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 Entered dateSiteRegionScramReactor typeEvent description
ENS 5406212 May 2019 15:28:00Grand GulfNRC Region 4Manual Scram

At 1039 CDT the reactor was manually (scrammed) due to a partial loss of plant service water. The loss of plant service water was caused by a loss of (balance of plant) BOP transformer 23. Reactor power was reduced in an attempt to restore pressure to plant service water. Reactor level is being maintained with condensate and feedwater. Reactor pressure is being maintained with bypass control valves. Standby Service Water A and B were manually initiated to supply cooling to Control Room A/C and (Engineered Safety Feature) ESF switchgear room coolers. The cause is under investigation. The NRC Resident Inspector has been notified. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B) as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical and also reported under 10 CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of RPS and Standby Service Water. The plant is currently in a normal electrical lineup.

  • * * UPDATE ON 5/12/19 AT 1846 EDT FROM GERRY ELLIS TO JEFFREY WHITED * * *

This is an update to the original notification. The Drywell and Containment exceeded the technical specification (TS) temperature limits of 135 degrees F (TS Limiting Condition of Operation (LCO) 3.6.5.5) and 95 degrees F (TS LCO 3.6.1.5), respectively. An 8-hour notification is being added for 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 control the release of radioactive material per 10 CFR 50.72(b)(3)(v)(C). Notified R4DO (Alexander).

ENS 5389423 February 2019 19:05:00Grand GulfNRC Region 4Automatic ScramActuation of RPS (Reactor Protection System) with the reactor critical. Reactor scram occurred at 1458 (CST) on 2/23/2019 from 100% power. The cause of the scram was due to Turbine Control Valve Fast Closure. All control rods are fully inserted. Currently reactor water level is being maintained by the Condensate Feedwater System in normal band and reactor pressure is being controlled via Main Turbine Bypass valves to the main condenser. No ECCS (Emergency Core Cooling System) initiation signals were reached and no ECCS or Diesel Generator initiation occurred. The Low-Low Set function of the Safety Relief Valves actuated upon turbine trip. This was reset when pressure was established on main turbine bypass valves. The cause of the turbine trip is still under investigation. There were no complications with scram response. The licensee notified the NRC Resident Inspector. There was no maintenance occurring on the main turbine at the time of the scram.
ENS 5378812 December 2018 17:29:00Grand GulfNRC Region 4Manual Scram

EN Revision Text: MANUAL REACTOR SCRAM DUE TO FAILED OPEN TURBINE BYPASS VALVE At 1351 CST, the reactor was manually shutdown due to 'A' Turbine Bypass Valve opening. The Main Steam Line Isolation Valves were manually closed to facilitate reactor pressure control. Reactor level is being maintained through the use of Reactor Core Isolation Cooling System, Control Rod Drive System, and High Pressure Core Spray System. High Pressure Core Spray System was manually started to initially support reactor water level control. Reactor Pressure is being controlled through the use of the Safety Relief Valves and the Reactor Core Isolation Cooling System. The plant is stable in MODE 3. The cause of the 'A' Turbine Bypass Valve opening is under investigation at this time. The NRC Resident Inspector has been notified.

  • * * UPDATE ON 12/14/18 AT 1140 EST FROM GERRY ELLIS TO TOM KENDZIA * * *

This is an update to EN # 53788 to correct an error on the event classification block of the form. The original notification did not have the block for 8 hour notification for Specified System Actuation checked. The actuation of Reactor Core Isolation Cooling System was discussed in original notification. The licensee notified the NRC Resident Inspector. Notified R4DO (Taylor).

ENS 5360814 September 2018 21:09:00Grand GulfNRC Region 4Manual ScramAt 1644 (CDT) a manual reactor scram was inserted by placing the Reactor Mode Switch to Shutdown. At 1643 (CDT) the Condensate Booster Pump A tripped on low suction pressure. At 1644 (CDT) the Reactor Feed Pump A tripped on low suction pressure. A Recirculation Flow Control Valve runback occurred as designed. Reactor Water level was approaching the Automatic Low Water Level 3 (11.4 inches) scram set point and manual actions were taken by placing the Mode Switch to Shutdown before the low level set point was reached. All systems responded as expected following the manual scram. The plant is stable in mode 3. This event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. The NRC Senior Resident Inspector has been notified. All control rods fully inserted, and decay heat is being removed through the turbine bypass valves to the main condenser. The licensee is investigating the cause of the event.
ENS 5318830 January 2018 21:56:00Grand GulfNRC Region 4Manual ScramGE-6On 1/30/2018 at 1750 (CST), the Reactor Pressure Control Malfunctions ONEP (Off Normal Event Procedure) was entered due to main turbine load oscillations of approximately 30 MWe peak to peak. At 1822 (CST), a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown due to continued main turbine load oscillations. Reactor SCRAM ONEP, Turbine Trip ONEP, and EP-2 were entered. Reactor water level was stabilized at 36 inches narrow range on startup level and reactor pressure stabilized at 933 psig using main turbine bypass valves. Reactor Water Level 3 (11.4 inches) was reached which is the setpoint for Group 2 (RHR to Radwaste Isolation) and Group 3 (Shutdown Cooling Isolation). No valve isolated in these systems due to all isolation valves in these groups being in their normally closed position. The lowest Reactor Water level reached was -36 inches wide range. No other safety system actuations occurred and all systems performed as designed. That event is being reported under 10CFR 50.72(b)(2)(iv)(B) as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical and also reported under 10CFR 50.72(b)(3)(iv)(A), as any event or condition that results in actuation of RPS. The MSIVs are open with decay heat being removed via steam to the main condenser using the bypass valves. Off site power is stable, and the plant is in a normal shutdown electrical lineup. RCIC (Reactor Core Isolation Cooling) was out of service for maintenance, and the reactor water level did not reach the system activation level. The cause of the main turbine load oscillations being investigated. The licensee notified the NRC Resident Inspector.
ENS 5309025 November 2017 06:02:00Grand GulfNRC Region 4Manual ScramGE-6

At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 (CST), with reactor power just above the point of adding heat, IRM (Intermediate Range Monitor) channels A, C, and D received a spurious upscale trip signal which immediately cleared. Upon investigation, operability of RPS (Reactor Protection System) scram function for Intermediate Range Detectors was placed in question. This event is being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. The licensee notified the NRC Resident Inspector.

  • * * UPDATE ON NOVEMBER 26, 2017, AT 1850 FROM GRAND GULF TO MICHAEL BLOODGOOD * * *

At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. At 0149 (CST), with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event is being reported under 10CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. This Revised Statement to Event Notification # 53090 is being made to make it clear that only four IRM channels (A, C, D, G) were Inoperable and that the IRM RPS SCRAM function was still available from the four remaining Operable IRM channels (B, E, F, and H). The licensee notified the NRC Resident Inspector. Notified R4DO (O'Keefe)

  • * * RETRACTION ON 01/16/2018 AT 1629 EST FROM JASON COMFORT TO DAVID AIRD * * *

On 11/25/17, at 0149 (CST), with reactor power just above the point of adding heat, Intermediate Range Monitor neutron flux detector (IRM) channels A, C, and D received a spurious Upscale Trip signal which immediately cleared. Upon investigation, IRM channels A, C, and D were declared Inoperable. IRM G was already Inoperable for another reason. At 0238 (CST) a manual reactor scram was inserted by placing the Reactor Mode Switch in Shutdown. RPS scram function from IRM channels B, E, F, and H was always Operable and available. That event was initially being reported under 10 CFR 50.72(b)(2)(iv)(B), as any event or condition that results in actuation of the Reactor Protection System (RPS), when the reactor is critical. After the trip alarms were received, the Operators spent approximately twenty minutes investigating possible causes and implications, and consulted with Reactor Engineering and the Shift Technical Advisor. The investigation showed that the plant was stable and the upscale IRM alarms were spurious. A review of plant technical specifications by the operators determined that a plant shutdown was not required. After further discussions, Operations concluded that a shutdown to allow further investigation of the issue was the prudent course of action. Prior to shutting down, Operations spent approximately twenty minutes reviewing procedures, notifying personnel to exit containment, and conducting a brief. The shutdown was then conducted by inserting a manual reactor scram by placing the reactor mode switch in SHUTDOWN. This was initially reported under 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the RPS. Based on the sequence of events, and Operator actions in conducting the shutdown, the event is considered 'part of a pre-planned sequence during testing or reactor operation' as specified in 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.73(a)(2)(iv)(A). In accordance with NUREG-1022, Section 3.2.6, the event is not reportable as an actuation of RPS. The licensee notified the NRC Resident Inspector. Notified R4DO (Taylor).

ENS 526634 April 2017 06:57:00Grand GulfNRC Region 4Manual ScramGE-6At 0010 (CDT), 04/04/2017, the reactor was manually scrammed from approximately 75 (percent) core thermal power due Condensate Storage tank level lowering to 24 feet. All control rods fully inserted and all systems actuated and operated as designed. No safety relief valves actuated. Reactor level and pressure are currently being controlled within normal bands. RCIC (reactor core isolation cooling) was manually initiated for level control. This event is reportable under 10CFR50.72(b)(2)(iv)(B) for the reactor trip and 50.72(b)(3)(iv)(A) for the manual start of the reactor core isolation cooling system. The cause of lowering level was a condensate pipe leak. Decay heat is being removed via steam dumps to the condenser. The electrical grid is stable and supplying plant loads. The licensee has notified the NRC Resident Inspector.
ENS 5204425 June 2016 18:30:00Grand GulfNRC Region 4Automatic ScramGE-6At 1407 (CDT), during power ascension to 100 percent, turbine control valves closed unexpectedly causing reactor protection trip signals that in turn caused a reactor scram. Reactor scram, turbine trip ONEPs (Off Normal Event Procedure), and EP2 (Emergency Procedure for Level Control) were entered. Reactor water level was stabilized at 36 inches narrow range on startup level and reactor pressure stabilized at 935 psig using bypass valves. No other safety system actuations occurred and all systems performed as designed. All control rods inserted. Reactor level is maintained by feedwater. Normal electrical shutdown configuration is through offsite electrical power sources. The Safety Relief Valves lifted, then closed. The plant is stable at normal level and pressure and remains in Mode 3. The event is under licensee investigation. The licensee notified the NRC Resident Inspector.
ENS 5201217 June 2016 06:21:00Grand GulfNRC Region 4Automatic ScramGE-6During planned stop and control valve testing, two main turbine high pressure stop valves closed instead of the expected one (stop valve 'B'). This caused the main turbine control valves, power, reactor pressure to swing and a division 2 half SCRAM. Control rods were inserted to reduce power and the power swings. At 0257 (CDT) the reactor automatically SCRAMMED. Reactor SCRAM, Turbine Trip (procedures) ONEPs and EP-2 were entered. Reactor water level was stabilized at 34 inches narrow range on startup level control and reactor pressure stabilized at 884 psig using main turbine bypass valves. No other safety related systems actuated and all systems performed as expected. The plant is in its normal shutdown electrical lineup using normal feedwater and turbine bypass valves for decay heat removal. Reactor pressure is slowly trending down. The licensee is investigating the cause of the second stop valve shutting. The licensee notified the NRC Resident Inspector.
ENS 4997229 March 2014 14:09:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of RPS with reactor critical. Reactor Scram occurred at 1008 (CDT) on 03/29/2014 from 87% CTP (core thermal power). The cause of the Scram appears to be a Turbine Generator Trip. 05-S-01-EP-2 RPV Control, 05-1-02-I-1 Reactor Scram ONEP and 05-1-02-l-2 Turbine Generator Trip ONEP were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF (engineered safety feature) power occurred. No ECCS (emergency core cooling systems) initiation signals were reached and no ESF or Diesel Generator initiations occurred. All control rods are fully inserted. MSIVs (main steam isolation valve) remained open and no SRVs (safety relief valves) lifted. Currently, reactor water level is being maintained by the Condensate and Feedwater system in normal band and reactor pressure is being controlled via Main Turbine Bypass Valves to the main condenser. There are no challenges to Primary or Secondary Containment at this time. The licensee has notified the NRC Resident Inspector.
ENS 4992017 March 2014 09:25:00Grand GulfNRC Region 4Manual ScramGE-6On 3/17/2014 at 0514 (CDT) the reactor was manually scrammed from approximately 41% core thermal power due to a steam leak in the turbine building. All control rods fully inserted and all systems actuated and operated as designed. All Main Steam Isolation Valves were manually shut. The Reactor Core Isolation Cooling System was manually initiated to assist in level control and pressure control. No safety relief valves actuated automatically. Manual cycling of safety relief valves and Reactor Core Isolation Cooling are being used to maintain reactor water level and pressure within normal bands. Group 2 and 3 RHR isolation signals were received; however no valve movement occurred since the affected valves are normally closed. This event is reportable under 10CFR50.72(b)(2)(iv)(B) for the reactor trip and 50.72(b)(3)(iv)(A) for the manual start of the reactor core isolation cooling system. The licensee informed the NRC Resident Inspector.
ENS 4867314 January 2013 22:04:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of RPS (Reactor Protection System) with reactor critical. The Reactor Scram occurred at 1805 (CST) 01/14/13 from 100% CTP (Core Thermal Power). The cause of scram appears to be a Turbine Generator Trip. 05-S-01-EP-2 RPV Control, Reactor Scram ONEP (Off Normal Event Procedure) 05-1-02-I-1, and Turbine and Generator Trips ONEP 05-1-02-1-2 were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF power occurred. No ECCS initiation signals were reached and no ECCS or Diesel Generator initiation occurred. All control rods are fully inserted. MSIVs remained open and SRVs lifted and reseated as designed. Currently, reactor water level is being maintained by the Condensate and Feedwater system in the normal band and reactor pressure is being controlled via Main Turbine Bypass valves to the main condenser. There are no challenges to Primary or Secondary Containment at this time. The licensee notified the NRC Resident Inspector.
ENS 486525 January 2013 03:09:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of RPS with reactor critical. Reactor Scram occurred at 2337 CST 01/04/13 from 94% CTP (Core Thermal Power). The cause of the scram appears to be a Generator/Turbine trip. Appropriate off normal event procedures were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF power occurred. No ECCS initiation signals were reached and no ECCS or Diesel Generator initiation occurred. MSIVs remained open and SRVs lifted and reseated as designed. Currently, reactor water level is being maintained by the Condensate and Feedwater system in normal band and reactor pressure is being controlled via bypass valves to the condenser. The NRC Resident Inspector has been informed. See similar EN #48637.
ENS 4863729 December 2012 05:05:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of RPS (Reactor Protection System) with reactor critical. Reactor Scram occurred at 0018 (CST), 12/29/12, from 100% CTP (Core Thermal Power). The cause of scram appears to be a Generator/Turbine trip. Appropriate off normal event procedures were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF (engineered safety feature) power occurred. No ECCS initiation signals were reached and no ECCS or Diesel Generator initiation occurred. MSIVs (Main Steam Isolation Valves) remained open and SRVs (Safety Relief Valves) lifted. Currently, reactor water level is being maintained by the condensate and feedwater system in normal band and reactor pressure is being controlled to limit cooldown. All control rods inserted. The plant is in hot shutdown with decay heat removal to the condenser and the electrical line-up is in a normal configuration. The cause of the turbine/generator trip is under investigation. The licensee notified the NRC Resident Inspector.
ENS 4767919 February 2012 22:00:00Grand GulfNRC Region 4Manual ScramGE-6On 2/19/2012 at 1904 hrs (CST) the reactor was manually scrammed from approximately 23% core thermal power due to lowering reactor water level. All control rods fully inserted and all systems actuated and operated as designed. The Reactor Core Isolation Cooling System was manually initiated to assist in level control. No safety relief valves actuated. Reactor level and pressure are currently being controlled within normal bands. Group 2 and 3 RHR Isolation signals were received, however no valve movement occurred since the affected valves are normally closed. This event is reportable under 10CFR50.72(b)(2)(iv)(B) for the reactor trip and 50.72(b)(iv)(A) for the manual start of the core isolation cooling system. The lowest Reactor Vessel Water Level (RVWL) observed was -38 inches WR (Wide Range). RVWL was restored by placing the "A" Reactor Feed Pump (RFP) in service. The "B" RFP which had been operating was secured for troubleshooting. The Unit was in the process of shutting down for its scheduled Refueling Outage #18. The NRC Resident Inspector was in the control room at the time of the transient.
ENS 457538 March 2010 19:47:00Grand GulfNRC Region 4Automatic ScramGE-6An 'A' reactor feed pump trip occurred and initiated a recirculation pump flow control valve runback. During the flow control valve runback, the 'A' recirculation hydraulic power unit tripped causing an incomplete runback. Reactor water level 3 (11.4 inches) was reached which is an RPS scram setpoint and also a setpoint for Group 2 (RHR to Radwaste) and Group 3 (Shutdown Cooling Isolation). No valves isolated in these systems due to (the valves) being in their normally closed position. The lowest reactor water level reached was -28 inches wide range. Appropriate off normal event procedures were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF power occurred. No ECCS initiation signals were reached, and no ECCS or Diesel Generator initiation occurred. All safety systems performed as expected. MSIVs remained open and no SRVs lifted. Main condenser and pressure control systems remained in service. Currently, reactor water level is being maintained by the condensate and feedwater system in the normal level band and reactor pressure is being controlled to limit cooldown. During the scram, all rods inserted into the core. The plant is in its normal shutdown electrical lineup. Decay heat removal is via the steam bypass valves to the condenser. The licensee has notified the NRC Resident Inspector.
ENS 4460126 October 2008 15:40:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of RPS with reactor critical. Reactor Scram occurred at 11:25, 10/26/08 from approximately 50% CTP (core thermal power). A turbine/generator trip and automatic RPS reactor scram on TCV (turbine control valve) fast closure occurred. Exact cause of turbine/generator trip is not known at this time. All withdrawn control rods fully inserted to position 00. Reactor Water Level 3 (11.4") was reached which is an RPS Scram Setpoint and also a setpoint for Group 2 (RHR to Radwaste) and Group 3 (Shutdown Cooling Isolation). No valves isolated in these systems due to their being in their normally closed position. Lowest reactor water level reached was -3" Wide Range. Appropriate off normal event procedures were entered to mitigate the transient with all systems responding as designed. No loss of offsite or ESF power occurred. No ECCS initiation signals were reached, and no ECCS or DG initiation occurred. All safety systems performed as expected. MSIVs remained open and no SRV's lifted. Main Condenser and pressure control system remained in service. Currently, reactor water level is being maintained by the condensate system in normal level band and reactor pressure is being controlled to limit cooldown. The licensee notified the NRC Resident Inspector.
ENS 4459523 October 2008 11:44:00Grand GulfNRC Region 4Automatic ScramGE-6'A' Reactor Feed Pump speed decreased to zero with no trip signal evident in the Control Room for the 'A' Reactor Feed Pump. The reactor scrammed due to loss of feedwater flow on a Level 3 (11.4") RPS scram signal as designed. Operators implemented appropriate off normal event procedures to mitigate the transient with all systems responding as designed. Lowest reactor water level observed was -35" wide range. All withdrawn control rods fully inserted to position '00'. The Reactor Core Isolation Cooling System was manually initiated and was used to restore water level to within the normal band. No ECCS initiations were received and all systems responded as designed. Additionally, no SRVs lifted as a result of this event. Level 3 is also a setpoint for Group 2 (RHR to Radwaste) and Group 3 (Shutdown Cooling Isolation) automatic isolation. No valves isolated in these systems due to them being in their normally CLOSED position prior to the event. Currently, reactor water level is being maintained by the condensate system in normal level band and reactor pressure is being controlled to limit cool down. The licensee has notified the NRC Resident Inspector.
ENS 4408621 March 2008 17:59:00Grand GulfNRC Region 4Automatic ScramGE-6Actuation of an RPS signal while the reactor was critical. At 1525 a generator trip signal on the main transformers initiated a reactor scram due to Turbine Stop and Control Valve fast closure. Safety relief valves operated initially to lower reactor pressure. Turbine bypass valves operated initially to lower reactor pressure. Turbine bypass valves are maintaining pressure control currently. Reactor recirc pumps A and B transferred to slow speed operation as expected. No ECCS initiations were received. Reactor level is being controlled with normal systems condensate and feedwater. Lowest level indicated was approximately -6" wide range. Level 3 initiations occurred to group 3 isolation valves. No valves operated, they are normally closed. The site is investigating the cause of the trip. A probable cause is the "C" phase differential trip which was received from the main transformer. All control rods fully inserted during the scram. The plant is on its normal shutdown electrical lineup. The licensee notified the NRC Resident Inspector.
ENS 4389912 January 2008 20:57:00Grand GulfNRC Region 4Manual ScramGE-6On 1/12/08 at 1626 hours a manual scram was inserted due to degraded cooling on the main transformers. All control rods fully inserted and all systems actuated and/or operated as designed. No safety relief valves opened during the event and reactor pressure is currently being controlled within normal bands with bypass valves. Reactor water level is also being controlled within normal bands with the condensate and feedwater system. Group 2 and 3 isolation signals were received however, no valve movement occurred since these valves are normally closed." The licensee is investigating a potential electrical fault which may have caused the event, but it appears that there was an electrical fault in the transformer cooling system. The grid is normal with no transmission system warnings in effect. All feeds are available. Reactor vessel level is 32.6 inches stable with normal condensate system feeding the vessel. Primary plant pressure is 815 psig. All safety and BOP electrical buses are energized normally. No bus power was lost. Decay heat path is via bypass valves to the main condenser. The licensee will notify the NRC Resident Inspector.