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| Entered date | Event description | |
|---|---|---|
| ENS 44392 | 7 August 2008 16:46:00 | On August 7, 2008 Browns Ferry Nuclear Plant Units 1, 2, & 3 reduced reactor power to 50 percent to ensure continued thermal compliance with water quality standards as regulated by the Alabama Department of Environmental Management. This was caused by an unexpected failure of cooling tower components, rendering the cooling towers unavailable. Plant Operations continues to monitor river conditions and may take further actions as required to maintain compliance. There were no safety systems challenged during the power reductions. This is an informational report based on media interest. TVA does not expect to make an official news release. The NRC Resident Inspector was notified. |
| ENS 44294 | 13 June 2008 11:01:00 | This is a 60 day telephone notification is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) describing an invalid actuation of general containment isolation signal (Group 6) affecting more than one system. On April 14, 2008 at 1308 hours Central Daylight Time (CDT), with Unit 3 in mode 4, an unanticipated Group 6 primary containment isolation signal (PCIS) was generated during the placement of a clearance. During the placement of the clearance, plant personnel removed a fuse which deenergized Group 6 PCIS logic. This resulted in the auto start of train A of the control room ventilation system, auto start of trains A and C of the standby gas treatment (SGT) systems, and the isolation of the reactor zone and refuel zone normal ventilation systems. All systems responded according to plant design. Train B of the SGT system did not auto start because only the A channel PCIS was affected during the implementation of the clearance. Train B of SGT is only affected by the B channel PCIS logic. By 1444 hours CDT, the fuse was reinstalled, the affected systems were returned to standby readiness. There were no safety consequences or impact to the health and safety to the public. The event was entered into TVA's corrective action program. The reference corrective action document is PER 142243. The Senior Resident inspector had been notified of this report. |
| ENS 41896 | 5 August 2005 21:50:00 | At 1708 on 08/05/2005, Unit 2 reactor scrammed from 100% power when reactor water level reached Level 3 Reactor Scram setpoint due to loss of 2C and 2B Reactor Feed Pumps. All rods inserted (fully). Unit 3 was also at 100% power and was unaffected by this event. Reactor water level reached level 2 (-45) HPCI & RCIC initiation setpoint and was recovered by HPCI and RCIC injection. All expected PCIS isolations, Group 2 (RHR S/D cooling), Group 3 (RWCU), Group 6 (ventilation), and Group 8 (TIP) were received along with the auto start of CREV, 3 SGT trains, HPCI and RCIC with injection into Reactor Vessel. Recirc Pumps tripped at -45" as expected. Four MSRVs lifted momentarily to stabilize reactor pressure. This event is reportable at 4 hour and 8 hour Non-Emergency Notification along with a 60 day written report in accordance with 10CFR50.72(b)(2)(iv)(A), 10CFR50.72(b)(2)(iv)(B), 10CFR50.72(b)(3)(iv)(A) and 10CFR50.73(a)(2)(iv)(A) as 'Any event or condition that results in a valid actuation of RPS and PCIS as described in (l) and (2) below.' Decay heat is being removed via steam to the main condenser using the bypass valves maintaining pressure at 895 psi. The licensee notified the NRC Resident Inspector.
Upon further evaluation by the trip investigation team, it has been determined that no MSRV's lifted during this event. Reactor pressure data indicated no increasing pressure spike during the transient. The post-scram pressure trends indicated the maximum reactor pressure was normal operating pressure at the start of the transient followed by a gradual decline. The initial report which stated that 4 MSRV's had lifted was in error. The licensee will notify the NRC Resident Inspector. Notified the R2DO (Landis). |