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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 55311 | 16 June 2021 19:50:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Atmospheric Steam Dump Valves Inoperable | On June 16, 2021, at 1550 EDT, Palisades Nuclear Plant was operating in Mode 1 at 100% power. At that time, operations identified an acrid odor in the control room. Investigation revealed that the steam dump control relay had failed, rendering all four atmospheric steam dump valves inoperable. The loss of function of all four atmospheric steam dump valves is reportable in accordance with 10 CFR 50.72(b)(3)(v)(D) as an 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 mitigate the consequences of an accident. Troubleshooting and replacement of the relay are in progress. The plant remains stable in Mode 1 at 100% power. The NRC Resident Inspector has been notified. Unit 1 is in a 24 hour LCO for Tech Spec 3.7.4.b, atmospheric steam dump valve inoperability. The Unit is in a normal offsite power line-up. | ||
| ENS 52647 | 29 March 2017 19:08:00 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Discovery of Non-Conforming Conditions During Tornado Hazards Analysis | During an evaluation of protection for Technical Specification (TS) equipment from the damaging effects of tornados, Palisades Nuclear Plant personnel identified conditions in the plant design such that specific TS equipment is considered not adequately protected from tornado missiles. Specifically, vulnerabilities were identified in the following systems and components: Service Water System - Service water pump discharge header and service water pump cable trays. Fuel Oil Transfer System - Fuel oil transfer piping and transfer pump cable trays. Emergency Diesel Generators - Vent lines on the fuel oil day tanks. Control Room Heating, Ventilation, and Cooling System - Both the normal and emergency intake ducts. Steam Driven Auxiliary Feedwater Pump - Feedwater pump relief valves. Component Cooling Water System - Component cooling water surge tank. The identified vulnerabilities are being addressed in accordance with Enforcement Guidance Memorandum (EGM), 15-002, and Interim Staff Guidance, DSS-ISG-2016-01. Initial compensatory measures are in place. The licensee notified the NRC Resident Inspector. | Feedwater Service water Emergency Diesel Generator Auxiliary Feedwater | |
| ENS 51820 | 24 March 2016 06:11:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Control Room Ventilation Declared Inoperable | At approximately 0211 (EDT), on March 24, 2016, both control room ventilation filtration trains were declared inoperable in accordance with Technical Specification 3.7.10, Condition B, due to a control room boundary door not being fully closed. Following routine security rounds, the door was unable to be fully closed due to the door's locking bolts not retracting back into the door body, causing interference between the door and door frame. Mitigating actions have been implemented that ensure control room envelope (CRE) occupant radiological exposures will not exceed limits, and CRE occupants are protected from chemical and smoke hazards. Repairs to the door are currently in progress. Technical Specification 3.7.10 allows control room boundary doors to be opened intermittently, under administrative control for preplanned activities, provided the doors can be rapidly restored to the design condition. Previous evaluations of the door not being fully closed for a limited time concluded no loss of safety function had existed. This condition had no impact on the health and safety of the public. The NRC Resident Inspector has been notified. | ||
| ENS 49276 | 13 August 2013 15:02:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Both Control Room Ventilation Filtration Trains Declared Inoperable | At approximately 1102 (EDT), August 13, 2013, both control room ventilation filtration trains were declared inoperable in accordance with Technical Specification 3.7.10, Condition B, due to a control room boundary door not being fully closed. The door was unable to be closed for approximately nine minutes due to an apparent mis-operation of the door operating mechanism. The door's locking bolts fully extended causing interference between the door and door frame. The door was restored to operable status at approximately 1111 (EDT), August 13, 2013. Technical Specification 3.7.10 allows control room boundary doors to be opened intermittently, under administrative control for preplanned activities, provided the doors can be rapidly restored to the design condition. Previous evaluations of the door not being fully closed for a limited time concluded no loss of safety function had existed. This condition had no impact on the health and safety of the public. The NRC Resident Inspector has been notified. | ||
| ENS 44645 | 7 November 2008 19:41:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Load Calulations for Edg Were Incorrect | During a review it was determined that the Diesel Generator load calculation (EA-ELEC-LDTAB-005) did not account for worst case load from the Containment Air Cooler Fan Motors (V-1A, V-2A, V-3A). Initial review indicates that with the worst case fan motor loading, Diesel Generator 1-2 could be loaded beyond its 2 hour rating following a Loss of Coolant Accident (LOCA) during the time period prior to Recirculation Actuation (RAS). The horsepower loading for the motors used in the Diesel Generator load calculation was based on the original specification for the motors. In 1993 calculation EA-DPAL93-110 was done to determine the impact of partial flooding of the air coolers coils on the cooling fan performance. The 1993 calculation calculated a fan motor load that was higher than what is used in the diesel generator load calculation. However, the diesel generator load calculation was not updated as a result of the 1993 calculation. The higher motor power requirement is 17 kW per fan. There are 3 Containment Air Cooler fans loaded on Diesel Generator 1-2. The extra loading, when combined with the possible additional load from operating the diesel generator at increased frequency, raises the calculated load to 2782 kW, which is above the 2 hour rating of 2750 kW. The overload only applies during a time segment of the diesel generator load profile prior to RAS. This could result in the loss of the diesel generator. There is only 1 Containment Air Cooler Fan Motor (V4A) loaded on Diesel Generator 1-1 and has 121 kW margin available. Therefore, there is no concern about overloading Diesel Generator 1-1. Placed hand switches (42-299CS & 42-277CS) for Turbine Generator Emergency Air Side Seal Oil Backup Pump (P-23) and Turbine Turning Gear Oil Pump (P-26) in Pull-To-Lock position, which prevents the pumps from automatically starting. This reduces the potential load on 1-2 D/G by 71 kW. This restores the load on the diesel to within the margin. Licensee has notified the NRC Resident Inspector
Entergy Nuclear Operations Inc. (ENO) is retracting Event Notification EN #44645 which reported a loss of a safety function due to the 1-2 emergency diesel generator (EDG) load calculation not accounting for the worst-case load from the containment air cooler fan motors. The initial review indicated that, with the worst-case fan motor loading, the 1-2 EDG could have been loaded beyond the 2750 kW two-hour peak loading limits following a loss-of-coolant accident during the time period prior to a recirculation actuation signal. This condition may have caused 1-2 EDG to become inoperable, and could have prevented fulfillment of a safety function. In a subsequent evaluation of loading capability, completed on December 18, 2008, ENO determined the 1-2 EDG was operable. The EDGs are rated for 2750 kW two-hour peak operation. It was determined that the postulated peak load for the 1-2 EDG would have been 2819 kW for a period of approximately thirty-eight minutes. However, based on engineering information obtained from the vendor of the 1-2 EDG, Fairbanks-Morris Engine, and reviewed by ENO, the 1-2 EDG could have been operated up to 2830 kW for fifty minutes before any susceptibility to damage might occur. In addition, under the peak loading condition of 2819 kW, the speed of the 1-2 EDG would have remained above the Technical Specification limit of 59.5 Hz. The subsequent review confirmed that the safety function would have been fulfilled. Therefore, ENO is retracting this event notification. The licensee has notified the NRC Resident Inspector. R3DO (Cameron) notified. | Emergency Diesel Generator | |
| ENS 42963 | 4 November 2006 21:30:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | Auxiliary Feedwater Not Aligned Properly in Startup Mode | On 11/3/2006 at 1834 hours, it was discovered that, with the Plant in Mode 2, both trains of Auxiliary Feedwater were not in the required pump automatic start configuration. One pump was operating and performing the heat removal function. Both Auxiliary Feedwater train pump controls were immediately placed into the Automatic configuration. It was determined that the pump start controls had been placed in Manual on 11/1/2006 at about 2152 hours. Upon discovery, it was believed that the Auxiliary Feedwater heat removal function was satisfied because one train was operating and had been in operation since before 2152 hours on 11/1/2006. Subsequently, on 11/4/2006 at 1630 hours it was determined that, with the pump controls in manual, coincident with a postulated Loss of Offsite Power and an Auxiliary Feedwater Actuation Signal, the operating Auxiliary Feedwater pump would trip and neither train pump would automatically start. This situation would constitute a condition that could have prevented the fulfillment of the safety function to mitigate the consequences of a Loss Of Offsite Power event and is reportable under 50.72(b)(3)(v)D. Had such an event occurred, the Operators would have restored Auxiliary Feedwater flow in accordance with station procedures. The licensee notified the NRC Resident Inspector. | Auxiliary Feedwater | |
| ENS 42959 | 2 November 2006 19:36:00 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | High Pressure Safety Injection (Hpsi) Pumps Alignment Blocks Improperly Installed | At 1436 hours on November 2, 2006, with the plant in Mode 3, it was determined that less than 100% of the required Emergency Core Cooling System (ECCS) flow was available per Technical Specification (TS) 3.5.2.D. Therefore, TS LCO 3.0.3 was entered. Each High Pressure Safety Injection (HPSI) pump (one in each ECCS train) is designed with alignment blocks in its mounting, which ensures pump and motor alignment for the thermal expansion experienced by the pump upon initiation of sump recirculation flow. These alignment blocks ( 2 per pump) were discovered to be improperly installed, or missing altogether. In this condition, the HPSI pump could potentially be rendered inoperable upon initiation of sump recirculation. This condition is reportable in accordance with 10CFR 50.72(b)(3)(ii)(B) and (b)(3)(v)(D) as an unanalyzed condition, and a condition that could have prevented the fulfillment of the safety function of the HPSI pumps to mitigate the consequences of an accident, respectively. The NRC Resident Inspector was notified of this event by the licensee.
EN # 42959 reported on November 2, 2006 that both Emergency Core Cooling System Trains were inoperable. The reason for that determination involved the observation that the alignment blocks (keys) associated with the mounting of the high pressure safety injection (HPSI) pumps were either incorrectly installed or were missing. The alignment keys were believed to be necessary to ensure appropriate HPSI pump and motor alignment for the thermal expansion experienced upon initiation of sump recirculation flow. The condition was reported as an unanalyzed condition and a condition that could have prevented the fulfillment of the safety function of the HPSI pumps to mitigate the consequences of an accident. Subsequently, further evaluation of the HPSI pump mounting configuration determined that the alignment keys are not required for pump operability. Therefore, there was no unanalyzed condition and no condition that could have prevented the fulfillment of the safety function of the HPSI pumps to mitigate the consequences of an accident. The licensee notified the NRC Resident Inspector. R3DO(Cameron) notified. |