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{{#ask: [[Category:ENS Notification]] [[Site::Seabrook]] [[Reporting criterion::10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation||10 CFR 50.72(b)(3)(iv)(A), System Actuation]]
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	Start date	Reporting criterion	Title	Event description	System	LER
ENS 56645	30 July 2023 19:26:00	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 LOW Main Turbine ELECTRO-HYDRAULIC Control (EHC) Oil Level	The following information was provided by the licensee via email: On July 30, 2023 at 1526 EDT, with unit 1 in mode 1 at 100 percent power, the reactor was manually tripped due to low main turbine electro-hydraulic control oil level. The trip was uncomplicated with all systems responding normally post-trip. Operations stabilized the plant in mode 3. Decay heat removal is being accomplished using the steam dumps in 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 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified.	Steam Generator Feedwater Main Turbine Decay Heat Removal Main Condenser
ENS 56565	6 May 2023 19:52:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Actuations of Reactor Protection System	The following information was provided by the licensee via email: On 05/06/2023, at 1552 (EDT) with Seabrook Unit 1 in Mode 3 at zero percent power, while performing digital rod position indication system surveillance testing, shutdown bank 'E' stopped withdrawing. In response, the reactor trip breakers were manually opened, initiating a valid actuation of the reactor protection system (RPS). Subsequently, at 2253 while continuing to perform digital rod position indication system surveillance testing, shutdown bank 'C 'stopped inserting. Reactor trip breakers were manually opened, initiating a valid actuation of the RPS. The RPS responded as designed during both events, and both actuations are being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A). The NRC Resident Inspector has been notified.	Reactor Protection System
ENS 56564	12 April 2023 15:07:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Actuation of "B" Emergency Diesel Generator Emergency Power Sequencer	The following information was provided by the licensee via email: On April 12, 2023, with Seabrook Station Unit 1 in Mode 6 at zero percent power, a valid actuation of the 'B' emergency diesel generator (EDG) emergency power sequencer occurred due to a loss of power to the 'B' train emergency bus. The 'B' EDG was removed from service for scheduled maintenance during this time. This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A) for a valid actuation of the 'B' EDG emergency power sequencer. The NRC Resident Inspector has been notified.	Emergency Diesel Generator
ENS 54740	6 June 2020 13:20:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Manual Reactor Trip When Group One, Bank 'B' Control Rods Inserted Into the Core	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.	Steam Generator Feedwater Decay Heat Removal Main Condenser Control Rod
ENS 54731	29 May 2020 18:03:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Manual Trip Due to Rod Bank Unexpectedly Inserting	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.	Steam Generator Feedwater Decay Heat Removal Main Condenser Control Rod
ENS 52718	29 April 2017 22:44:00	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 Steam Generator Hi-Hi Level Signal and Feedwater Isolation	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.	Steam Generator Feedwater Decay Heat Removal Control Rod	05000443/LER-2017-001
ENS 51765	2 March 2016 18:12:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Valid Actuation of Emergency Feedwater	On 3/2/2016, (at) 1312 hours EST, while in the process of a plant cooldown, a valid actuation of the emergency feedwater system (EFW) occurred when B steam generator levels were reduced to 20 (percent). The lowering level was a result of the unanticipated tripping of the start up feed pump on low condensate storage level while it was the feed source to the steam generators. The start up feed pump was restarted and feed flow had been restored when the actuation took place. The EFW flow was secured per procedure and the start up feed pump remains the feed source to the steam generators. This is reportable under 50.72(b)(3)(iv)(A). The licensee notified the NRC Resident Inspector.	Steam Generator Feedwater	05000443/LER-2016-002
ENS 51762	2 March 2016 07:53:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Turbine Trip Causing a Reactor Trip	The turbine tripped for an unknown cause followed by a reactor trip. All systems are functioning as designed. Operators have transitioned out of the EOP (Emergency Operating Procedure) network into normal operating procedures. The plant is stable in mode 3. All control rods fully inserted during the trip and no safety or relief valves lifted. The plant is in its normal shutdown electrical lineup. Emergency Feedwater actuation occurred to restore steam generator levels. The plant expects to make a press release. The licensee notified the NRC Resident Inspector. * * UPDATE AT 1043 EST ON 3/2/16 FROM BARRY BRADBURY TO S. SANDIN * * * The licensee will not issue a press release for this event. The licensee will inform the NRC Resident Inspector. Notified R1DO (Cook).	Steam Generator Feedwater Control Rod	05000443/LER-2016-001
ENS 49979	1 April 2014 04:26:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Trip Due to Electrical Issue	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.	Steam Generator Feedwater Decay Heat Removal Control Rod
ENS 48310	15 September 2012 00:25:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation	Automatic Reactor Trip Due to Low Steam Generator Water Level	(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.	Steam Generator Feedwater
ENS 47327	6 October 2011 16:26:00	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 Low Steam Generator Water Level	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.	Steam Generator Feedwater Reactor Protection System	05000443/LER-2011-002
ENS 45403	2 October 2009 02:39:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Unit Experienced a Valid Rps Actuation During Plant Cooldown on Low Steam Generator Levels	On Thursday, October 1, 2009 @ 2239 hrs EDT Seabrook Station Unit 1 was in Mode 4 in the process of removing feedwater heating and raising steam generator levels during a plant cooldown. A valid actuation of the reactor protection system occurred when both the A and C steam generator (SG) levels were reduced to the SG low level reactor trip setpoint of less than 20%. This occurred twice on both the A and C steam generators approximately 10 minutes apart. Steam generator levels have since been restored to normal operating levels and plant is now in Mode 5. This is reportable under 50.72 (b)(3)(iv) as an event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) of this section, except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. The reactor trip breakers were open and the emergency feedwater system removed from service when the event occurred. The licensee notified the NRC Resident Inspector.	Steam Generator Feedwater Reactor Protection System
ENS 43921	20 January 2008 04:02:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Automatic Reactor Trip Following Turbine Trip	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 3.8.1.1 (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.	Steam Generator Feedwater Auxiliary Feedwater Decay Heat Removal Control Rod	05000443/LER-2008-001
ENS 41655	1 May 2005 15:09:00	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 Main Turbine High Vibration	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.	Steam Generator Feedwater Main Turbine Decay Heat Removal Main Condenser Control Rod
ENS 41593	13 April 2005 08:50:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	During Core Reload Reactor Trip Breakers Opened	The plant is in Mode 6 (Refueling) and core reload is in progress with the reactor trip breakers open; both trains of solid state protection system are in the operate mode. While restoring a line up to place the 'D' steam generator on recirculation, a path was opened that allowed the 'B' steam generator to transfer water to the 'D' steam generator. This alignment lowered the 'B' steam generator to its low-low set point level. This initiated a reactor trip signal (RPS). With the reactor trip breakers open and the reactor core reload in progress, no components actuated as a result of the signal. If the emergency feedwater system had been in service, this would have resulted in equipment actuation. This is an 8-hour report per 10 CFR 50.72 (b)(3)(iv)(A). The resident inspector has been notified.	Steam Generator Feedwater
ENS 41428	22 February 2005 08:08:00	10 CFR 50.72(b)(3)(iv)(A), System Actuation	Emergency Diesel Generator and Emergency Feedwater Auto Start on Vital Bus Failure to Transfer	To support routine preventative maintenance on the 4160V Unit Auxiliary Transformer breaker, 4160V Vital Bus 5 did not successfully transfer to the Reserve Auxiliary Transformer. Bus 5 momentarily de-energized and the Emergency Diesel Generator started and loaded as expected supplying Bus 5. The Emergency Feedwater System actuated as expected on momentary undervoltage to Bus 5. The plant remains stable at 100% power. A station troubleshooting team has been established. The reason that Bus 5 did not transfer to the Reserve Auxiliary Transformer is not known at this time. The licensee notified the NRC Resident Inspector.	Feedwater Emergency Diesel Generator
ENS 40286	1 November 2003 00:48:00	10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation	Reactor Trip on Low Steam Generator Water Level	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.	Steam Generator Feedwater Control Rod	05000443/LER-2003-002

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