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| Discovered date | Reporting criterion | Title | Description | LER | |
|---|---|---|---|---|---|
| ENS 40100 | 25 August 2003 13:45:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Turbine Trip/Reactor Trip Due to a Sudden Pressure Relay Signal from Main Transformer Bank "1C | On August 25, 2003, Watts Bar (WBN) Unit 1 was operating at 100 percent power when there was an operation of a "Sudden Pressure Relay" for Main Transformer Bank 1C. The actuation of the relay resulted in a turbine trip and a subsequent reactor trip at approximately 0945 EDT. The cause of the relay actuation is under investigation at this time. All control rods inserted as required and the safety systems actuated as designed including the motor and turbine driven pumps for the Auxiliary Feedwater (AFW) System. AFW pump 1B-B was inoperable at the time of the trip due to work on an area cooler. However, the pump was available for service and started as required. Unit 1 is currently stable in Mode 3 and will remain in this mode until the completion of the investigation into the cause of the trip. At the time of the Sudden Pressure Relay for Main Transformer Bank 1C, an oil sample was being taken of the Transformer. Fire Brigade was sent but there was no fire and no explosion to the Transformer. The electrical grid is stable, and Emergency Core Cooling systems and the Emergency Diesel Generators are fully operable if needed. At this time only the 1B-B Motor Driven Auxiliary Feedwater pump is still operating. The NRC Resident Inspector was notified of this event by the licensee. | |
| ENS 40200 | 26 September 2003 12:50:00 | Other Unspec Reqmnt | Greater than 1 Percent of Steam Generators 1,2 & 4 Tubes Inspected Indicate That the Inspected Tubes Require Plugging. | At 0850 EST on September 26, 2003, with Watts Bar Nuclear Plant Unit 1 defueled, steam generator inspections were being performed in accordance with Technical Specification (TS) 5.7.2.12, 'Steam Generator Tube Surveillance Program.' The results of the inspections performed on Steam Generator Numbers 1, 2, and 4 indicated that greater than 1% of the inspected tubes require repair. Based on TS 5.7.2.12, this determination results in the classification of C-3. The current inspection results do not meet the criteria specified for steam generator tube degradation in Revision 2 of NUREG 1022, Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73. However, for classification C-3, WBN TS Table 5.7.2.12-1, 'SG Tube Inspection Supplemental Sampling Requirements, 'requires that the results of the inspection be reported under 10 CFR 50.72. At this time, the submittal of the Licensee Event Report in accordance with 10 CFR 50.73 is not planned. The NRC Resident Inspector was notified of this event by the licensee.
In addition, at 0800 on September 29, 2003 Steam Generator Number 3 has been determined to be in the classification of C-3 (48 tubes). The current inspection results do not meet the criteria specified for team generator tube degradation in Revision 2 of NUREG 1022, Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73. However, for classification C-3, WBN TS Table 5.7.2.12-1, 'SG Tube Inspection Supplemental Sampling Requirements,' requires that the results of the inspection be reported under 10 CFR 50.72. At this time, the submittal of a Licensee Event Report in accordance with 10 CFR 50.73 is not planned." R2DO (Mark Lesser) notified. The NRC Resident Inspector was notified of this update by the licensee. | |
| ENS 40221 | 3 October 2003 19:16:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Accident Mitigation System Degraded Due to Both Trains of Auxiliary Building Gas Treatment System Inoperable | The following information was obtained from the licensee via facsimile: On 10/03/2003, Watts Bar Nuclear Plant Unit 1 was in Mode 6 during a refueling outage with core re-load in progress. At 1516 (hrs EDT), the control room became aware that an activity in preparing for an upcoming test had placed the B Auxiliary Building Gas Treatment System (ABGTS) 480v Breaker in the off position. An operator was immediately dispatched to close the ABGTS breaker and the breaker was closed at 1521 (hrs), restoring the train to OPERABLE status. The opening of this breaker at about 1324 (hrs) caused the B ABGTS train to be INOPERABLE at a time when the A ABGTS train was available to start but technically INOPERABLE due to the emergency power supply ( A Train Diesel Generator) and a room cooler being out of service. The ABGTS system is required for the mitigation of a postulated fuel handling accident. Site emergency procedures require the operator to promptly confirm ABGTS is in operation, indication is provided in the control room on ABGTS status and breaker restoration can be quickly performed. In addition, with off site power available, the A ABGTS train would have immediately responded to an event and begun to perform the filtration function while the otherwise operable B train was manually restored. However, at the time of discovery, the system could not have performed its function in the event of a postulated accident coincident with a loss of off site power. Accordingly, TVA has determined this event is reportable in accordance with 10 CFR 50.72 (b)(3)(v)(D). The licensee has notified the NRC Resident Inspector. | |
| ENS 40454 | 16 January 2004 16:37:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip Due to Turbine Trip | At 1137 hours EST on January 16, 2004, with Watts Bar Unit 1 in Mode 1 at 100 % power, a turbine trip and reactor trip occurred. This is reportable as a 4-hour notification under 10 CFR 50.72 (b)(2)(iv)(B) and an 8-hour notification under 10 CFR 50.72 (b)(3)(iv)(A). In addition, per design, there was auto start of the Auxiliary Feedwater system which is reportable as an 8-hour notification under 10 CFR 50.72 (b)(3)(iv)(A). Plant safety systems performed as designed and the reactor is currently stable in mode 3. At the time of the trip, plant personnel were performing scheduled Solid State Protection System (SSPS) surveillance testing on the B Train Reactor Trip Breaker. Plant personnel are currently investigating the cause of the event. The licensee also reported that all control rods inserted on the reactor trip, no primary or secondary system relief valves operated, and that reactor temperature is being maintained using steam dump to the condenser. Steam generator water levels are being maintained using auxiliary feedwater. The station electrical system is available and in a normal configuration. All ECCS equipment is available. The reactor is currently stable at 2230 psig, 559 degrees Fahrenheit. The licensee has notified the NRC Resident Inspector. | |
| ENS 41049 | 17 September 2004 09:00:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(xiii), Loss of Emergency Preparedness | Loss of Emergency Siren Capability and Notification of Offsite Agency | On Sept. 17, 2004, with Watts Bar Unit 1 at 100% power, the main control room was notified that the 99 sirens which make up the Public Prompt Notification System were not functional. The system uses two repeaters to control the sirens. As the remnants of Hurricane Ivan were passing through the Tennessee River Valley one of the repeaters (Pone Knob) was found to be without power around midnight. The siren system operators confirmed the second repeater (Grandview) was still functioning. Approximately 5:00 a.m., however, communications were lost with the second repeater. A maintenance crew was dispatched to the second repeater on loss of communications and they determined the radio transmitter was not functioning at 0955 and Watts Bar was immediately notified. This event is reportable under 10 CFR 50.72(b)(3)(xiii) as a loss of emergency preparedness capability. . As a result of the above siren loss, TVA notified the Tennessee Emergency Management Agency (TEMA) at 10:13a.m. Sept. 17, 2004. This government agency notification is reportable under 10 CFR 50.72(b)(2)(xi). No TVA press release is planned and TVA is not aware of any specific actions planned to be taken by TEMA. Maintenance activities to restore power to the first repeater station by the use of a portable generator are underway. The 99 sirens constitute 100% of the emergency siren capability. The licensee had no estimate for completion of repairs and restoration of the siren capability. The licensee informed the State of Tennessee and the NRC Resident Inspector.
Restoration of power by use of a portable generator has been completed, reducing the number of non-functional sirens to seven of ninety-nine. The licensee informed local and State authorities, and the NRC Resident Inspector. Notified R2 DO (A. Boland). | |
| ENS 41054 | 19 September 2004 08:56:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip in Response to Indication of Dropped Control Rods | The following was received from the licensee via facsimile: While operating at 100% power, the Watts Bar Unit 1 reactor was manually tripped at approximately 0456 EDT on September 19, 2004, in response to an apparent four dropped rods in control bank 'B'. The cause of the dropped rods is being investigated. Safety systems functioned as expected in response to the trip. All control rods inserted properly in response to the reactor trip. The Auxiliary Feedwater (AFW) System actuated as designed in response to the trip. One reactor coolant pump (RCP) did not transfer to its alternate power supply. The manual actuation of the Reactor Protection System (RPS) is being reported as a four hour report under 10 CFR 50.72 (b)(2)(iv). The actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv). Notification to NRC was made by Rick O'Rear at 0744 EDT. The NRC Senior Resident Inspector was notified of this event. The licensee also reported that the reactor is being maintained at the normal temperature and pressure for this condition. All station service electrical systems and the emergency diesel generators are available and in normal configuration. All emergency core cooling systems are available. Decay heat is being removed using steam dump to the main condenser and feedwater to the steam generators is being provided by the electric main feedwater pump. | |
| ENS 41183 | 15 September 2004 14:14:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Vent Isolation Valve | The following information is provided as a 60 day telephone notification to NRC under 10 CFR 50.73(a)(1) in lieu of submitting a written LER to report a condition that resulted in an invalid actuation of the WBN (Watts Bar Nuclear) Train A Containment Vent Isolation signal. NUREG1022 Revision 2 identifies the Information that needs to be reported as discussed below. (a) The specific train(s) and system(s) that were actuated. On September 15, 2004, at 0914 EDT, a Train A Containment Vent Isolation (CVI) signal was received when the A Train Containment Purge Radiation Monitor momentarily spiked above the High Radiation Trip set-point. The B Train Containment Purge system was in operation at the time of the CVI signal and automatically shutdown as designed. (b) Whether each train actuation was complete or partial. The actuation was considered complete. The CVI signal for Train A automatically isolated the containment ventilation system as designed. The A Train Containment Purge Radiation Monitor was removed from service and considered inoperable due to no supporting indication of actual radiation by redundant radiation monitors or recorded trend data. (c) Whether or not the system started and functioned successfully. Train A Containment Vent Isolation signal automatically actuated and functioned successfully. The CVI signal was not in response to an actual plant condition. Maintenance on the Train A Containment Purge Radiation Monitor, revealed a loose connection in the detector cable. The radiation monitor was repaired and returned to service and the containment ventilation air cleanup unit was also returned to service." The NRC Resident Inspector was notified of this by the licensee. | |
| ENS 41400 | 10 February 2005 22:01:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Tritium Sample Exceeding Offsite Dose Calculation Manual (Odcm) Reporting Level | The following information was obtained from the licensee via facsimile: On 2/10/2005 with Watts Bar, Unit 1 operating at 100 percent Reactor Power, TVA plans to voluntarily notify the State of Tennessee's radiological and environmental health agencies and Department of Energy that a tritium sample obtained from a onsite monitoring well was confirmed to be above the Offsite Dose Calculation Manual (ODCM) reporting level for ground water samples. This result was for an ODCM required composite sample obtained over a month (12/29/04 through 1/25/05). On 2/8/2005, Chemistry confirmed this result and established a team to investigate the source of this contamination, the cause of the increased tritium levels, and the extent of where the tritium is found. Additional samples have been collected from selected monitoring wells, and the results of these tests are being analyzed. At this time, there is no indication of any offsite release, there is no threat to the public or company employees, and the situation does not pose a public health hazard. This notification is in accordance with 10 CFR 50.72, (b)(2)(xi), 'News Release or Notification of Other Government Agency'. The licensee has notified the NRC Resident Inspector. | |
| ENS 41482 | 11 March 2005 19:29:00 | Other Unspec Reqmnt | It Was Determineded That Greater than 1% of Inspected S/G Tubes Must Be Repaired. | As part of the Cycle 6 refueling outage, inspections are being performed in accordance with Technical Specification (TS) 5.7.2.12, 'Steam Generator (SG) Tube Surveillance Program.' Based on a review of the inspection results to date, it was established at approximately 14:29 EST on March 11, 2005, that greater than 1 percent of the inspected SG tubes must be repaired. In accordance with the criteria stated in TS 5.7.2.12 and the inspection findings, the four SGs must be classified as C-3. The current inspection results do not meet the criteria specified for steam generator tube degradation in Revision 2 of NUREG 1022, 'Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73.' However, for the C-3 classification, WBN TS Table 5.7.2,12-1, 'SG Tube Inspection Supplemental Sampling Requirements,' requires that the results of the inspection be reported under 10 CFR 50.72. At this time, the submittal of a Licensee Event Report in accordance with 10 CFR 50.73 is not planned. The NRC Resident Inspector was notified. | |
| ENS 42140 | 14 November 2005 16:41:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Cladding Failure to One Spent Fuel Rod Found During Inspection of Spent Fuel in the Spent Fuel Pool | On November 14, 2005, WBN was operating at 100% power and an inspection of spent fuel stored in the spent fuel pool (SFP) was being performed. The inspection confirmed that an opening existed in one rod (P9) located in G45 fuel assembly. This assembly is a 17 x 17 Vantage +/Performance + (V+/P+) fuel assembly and it has been used in the core during two previous cycles. The inspection noted some rod cladding failure different than what could be expected. TVA is making a non-emergency notification in accordance with 10 CFR 50.72(b)(3)(ii)(A). For this event, the cladding failure could be considered to exceed expected values. TVA's investigation of the cause of the rod failure is currently ongoing. The NRC Resident Inspector was notified of this event by the licensee. | 05000390/LER-2005-002 |
| ENS 42610 | 30 May 2006 21:00:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip on High Turbine Vibration | At approximately 1700 hours on May 30, 2006, with Watts Bar Nuclear Plant Unit 1 operating normally at 100% power, main turbine vibration increased to a value above the procedure limit and reactor operators manually tripped the reactor in accordance with site procedure requirements. All control rods inserted and the auxiliary feedwater system automatically actuated per design. No other significant equipment issues were identified and the reactor was stabilized in mode 3. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) for the manual reactor trip (4-hour report) and under 10 CFR 50.72(b)(3)(iv)(A) for the RPS and AFW actuations (8-hour report). Watts Bar had been monitoring indications of slightly elevated turbine vibration on the main turbine, but the reason for the increase above the procedure limit of 14 mils is not known at this time. TVA will be investigating the cause of the increased vibration to make necessary repairs before turbine startup. Decay heat is being removed by dumping steam to the main condenser. No safety or relief valves lifted. The licensee notified the NRC Resident Inspector.
As a result of the initial assessment of the turbine vibration discussed above, TVA has identified damage to the turbine end of the 'C' low pressure turbine. This is consistent with the initial indications of high vibration on the number 7, 8 and 9 bearings and not thought to be associated with previous condition monitoring of the number 11 bearing. Assessment and repair of secondary plant components damaged in the transient are in progress. The licensee will notify the NRC Resident Inspector. Notified R2DO (C. Ogle) | |
| ENS 42690 | 7 July 2006 18:45:00 | Other Unspec Reqmnt | Alternative Report for Non-Declared Emergency Condition in Accordance with Nureg-1022 | On July 7, 2006, at 1445 hours with Watts Bar Unit 1 at 100% power, operations were underway to prepare to sluice resin to the spent resin storage tank. Due to a suspected valve alignment anomaly, approximately 60 gpm from the CVCS volume control tank transferred thru the cation vessel to the tritiated drain collector tank. This is considered identified leakage in accordance with EAL 2.6 RCS Leakage greater than 25 gpm. This condition was immediately corrected within about 3.5 minutes but could have met the conditions for a NOUE had the event continued. Accordingly a NOUE was not declared, but this NRC ENS notification is being made in accordance with NUREG-1022 as an acceptable alternative to the immediate notification requirement of 50.72(a)(1)(i). The licensee informed the NRC Resident Inspector. | |
| ENS 42744 | 31 July 2006 16:13:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip Due to Main Generator Trip | At approximately 1213 hours on July 31, 2006, with Watts Bar Nuclear Plant Unit 1 operating normally at 100% power, the main generator tripped resulting in a reactor trip per design. All control rods inserted (fully) and the auxiliary feedwater system (AFW) automatically actuated per design and the reactor was stabilized in mode 3. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) for the reactor trip (4-hour report) and under 10 CFR 50.72(b)(3)(iv)(A ) for the RPS (reactor protection system) and AFW actuations (8-hour report). The cause of the generator trip is currently under investigation. Steam is being released via steam dump to the condenser and all systems functioned as required. The licensee notified the NRC Resident Inspector. | |
| ENS 42746 | 1 August 2006 07:35:00 | 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Rcs Pressure Boundary Leakage | At approximately 0335 EDT, LCO 3.4.13, RCS Operational Leakage, Action C was entered due to the identification of a pressure boundary leak. Reactor Coolant System (RCS) leak is believed to be a small pinhole on the weld on the downstream side of the check valve on Loop 1 Cold Leg Safety Injection Line. The estimated RCS leak rate is 0.1 gallons per minute. The Unit was in Mode 3 at the time of discovery. This event is being reported under 10 CFR 50.72(b)(3)(ii)(A). The plant is currently evaluating the appropriate repair method for this condition. The licensee notified the NRC Resident Inspector. | |
| ENS 43002 | 21 November 2006 11:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Unidentified Leakage | Licensee reported 20 GPM of unidentified leakage from indication of VCT lowering level. RCS pressure is 50 psig. Source of the leak has not been identified and it is not known at this time where the RCS leakage is going. All air and liquid releases are within specifications and no protective action recommendations are needed at this time. The licensee has notified the State and Local emergency agencies. The licensee will notify the NRC Resident Inspector.
Unidentified leakage is now calculated to be 2 GPM based on inventory balance using charging and letdown flow and VCT level. It is believed that the indication of a leak may be from an incomplete vacuum fill of the S/G after the S/G replacement modification and when the RCS was pressurized, the remaining voids in the S/Gs were filled. There has been no visible leakage found outside of the RCS. Notified NRREO (Wermiel), R2DO (Haag), IRD Manager (Wilson / Leach).
The licensee terminated the Unusual Event (UE) at 0737 due to indicated RCS leakage being less than 2 GPM. The site's emergency action criteria for a UE is 10 GPM unidentified leakage. No water has been found to have leaked outside the RCS. The licensee notified the NRC Resident Inspector. Notified NRREO (Wermiel, Ross-Lee), R2DO (Haag), IRD Manager (Wilson, Leach), DHS SWO (Gray), FEMA (LaForty)
The cause of the apparent leakage is under investigation by plant and TVA personnel. No actual leakage is believed to have transpired. Current plant conditions are stable. The licensee notified the NRC Resident Inspector. Notified R2DO (Haag), NRREO (Ross-Lee), IRD Manager (Wilson)
As a result of the declaration of a Notification of Unusual Event earlier today relative to a suspected RCS leak, a News Release is being made. The purpose of the release is to clarify to local officials and residents the nature of the suspected leak and the actions taken by school officials. The cause of the suspected leak remains under investigation. The licensee notified the NRC Resident Inspector. Notified R2DO (Haag). | |
| ENS 43894 | 11 January 2008 20:10:00 | 10 CFR 76.120(a)(4) | Discovery of an After the Fact Unusual Event | At 1510, "(Watts Bar Nuclear (WBN)) had identified RCS leakage in excess of 25 gallons per minute (gpm). The leakage was estimated at 105 gpm. This is a report notification only and not a declaration. The EAL that was exceeded was 2.6, RCS identified leakage. While placing a mixed bed demineralizer in service VCT level was observed to have dropped 10%. The demineralizer was immediately removed from service. This terminated the drop in VCT level. In accordance with WBN EPIP-1 Emergency Classification Flowchart, section 3.0 step 3.3.7, if an EAL was exceeded but the emergency has been totally resolved (prior to declaration), the emergency condition that was appropriate shall not be declared but reported only. The duration of the leakage was approximately 15 minutes. The unit remains at mode 1 and 100% power. The cause for the unexpected level decrease is under investigation at this time. There were no radiological releases associated. The licensee will notify the NRC Resident Inspector.
The original report contains a typographical error. The leak duration was reported as 15 minutes. The correct time period is 1.5 minutes. Notified R2DO(Moorman)
On January 11, 2008, TVA notified the NRC of the discovery of an after the fact unusual event. The reported event described potential RCS leakage in excess of 25 GPM that was approximately 1 and 1/2 minutes in duration. The estimated magnitude of this leak was based on a step change in Volume Control Tank (VCT) level that occurred when placing the 1A Mixed Bed Demineralizer in service. TVA's post-event investigation concluded the cause of the VCT level change was the filling of a void in the 1A Mixed Bed Demineralizer. The cause of the void was a procedural deficiency in the flush methodology used when returning the demineralizer to service. Based on the evaluation of this event, TVA has concluded that no actual RCS leakage occurred. The RCS pressure boundary remained intact throughout this evolution. Based on the result of this evaluation and the subsequent successful alignment of the demineralizer without incident, TVA is retracting this event. The licensee has notified the NRC Resident of this retraction. Notified the R2DO (Munday) and NRR EO (Brown). | |
| ENS 43957 | 4 February 2008 15:20:00 | 10 CFR 20.1906(d)(2) | External Readings Exceeded Allowable Dose Rate | On February 4, 2008 at approximately 10:20 EST, the Radiation Protection organization at Watts Bar Nuclear Plant (WBN), notified the Shift Manager (Licensed SRO) that a shipment of miscellaneous equipment exceeded the 200 mrem/hour dose rate specified in 10 CFR 71.47. The equipment was being received for use in an upcoming refueling outage. Radiation Protection surveyed the shipping container and obtained a reading of approximately 2000 mrem/hour. In accordance with 10 CFR 10.1906(d) the final delivery carrier has also been notified. This immediate notification is being made in accordance with the requirements of 10 CFR 20.1906(d)(2) and 10 CFR 71.47. The licensee notified the NRC Resident Inspector. | |
| ENS 44085 | 21 March 2008 13:13:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | System Injection Determined Inoperable by Failure to Remove Electrical Jumper Prior to Mode Change | In accordance with Instrument Maintenance Instruction (IMI) 99.040, 'Auto Safety Injection (SI) Block, Feedwater Isolation Block, and Maintain Source Range In Service Jumpers,' jumpers were placed to block the SI automatic actuation logic and actuation relays during WBNs (Watts Bar Nuclear) Cycle 8 refueling outage. The automatic actuation function for SI is required in Modes 1, 2, 3, and 4 per Function 1.b of Table 3.3.2-1 of Technical Specification (TS) 3.3.2, 'ESFAS Instrumentation.' WBN entered Mode 4 at 0020 EDT on March 20, 2008 and Mode 3 at 0100 EDT on March 21, 2008. On March 21, 2008, it was discovered that the jumpers installed per IMI-99.040 had not been removed. Due to this, Limiting Condition for Operation (LCO) 3.0.3, was entered at 0913 EDT and exited at 0958 EDT when the system was restored. The jumpers being in place in Mode 4 and 3 rendered both trains of SI automatic actuation inoperable for approximately 33 hours and 38 minutes. This event is being reported under 10 CFR 50.72(b)(3)(v)(D), 'Event or Condition that could have Prevented Fulfillment of a Safety Function.' The licensee attributes the error to a combination of both procedural inadequacy (i.e., the step removing the jumper did not require verification) and personnel error. The licensee informed the NRC Resident Inspector.
This is a follow-up notification to EN#44085 to amend reported information. At 2133 on 3/21/08 when permissive P-11(Low Pressure and Low Steamline Pressure) blocks were cleared, the on-shift crew questioned the presence of the 'AUTO SI Blocked' alarm and determined that it should have been cleared when the SI automatic logic jumper was removed earlier in the day. The crew utilized the procedural guidance of GO-1 to cycle the reactor trip breakers and reinstate the automatic safety injection logic at 2206 on 3/21/08. The previous report that identified that LC0 3.0,3 was exited at 0958 EDT is to be amended. LCO 3.0.3 was exited at 2206 when SI automatic logic was completely reinstated by cycling the reactor trip breakers. The licensee notified the NRC Resident Inspector. Notified R2DO(Ernstes) | 05000391/LER-2016-001 05000390/LER-2008-001 |
| ENS 44160 | 23 February 2008 04:00:00 | 10 CFR 50.73(a)(1), Submit an LER | 60-Day Verbal Notification of Invalid Specified System Actuation | On February 23, 2008, a control room operator was aligning the Containment Purge system for Train B operation and triggered an invalid Containment Vent Isolation (CVI) and Auxiliary Building Isolation (ABI). The operator was removing Train A of the system from operation in accordance with system Operating Instruction (SOI) 30.02, 'Containment Purge System'. The operator made an incorrect assumption that a portion of SOI 90.02, 'Gaseous Process Radiation Monitors', that would have properly blocked and aligned power to the Purge Radiation Monitors had been performed. Therefore, when the operator proceeded with the next step in realigning the radiation monitors, a spike occurred on Radiation Monitor 1-RM-90-131. This caused an invalid actuation of Train B of the CVI and ABI systems. Operators verified the isolation and its cause, and suspended movement of irradiated fuel within the Spent Fuel Pool in response to the Train B CVI/ABI signal. The ABI/CVI signal was reset and Auxiliary Building ventilation was restored in accordance with SOI 30.05, 'Auxiliary Bldg HVAC Systems'. The following information addresses the criteria for a 60 day verbal report defined in Section 3.2.6, 'System Actuation' of NUREG 1022, 'Event Reporting Guidelines 10 CFR 50.72 and 50.73'. This telephone notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A). (a) The specific train(s) and system(s) that were actuated: The spike on the Radiation Monitor initiated an invalid actuation of Train B of the CVI system and ABI system. (b) Whether each train actuation was complete or partial: The Train B CVI and ABI actuation was complete. (c) Whether or not the system started and functioned successfully: The system started and functioned successfully, and all components operated as expected. The licensee has notified the NRC Resident Inspector. | |
| ENS 44363 | 24 July 2008 19:02:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Tech Spec Required Shutdown Due to Loss of Essential Raw Cooling Water Pump with 2 Edg'S Oos | WBN Unit 1 experienced a failure of the B-A ERCW pump on July 21, 2008, at 2:46 p.m. EDT. The plant entered LCD 3.7.8, Condition A, for one ERCW train inoperable and LCD 3.8.1, Condition C, with two required DGs in Train A inoperable concurrently. Required Actions for LCO 3.7.8 and LCD 3.8.1 required restoration of the inoperable ERCW train and one DG to OPERABLE status in 72 hours, respectively. Plant shutdown was initiated in accordance with LCD 3.7.8, Condition B and LCD 3.8.1, Condition G when the above Required Actions were not met. The root cause of the pump failure is unknown at this time. An event team has been set-up to determine cause of pump failure. Currently, the unit is performing a control shutdown, and all systems are functioning as expected. The licensee does not expect the ERCW pump to be returned to service and will downpower at 15% per hour. The licensee expects to be in Mode 3 by 2030 EDT. All required safety systems for safe shutdown are operable. The licensee has notified the NRC Resident Inspector.
The TS required shutdown has been terminated on 7/24/08 at 1910 EDT, based on the receipt of an Emergency TS change. The plant exited LCO 3.8.1, Condition C and LCO 3.7.8, Condition A, and entered new LCO 3.7.8, Condition C. The revised TS will allow continued operation for an additional 7 days based, in part, on the implementation of an NRC approved Temporary Alternation. It is expected that the failed ERCW pump will be repaired within the new 10 day allowed outage time as specified in the Emergency TS change for LCO 3.7.8, Condition C (3 days were already used due to the inoperability of the B-A ERCW Pump occurred on 7/21, this leaves approximately 7 days left in the new action time.) The licensee notified the NRC Resident Inspector. Notified R2DO(Lesser). | |
| ENS 44388 | 7 August 2008 06:28:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Trip from 50% Power Following Low Pressure Heater String Isolation | On August 7, 2008 at 0228 EDT, TVA was reducing reactor power in preparation for a planned reactor shut down. While at approximately 50% power, the feedwater system isolated due to high levels in the low pressure heater strings. Based on the condition stated, the reactor was manually scrammed. All systems functioned as designed in response to the scram. The plant is currently being maintained in Mode 3 Hot Standby condition. All control rods fully inserted on the manual trip. Decay heat is being removed via auxiliary feedwater to the steam generators steaming to the main condenser. Offsite power is supplying safety buses and emergency diesel generators are available if required. The licensee notified the NRC Resident Inspector. | |
| ENS 44506 | 20 September 2008 13:06:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Reactor Trip Due to Turbine Trip | At 0906 EDT Watts Bar Unit 1 experienced a Reactor trip in response to a Turbine trip. This caused an automatic AFW Pump start from P-4 coincident with Lo Tave signal. First indications are that the Exciter Field Breaker tripped open. The cause is under investigation. All ESF systems responded as designed with no other issues. The plant is currently stable and is being maintained in Mode 3. Plans for plant restart are pending awaiting the cause investigation. All control rods fully inserted into the core. Plant decay heat removal is through the steam dumps to the main condenser. The offsite power is available and lined up to plant system loads. The licensee notified the NRC Resident Inspector. | 05000390/LER-2008-004 |
| ENS 44632 | 6 November 2008 03:54:00 | 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | Both Trains of Control Room Emergency Air Temperature Control Declared Inop | WBN Unit 1 initiated a Tech Spec required shutdown at 2254 on 11/05/08. The plant entered TS 3.0.3 at 2135 on 11/05/08 due to both trains of Control Room Emergency Air Temperature Control (CREATCS) being declared inoperable. Initially Train 'B' CREATCS was inoperable due to the scheduled maintenance of Train 'B' auxiliary air system. With one train of Aux Air inoperable this renders that respective train of CREATCS inoperable. During this planned maintenance the 'A' train CREATCS chiller lost ability to cool the Main Control Room due to a failure in the control circuitry. This rendered 'A' train inoperable which led to entry into TS 3.0.3 for both trains CREATCS being inoperable. The plant exited TS 3.0.3 at 2345 on 11/05/08 upon completion of Post Maintenance Testing on the train 'B' Aux Air system and return to operability of the 'B' train Aux Air and therefore the 'B' train of CREATCS. The planned plant shutdown was stopped upon exit of TS 3.0.3 at 2345 11/05/08 and Rx power restored to 100%. The licensee notified the NRC Resident Inspector | |
| ENS 44721 | 15 December 2008 18:33:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Report | A non-licensed employee supervisor had a confirmed positive for illegal drugs during a random fitness-for-duty test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee has notified the NRC Resident Inspector. | |
| ENS 44752 | 5 January 2009 05:00:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Involving Unit 2 Construction Employee | A non-licensed contract employee was discovered to be in possession of an illegal substance inside the Unit 2 side of the common protected area following a for cause investigation. The contract employee was working in the construction of Unit 2. The contract employee's badge and access to the plant has been revoked. Contact the Headquarters Operations Officer for additional details. The licensee has notified both the Unit 1 and Unit 2 NRC Resident Inspectors. | |
| ENS 45110 | 27 May 2009 23:05:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Both Trains of Auxiliary Building Gas Treatment System Rendered Inoperable | On May 27, 2009, Plant Operations was shutting down the Auxiliary Building General Ventilation system (ABGTS) as a compensatory measure in response to an historical deficiency that was identified in the surveillance procedure for conducting TS SR 3.7.12.4. The building's general ventilation was being shut down to place the plant in a known tested configuration to ensure continued safe operation while plans were being developed to properly perform SR 3.7.12.4. While shutting down the building's ventilation system, the operator shut down the building's supply fans followed by the shut down of building's exhaust fans. This sequence resulted in an unacceptable differential pressure condition across a set of Auxiliary Building Secondary Containment Enclosure (ABSCE) doors. Upon identification of the failed doors at 1905 EDT on May 27, the plant entered TS Condition 3.7.12.B for 2 trains of ABGTS being inoperable. Repairs to re-establish the integrity of the ABSCE were immediately initiated and TS Condition 3.7.12.B was exited at 2239 EDT, approximately 3 and 1/2 hours later. The reportability of this condition was not recognized at the time of this event. Based upon a review subsequent to the event on June 1, 2009, this event was determined to be reportable under 10 CFR 50.72(b)(3)(v)(C) and (D) as a condition that could have prevented the safety function of structures or systems that are needed to: (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident. The licensee has notified the NRC Resident Inspector. | |
| ENS 45170 | 27 June 2009 17:20:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | Auxiliary Building Gas Treatment System Rendered Inoperable | On June 27, 2009, Plant Operations was starting up the U2 (Unit 2) Auxiliary Building General Ventilation System upon completion of U2 damper maintenance. During startup of the U2 Auxiliary Building Ventilation System, the operator started the U2 General Exhaust fan followed by the startup of the U2 General Supply fan. During the time span of less than 1 minute, when the U2 General Exhaust fan was running but before the U2 General Supply fan was running, the differential pressure condition across a set of Auxiliary Building Secondary Containment Enclosure (ABSCE) doors caused the doors to come off of the tracks and therefore created an ABSCE breach. A breach of this magnitude renders both trains of Auxiliary Building Gas Treatment System (ABGTS) inoperable. Upon identification of the failed doors at 1320 EDT on June 27, 2009 the plant entered TS Condition 3.7.12.B for 2 trains of ABGTS being inoperable. Repairs to re-establish the integrity of the ABSCE were immediately initiated and TS Condition 3.7.12.B was exited at 1649 EDT, approximately 3 and 1/2 hours later. This event is reportable under 10 CFR 50.72(b)(3)(v)(C) and (D) as a condition that could have prevented the safety function of structures or systems that are needed to : (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident. The licensee has notified the NRC Resident Inspector. | |
| ENS 45210 | 17 July 2009 21:42:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Actuation of Emergency Diesel Generators Due to Loss of Power to Safety Related Bus | At 1742 EDT on July 17, 2009, while attempting to restore normal alignment providing offsite power following repair of the 'D' Common Station Service Transformer (CSST), the transfer from the alternate to the normal power supply for the 6.9kV Shutdown Board 2B-B failed because of an apparent failure of the interlock that should have prevented closing the normal breaker until an undervoltage condition existed on the alternate feed. The emergency diesel generators received a blackout signal and all four diesel generators started. Loads transferred and shed properly, and all systems functioned as expected. WBN (Watts Bar Nuclear) had been in LCO 3.8.1 condition A since 0032 EDT on July 16, 2009 due to the outage of the D CSST. Because loads did not transfer to the offsite power source, WBN remains in LCO 3.8.1 A which requires restoration of the offsite power supply by 0032 EDT 7/19/2009. All systems are operating properly and the plant is stable. Troubleshooting and maintenance has begun and WBN anticipates return of the normal offsite power supply to the 2B-B Shutdown Board within the time required by technical specifications. This event is reportable under 10 CFR 50.72(b)(3)(iv) as an event or condition that resulted in valid actuation of the emergency diesel generators. The licensee has notified the NRC Resident Inspector The 6.9kV Shutdown boards at Watts Bar are safety related busses. The electrical configuration prior to the event had the 1A-A and 2A-A Shutdown Boards aligned to their normal offsite power source. The 1B-B and 2B-B Shutdown Boards were aligned to an alternate offsite power source because their normal source, the 'D' CSST had been out of service for repairs. Following completion of the repairs to the 'D' CSST, the licensee attempted to restore normal offsite power to the 2B-B Shutdown Board from the 'D' CSST using a fast transfer from the alternate power supply. For unknown reasons, the normal supply breaker attempted to close onto the 2B-B bus before the alternate supply breaker had opened. This, in effect, would have paralled both the primary and alternate sources of power to the 2B-B bus. An interlock prevents paralleling these two sources and resulting in both supply breakers tripping and the bus being de-energized. This generated a blackout signal that started all four emergency diesels generators (EDGs). All the EDGs started as required, only the 2B-B loaded onto its associated shutdown bus, as expected, because of the bus had been de-energized. The other busses (1A-A, 1B-B, and 2A-A) remained energized and the associated EDGs did not load. The 1A-A, 1B-B, and 2A-A EDGs were shutdown and returned to a standby condition. The 2B-B EDG continued to power the 2B-B Shutdown Board while the licensee investigated the fast transfer problem. All systems functioned as required during this event except for the 2B-B fast bus transfer from the alternate to normal offsite power supply. | |
| ENS 45215 | 21 July 2009 12:03:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Report - Contract Supervisor Tested Positive for Alcohol | A non-licensed supervisory contractor employee had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access has been revoked. Contact the Headquarters Operations Officer for additional details. The licensee has notified the NRC Resident Inspector. | |
| ENS 45331 | 8 September 2009 01:20:00 | Other Unspec Reqmnt | Discovery of After-The-Fact Emergency Condition Unusual Event | This report documents a condition in which WBN (Watts Bar Nuclear) Unit 1 met the criteria to declare a NOUE (Notification of Unusual Event) based on RCS (Reactor Coolant System) unidentified leakage. Prior to declaration, the event was terminated thus no declaration was made. This event is reportable within one hour as an acceptable alternative to reporting in accordance with 10CFR50.72(a)(1)(i) - declaration of any of the emergency classes specified in the licensees approved emergency plan. During tagout installation in support of planned maintenance on the cation bed flush valve (1-FLV-62-921) in the CVCS/Letdown system, isolation boundary valve leakage of approximately 80 gpm was present for approximately three minutes. The leakage was terminated by reclosing opened vent (1-VTV-62-917) and drain valves (1-DRV-62-920). Cation Bed Inlet (l-ISV-62-915) and Outlet (1-ISV-62-916) and all other boundary valve isolations were verified to be in the correct, closed position per the tagout instructions. This RCS leakage was directed to the Tritiated Drain Collector Tank, thus all leakage was contained within plant systems and no radiological releases resulted. A work order will be initiated to troubleshoot and repair the faulty isolation valve. This amount of leakage is in excess of the amount specified in WBN Emergency Plans for declaration of an NOUE based on >10 gpm unidentified leakage per EAL 2.5. Prior to declaration, the event was terminated, thus no declaration was made. The State of Tennessee and the NRC Resident Inspector has been notified.
Event Notice 45331 reported a condition in which WBN Unit 1 conservatively determined it met the criteria to declare a NOUE based on RCS unidentified leakage. Prior to declaration, the event was terminated thus no declaration was made. Based upon further review and discussion with others in the industry, the NOUE criterion cited, EAL 2.5, applies to specific sources of excessive RCS leakage. The source of the leakage discussed in the event has been confirmed as CVCS leakage, not RCS leakage. An action to clarify the basis and scope of this EAL is being pursued within TVA's Corrective Action Program. Therefore, Event Notice 45331 is being retracted. The NRC resident has been notified. Notified the R2DO (Blamey). | |
| ENS 45531 | 30 November 2009 19:27:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Non-Licensed Supervisor | A non-licensed contractor supervisor had a confirmed positive for illegal drugs during a random fitness-for-duty test. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. The licensee notified the NRC Resident Inspector. | |
| ENS 45827 | 8 April 2010 04:00:00 | Other Unspec Reqmnt | Diesel Generators Wired Incorrectly | Action F of LCO 3.8.1, 'AC Sources - Operating,' was entered at 20:57 EDT April 7, 2010 for the 2A-A and the 2B-B diesel generators (DGs) being inoperable. Action F has a two hour allowed outage time (AOT). The DGs were determined to be inoperable due to incorrectly implemented wiring changes made by personnel performing construction work on Watts Bar Unit 2. The impact of the change is that during (an) actual or simulated ESF actuation signal, if the diesel is in test mode, and the output breaker is closed in parallel with the board supply breakers, the DG would not return to a 'ready to load' state meaning the output breaker would not have opened as designed for this condition. This function is tested as required on an 18 month frequency as a part of Surveillance Requirement (SR) 3.8.1.17. The wiring changes which affected the DGs were made in accordance with Unit 2 Work Order (WO) 09-954447 and 09-954448. The WOs as developed would not have an impact on Unit 1 operations. A review of the Unit 1 Operator Logs from January 1, 2010 to present, did not find any entries establishing the Unit 2 work had been authorized by Unit 1. The proper technical specification entry would have been Action 8 of LCO 3.8.1 for this activity. Entry into Action B of LCO 3.8.1 requires the implementation of several actions including a verification of the operability of the offsite circuits. Since these Technical Specification required actions were not complied with, WBN is providing this 24-hour notification in accordance with Section 2.G of the Watts Bar Unit 1 Facility Operating License. During the review of work performed by Unit 2 it was identified that the wiring was initially lifted on January 6. 2010. At the time of this report, actions have been taken to restore the wiring to its appropriate configuration on both of the DG circuits. 2B-B DG wiring was restored at 22:18 on April 7, 2010 and the 2B-B DG was declared operable. Action F of LCO 3.8.1 was exited at this time and Action B was entered for the 2A-A DG (14 day AOT). 2A-A DG circuitry was restored at 00:37 on April 8, 2010, and all LCO actions were exited. This event has been entered into TVA's corrective action program and actions are being initiated to establish the reason the leads were incorrectly lifted and to verify that no other similar wiring issues exist. The licensee notified the NRC Resident Inspector. * * * RETRACTION FROM WES DANIEL TO PETE SNYDER AT 1646 ON 5/10/10 * * * The Watts Bar Nuclear Plant (WBN) Unit 2 diesel generators (DGs) were not inoperable. The Unit 2 DGs were initially declared inoperable because of an inappropriate wiring change that disabled a DG output breaker trip in the event of an actual or simulated ESF actuation signal while the DG is in test mode and the output breaker is closed in parallel with the board supply breakers. Because Surveillance Requirement (SR) 3-8.1.17 required verification of this function for the Unit 1 DGs, and TVA was uncertain of the impact of the loss of this function to the Unit 2 DGs, TVA conservatively declared the Unit 2 DGs inoperable because they would not be able to meet this SR. Upon review TVA determined that it was proper to exclude this surveillance requirement for the Unit 2 DGs. Since SR 3.8.1.17 only applies to Unit 1 DGs, inability of Unit 2 DGs to meet this requirement is not a basis for inoperability. TVA has concluded that the Unit 2 DGs and offsite power sources were operable, and WBN was in compliance with its Technical Specifications throughout the period that the wiring change was installed. Therefore, this event was not reportable under WBN License (NPF-90) Condition 2.G, 10 CFR 50.72, or 10 CFR 50.73. The licensee notified the NRC Resident Inspector. Notified R2DO (O'Donohue). | |
| ENS 45944 | 21 May 2010 23:37:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip on Turbine Trip | At 1937 Eastern Daylight Saving Time (EDT), Watts Bar Nuclear Power Plant Unit 1 experienced a reactor trip due to a turbine trip. This caused an automatic AFW Pump start from P-4 coincident with Lo Tave signal. The cause of the turbine trip has not yet been identified, and is under investigation. The plant is stable and is being maintained in Mode 3, at normal operating pressure and temperature, with steam generator and pressurizer levels normal. Plant systems responded to return the plant to a stable condition without complication, and all systems performed as expected with one exception: The 'B' Motor Driven Auxiliary Feedwater Backpressure Control Valve failed closed, but the Steam Driven Auxiliary Feedwater Pump provided sufficient feedwater so that all Steam Generators were provided sufficient feedwater to maintain cooling and normal steam generator level. Plans for plant restart are pending awaiting the cause investigation. All control rods inserted into the core. Plant decay heat removal is through the steam dumps to the main condenser. Offsite power is available and lined up to plant system loads. Watts Bar (NRC) Resident Inspector has been notified of this event. | |
| ENS 46177 | 15 August 2010 19:24:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Valid Aux Feedwater System Actuation During Power Reduction for Turbine Maintenance | At 1524 EDT, on 8/15/2010, Watts Bar Nuclear Plant Unit 1 had a valid actuation of the Auxiliary Feedwater System in response to a trip of all Main Feedwater Pumps. The Auxiliary Feedwater Pumps were started manually in anticipation of the trip of all Main Feedwater Pumps. Main Feedwater Pump B had been tripped manually as part of the power reduction in preparation for taking the Main Turbine offline to perform repairs on the Electrohydraulic Control System. Main Feedwater Pump A was tripped manually before it experienced a loss of suction in response to an unplanned isolation of the Intermediate Pressure Heater string. Following manual actuation of the Auxiliary Feedwater Pumps, reactor power was further reduced, and at 1526 (EDT), Watts Bar Unit 1entered MODE 2. No plant safety systems beyond Auxiliary Feedwater were required or actuated in response to this event. The plant was stabilized using Auxiliary Feedwater and the Main Steam dump valves. Operators followed their Abnormal Operating Instruction, and reactor trip was not required. This event is being reported as a valid actuation of the auxiliary feedwater system in accordance with 10 CFR 50.72(b)(3)(iv). Offsite power is normal and EDG's are operable. The licensee notified the NRC Resident Inspector. | |
| ENS 46418 | 14 November 2010 11:52:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Trip Due to Loss of Cooling to the 'A' Phase Main Bank Transformer | At 0617 (hrs. EST), Watts Bar experienced a failure of the cooling system to the 'A' phase Main Bank Transformer. Due to rising oil temperatures on the 'A' phase Main Bank Transformer, the reactor was manually tripped at 0652 hrs. All systems responded as designed with no issues. All rods inserted during the trip. There were no primary or secondary relief valves that lifted during the transient. The grid is stable and the plant is in a normal shutdown electrical line-up. The reactor is at normal pressure and temperature with decay heat being removed via the steam dumps to condenser with auxiliary feedwater providing steam generator make-up. The cause of the loss of cooling to the 'A' phase Main Bank Transformer was the failure of a control power transformer that supplies the Main Bank Transformer cooling system components. The licensee has notified the NRC Resident Inspector. | |
| ENS 46448 | 2 December 2010 21:10:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to an Individual Contamination | TVA notified TN Dept of Environment and Conservation (TDEC) of an incident at Watts Bar as follows: On December 2, 2010, a contractor employee of PAR-Westinghouse was processing in through Watts Bar Nuclear Plant Radiological Protection Program for his first day of work. He was discovered to have been previously contaminated with radioactive material from another worksite. It is clear that the radioactive contamination did not come from any TVA source and was found before he entered the rad control area. The contamination was discovered during required in-processing activities for workers by TVA's radiation monitoring and detection equipment. The contamination was found to be a particle on the individual's shoe. The individual's clothing was also found to contain measurable contamination and was confiscated. The radioactive contamination found on the individual has been safely contained. TDEC Division of Radiological Health was notified of this event as of 1610 Eastern Time and this notification under 10 CFR 50.72(b)(2)(xi) is for that Government Agency notification. TVA has notified the NRC Resident Inspector and Regional Administrator of this incident. | |
| ENS 46469 | 6 December 2010 13:15:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification - Osha Contacted Due to Fatality of Contractor Employee | At 0815 Eastern Standard Time on December 6, 2010, TVA Construction Contractor, Bechtel, notified the Occupational Safety and Health Administration (OSHA), in accordance with 29 CFR 1904.39, that a Bechtel employee had suffered a fatality from an apparent heart attack, while working on the Watts Bar Unit 2 Construction completion project. This information was also provided to Tennessee Department of Labor and Workforce Development, Division of Occupational Safety and Health (TOSHA). This event had no consequences to the health and safety of the public, other onsite workers, or the environment. The NRC Resident Inspector has been notified of this event. The employee's heart attack happened while he was operating a fork lift at the Parts/Receiving area. Offsite responders were called to the scene, however, the employee was unresponsive to their actions. Employee was transported to the Rhea County Hospital where he was pronounced dead. | |
| ENS 46812 | 3 May 2011 04:00:00 | 10 CFR 26.719, FFD Reporting requirements | Contract Supervisor Tested Positive for Illegal Drug | A contract supervisor had a confirmed positive for an illegal drug during a random fitness-for-duty test. The employee's access to the plant has been terminated. The licensee has notified the NRC Resident Inspector. Contact the Headquarters Operations Officer for additional details. | |
| ENS 46839 | 9 May 2011 19:18:00 | Other Unspec Reqmnt | Potential Valve Mispositioning Led to a Condition Prohibited by Technical Specifications | On May 9, 2011, at 1518 Eastern Daylight Saving Time (EDT), WBN (Watts Bar Nuclear) started a Safety Injection Pump and began to inject into the Reactor Coolant System contrary to Technical Specification Limiting Condition for Operation 3.4.12, which requires in part for Mode 5 that a Cold Overpressure Mitigation System (COMS) shall be OPERABLE with a maximum of one charging pump and no safety injection pump capable of injecting into the RCS and the accumulators isolated. The RCS pressure rise was recognized immediately, and the pump was secured within 27 seconds. The pressure reached a maximum of 328 psig. which is below the relief valve setpoint, so no structure, system, or component pressure limit was exceeded at any time. LCO 3.4.12 Condition A was entered immediately. At 1521, the pump breaker was directed to be racked out, and the breaker was reported racked out and verified by 1600, at which time LCO 3.4.12 was exited. This event was determined to be reportable as a condition prohibited by Technical Specifications in accordance with 10 CFR 50.73(a) (2)(i)(b). This notification is made in accordance with Watts Bar License condition 2.G. The NRC Resident Inspector has been notified of this event and event notification. The licensee is investigating the likelihood of a valve mispositioning. | |
| ENS 46885 | 14 May 2011 18:28:00 | Other Unspec Reqmnt | Violation of License Condition | On May 16, 2011, at 2013 Eastern Daylight Saving Time (EDT), Watts Bar Nuclear Plant Unit 1 (WBN) entered Technical Specification (TS) Limiting Condition for Operation (LCO) 3.7.5, Condition B, because based on performance of Surveillance Requirement (SR) 3.7.5.2, the Turbine Driven Auxiliary Feedwater system was determined to be inoperable. Failure of the surveillance was caused by loss of the ability to control the turbine driven auxiliary feedwater pump (TDAFWP) manually. This was the first operation of the TDAFWP since the turbine had been rebuilt and had a new governor and servo installed during the WBN refueling outage 10 in May 2011. Misalignment of the servo caused the controller to stick, so that the TDAFWP pump could not be controlled in manual. The servo was replaced and the TDAFWP subsequently passed its required surveillance. LCO 3.7.5 was exited at 1745 on May 19, 2011. Although the TDAFWP was not known to be inoperable until performance of the surveillance, TVA has concluded that the inoperability existed from the time that WBN entered Mode 3. WBN had entered Mode 3 at 1428 EDT, on May 14, 2011. LCO 3.0.4 prohibits MODE changes when an LCO is not met except under certain conditions that were not applicable to this event. Therefore, TVA considers that WBN entered Mode 3 without the required three operable trains of AFW. TVA also determined that the TDAFWP was inoperable for a period of 123 hours and 17 minutes while the plant was in Mode 3, which exceeded the 96 hours allowed for an inoperable train of AFW in LCO 3.7.5. (72 hours to restore, 6 hours to be in MODE 3, and 18 hours to be in MODE 4). It should be noted that actions were taken and completed within the required time from time of discovery of the condition. Changing MODEs when LCO 3.7.5 was not met, and exceeding the time allowed for an inoperable train of auxiliary feedwater (AFW) were determined to be reportable as a condition prohibited by Technical Specifications in accordance with 10 CFR 50.73(a)(2)(i)(b). Since these conditions are a violation of the requirements contained in Section 2.c of the WBN License (Technical Specifications), this notification is made in accordance with Watts Bar License condition 2.G. The NRC Resident (Inspector) has been notified. | |
| ENS 46902 | 29 May 2011 05:55:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Trip Due to Turbine Trip | At 0155 EDT, the Watts Bar Unit 1 reactor tripped from 100% power due to a turbine trip above P-9 (reactor trip on turbine trip permissive). The cause of the turbine trip is under investigation at this time. All systems functioned as designed with the exception of Pressurizer Backup Heaters which failed to energize on lowering Pressurizer pressure. The unit is stable in Mode 3 with Auxiliary Feedwater supplying the Steam Generators. The electrical system is in normal shutdown alignment with all Emergency Diesel Generators available in standby. There are no abnormal radiological conditions at this time. The reason the Pressurizer Backup Heaters failed to energize is unknown at this time. All control rods fully inserted. No relief valves or safety valves lifted. The licensee notified the NRC Resident Inspector. | |
| ENS 46967 | 16 June 2011 17:09:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Chemical Release from Intake Pumping Station. | A notification of the event discussed below was made to the Tennessee Department of Environment and Conservation (TDEC) at approximately 09:48 (hrs EDT) on June 17,2011. As a result of the notification made to the state, NRC is being notified in accordance with 10 CFR 50.72(b)(2)(xi), 'News Release or Notification of Other Government Agency.' On June 16, 2011, a chemical treatment of the raw water system for Watts Bar Nuclear Plant (WBN) was underway. The treatment was a routine injection of biocide (Sodium Hypochlorite and Flogard MS6237) for the treatment of microbiologically induced corrosion (MIC) and to inhibit the growth of asiatic clams. At approximately 13:09 (hrs EDT) on June 16, 2011, WBN personnel noticed that a small stream of water was releasing through the splash guard of a trough on the outside (lake side) of the Intake Pumping Station (IRS) and entering the Intake Forebay. This initial leak was secured by approximately 14:30. At approximately 14:35, a second leak from a broken pipe was identified. The second leak was terminated at approximately 16:05. The cause of the initial leak was determined to be a tree growing in a trough in the intake structure and degraded sealant on the trough's splash guard. TVA's (Tennessee Valley Authority) biologist performed a survey of the intake channel and the river downstream from the plant and found no dead fish or abnormal bird activity. TVA's review of the chemical release to the lake determined that no Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) reportable quantities were exceeded. The reporting requirements contained in WBN's Environmental Protection Plan (EPP) were reviewed and not found applicable to this event. WBN's (NRC) Resident Inspector has been notified of the event and the need for the event notification. | |
| ENS 47021 | 4 July 2011 17:36:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Offsite Notification Due to Spurious Siren Activation | TVA received notification from Tennessee Emergency Management Agency (TEMA) at 1336 Eastern Daylight Saving Time (EDT) that Rhea County 911 operators had received several calls (approximately 6) regarding a siren sounding in north Rhea County. An electronic poll of the siren closest to the location of the reporting parties (Siren 43) indicated no response, although that siren did successfully respond to the 0700 daily poll on 7/4/2011. This may indicate that this siren is not operable. A severe thunderstorm warning had been issued by the National Weather Service for the time period this potential activation was reported. During this period there were several spurious acoustic monitor alarms from three additional sirens, although there were no other indications of siren activations (e.g., rotate or timer signals). A field investigation has been initiated, and the siren will be repaired as needed in accordance with TVA's corrective action program. There was no plant event that required siren actuation, and all plant systems are operating as required. The licensee will notify the NRC Resident Inspector. | |
| ENS 47348 | 18 October 2011 00:50:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unit 1 Declared an Unusual Event Based on Ammonia Levels Exceeding Osha Limits | Normal Operation of WBN (Watts Bar Nuclear) Unit 1 impeded in the Turbine Building, El. 685, West side of the Unit 1 Main condenser due to Toxic Gas (ammonia) concentrations of 75-79 ppm exceeding the OSHA Permissible Exposure Limit (PEL) of 50 ppm, and the ACGIH (American Conference of Governmental Industrial Hygienists) limit of 25 ppm. WBN Unit 1 returned to approximately 100% RTP on Monday, October 17, 2011, following a maintenance outage. Suspect excessive ammonia concentrations due to condenser vacuum pump continuous drains which may need throttling open to increase drain flow, following Unit startup. (Ammonia is used to treat feedwater for secondary chemistry control). There have been no injuries from this event. NRC Senior Resident (Inspector) has been notified. (Event Class 4.4.A, Toxic Gas, Unusual Event). The licensee informed both the State and local agencies. Notified FEMA (Blankenship) and DHS (Konopka).
At 0047 EDT on 10/18/2011, the licensee terminated the Notification of Unusual Event condition based on ammonia concentrations having been reduced to approximately 6 ppm. Normal personnel access to the affected area has been restored. Unit 1 remained at 100% power during this event with no changes or challenges to plant operations. During the event there were no additional EAL designators. During the event there were no significant changes in plant conditions. During the event there were no significant changes in plant radiological conditions. During the event there were no offsite protective recommendations made by the licensee. The licensee notified the NRC Resident Inspector and State and local agencies. Notified R2DO (Lesser), NRR EO (Brown), IRD (Morris), DHS (Gates), and FEMA (Blankenship).
This information is being provided to the NRC for a 10CFR50.72(b)(2)(xi) notification. TVA is planning on making a news release to local media affiliates and posting the news release on TVA's website. This news release is in reference to the Notification of Unusual Event (NOUE) Watts Bar Nuclear Plant recently entered and exited for ammonia levels exceeding OSHA limits (reference EN 47348 and update). The licensee notified the NRC Senior Resident Inspector." Notified R2DO (Lesser). | |
| ENS 47388 | 28 October 2011 20:44:00 | 10 CFR 26.719, FFD Reporting requirements | Fitness for Duty Involving a Employee Supervisor | A non-licensed supervisor was arrested for possession of a controlled substance with the intent to distribute. The employee's access to the plant has been terminated. Contact the Headquarters Operations Officer for additional details. | |
| ENS 47609 | 17 January 2012 22:46:00 | Other Unspec Reqmnt | 24-Hour Report Per Section 2.G of Unit 1 Operating License | Surveillance Requirement 3.8.4.14 for LCO 3.8.4, "DC Sources - Operating," was performed on 02/10/11 for the 125 VDC Vital Battery 4 (VB4). The recorded capacity was 80.2% and VB4 was declared OPERABLE at that time. On 06/27/11 VB4 failed the service test as required by SR 3.8.4.13. Prior to the test VB5 was aligned to Vital Battery Board IV. VB5 had previously passed its required SRs within the required surveillance frequency. With VB5 re-aligned to Vital Battery Board IV, the plant was in a configuration that would allow it to meet all design bases events including a four hour station blackout. The eight weakest cells in VB4 were replaced and VB4 re-tested in accordance with SR 3.8.4.13. VB4 passed its acceptance criteria and VB4 was returned to service on 07/06/11. However, on 01/17/12, an independent analysis of the computer generated test data indicated that the actual battery capacity calculated on 02/10/11 was 79.87% which is less than the acceptance criteria of 80%. Therefore, between 02/10/11 and 06/27/11, VB4 was inoperable and the plant was in a condition prohibited by TS. On 01/06/12 a functional test was performed on VB4. The functional test is a service test using a single unit load profile. The single unit load profile consists of Unit 1 loads, common loads, and loads transferred from Unit 2 to Unit 1. VB4 passed the acceptance criterion (105 Vdc) with a terminal voltage of 111.9 Vdc. This test indicates that VB4 was functional from 02/10/11 to 06/27/11. VB4 has been replaced with new battery cells and the acceptance criteria for SR 3.8.4.13 and SR 3.8.4.14 were met. The error in the recorded capacity of 80.2% was discovered during a root cause investigation and attributed to arithmetical rounding errors. The licensee is continuing their investigation to determine extent of condition. The licensee informed the NRC Resident Inspector. | |
| ENS 48056 | 29 June 2012 14:28:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Unanalyzed Condition Due to Increase in Probable Maximum Flood Level | On June 29, 2012, TVA issued an updated calculation titled 'PMF Determination for Tennessee River Watershed' The calculation resulted in an increase in the Watts Bar Nuclear (WBN) probable maximum flood (PMF) level from Elevation 734.9 to Elevation 739.2. All flood sensitive safety related systems, structures, and components have been reviewed and been determined to remain unaffected by the revised PMF surge elevation, with the exception of the Thermal Barrier Booster Pump Motors and Essential Raw Cooling Water (ERCW) equipment required for flood mode operation located on Elevation 722 of the Intake Pumping Station (IPS). The updated PMF of Elevation 739.2 could impact the ability of the thermal barrier booster pumps and the Elevation 722 IPS ERCW equipment to perform their design accident protection function. Because of the unanalyzed condition. the potential existed for WBN to exceed its PMF design basis and adversely affect plant safety. This notification is being made pursuant to 10 CFR 50.72(b)(3)(ii)(B). Compensatory measures have been prepared to install a temporary flood protection barrier around the thermal barrier booster pumps and provide additional protection of Elevation 722 of the IPS in the event of a flood alert. The potential for the increased PMF level and the associated compensatory measures were previously discussed in a public meeting between TVA and the NRC on May 31, 2012 and in correspondence between TVA and the NRC dated June 13, 2012 and June 25, 2012. All safety related equipment is currently operable. There are no indications of conditions that might result in a flood in the near term. The licensee notified the NRC Resident Inspector of this condition.
Based upon continuing engineering reviews, the chilled water circulating pump motors for the Train A and B Main Control Room and 6.9kV Shutdown Board Room, including various sub-components, would be partially submerged during a Probable Maximum Flood (PMF) event. These components were not previously considered as affected by the PMF. The affected components are located on floor elevation 737.0 of the auxiliary building. This notification is being made pursuant to 10 CFR 50.72(b)(3)(ii)(B). Compensatory measures have been prepared to install temporary flood protection barrier around the chilled water circulating pump motors and provide additional protection of Elevation 722 of the IPS in the event of a flood. All safety related equipment is currently operable. There are no indications of conditions that might result in a flood in the near term. The licensee notified the NRC Resident Inspector of this condition. Licensee Event Report 50-390/2012-002-00 will be supplemented to include a description of the potential PMF affects on the chilled water circulating pump motors. Notified the R2DO (Ernstes). | |
| ENS 48075 | 6 July 2012 14:12:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release | Loss of 7 Offsite Sirens Due to Inclement Weather | On the evening of July 5, 2012, a severe thunderstorm warning was issued by the National Weather Service for the Tennessee Valley Authority (TVA) area. These storms included wind and tree damage to the surrounding area. On the morning of July 6, 2012, TVA pulsed the sirens in the emergency response system by providing an electrical signal to each of the siren towers. It was determined there had been localized power outages and possible tree damage to 7 out of the total of 99 offsite sirens. While the number of sirens out does not meet the required notification, this data was given to the state for informational update. This information was provided to the Tennessee Emergency Management Agency (TEMA) at 1012 EDT. Due to the interaction with the state and local government agencies, this report is being made as a four hour notification under 10 CFR 50.72(b)(2)(xi). The sirens will be repaired as needed and returned to service. There were no plant events that required siren actuation, and all plant systems are operating as required. The NRC Senior Resident Inspector has been notified. | |
| ENS 48175 | 10 August 2012 12:48:00 | 10 CFR 50.72(a)(1)(i), Emergency Class Declaration | Unusual Event Declared Due to Toxic Gas Release | At 0848 EDT, on 8/10/12, Watts Bar declared an Notification of Unusual Event (NOUE), EAL Tab 4.4, based on access restrictions to the turbine building due to a toxic gas release (Ammonia). The leak has been secured. Operators are currently in protective gear in the turbine building in an effort to ventilate the residual gas from all affected areas and re-establish normal access. The gas release has caused no personnel injuries or equipment damage. The licensee continues to operation at 100% power. Watts Bar will remain in an NOUE until the area can be ventilated and normal access is reestablished. The NRC Resident Inspector will be notified. The licensee has notified state and local government. Notified DHS SWO, FEMA OPS, DHS NICC, and NUCLEARSSA via email.
At 1325 EDT Watts Bar terminated the Notification of Unusual Event (NOUE). The Ammonia leak was due to a valve in the fill line to the Ammonia Mixing Tank not being fully closed, thereby causing the tank to overflow. The NRC Resident Inspector has been notified. Notified R2DO (Rich), NRREO (Evans), IRD MOC (Marshall). Notified DHS SWO, FEMA OPS, DHS NICC, and NUCLEARSSA via email. | |
| ENS 48204 | 19 June 2012 03:49:00 | 10 CFR 50.73(a)(1), Submit an LER | Invalid Actuation of Containment Ventilation Isolation | Watts Bar Nuclear Plant's (WBN's) containment ventilation isolation systems provide the means of isolating ventilation systems that pass through containment penetrations to confine to the containment any radioactivity that may be released following a design basis event. The containment ventilation system isolates following a manual or automatic safety injection signal, high containment purge exhaust radiation levels, or manual actuation. On 6/18/12 at 2349 EDT, a B train containment ventilation isolation signal was received in the Main Control Room due to an invalid high radiation signal from a containment purge exhaust radiation monitor (1-RM-131). Corrective action replaced the 1-RM-131 ratemeter following the 6/18/12 B train containment ventilation isolation. However, on 7/2/12 at 1252 EDT, a second B train containment ventilation isolation signal was received in the Main Control Room due to another invalid high radiation signal from 1-RM-131. An investigation found that 1-RM-131 was spiking repeatedly due to a defective Power On indicating light socket which affected the 120 VAC power circuit that is common with the 24 volt power supply. 120 VAC signal fluctuations could affect the 24 volt power supply signal to the rate meter causing output spikes. Corrective action replaced the defective Power On indicating light socket on 7/3/12. This event notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) as a 60 day telephone notification of the invalid initiation of a containment isolation signal. The specific system and train that was actuated was B train containment ventilation isolation. The system functioned as designed and the complete train operated. WBN's NRC Resident Inspector has been notified. |