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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 52839 | 3 July 2017 14:15:00 | 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Manual Reactor Scram on Low Condenser Vacuum | At 1015 (EDT) a manual reactor scram was inserted due to degrading main condenser vacuum. All rods inserted into the core as expected and all systems functioned as expected during the scram. 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 Reactor Protection System (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.' At 1033 (EDT) an automatic reactor scram occurred on low reactor water level. Due to the previous manual reactor scram, all rods were (already) inserted. This event is reportable within 8 hours per 10 CFR 50.72(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) of this section, except when the actuation results from and is part of a preplanned sequence during testing or reactor operation. (1) Reactor protection system (RPS) including : Reactor scram and reactor trip.' Decay heat is being removed using main feedwater and the turbine bypass valves. The licensee notified the NRC Resident Inspector. This event was characterized as a "configuration control event" where a valve misposition allowed the offgas line to flood. | Feedwater Reactor Protection System Main Condenser | |
| ENS 49648 | 18 December 2013 00:57:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Reactor Protection System (Rps) Actuation with the Reactor in Hot Shutdown | Pursuant to 10CFR50.72(b)(3)(iv)(A), notifications are being performed for a valid actuation of the reactor protection system resulting in a full scram. The actuation was a result of the reactor mode switch being placed from the refuel position to the shutdown position without the scram bypass jumpers installed. The reactor was subcritical with all rods inserted at the time of the actuation. All systems functioned as designed. The licensee notified the NRC Resident Inspector. | Reactor Protection System | |
| ENS 48452 | 29 October 2012 22:55:00 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Notice of Unusual Event Declared Due to High Intake Structure Water Level | At 1855 EDT on 10/29/2012, the licensee declared a Notice of Unusual Event (NOUE) per criteria HU4 for high water level in the station intake structure of greater than 4.5 feet. At the time of the notification, water level in the intake structure was approximate 4.8 feet and slowly rising. The cause of the increased water level was due to storm surge associated with Hurricane Sandy. No other station impacts were reported at the time. The licensee continues to monitor the intake levels and ocean tides. The licensee has notified the NRC Resident Inspector and the State of New Jersey.
At 2044 EDT on 10/29/2012, the licensee escalated its emergency declaration to an Alert per criteria HA4 for high water level in the station intake structure of greater than 6.0 feet. At the time of the notification, water level in the intake structure was approximately 6.6 feet. The site also experienced a loss of offsite power event concurrent with the additional water level increase. Both emergency diesel generators started and are supplying power to the emergency electrical busses. Shutdown cooling and spent fuel pool cooling have been restored. Reactor pressure vessel level is steady at 584.7 inches. Intake levels continues to rise slowly and the licensee is monitoring. The licensee has notified the NRC Resident Inspector and the State of New Jersey. Notified DHS SWO, FEMA Ops Center, USDA Ops Center, HHS Ops Center, DOE Ops Center, DHS NICC Watch Officer, EPA EOC, and NuclearSSA via e-mail.
The licensee updated this report with an 8-hour non-emergency notification of emergency diesel generator auto-actuation due to the actual loss of off-site power event (which occurred at 2018 EDT on 10/29/2012). This event caused a valid RPS actuation with automatic containment isolations that resulted in a temporary loss of shut-down cooling to the reactor. Shutdown cooling was subsequently restored with power provided by the emergency diesel generators. The licensee has notified the NRC Resident Inspector. Notified R1DO (Caruso).
Termination of Alert. The Oyster Creek Station has terminated the Alert that was declared at 2044 (EDT) on 10/29/12 due to Intake Structure high water level greater than 6.0 ft. MSL (EAL HA4). Intake water level has returned to normal and is now below the Unusual Event EAL threshold (4.5 ft. MSL) and continues to lower. The licensee informed state and local agencies and the NRC Resident Inspector. Notified Region I IRC (Clifford), NRR (Evans), and IRD (Marshall). Notified DHS SWO, FEMA Ops Center, USDA Ops Center, HHS Ops Center, DOE Ops Center, DHS NICC Watch Officer, EPA EOC, and NuclearSSA via e-mail. | Emergency Diesel Generator Shutdown Cooling Reactor Pressure Vessel | |
| ENS 48125 | 23 July 2012 07:29:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unusual Event Due to Loss of Offsite Power | At 0329 EDT, Oyster Creek experienced a loss of offsite power. As a result of the loss of offsite power, the unit automatically scrammed from 100% with all control rods fully inserting and all safety systems functioning as required. Both Emergency Diesel Generators automatically started and are carrying loads on the safety buses. At 0341 EDT, Oyster Creek declared an Unusual Event based on a loss of offsite power for greater than 15 minutes. The unit is stable in Hot Shutdown with decay heat removal via the Isolation Condenser. The cause of the loss of offsite power is currently under investigation by JCP&L. The licensee notified the State and local agencies, as well as the NRC Resident Inspector. The licensee will be making a press release.
Oyster Creek has terminated from the loss of offsite power Unusual Event (at 0538 EDT). All safety systems functioned as expected for this event. The licensee has notified the NRC Resident Inspector. Notified R1DO (Dimitriadis), NRR EO (Nieh), IRD (Gott), DHS SWO, FEMA, and DHS NICC.
As a result of the loss of offsite power, both Emergency Diesel Generators automatically started and carried loads on the safety buses, as required. Offsite power was returned to service at 0457 EDT and both Emergency Diesel Generators were secured at 0520 EDT. Per 50.72(b)(3)(iv)(A), Oyster Creek is reporting any event or condition that results in valid actuation of an Emergency AC electrical power system. Additionally, the Reactor Building (Secondary Containment) differential pressure indicated positive 0.25 inches W.G. at approximately 0357 EDT. Reactor Building differential pressure indication returned to normal at 0434 EDT. Oyster Creek is currently investigating the cause of the positive Reactor Building pressure indication. Per 50.72(b)(3)(v)(C), Oyster Creek is reporting an event that could have prevented the fulfillment of the safety function of a system needed to control the release of radioactive material. The licensee notified the NRC Resident Inspector. Notified R1DO (Gray).
As a result of further investigation it was found that the Reactor Building Differential Pressure issue was an indication issue only and not indicative of a loss of the secondary containment barrier. The positive indication was caused by a degradation of instrument air pressure to the instrument used to generate the differential pressure indication. The degradation of instrument air pressure was an expected condition caused by the loss of offsite power. Alternate indication, not affected by instrument air pressure, was available throughout the event. The alternate indication read negative 0.4 Inches water gauge throughout the event. Based on this information Oyster Creek is retracting the portion of this report that was reported per 50.72(b)(3)(v)(C), an event that could have prevented the fulfillment of the safety function of a system needed to control the release of radioactive material. The licensee has notified the NRC Resident Inspector. R1DO (Newport) notified. | Secondary containment Emergency Diesel Generator Decay Heat Removal Control Rod | |
| ENS 46315 | 7 October 2010 14:41:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Loss of 4160 Volt Safety Bus | Oyster Creek experienced a loss of 4160 volt 'D' safety bus. Emergency diesel generator number 2 fast started and re-powered the 'D' bus, as expected. All other safety systems responded as expected. Investigation into the loss of 'D' 4160 volt safety bus is in progress. The licensee was performing grid undervoltage testing on the 'D' 4160 at the time of the event. The licensee has staffed the Outage Control Center. There is no affect on the other 4160 volt bus. Offsite power is normal. Plant risk was 'yellow' prior to and following the event as a result of Reactor Building Closed Cooling Water Pump 1-2 out of service for planned maintenance. The licensee notified the NRC Resident Inspector. | Emergency Diesel Generator | |
| ENS 45196 | 12 July 2009 05:48:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(a)(1)(i), Emergency Class Declaration 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unusual Event Declared Due to a Loss of Offsite Power | At 0135 EDT on 07/12 both Startup Transformers "SA" and "SB" were deenergized due to the loss of the 34.5kV power distribution lines (offsite power). The licensee declared an Unusual Event at 0148 EDT based on the loss of power to both transformers for greater than 15 minutes (EAL MU1). As a result of the loss of offsite power, the Unit automatically scrammed with all control rods fully inserting. Both Emergency Diesel Generators EDG #1 and EDG #2 auto started and are carrying vital loads. The Unit is stable in Hot Shutdown with decay heat removal via the Isolation Condenser. The licensee reported that the transient may be due to a possible lightning strike caused by adverse weather. The licensee informed the NJ State Police and the NRC Resident Inspector.
At 0405 EDT on 07/12 the licensee terminated the Unusual Event based on restoration of offsite power and reenergizing both Startup Transformers. The licensee informed the NJ State Police and the NRC Resident Inspector. Notified R1 (Lew), EO (Holian), IRD (Gott), FEMA (Austin) and DHS (Inzer).
Licensee changed one reporting requirement from 50.72(b)(3)(v)(B) to 50.72(b)(3)(iv)(A). Notified R1DO (Dentel). | Emergency Diesel Generator Decay Heat Removal Control Rod | |
| ENS 44688 | 29 November 2008 02:01:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Scram Due to Main Transformer Fault | At 98% power, a reactor scram occurred due to a Main Transformer fault. The plant is currently stable in the Hot Shutdown Mode. Isolation Condensers initiated as part of this event are currently in Standby Mode. This event is reportable in accordance with 10CFR50.72(b)(2) and (b)(3) and the Station Reportability Manual section SAF 1.6 and SAF 1.7. The cause of the transformer fault is unknown and under investigation. There was no fire or explosion associated with the fault. All rods inserted during the scram. As a result of the transient, one electromatic relief valve lifted and subsequently reseated. There were no other isolations or safety equipment actuations during the transient. The station electrical system is in its normal shutdown lineup with offsite power available. Decay heat is being removed via the turbine bypass valves to the main condenser. Pressure is currently at 700 psi with water level being maintained at 160" via the main feed system. The licensee has notified the NRC Resident Inspector and will be notifying the State of New Jersey.
Notification performed to NJDEP of fish mortality following a reactor scram. As of this report, one dead bluefish spotted and three distressed bluefish spotted. Licensee has notified the NRC Resident Inspector. Notified R1DO (Doerflein). | Main Transformer Main Condenser | |
| ENS 43495 | 17 July 2007 09:22:00 | 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Automatic Reactor Scram on Low Reactor Vessel Water Level (Rvwl) | An automatic reactor scram occurred at 0522 on 07/17/07 due to a low reactor water level, following a trip of the 'C' Reactor Feed Pump. Reactor water level lowered to the low-low level setpoint and a reactor isolation occurred. Reactor level has been returned to the normal band and a reactor cooldown has been initiated using isolation condensers. The cause of the "C" RFP trip is attributed to an electrical fault as sensed on ground sensing and differential sensing instrumentation. No flames or smoke was observed, however, operators reported an acrid smell of insulation. Following the automatic scram on low reactor water level (138" above top of active fuel (TAF)), level continued to decrease to the low-low setpoint of 86" TAF resulting in a reactor isolation signal. The reactor isolation signal initiates closure of the Main Steam Isolation Valves (MSIVs), trip of the Recirc Pumps and actuation of the Isolation Condensers. Current reactor pressure is 520 psig with a cooldown rate of 82F/hr. The licensee plans to issue a press release and will take the Unit to cold shutdown for repairs. The licensee informed the NRC Resident Inspector.
The following information reported under 10CFR50.72(b)(3)(iv)(A) was provided as an update: The following systems actuated upon receipt of a lo-lo reactor water level signal, subsequent to the reactor scram, reported under EN #43495, which occurred at 0522 on 07/17/07: MSIVs - Isolation Isolation Condensers - Initiation Standby Gas Treatment - Initiation Recirc Pumps - Trip Containment Valves - Isolation Core Spray - Start, but no injection Containment Spray - Manual initiation only, following use of EMRVs to control Rx pressure, causing elevated Torus water temperature. The licensee informed the NRC Resident Inspector. Notified R1DO (Krafty).
The following information reported under 10CFR50.72(b)(2)(xi) was provided as an update: Notified the New Jersey D.E.P. of an unplanned plant shutdown which occurred at 0522 07/17/07. There was no environmental impact from the plant shutdown. This notification is required to be made within 12 hours of an unplanned plant shutdown. The licensee informed the NRC Resident Inspector. Notified R1DO (Krafty). | Main Steam Isolation Valve Core Spray Containment Spray | |
| ENS 42558 | 6 May 2006 10:07:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Unplanned Manual Reactor Scram During Shutdown | A manual reactor scram was inserted to expedite a reactor shutdown. The reactor was subcritical at the time of the manual scram. All control rods inserted to less than or equal to position 02 as required. The unit entered a forced outage for necessary repairs including replacement of the "B" recirc pump motor. All systems functioned as required for the manual reactor scram. The licensee informed the NRC Resident Inspector. | Control Rod | |
| ENS 41945 | 25 August 2005 03:37:00 | 10 CFR 50.72(b)(3)(iv)(A), System Actuation | Emergency Diesel Generator Automatic Start Due to Bus Supply Breaker Trip | 4160 volt Bus 1D normal supply Breaker 1D tripped open. The associated No. 2 EDG automatically started and is supplying the 1D 4160 volt Bus. Plant equipment responded as expected. Troubleshooting is in progress to determine the cause of the breaker trip. The licensee notified the NRC Resident Inspector. | Emergency Diesel Generator |