|Entered date||Site||Region||Scram||Reactor type||Event description|
|ENS 54740||6 June 2020 12:25:00||Seabrook||NRC Region 1||Manual Scram||At 0920 (EDT), with the unit in Mode 1 and 100 percent power, the reactor was manually tripped due to group 1 of control rod bank 'B' fully inserting into the core. All systems responded normally post trip. Operations has stabilized the plant in mode 3 at NOP/NOT (normal operating pressure and temperature). Decay heat removal is being accomplished via the steam dumps in the steam pressure mode to the main condenser. Emergency feedwater actuated due to low low steam generator level as expected. This event is being reported pursuant to 10CFR50.72(b)(2)(iv)(B) and 10CFR50.72(b)(3)(iv)(A) The senior NRC Resident Inspector has been notified. The plant response to the trip was uncomplicated. All safe shutdown equipment is available. There were no reliefs or safeties actuated during the transient. The licensee manually tripped eight days ago for the same condition. See EN #54731.|
|ENS 54731||29 May 2020 16:41:00||Seabrook||NRC Region 1||Manual Scram||At 1403 EDT, with the unit in Mode 1 and 100 percent power, the reactor was manually tripped due to Group 1 of Control Rod Bank 'B' unexpectedly inserting. All systems responded normally post-trip. Operations stabilized the plant in Mode 3 at 557 degrees Fahrenheit. Decay heat removal is being accomplished via the steam dumps in the steam pressure mode to the main condenser. Emergency feedwater actuated due to low low steam generator level as expected. This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR (b)(3)(iv)(A). The NRC Senior Resident Inspector has been notified.|
|ENS 52718||29 April 2017 21:19:00||Seabrook||NRC Region 1||Manual Scram||Westinghouse PWR 4-Loop||At 1844 (EDT) on 04/29/2017, while the unit was in a low power condition exiting from a refueling outage, the reactor was manually tripped following a P-14 signal (Steam Generator Hi-Hi Level) and a resulting feedwater isolation signal. All control rods were verified to be fully inserted. The cause of the ('B') steam generator high level is currently being investigated. Emergency feedwater actuated at 1845 due to a low-low water level in steam generator 'D'. Plant equipment response is being evaluated and the plant is stabilized in Mode 3 with decay heat removal through the steam dump system to the condensers. There was no release and the emergency feedwater system has been restored to standby. The event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow up notification will be made via the ENS or under the reporting requirements of 10 CFR 50.73. The licensee notified the NRC Resident Inspector.|
|ENS 49979||1 April 2014 02:44:00||Seabrook||NRC Region 1||Automatic Scram||Westinghouse PWR 4-Loop||At 0026 on 04/01/2014, following the turbine shutdown and removal of the main generator from service in preparation for refueling outage 16, Seabrook had a reactor trip and all control rods were fully inserted. The trip was caused by an electrical issue that caused 345 KV bus 6 to deenergize and power was lost to the Unit Auxiliary Transformers (UATs). The in-house busses transferred to the Reserve Auxiliary Transformer (RAT) supplies and the momentary loss of power to in-house Bus 1 caused 2 reactor coolant pumps to trip, generating a 2 loop loss of flow reactor trip signal. The exact cause of the initiating electrical issue is being investigated. The NRC Resident Inspector has been notified. Emergency feedwater actuated at 0035 due to a low low water level in steam generator 'C'. Plant equipment response is being evaluated and the plant is stabilized in Mode 3 with decay heat removal through the steam dump system to the condensers. There was no release and the emergency feedwater system is being restored to standby. The event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.|
|ENS 48310||14 September 2012 22:05:00||Seabrook||NRC Region 1||Automatic Scram||Westinghouse PWR 4-Loop||(At) 2025 (EDT) reactor tripped on 'C' Steam Generator Low Low Level due to feed water regulating valve failing closed due to a 7300 process cabinet card failure. Control Room entered E-0, Reactor Trip or Safety Injection, then transitioned to ES-0.1, Reactor Trip Response. Emergency Feedwater actuated due to the Low Low Steam Generator Level. All other plant equipment functioned as expected. Plant is being stabilized in mode 3. Emergency News Manager will update the states and local media. NRC Resident Inspector was notified at 2045 (EDT). The trip was uncomplicated and all rods fully inserted. Decay heat is being removed to the condenser via the turbine bypass valves. Electrical buses are powered by offsite power.|
|ENS 47327||6 October 2011 15:17:00||Seabrook||NRC Region 1||Automatic Scram||Westinghouse PWR 4-Loop||At 1226 (EDT) today, Seabrook experienced an automatic reactor trip on low steam generator water levels. The low steam generator levels resulted following a trip of one of the two operating main feed pumps. Main feed pump 'A' tripped on low suction pressure while a condensate pump was being returned to service following maintenance on the pump. The emergency feedwater system actuated automatically and recovered steam generator levels. All systems actuated and functioned as designed. The wide range level indication on steam generator 'C' indicated erratically and was declared Inoperable. The plant is stable and being maintained in Mode 3. The station plans to cool the plant to Mode 5 for a previously planned forced outage. This notification provides a four-hour report for an actuation of the reactor protection system while the reactor is critical and an eight-hour report for a valid actuation of the emergency feedwater system. All rods fully inserted. Emergency feedwater has been secured and placed in standby and startup feedwater is supplying the steam generators. Decay heat is being removed to the condenser via the turbine bypass valves. Electrical systems are in a normal shutdown alignment. There is nothing unusual or not understood and all systems functioned as required. The licensee has notified the NRC Resident Inspector.|
|ENS 43921||20 January 2008 02:55:00||Seabrook||NRC Region 1||Automatic Scram||Westinghouse PWR 4-Loop|
Initiating alarm received was a Turbine Trip. All on site buses 1, 2, 4, 5 and 6 swapped to the Reserve Auxiliary Transformer power supplies. Bus 3 did not swap as expected. The station has entered a Technical Specification 184.108.40.206 (a) 72 hour action statement for offsite power distribution with 345 kV Bus 3 unavailable. All safety systems operated correctly. The station continues to troubleshoot the initiating cause of the Turbine Trip. The plant is stable in Mode 3. During the swap of non safety buses to the Reserve Auxiliary Transformer the Reactor Coolant Pumps (RCP) tripped. Following the loss of power to the RCPs the reactor stabilized in natural circulation. A Pressurizer PORV cycled following the trip. One RCP was restarted to restore forced circulation. Auxiliary Feedwater Pumps started as expected on the trip and were subsequently secured. All control rods fully inserted on the trip. The current decay heat removal path is Start-up Feedwater supplying water to the Steam Generators steaming to the Condenser Steam Dumps. The licensee notified the NRC Resident Inspector.
* * * UPDATE AT 0348 ON 1/20/08 FROM FORREST TO HUFFMAN * * *
The licensee has indication of a differential voltage fault on the C phase of the 345 kV line that feeds the Unit Auxiliary Transformer and the generator step-up transformers. The licensee also wanted to ensure that the report reflected the specified system actuation of Auxiliary Feedwater.
|ENS 41655||1 May 2005 12:57:00||Seabrook||NRC Region 1||Manual Scram||Westinghouse PWR 4-Loop||Seabrook Station initiated a Manual Reactor Trip during initial start of the main turbine following a refueling outage. Turbine vibrations elevated to the automatic trip setpoint during initial increase to normal operating speed. The reactor was manually tripped to allow breaking main condenser vacuum and reduce main turbine speed. The plant is currently stable in Mode 3. All control rods (fully) inserted and decay heat removal is via the main condenser steam dumps. Emergency feedwater (EFW) pump actuation occurred because of lowering steam generator level due to the reactor trip. Steam generator level control was maintained using EFW. Condenser vacuum was broken until the turbine vibration alarms cleared and was then restored, allowing the condenser to be used for dumping steam. The licensee notified the NRC Resident Inspector.|
|ENS 40286||31 October 2003 21:15:00||Seabrook||NRC Region 1||Automatic Scram||Westinghouse PWR 4-Loop||Automatic Reactor Trip due to low Steam Generator levels. All systems responded normally. Plant is stable at NOT/NOP (normal operating temperature and pressure) in Mode 3. Emergency Feedwater system actuated as designed due to reactor trip. Lowest Steam Generator level reached was just below the trip setpoint of 25%. Low level caused by trip of one of two Main Feed Pumps. All control rods fully inserted. No primary or secondary relief valves lifted. The electrical system is stable and the EDG's remain in standby. Decay heat is being removed via steam dumps. The licensee has notified the NRC Resident Inspector.|