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| Entered date | Event description | |
|---|---|---|
| ENS 47299 | 28 September 2011 08:26:00 | At 0414 (CDT) on 9/28/2011, the Unit 3 reactor automatically scrammed due to actuation of the Reactor Protection System (RPS) from a turbine trip. Preliminary indications show the turbine tripped on a generator trip with generator neutral overvoltage (359GN) relay actuation. Cause of relay actuation is under investigation. Seven Safely Relief Valves (SRVs) cycled due to the reactor pressure transient with reactor pressure automatically controlled by the Main Turbine Bypass Valves. All systems responded as expected to the turbine trip. No Emergency Core Cooling System (ECCS) or Reactor Core Isolation Cooling (RCIC) reactor water level initiation set points were reached. Primary containment isolation and initiation signals for groups 2, 3, 6 & 8 were received as expected. Reactor water level is being automatically controlled by the feedwater system. This event is reportable within 4 hours per 10 CFR 50.72(b)(2)(iv)(B) 'any event or condition that results in actuation of the RPS when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.' It is also reportable within 8 hours per 10 CFR 50.72(b)(3)(iv)(A) and requires an LER within 60 days per 10 CFR 50.73(a)(2)(iv)(A). The NRC Resident Inspector has been notified. All control rods fully inserted. The plant is being supplied from offsite power and is in a normal shutdown configuration. The MSIVs are open with decay heat being removed via steam to the main condenser using the bypass valves. There was no impact on Units 1 or 2. |
| ENS 46986 | 25 June 2011 22:51:00 | At approximately 1615 (hrs. CDT) on 6/25/11, the Meteorological Monitoring Instrumentation at Browns Ferry Nuclear Plant was lost due to a loss of normal and backup power to the Meteorological Monitoring station. This is reportable as an 8 hour ENS report in accordance with 10CFR50.72(b)(3)(xiii) as 'Any event that results in a major loss of emergency assessment capability...' Meteorological monitoring was restored to operation at 1841 on 6/25/11. BFN Units 1, 2, and 3 remained in Mode 1 at 100% power throughout the event. The NRC Resident has been notified. |
| ENS 46713 | 30 March 2011 19:57:00 | On March 30, 2011 at 1443 CDT, during a refueling outage, Browns Ferry Unit 2 received an invalid Common Accident Signal (CAS) as a result of maintenance activities. All four Unit 1/2 diesel (generators) auto started and all four Unit 3 diesel (generators) auto started. Unit 2 received a full Reactor SCRAM and Core Spray pumps A, B, C, and D auto started and injected into the reactor. Unit 2 Division I RHR (Residual Heat Removal) system was in Shutdown Cooling with only the C pump in service. The A RHR pump auto started and Shutdown Cooling flow increased, as expected. Unit 2 Division II RHR system was tagged out for maintenance. HPCI (High Pressure Coolant Injection) and RCIC (Reactor Core Isolation Cooling) received auto initiation signals, however the steam isolation valves were tagged closed and the systems did not start. MSIVs (Main Steam Isolation Valves) isolated as a result of the CAS signal. Unit 1 was at 100% power when the CAS on Unit 2 occurred. This caused initiation of the Preferred Pump Logic which designates Division I CS (Core Spray) and LPCI (Low Pressure Coolant Injection) pumps on Unit 1 (1A and 1C) and the Division II pumps on Unit 2 (2B and 2D) and prevents Unit 1 Division II pumps from auto starting. This resulted in the Division II RHR and CS pumps (being) inoperable for Unit 1. Unit 1 subsequently entered Technical Specification 3.5.1, Condition H (two or more low pressure ECCS (Emergency Core Cooling System) injection/spray subsystems inoperable) which requires entering LCO 3.0.3 immediately. Unit 1 entered LCO 3.0.3 at 1443, which requires that actions shall be initiated within one hour to place the unit in Mode 2 within 10 hours; Mode 3 within 13 hours; and Mode 4 within 37 hours. At 1542 Unit 1 began lowering power in order to comply with LCO 3.0.3. CAS logic was reset at 1812 and Unit 1 exited LCOs 3.5.1.H and 3.0.3. This condition requires a four hour report in accordance with 50.72(b)(2)(i) - 'The initiation of any nuclear plant shutdown required by the plant's Technical Specifications.' The NRC Resident Inspector was notified. Service Request #346544 was initiated in the Corrective Action Program. |
| ENS 46019 | 16 June 2010 21:01:00 | On 06/16/10 at 1320 CDT, while performing 2-SR-3.3.6.1.6(3), HPCI Time Delay Relay Calibration, HPCI was discovered to be isolated. After review of the Integrated Computer System (ICS), HPCI (steam supply valve) had isolated at 1258 CDT. Cause of isolation is unknown with investigation in progress. This incident is reportable as an 8-hour ENS notification under 10CFR 50.72 (b)(3)(v) as 'any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.' It also requires a 60 day written report. The NRC Resident Inspector has been notified. |
| ENS 46054 | 29 June 2010 15:25:00 | This 60-day telephone notification is being made in lieu of a written report, under reporting requirements specified by 10 CFR 50.73(a)(1), 10 CFR 50.73(a)(2)(iv)(A) to describe an invalid actuation of general containment isolation signals affecting more than one system. On April 30, 2010, at 1648 hours Central Daylight Time (CDT) with Unit 1 at 100 percent thermal power, while attempting to change a light bulb, the light socket shorted causing a loss of 1A RPS. The loss resulted in Groups 2, 3, 6, and 8 primary containment isolations, and initiation of Standby Gas Treatment and Control Room Emergency Ventilation. BFN's review of the event found that the bulb caused a direct short and caused the loss of RPS 1A. Plant conditions which require PCIS actuations and system initiations (e.g., low reactor water level, high drywall pressure, abnormal area radiation level, high area temperature) did not exist, therefore the actuation was invalid. The affected equipment responded as designed. On April 30, 2010, at approximately 1702 hours CDT Unit 1 operations personnel restored 1A RPS and by 1728 hours CDT, the recovery of the loss of 1A RPS was complete. This event had no safety consequences or impact on the health and safety of the public. The event is documented in the Corrective Action Program (PER 227662). The NRC Resident Inspector has been notified. |
| ENS 45820 | 7 April 2010 20:28:00 | Browns Ferry Nuclear Plant (BFN) is notifying state and local agencies of a spill of water containing tritium as specified in section 2.2.a.iii, of Nuclear Energy Institute document NEI 07-07 entitled 'Industry Groundwater Protection Initiative.' On April 7, 2010 from 02:30 to 03:00, BFN operations personnel were transferring water from one Condensate Storage Tank (CST 3) to another Condensate Storage Tank (CST 5). At 08:25, an operator conducting rounds noticed water flowing from an open test valve near the top of CST 5. The estimated flow rate from the test valve was approximately two gallons per minute (gpm). Attempts to isolate the open test valve by plant operations personnel were unsuccessful. Plant operations personnel lowered level in CST 5 and water flowing from the test valve stopped at 10:35. The volume of water spilled to ground is estimated to be approximately 1,000 gallons. At 16:10, laboratory analysis results indicated this water contained 2.05 E-03 uCi/ml tritium. Mitigative actions will be developed and implemented. BFN Procedure: SPP 5.14 requires that state and local agencies be notified within one business day of verification of a discovery when: ' the spill or leak has or can potentially migrate to groundwater: 1. An unmonitored and inadvertent contaminated leak or spill of liquids of unknown volume and reasonably determined to be greater than 100 gallons to the environment occurs ' This event is reportable as a 4-hour non-emergency notification report in accordance with 10 CFR 50.72(b)(2)(xi), 'Any event or situation, related to the health and safety of the public or onsite personnel, or protection of the environment, for which a news release is planned or notification to other government agencies has been or will be made.' The licensee notified the NRC Resident Inspector. |
| ENS 45687 | 8 February 2010 18:52:00 | A non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access has been suspended. Contact the Headquarters Operations Officer for additional details.
Updated information provided by the licensee. Contact the Headquarters Operations Officer for additional details. |
| ENS 45505 | 18 November 2009 03:19:00 | On 11/17/09 a 2034 (CST), while performing 2-SR-3.3.6.1.3(3DFT) HPCI Steam line space high temperature functional test, HPCI isolated due to B2 and A1 PCIS Channels picking up. A1 was the channel under test at the lime the isolation occurred. Following the immediate investigation it appears the isolation was due to test equipment configuration failure. This test equipment is still under investigation. This incident is reportable as an 8-hour ENS notification under 10CFR 5O.72 (b)(3)(v) as 'any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: d. Mitigate the consequences of an accident.' It also requires a 60 day written report in accordance with 10CFR50.73(a)(2Xvii). The NRC Resident Inspector has been notified. SR number associated with this report: 93270. The HPCI system has been restored to operable status. |
| ENS 43664 | 26 September 2007 11:37:00 | At 0650, 09/26/2007, BFN (Brown Ferry Nuclear) was notified by Site Environmental Organization that there is an oil sheen in the forebay that appears to be coming in from the river. Operations responded per site procedure RW1-007, Spill Prevention Control and Countermeasure Plan. Environmental and Fire Operations also responded to the scene. The following organizations have been notified: TVA Operations Duty Specialist, National Response Center (event #849942), Alabama Dept. of Environmental Management (Montgomery and Decatur, AL), and Corporate TVA Environmental (TVA Env. Event #1500). Site NRC Residents have been notified. The spill has been estimated to be between 50 to 100 gallons located outside the BPN Intake Structure with a sheen on the inside of the intake. The sheen has been contained to prevent entry into plant operating spaces. TVA Muscle Shoals Response Team is in route to perform cleanup. It has been verified this spill is not coming from BFN. This event is reportable to the NRC via ENS as a 4 hour report under 10CFR50.72(b)(2)(xi), as 'Any event or situation, related to the health and safety of the public or on-site personnel, or protection of the environment, for which a news release is planned or notifications to other government agencies has been or will be made.' The licensee notified the NRC Resident Inspector. |
| ENS 40862 | 11 July 2004 01:31:00 | On 07/10/2004 at 2235 (CST), during Browns Ferry Unit 2 startup activities, as IRMs (Intermediate Range Monitors) were being ranged up, an upscale trip on IRM E (RPS (Reactor Protection System) A Channel) and IRM F (RPS B Channel) was received, resulting in a full reactor scram. Mode Switch was in STARTUP, Mode 2 at time of trip. IRMs were on ranges 6 and 7, and reactor pressure was approximately 950 psig. All systems responded as designed, all control rods are at full-in. No ECCS (Emergency Core Cooling System) or PCIS (Primary Containment Isolation System) actuation set points were reached. This is reportable as 4 hour ENS (Emergency Notification System) report per 10CFR50.72(b)(2)(iv)(B), 'Any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of pre-planned sequence during testing or reactor operation.' It is also reportable as an 8 hour ENS report per 10CFR50.72(b)(3)(iv)(A), 'Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B). (1) Reactor protection system (RPS) including: Reactor scram and reactor trip.' Also reportable as a sixty day written report per 10CFR50.73(a)(2)(iv)(B). Mode Switch is presently in shutdown, Mode 3. Investigation is still on going. NRC Resident (Inspector) was notified at approximately 2310 (CST). |