0 25 inches water gauge (wg) to assure that the guidelines in 10 CFR 100 and General Design Criteria (GDC) 19 are not exceeded. Sufficient air is drawn from the ABSCE to establish and maintain the desired building negative pressure. The negative pressure chosen for post-accident operation is sufficiently low to ensure that airborne contamination in the AB is not released to the environment without being processed by the ABGTS units. Although the maximum permissible ABSCE leakage rate is 9900 cubic feet per minute (cfm) at -0.25 inches wg with respect to the outside environment, ABGTS will maintain a minimum fan capacity of 9300 cfm at all times. This will allow for adequate airflow for a maximum allowable ABSCE infiltration rate of 7930 cfm, and margin for a postulated one inch service air line break (1370cfm) due to a Safe Shutdown Earthquake (SSE), at a negative differential pressure of -0 25 inches wg The inability of ABGTS Train A to meet the required greater than or equal to 1370 cfm total vacuum relief line airflow required by the design does not necessarily render ABGTS Train A incapable of performing its specified safety function during a Loss of Coolant Accident (LOCA) (maintaining ABSCE at a negative pressure, -0.25 inches wg and -0 5 inches wg) The difference between the actual vacuum relief measured value (corrected for pressure) and 1370 cfm (from a postulated one inch air line break) provides the margin for ABSCE breaching permits during plant operation The ABSCE breach margin is calculated using ABGTS total flow, vacuum relief line flow, and AB pressures Therefore, once either train of ABGTS's breach margin is exceeded that unit of ABGTS becomes inoperable and unable to perform its specified safety function.
Testing performed on September 6, 2017 showed the failure of damper 2-FC0-30-108 to fully close impacted the ability to accommodate the postulated one inch service air line break when the calculated breaches through the ABSCE exceeded 63 9 square inches for Train A. This breach margin was exceeded between July 7, 2017 at 2030 EDT and September 5, 2017 at 1645 EDT. Following correction of damper 2-FC0-30-108, the ABSCE breach margin increased to over 170 square inches.
V. ASSESSMENT OF SAFETY CONSEQUENCES
As described in the previous section, the ABGTS Train A was not able to perform its safety function for a design basis accident with a one inch service airline failure The postulation of a seismic event and a Design Basis Event (DBE) are not assumed to occur concurrently, but are considered for the purposes of design and operability. The consequences of this event are judged to be low, and are not modeled in the plant Probabilistic Risk Assessment (PRA) A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event Train B of ABGTS remained operable during this time period 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
2017 - 01 013 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 Train B of ABGTS remained operable during this time period.
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 Train A of ABGTS was operable based on ABSCE breaches in effect when the condition of damper 2-FC0-30-108 was identified. The condition identified on September 6, 2017 was corrected on September 19, 2017
VI. CORRECTIVE ACTIONS
This event was entered into the Tennessee Valley Authority (TVA) Corrective Action Program and is being tracked under Condition Report (CR) 1335791 A Immediate Corrective Actions The improperly adjusted damper was corrected after identification.
B Corrective Actions to Prevent Recurrence or to Reduce Probability of Similar Events Occurring in the Future A training needs analysis will be performed to evaluate training solutions for damper linkage adjustments. Damper preventative maintenance activities will be revised to address smooth operation and absence of mechanical binding.
VII PREVIOUS SIMILAR EVENTS AT THE SAME SITE
that the closure of non-safety ventilation dampers may have masked the performance of safety related dampers In addition, as part of this report, two failures of a temporary boundary door used to facilitate Unit 2 construction were reported Corrective actions included revising procedures to ensure that non- safety dampers could not mask the performance of safety related dampers during testing. The event described in LER 390-2017-013 is different in that it is related to performance of post maintenance inspections, not surveillance procedures.
VIII. ADDITIONAL INFORMATION
None
IX COMMITMENTS
None
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