Semantic search
| Entered date | Site | Region | Reactor type | Event description | |
|---|---|---|---|---|---|
| ENS 58007 | 26 October 2025 09:29:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: On October 26, 2025, at 0040 CDT, the Waterford 3 Steam Electric Unit 3 operating crew declared the control room envelope inoperable in accordance with technical specification (TS) 3.7.6.1 due to the discovery of a hairline crack in the station air supply header in the passageway outside the control room. Operations entered TS 3.7.6.1 action b. TS 3.7.6.1 action b was complied with by closing manual valves SA-502 and SA-514, thus isolating the section of piping that developed the crack. The station air leak was isolated at time 0120. There was no impact on the health and safety of the plant or plant personnel. This event is reportable pursuant to 10 CFR 50.72(b)(3)(v)(D), event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to `(D) mitigate the consequences of an accident,' due to the control room envelope being inoperable. The licensee notified the NRC Resident Inspector. |
| ENS 58006 | 26 October 2025 08:14:00 | Palisades | NRC Region 3 | CE | The following information was provided by the licensee via phone and email: On 10/25/25, at approximately 1230 EDT, 3 empty alcohol bottles were found in the protected area by a contract employee. Site security was notified and took possession of the empty bottles which were removed from the protected area. The individual who accidentally brought in the empty alcohol bottles with other non-alcoholic empty bottles was tested for FFD and was negative. This event is reportable in accordance with 10 CFR 26.719(b). The NRC Resident Inspector has been notified. |
| ENS 57998 | 22 October 2025 08:06:00 | Palisades | NRC Region 3 | CE | The following information was provided by the licensee via phone and email: On October 22, 2025, at 0452 EDT, chemistry determined that a report to the State of Michigan, Department of Environment, Great Lakes, and Energy, would be required based on exceeding the National Pollutant Discharge Elimination System permit limit for hydrazine. This exceedance did not exceed any NRC regulations or reporting criteria. This notification is being made solely as a four-hour, non-emergency notification for a notification to another government agency. This event is a 4-hour non-emergency report in accordance with 10 CFR 50.72(b)(2)(xi). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector will be notified. |
| ENS 57996 | 21 October 2025 16:52:00 | Palisades | NRC Region 3 | CE | The following information was provided by the licensee via phone and email: On 10/21/2025 at 0930 EDT an individual fell into the reactor cavity. The reactor cavity is full of water. They ingested some amount of cavity water. The individual was decontaminated by radiation protection personnel but had 300 counts per minute detected in their hair. At 1632 EDT they were sent off site to seek medical attention. This is an eight-hour notification, non-emergency, for the transportation of a contaminated person offsite. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xii). The NRC Resident Inspector has been notified. |
| ENS 57912 | 10 September 2025 05:23:00 | Millstone | NRC Region 1 | CE | The following information was provided by the licensee via phone and fax: Entry into shutdown technical specification action statement due to an identified breach in ventilation ductwork. At 2250 EDT on September 9, 2025, it was discovered that there was degraded manway sealant on the manway to fire damper HV-298A. This degraded sealant results in a direct path from the enclosure building to the atmosphere, challenging the enclosure building boundary. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(C). There is no impact on the health and safety of the public or plant personnel. The plant is currently in a 24-hour technical specification action statement (3.6.5.2) for Unit 2. Unit 3 is not impacted and continues to operate at 100 percent power. The Resident Inspector has been notified.
The following information was provided by the licensee via phone and fax: Millstone Unit 2 is retracting NRC Event Notification (EN) 57912, made on September 10, 2025, at 0523 EDT, regarding a condition identified at Millstone Power Station Unit 2. The condition involved degraded sealant on manways to fire dampers HV-298A/B/G, which resulted in a direct path from the enclosure building to the atmosphere, challenging the integrity of the enclosure building boundary. This condition was initially reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(C) for an event or condition that could have prevented the fulfillment of a safety function (control of release of radioactive material). A subsequent review using additional information on hatch design and actual seating surface determined that there is reasonable assurance the enclosure building boundary remained operable and retained its safety function to control the release of radioactive material and mitigate the consequences of an accident. Based on this assessment, Unit 2 exited Technical Specification action statement 3.6.5.2, and the condition is not reportable under 10 CFR 50.72(b)(3)(v)(C). Therefore, NRC EN 57912 is being retracted. The Resident Inspector has been notified. Notified R1DO (Ford). |
| ENS 57844 | 31 July 2025 23:59:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 1744 EDT, on 7/31/2025, it was discovered both trains of control room emergency ventilation (CREVS) and control room emergency temperature system (CRETS) were simultaneously inoperable due to a damper going shut in the control room ventilation system. The damper went back to its normal open position in less than a minute. Due to this inoperability, the system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified." The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Multiple technical specification limiting conditions for operation (LCOs) such as LCO 3.0.3, 3.7.8, and 3.7.9 were entered as a result of this event. |
| ENS 57794 | 2 July 2025 12:11:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 0842 EDT on 7/2/25 with Unit 2 in mode 1 at 100 percent reactor power, an actuation of the emergency safety features actuation system (ESFAS) undervoltage (UV) occurred on the safety related 4kV bus '21' during steady state conditions. The cause of the UV actuation was the loss of the 13/4 kV transformer 'U-4000-12' due to its feeder breaker tripping open. The '2A' emergency diesel generator automatically started as designed when the UV signal was received and re-powered 4kV bus '21'. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the ESFAS. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 57752 | 10 June 2025 18:30:00 | Saint Lucie | NRC Region 2 | CE | The following information is a summary provided by the licensee via phone and email: At 1230 EDT on June 10, 2025, a non-licensed supervisor failed a fitness for duty test. The NRC Resident Inspector has been notified. |
| ENS 57703 | 11 May 2025 09:22:00 | Millstone | NRC Region 1 | CE Westinghouse PWR 4-Loop | The following information was provided by the licensee via phone and fax: On May 10, 2025, at approximately 1130 EDT, security discovered a full, un-opened can of beer in a rental vehicle inside the protected area. Security took possession of the item and removed it from site. The NRC Resident Inspector and Connecticut State Department of Energy and Environmental Protection were notified. |
| ENS 57659 | 10 April 2025 10:29:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: On 4/10/2025, Unit 1 was defueled at 0 percent power. The `A' train class bus was being powered by the `A' diesel generator (DG) and the `B' train bus was out of service for maintenance. Additionally, the `A' train offsite power transformer is currently out of service for maintenance. Abnormal indication was observed on the `A' DG with lowering voltage and the decision was made to manually trip the `A' DG. Power was restored to the `A' class bus by crosstieing `B' train offsite power via engineering safety feature transformer NBN-X04. This resulted in a loss of all but one AC power source to emergency buses for 15 minutes or longer which is an Unusual Event (UE) CU2.1. It is currently not known at this time what caused the abnormal voltage indications on the `A' DG. State and local agencies were notified. The NRC Resident Inspector has been notified. Notified DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email). The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Palo Verde Units 2 and 3 were not affected by this event. The licensee restored spent fuel pool cooling.
The following information was provided by the licensee via phone and email: The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to the 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. Train `A' emergency diesel generator (DG) was supplying power to PBA-S03 bus. At 0658 MST on April 10th, 2025, train `A' DG was exhibiting erratic and degraded voltage and was placed in emergency stop, which caused a loss of power to PBA-S03. When the `A' DG was stopped, train `A' balance of plant engineered safety features actuation system (BOP ESFAS) detected the loss of power condition on PBA-S03, and sent an emergency start signal to the train `A' DG. Train `A' DG did not respond as it was placed in emergency stop. Operators restored power to PBA-S03 at 0703 MST. At the time of the (loss of power), the reactor was defueled with the core offloaded to the spent fuel pool. Unit 2 and Unit 3 are not impacted by this event and remain in Mode 1, 100 percent power. Unit 1 is still currently in Unusual Event, CU2.1 This (update) is in addition to the event reported at 1029 EDT EN 57659. The original EN reported an Emergency Classification definition as a loss of all but 1 AC power source to emergency buses for 45 minutes. The correct time is 15 minutes. The NRC Senior Resident Inspector has been notified of the update. (This update is an 8-hour, non-emergency, 10 CFR 50.72(b)(3)(iv)(A) report of a valid specified system actuation due to the BOP ESFAS attempting to start 'A' DG upon loss of the PBA-SO3 bus during the initial event.) Notified R4DO (Vossmar).
The following information was provided by the licensee via phone: On 4/10/2025, at 2224 EDT, Palo Verde Unit 1 terminated the Unusual Event. Restoration of 'A' DG was made by swapping to its redundant automatic voltage regulator and performance of a functional startup. This restores two sources of power to the class 1E bus: offsite power and 'A' DG in a standby configuration. The redundant automatic voltage regulator was tested in surveillance in the previous cycle and remains operable. The issues that led to the declaration of Unusual Event with 'A' DG have been entered into the corrective action program. State and local authorities have been notified. The NRC Resident Inspector has been notified. Internal notifications: R4DO (Vossmar), NRR EO (Felts), IR MOC (Crouch), R4 RA (Monninger), NRR (King), R4 PAO (Dricks), and NSIR (Erlanger) External notifications: DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email) |
| ENS 57656 | 9 April 2025 03:26:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: At 1924 MST on April 8, 2025, a loss of power (LOP) occurred to 'Train-A' 4.16 kV class 1E electrical bus while re-energizing 'Train-A' balance of plant (BOP) engineered safety features actuation system (ESFAS) from pre-planned maintenance. The LOP occurred when the circuit breaker supplying off-site power to the 'Train-A' 4.16 kV class 1E bus tripped when 'Train-A' BOP ESFAS system was re-energized. Operators restored power to 'Train-A' 4.16 kV class 1E bus with 'EDG-A' (emergency diesel generator for 'Train-A') at 1934 MST. Operators restored all necessary plant loads which had lost power. Per the Palo Verde emergency plan, no emergency classification was required. At the time of the LOP, the reactor was defueled with the core offloaded to the spent fuel pool. Unit 2 and Unit 3 are not impacted by this event and remain in mode 1, 100 percent power. The cause of the circuit breaker supplying off-site power to the 'Train-A' 4.16 kV class 1E bus tripping is under investigation. NRC Resident Inspector has been notified. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of emergency AC electrical power systems. |
| ENS 57633 | 28 March 2025 07:38:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via phone or email: On 3/28/2025 at 0106 MST, Palo Verde Generating Station Unit 1 entered Technical Specification Limiting Condition for Operation (LCO) 3.0.3 due to discovering `A' essential chiller (EC) oil temperature at 80 degrees Fahrenheit, which is below the operability limit of 120 degrees Fahrenheit. `A' EC inoperable rendered the `A' high pressure safety injection (HPSI) pump inoperable. At the time of discovery, `B' HPSI was inoperable due to recirculating the refueling water tank for chemistry purposes (LCO 3.5.3 condition B entered on 3/27/2025 at 2127 MST). This resulted in inoperability for both trains of HPSI, leading to a loss of the HPSI safety function. On 3/28/2025 at 0115 MST, `B' HPSI was restored to operable condition, LCO 3.0.3 was exited, and the loss of safety function was restored. There were no power reductions (control rod insertions or boron concentration changes). The event did not result in any challenges to the fission product barrier or result in any release of radioactive materials. Unit 2 and 3 remained at 100%. NRC resident has been notified of the event. |
| ENS 57572 | 26 February 2025 17:12:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: A licensed operator had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been terminated. The NRC Resident Inspector has been notified. |
| ENS 57555 | 18 February 2025 09:31:00 | Millstone | NRC Region 1 | CE Westinghouse PWR 4-Loop | The following information was provided by the licensee via phone and email: At approximately 0230 EST on 2/18/2025, it was determined that the primary and backup methods of activating the site Emergency Response Organization (ERO) were not available. External network access was unavailable, to include access to the Dominion Energy Emergency Notification System (DEENS) rendering the system non-functional. Subsequently, the backup method for activating the station ERO was attempted and was unable to be verified. On 2/18/2025, at approximately 0400, an additional backup ERO activation phone number was provided and verified to be functional. At approximately 0740 on 2/18/2025, external network access was restored and DEENS was restored to functional. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(xiii). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
The following information was provided by the licensee via phone and email: It has since been determined that the (backup) phone number provided at 0400 would not have worked to activate the ERO. The NRC Resident Inspector has been notified. Notified R1DO (Deboer) |
| ENS 57425 | 15 November 2024 12:14:00 | Saint Lucie | NRC Region 2 | CE | The following information was provided by the licensee via phone and email: At 1001 EST, on November 15, 2024, with Unit 1 in mode 1 at 100 percent power, the reactor was manually tripped due to three control element assemblies fully inserting into the core. The trip was uncomplicated with all systems responding normally post trip. Operations stabilized the plant in mode 3. Decay heat is being removed by the steam bypass control system and main feedwater. Unit 2 was not affected. This event is being reported pursuant to 10 CFR 50.72 (b)(2)(iv)(B). The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The insertion of the three control rods is suspected to be caused by an electrical failure; however, the cause is still being investigated. |
| ENS 57372 | 10 October 2024 08:45:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 0557 EDT on 10/10/2024, with Unit 2 in mode 1 at 100 percent power, the reactor automatically tripped due to turbine generator loss of field. The trip was not complex with all systems responding normally post-trip. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Operations responded using EOP-0, post trip immediate actions, and stabilized the plant in mode 3. Decay heat is removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 is not affected. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The exciter is suspected to being the cause and is under investigation. All control rods fully inserted. |
| ENS 57369 | 8 October 2024 18:12:00 | Arkansas Nuclear | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: At 1431 CDT, on October 8, 2024, Arkansas Nuclear One, Unit 2 (ANO-2) completed the analysis related to an indication revealed on head penetration '71' during reactor vessel closure head inspections. It was determined that the indication is not acceptable under the American Society of Mechanical Engineers (ASME) code requirements. The indication displays characteristics of abnormal degradation of a barrier that requires taking corrective actions to ensure the barriers capability. No leak path signal was identified during ultrasonic testing or bare metal visual inspections. The plant was in cold shutdown at zero percent power and defueled for a refueling outage at the time of discovery. Repair actions will be completed prior to plant startup from the outage. This condition has no impact to the health and safety of the public. This report is being made in accordance with 10 CFR 50.72(b)(3)(ii)(A) for degradation of a principal safety barrier. This is the only indication that is currently present; however, if additional indications are found, they will also be repaired prior to the plant startup. The NRC Senior Resident Inspector has been notified. |
| ENS 57249 | 28 July 2024 21:58:00 | Saint Lucie | NRC Region 2 | CE | The following information was provided by the licensee via phone and email: At 1837 EDT on 7/28/24, with Unit 1 in mode 1 at 100 percent power, the reactor automatically tripped due to inadvertent closure of a main steam isolation valve. During the trip, auxiliary feedwater actuated. All other systems responded normally post-trip. Operations stabilized the plant in mode 3. Decay heat is being removed by atmospheric dump valves and auxiliary feedwater. Unit 2 is not affected. 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. |
| ENS 57233 | 18 July 2024 18:33:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 1524 (EDT) on 07/18/2024, with Unit 2 in Mode 1 at 100 percent power, the reactor automatically tripped due to a turbine trip. The trip was not complex, with all systems responding normally post-trip. Operations responded and stabilized the plant. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 implemented AOP-7K (abnormal operating procedure), overcooling event, due to a grid transient. Operations responded and stabilized Unit 1 in Mode 1 at 100 percent power. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). There was no impact on the health and safety of the public or plant personnel. The NRC resident inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All rods fully inserted. There were no other specified system actuations. |
| ENS 57177 | 18 June 2024 06:52:00 | Saint Lucie | NRC Region 2 | CE | The following information was provided by the licensee by email: On 06/18/2024 at 0317 EDT with Unit 2 at 18 percent power, the reactor was manually tripped due to elevated secondary chemistry levels (sodium and chlorides). The trip was uncomplicated with all systems responding normally post trip. Operations stabilized the plant in Mode 3. Decay heat is being removed by auxiliary feedwater and atmospheric dump valves. St. Lucie Unit 1 was unaffected and remains at 100 percent power. This event is being reported pursuant 10CFR 50.72(b)(2)(iv)(B). The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All rods fully inserted. An investigation is underway to determine the root cause of the elevated chemistry levels.
The following retraction was provided by the licensee via email: The purpose of this notification is to retract a previous report made on 06/18/2024 at 0652 (EDT) (EN# 57177). Notification of the event to the NRC was initially made because of inserting a manual reactor trip due to elevated secondary chemistry levels (sodium and chlorides). After the initial report, Florida Power and Light has concluded that the event did not meet the reporting requirements on 10 CFR 50.72(b)(2)(iv)(B) since it was part of a normal plant shutdown. Therefore, this event is not considered an unplanned scram and is not reportable to the NRC as a Licensee Event Report per 10 CFR 50.73. The NRC Senior Resident Inspector has been notified. |
| ENS 57175 | 16 June 2024 16:41:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: On June 16, 2024, at 1233 CDT, Waterford Steam Electric Station Unit 3 was operating at 93 percent power when an automatic reactor trip occurred. Immediately following the reactor trip, emergency feedwater (EFW) actuated automatically. The unit is currently in Mode 3. All control rods fully inserted. Decay heat removal is via the main condenser. Preliminary evaluation indicates that all plant systems functioned normally after the reactor trip, except steam generator (SG) feedwater pump 'A' tripped and SG '1' main feed regulatory controller went to manual. Steam generator water levels are being controlled with the SG feedwater pump 'B'. The cause of the trip is currently being investigated. This event is being reported as a 4-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the reactor protection system when the reactor is critical and as an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as a valid actuation of the EFW system. The NRC Resident Inspector has been notified. |
| ENS 57161 | 4 June 2024 17:19:00 | Saint Lucie | NRC Region 2 | CE | The following information was provided by the licensee via email: At 1352 EDT, on June 4, 2024 with Unit 2 at 92 percent power, the reactor was manually tripped due to a loss of condenser vacuum resulting from a circulating water pump trip. The trip was uncomplicated with all systems responding normally post trip. Operations stabilized the plant in mode 3. Decay heat is being removed by steam discharge to the main condenser using the turbine bypass valves. St. Lucie Unit 1 was not affected and remains at 100 percent power. This event is being reported pursuant to 10 CFR 50.72 (b)(2)(iv)(B). The NRC Resident Inspector has been notified. |
| ENS 57145 | 25 May 2024 15:26:00 | Millstone | NRC Region 1 | CE Westinghouse PWR 4-Loop | The following information was provided by the licensee by phone and email: A 50 ml bottle of vodka was found in the Unit 3 debris basket on the exterior of the intake structure. The bottle likely came from the ultimate heat sink (Niantic Bay) during normal backwash operations by the system that collects debris. Security has discarded the contraband. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers report guidance: The bottle was found unsealed. |
| ENS 57137 | 23 May 2024 11:24:00 | Arkansas Nuclear | NRC Region 4 | CE B&W-L-LP | The following information was provided by the licensee via email: During a security inspection, it was determined that some past events at Entergy sites that were not reported may have met the reporting criterion of 10 CFR 26.719(b)(4). As a result, the following events at Arkansas Nuclear One, Units 1 and 2 are now being conservatively reported: On February 2, 2023, a condition report was written to document that an individual who should have been placed in a follow-up fitness for duty (FFD) program was not tested according to this program. On September 6, 2023, a subsequent condition report was written to document that a different individual who should have been placed in a follow-up FFD program was not tested according to this program. The resident inspector has been notified. |
| ENS 57140 | 23 May 2024 11:24:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: During a security inspection, it was determined that some past events at Entergy sites that were not reported may have met the reporting criterion of 10 CFR 26.719(b)(4). As a result, the following event at Waterford Steam Electric Station, Unit 3 is now being conservatively reported: On May 15, 2023, a condition report was written to document that an individual who should have been placed in a follow-up fitness for duty program was not tested according to this program. The individual was no longer badged at Waterford 3 but is currently badged at another Entergy site. The resident inspector has been notified. |
| ENS 57122 | 11 May 2024 22:49:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: At 1655 CDT, Waterford Steam Electric Station, Unit 3 was in Mode 3 with all control rod element assemblies (CEA) fully inserted with reactor trip circuit breakers closed and individual CEA disconnects open for plant startup. During the performance of emergency feedwater surveillance testing, reactor protection system (RPS) trip set point and emergency feedwater actuation system (EFAS) initiation set point for steam generator level low was exceeded for steam generator 1. Preliminary evaluation indicates that all plant systems functioned normally. The unit is currently stable in Mode 3. All control rods remain fully inserted. This event is being reported as a eight-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as valid actuation of the RPS and emergency feedwater systems. The NRC Resident Inspector has been notified. |
| ENS 57066 | 4 April 2024 19:35:00 | Palo Verde | NRC Region 4 | CE | The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: On 4/4/2024 at 1618 MST, a Notification of Unusual Event, HU4.2 was declared based on an unverified fire alarm in the containment building greater than 15 minutes. Palo Verde, Unit 3 was operating in Mode 1 at 91 percent power due to end of cycle coast down to a refueling outage. There is no known plant damage at this time. Offsite assistance cannot enter the containment building, therefore, offsite assistance was not requested. The plant is stable in Mode 1. The licensee notified State and local authorities and the NRC Senior Resident Inspector. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email).
The following information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: At 2013 MST, Palo Verde Unit 3 terminated the notification of unusual event. The basis for termination was that a containment entry was performed. All levels were inspected, and no fires were found. The NRC Resident Inspector has been notified. Notified R4DO (Deese), IR-MOC (Crouch), NRR-EO (Felts), DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email). |
| ENS 57047 | 25 March 2024 00:48:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via email: At 1634 MST on March 24, 2024, an engineered safety features (ESF) service transformer deenergized resulting in a loss of power to the Unit 2 Train B 4.16 kV Class 1E Bus. The Unit 2 Train B emergency diesel generator (EDG) automatically started and energized the Unit 2 Train B 4.16 kV Class 1E Bus. As a result of the loss of power on the Unit 2 Train B 4.16 kV Class 1E Bus and subsequent load sequencing after the Unit 2 Train B EDG started, the Unit 2 Train B auxiliary feedwater (AFW) pump automatically started as designed. The Train B AFW pump was not needed for steam generator level control and no auxiliary feedwater valves repositioned. The Train B AFW Pump did not supply feedwater to the steam generators. All systems operated as designed. Per the emergency plan, no classification was required due to the event. Units 1, 2, and 3 remain in Mode 1 at 100 percent power. The 4.16 kV Class 1E Buses in Units 1 and 3 were not affected by the deenergization of the ESF service transformer. The cause of the ESF service transformer being deenergized is under investigation. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of emergency AC electrical power systems and auxiliary feedwater system. The NRC Resident Inspectors have been informed. |
| ENS 57042 | 22 March 2024 01:17:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee: A Notification of Unusual Event, HU4.4 (see note below) was declared based a fire in the protected area requiring off site assistance to extinguish. The fire was in the main transformer yard. The fire was detected at 2328 CDT on March 21, 2024, and the fire was declared out at 0009 CDT on at March 22, 2024. An automatic reactor trip was initiated due to a loss of offsite power to the "B" train and a failure to automatically transfer from unit auxiliary transformer "B" to startup transformer "B. The licensee notified State and local authorities and the NRC Resident Inspector. The NRC remained in Normal. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email). NOTE: Due to a typographical error initiating condition HU4.1 was initially recorded for the event. The correct initiating condition is HU4.4 as now shown.
The licensee terminated the Notification of Unusual Event at 0221 CDT on 3/22/24. The licensee notified the NRC Resident Inspector. Notified R4DO (Gepford), IR-MOC (Grant), NRR-EO (Felts), DHS-SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), CWMD Watch Desk (email), DHS NRCC THD Desk (email), and DHS Nuclear SSA (email).
RPS ACTUATION The following information was provided by the licensee via email: On March 21, 2024, at 2328 CDT, Waterford 3 Steam Electric Station, Unit 3 was operating at 98 percent power when an automatic reactor trip was initiated due to a loss of offsite power to the B train and a failure to automatically transfer from unit auxiliary transformer B to startup transformer B. Emergency feedwater actuation signal 2 (EFAS), safety injection actuation signal (ECCS), containment isolation actuation signal and emergency diesel generators automatically actuated. The unit is currently stable in Mode 3. All control rods fully inserted and all other plant equipment functioned as expected. Forced circulation remains with one reactor coolant pump per loop running. Decay heat removal is via the main condenser. A train safety bus is being supplied by off-site power, and B train safety bus is being supplied by emergency diesel generator B. Following the loss of offsite power to the B train, it was reported that main transformer B and startup transformer B were both on fire. The Emergency Director declared an Unusual Event at time 2337 CDT. The fire was reported extinguished at 0009 CDT on March 22, 2024, and the Unusual Event was terminated at 0221 CDT on March 22, 2024. Offsite assistance was requested. The local fire department responded to the site but the fire was extinguished by the on-shift fire brigade. NRC Region IV management was contacted regarding the emergency plan entry at 0030 CDT on March 22, 2024. This event is being reported as a 4-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the reactor protection system (RPS) when the reactor is critical and as an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as valid actuation of the EFW system, ECCS, Containment Isolation and Emergency Diesel Generators. The NRC Resident Inspector has been notified. Notified R4DO (Gepford)
The initial notification in event notice #57042 by Waterford Steam Electric Station, Unit 3, reported a Notice Of Unusual Event (NOUE) emergency declaration due to a fire in the protected area requiring off site support to extinguish. The basis for retraction of the initial emergency notification is that this event did not meet the definition of a fire in the protected area that requires off site support to extinguish. Guidance provided in Nuclear Energy Institute (NEI) 99-01, Rev. 6 and implemented in Waterfords Emergency Plan procedure, initiating Condition HU4.4 states, The dispatch of an offsite firefighting agency to the site requires an emergency declaration only if it is needed to actively support firefighting efforts because the fire is beyond the capability of the Fire Brigade to extinguish. (NOTE: The Initial Notification Form sent from the Control Room at 2341 CDT on March 21, 2024, requested by and provided to the NRC Headquarter Operations Center via e-mail at 0302 CDT on March 22, 2024, stated that the Emergency Classification had been made on Initiating Condition HU4.4 rather than HU4.1)" When the event occurred on March 21, 2024, the Emergency Director declared an Unusual Event at 2337 CDT and requested offsite support based on the information available at that time including the initial assessment by the fire brigade leader and expected need for offsite support to extinguish the fire. As reported in the 0420 EDT update on March 22, 2024, the fire was reported extinguished at 0009 CDT on March 22, 2024, by the Waterford Fire Brigade without the need of offsite support." Notified R4DO (Kellar).
The initial notification in EN 57042 by Waterford Steam Electric Station, Unit 3, reported an emergency declaration of an Unusual Event due to a fire in the protected area requiring off site support to extinguish. The basis for the update to the initial notification is that this event did not meet the definition of a Fire in the Protected Area that requires offsite support to extinguish. As provided in NEI 99-01, Rev. 6 and implemented in Waterfords emergency plan procedure, initiating condition HU4.4 states, The dispatch of an offsite firefighting agency to the site requires an emergency declaration only if it is needed to actively support firefighting efforts because the fire is beyond the capability of the Fire Brigade to extinguish. Additionally, EAL 4.1 for a fire not extinguished within 15 minutes of detection in any Table H-1 fire area was not applicable because the fire did not occur in a Table H-1 fire area. When the event occurred on March 21, 2024, the Emergency Director declared an Unusual Event at 2337 CDT and requested offsite support based on the information available at that time including the initial assessment by the fire brigade leader and expected need for offsite support to extinguish the fire. As reported in the 0420 EDT update on March 22, 2024, the fire was reported extinguished at 0009 CDT on March 22, 2024, by the Waterford Fire Brigade without the need of offsite support. (NOTE: The Initial Notification Form sent from the Control Room at 2341 CDT on March 21, 2024, requested by and provided to the Headquarters Operation Center via e-mail at 0302 CDT on March 22, 2024, stated that the emergency classification had been made on initiating condition HU4.4 rather than HU4.1) In accordance with NRC Approved guidance in FAQ 21-02 (ML21117A104), Waterford 3 is retracting the initial event notification made at 0117 EDT on March 22, 2024. The remaining events that were reported in EN 57042 as a 4-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the reactor protection system (RPS) when the reactor is critical and as an 8-hour non-emergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as valid actuation of the EFW (emergency feedwater) system, ECCS (emergency core cooling system), containment isolation and emergency diesel generators are still applicable and require no additional update at this time. The licensee also provided a site map. Notified R4DO (Kellar) |
| ENS 57032 | 16 March 2024 18:36:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: At 1449 CDT, Waterford 3 Steam Electric Station was operating at 100 percent power when a manual reactor trip was initiated due to main feed isolation valve (FW-184B) and main steam isolation valve (MS-124B) going closed unexpectedly. Emergency feedwater (EFW) was automatically actuated. Preliminary evaluation indicates that all plant systems functioned normally after the reactor trip. The unit is currently stable in Mode 3. All control rods fully inserted as expected. This event is being reported as a 4-hour non-emergency notification in accordance with 10 CFR 50.72(b)(2)(iv)(B) as an actuation of the reactor protection system (RPS) when the reactor is critical and as an 8-hour nonemergency notification in accordance with 10 CFR 50.72(b)(3)(iv)(A) as valid actuation of the EFW system. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Decay heat is being removed through the turbine bypass valves and the atmospheric dump valve on loop '2'. There is no primary to secondary system leakage. The cause of the isolations is still being investigated. |
| ENS 56997 | 28 February 2024 17:46:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 1350 EST on 2/28/2024, with Calvert Cliffs Unit 1 in Mode 5 at 0 percent power and Unit 2 in Mode 1 at 65 percent power, an actuation of the '1A' and '2A' emergency diesel generators' auto-start occurred due to an undervoltage condition on the number 11 and number 21 4kV buses which are fed from the number 11 13kV bus. The '1A' and '2A' emergency diesel generators automatically started as designed when the 4kV buses' undervoltage signals were received. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid actuation of the '1A' and '2A' emergency diesel generators. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The undervoltage condition was caused by the feeder breaker to the number 11 13 kV bus opening during electrical maintenance. |
| ENS 56991 | 24 February 2024 18:08:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via email: At 1546 EST, with unit 2 at 100 percent power, the reactor was manually tripped due to the '22' steam generator feed pump tripping. The trip was uncomplicated with all systems responding normally post-trip. Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Operations responded using emergency operation procedure EOP-0, Post Trip Immediate Actions and EOP-1, Uncomplicated Reactor Trip and stabilized the plant in mode 3. Decay heat is removed by discharging steam to the main condenser using the turbine bypass valves. Unit 1 is not affected. ESFAS (engineered safety features actuation systems) actuation (auxiliary feedwater manual actuation) is reportable under 10 CFR 50.72(b)(3)(iv)(A) 8-hour report. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 56912 | 3 January 2024 15:38:00 | Saint Lucie | NRC Region 2 | CE | At 1257 EST on January 3, 2024, it was determined that a class 1 system barrier had a through wall flaw with leakage. The leakage renders both trains of high pressure safety injection inoperable. The unit is being cooled down to cold shutdown to comply with technical specifications. This event is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(A) and 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officer Report Guidance: At the time of the discovery, the unit was shutdown in mode 3. The unit was experiencing signs of reactor coolant system leakage and a shutdown was initiated in order to search for possible sources. The unit is currently cooling down and proceeding to mode 5, where the safety function is not required. |
| ENS 56893 | 16 December 2023 04:04:00 | Saint Lucie | NRC Region 2 | CE | At 2045 EST on December 15, 2023, it was determined that the reactor coolant system barrier had a through wall flaw with leakage. The leakage is minor in nature and unquantifiable. The leakage is coming from the welded connection of a vent valve for safety injection tank 2A2 outlet valve rendering both trains of high-pressure safety injection inoperable. The unit is being cooled down to cold shutdown to comply with technical specifications. This event is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(A) and 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The unit was heating up after a maintenance outage. The leak was discovered during mode 3 walkdown.
The purpose of this notification update is to retract a portion of a previous report, made on 12/16/2023 at 0404 EST (EN 56893). Notification of the event to the NRC was initially made as a result of declaring both trains of unit 2 high pressure safety injection system inoperable due to reactor coolant barrier through wall leak on the vent line for the 2A2 safety injection tank. Subsequent to the initial report, Florida Power and Light has concluded that the through wall leak rate was insignificant, and therefore the safety injection system's safety-related function was maintained. Therefore, this portion of the event is not considered a safety system functional failure and is not reportable to the NRC pursuant 10 CFR 50.72(3)(v)(D). This update does not affect the original 10 CFR 50.72(b)(3)(ii)(A) report for the degraded condition related to the reactor coolant barrier through wall leak. The NRC Resident Inspector has been notified. Notified R2DO (Miller). |
| ENS 56856 | 16 November 2023 05:15:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via email: At 0227 EST on 11/16/23, Calvert Cliffs Unit 2 experienced an automatic trip from the reactor protection system (RPS) based on reactor trip bus undervoltage (UV). At that time, a loss of U-4000-22 (13 kV to 4 kV transformer) caused a loss of 22, 23, and 24 4 kV busses. This resulted in a loss of both motor generator (MG) sets causing the reactor trip bus UV. The loss of 22 and 23 4 kV non-safety related busses resulted in a loss of main feedwater. Auxiliary feedwater (AFW) was manually initiated and is feeding both steam generators. The 2B diesel generator (DG) started and restored the 24 4 kV safety related bus. Heat removal is via the normal turbine bypass valves to the main condenser. RPS actuation is reportable under 10 CFR 50.72(b)(2)(iv)(B) - 4 hour report ESFAS (engineering safety features actuation system) actuation (2B DG start on UV) is reportable under 10 CFR 50.72(b)(3)(iv)(A) - 8 hour report AFW operation is reportable under 10 CFR 50.73(a)(2)(iv)(A) - 60 day report The NRC Senior Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: All rods fully inserted. There was no impact on Unit 1 operations. Unit 2 is stable in mode 3.
ESFAS actuation (AFW manual initiation) is reportable under 10CFR50.72(b)(3)(iv)(A) - 8 hour report Notified R1DO (Defrancisco). |
| ENS 56849 | 11 November 2023 00:23:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: At 1545 CST on November 10, 2023, personnel at Waterford Steam Electric Station Unit 3 determined that 19 conduits in the engineered safety features actuation system (ESFAS) auxiliary relay cabinets A and B did not have the required fire seals for bay separation. This condition meets the criteria involving an unanalyzed condition that significantly affects plant safety. The plant is currently defueled. Decay heat is being removed by normal spent fuel cooling system operations. ESFAS is not required to be operable in the current plant mode. This event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(B) as an unanalyzed condition that significantly degrades plant safety. There was no impact to the health and safety of the public or plant personnel. The NRC Region 4 Branch Chief (Dixon) has been notified.
On November 10, 2023, Waterford Steam Electric Station Unit 3 reported in EN 56849 that 19 conduits in engineered safety features actuation system (ESFAS) auxiliary relay cabinets A and B did not have the required fire seals for bay separation. This condition met the criteria involving an unanalyzed condition that significantly affects plant safety. Waterford 3 has determined that the ESFAS auxiliary relay cabinets A and B jumper conduits do not require fire seals based on review of an engineering specification that specifies the size and length of conduits which require fire seals to be installed. None of the nineteen affected conduits meet the size and length criteria that would necessitate installation of a fire seal. Based on this, the condition described in EN 56849 is not considered to be an unanalyzed condition that significantly affects plant safety as described in 10 CFR 50.72(b)(3)(ii)(B) and therefore is not reportable. The licensee notified the NRC Resident Inspector. Notified R4DO (Gaddy) |
| ENS 56841 | 8 November 2023 13:27:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 0645 EST, on November 8, 2023, with Unit 2 in Mode 3 at zero percent power, a manual actuation of the auxiliary feedwater system (AFW) occurred during a planned plant cooldown. The reason for the AFW manual-start was a trip of the 22 steam generator feed pump due to a high casing level. The 23 AFW motor driven pump was manually started in accordance with implementation of AOP-3G, Malfunction of Main Feedwater System to restore steam generator levels. There was no impact to Unit 1. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the AFW system. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: No other systems were affected. No other compensatory or mitigation strategies implemented. Plant cooldown was the only significant evolution in progress. No impact to other technical specifications or limiting conditions for operation. All systems functioned as required. The electric plant is being supplied by offsite power with all diesel generators available. No significant increase in plant risk. There was nothing unusual or not understood. |
| ENS 56839 | 7 November 2023 18:42:00 | Calvert Cliffs | NRC Region 1 | CE | The following information was provided by the licensee via email: At 1617 on 11/7/2023, Calvert Cliffs Unit 2 experienced an automatic trip from a Reactor Protection System (RPS) based on reactor trip bus under voltage (UV). At that time a loss of U-4000-22 caused a loss of 22, 23, and 24 4kV busses. This resulted in a loss of both motor generator (MG) sets causing the reactor trip bus UV condition. The loss of 22 and 23 4kV non-safety related busses resulted in a loss of main feedwater. Auxiliary feedwater (AFW) was manually initiated and is feeding both steam generators. The 2B diesel generator (DG) started and restored the 24 4kV safety related bus. Heat removal is via the normal turbine bypass valves to the main condenser. RPS actuation is reportable under 10 CFR 50.72(b)(2)(iv)(B) - 4-hour report. ESFAS actuation (2B DG start on UV) is reportable under 10CFR50.72(b)(3)(iv)(A) - 8-hour report. ESFAS actuation (AFW manual initiation) is reportable under 10CFR50.72(b)(3)(iv)(A) - 8-hour report. Site Senior NRC resident inspector has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Unit 1 was unaffected. Estimation of duration of shutdown is 24 hours. |
| ENS 56834 | 5 November 2023 17:52:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: At 1033 CST on November 5, 2023, while in a refueling outage, it was determined that Waterford Steam Electric Station, Unit 3, did not meet the performance criteria for steam generator structural integrity in accordance with Technical Specification 6.5.9.b.1, Steam Generator Program, due to two tube failures in the number 1 steam generator. The condition was identified during performance of in-situ pressure testing. The affected tubes will be plugged. The plant is currently stable with all fuel in the spent fuel pool. Decay heat is being removed by normal spent fuel cooling system operation. This event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(A) as a degraded condition. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 56785 | 10 October 2023 00:38:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via email: On October 9, 2023, during the Palo Verde Nuclear Generating Station Unit 1 refueling outage, while performing a small nozzle inspection in support of boric acid walkdowns, boric acid leakage was found on the area of the weld of a pressurizer thermowell. At 1507 MST, non-destructive examination of the weld indicated leakage through the reactor coolant pressure boundary. The exam result constitutes welding or material defects in the primary coolant system that are unacceptable under ASME Section XI. This event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(ii)(A). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 56727 | 7 September 2023 23:35:00 | Arkansas Nuclear | NRC Region 4 | CE B&W-L-LP | The following information was provided by the licensee via email: On September 7 at 1230 CDT, Arkansas Nuclear One personnel identified 5 bottles of vanilla extract in kitchen areas located inside the Protected Area. A total of 5 bottles were identified. The bottles ranged in sizes of 1 to 4 ounces. Ingredients were listed as vanilla extracts in water and alcohol. The percentage by volume of alcohol varied from 13 - 41 percent. This report satisfied the reporting criteria of 10 CFR 26.719. The NRC Resident Inspector has been notified. |
| ENS 56722 | 6 September 2023 19:22:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: A supplemental contract supervisor had a confirmed positive for an illegal substance during a random fitness-for-duty test. The employee's access to the plant has been terminated. |
| ENS 56644 | 30 July 2023 17:25:00 | Waterford | NRC Region 4 | CE | The following information was provided by the licensee via email: On July 30, 2023 at 1119 CDT, Waterford Steam Electric Station Unit 3 declared the control room envelope inoperable in accordance with technical specification (TS) 3.7.6.1 due to the control room envelope doors failing a door seal smoke test creating a breach in the control room envelope. Operations entered TS 3.7.6.1 Action b. Mitigating actions were implemented and tested satisfactorily by 1215 CDT. There was no impact on the health and safety of the public or plant personnel. This event is reportable pursuant to 10 CFR 50.72(b)(3)(v)(D), as an event or condition that could have prevented fulfillment of a safety function of structures or systems that are needed to mitigate the consequences of an accident, due to the control room envelope being inoperable. The NRC Resident Inspector has been notified.
The original operability determination of inoperable was made based on a conservative evaluation that with presence of smoke in-leakage through Door 261 and 262, the CRE boundary could not perform its safety function. A more detailed engineering evaluation was subsequently performed. No maintenance or intrusive testing was performed on the doors after initial test failure. As documented in version 2 operability determination for condition report WF3-2023-14604, the CRE boundary remained intact for the condition identified and was able to fulfill its safety function. The licensee has notified the NRC Resident Inspector. Notified R4DO (Warnick). |
| ENS 56637 | 25 July 2023 16:06:00 | Millstone | NRC Region 1 | CE | The following information was provided by the licensee via email: At 0924 (EDT) on July 25, 2023, it was discovered that both trains of control room air conditioning system were simultaneously inoperable due to an inoperable control room envelope boundary. The boundary was restored at 0925 (EDT) on July 25, 2023. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. There has been no impact to Unit 3 which remains at 100% power.
The licensee determined in a subsequent engineering evaluation of the conditions that existed at the time, that the access hatch being open did not have an adverse impact upon the control room emergency ventilation system and the control room envelopes boundary's ability to perform their safety function including: Radiation dose to the occupants did not exceed the licensing basis, design basis accident calculated value. Protection of control room occupants from hazardous chemicals and smoke. Therefore, this condition is not reportable and NRC Event EN56637 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Lally) |
| ENS 56610 | 6 July 2023 16:48:00 | Millstone | NRC Region 1 | CE | The following information was provided by the licensee via email: On July 6, 2023, at 1232 EDT, while operating in Mode 1 at 100 percent power, the supply check valve from the number 2 steam generator to the turbine driven auxiliary feedwater pump was determined during troubleshooting that it is not able to perform its isolation function. This failure would have resulted in the blowdown of both steam generators during a main steam line break in the number 2 steam generator main steam line upstream of the main steam isolation valves until the operators could isolate the faulted steam generator. Previous evaluation has determined that this condition constituted an unanalyzed condition that could impact containment pressure. There was no radioactive release to the environment. The steam line from the steam generator to the turbine driven auxiliary feedwater pump was isolated by use of a motor operated valve in the discharge line of the number 2 steam generator. There was no impact to Unit 3 which remains at 100 percent power. The NRC Senior Resident Inspector was notified. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B) as a condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. |
| ENS 56551 | 2 June 2023 10:44:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via email: The following 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 (Emergency Notification System) or under the reporting requirements of 10 CFR 50.73. At 0405 MDT on June 2, 2023, the Unit 2 reactor automatically tripped on low steam generator water levels due to degraded flow from the A main feedwater pump. Steam generator water levels reached the automatic Auxiliary Feedwater Actuation System (AFAS) setpoint resulting in automatic AFAS-1 and AFAS-2 actuations and subsequent start of both class auxiliary feedwater pumps. Steam Generator water levels are being restored to normal band with the class 1E powered motor driven auxiliary feedwater pump. Following the reactor trip, all control element assemblies inserted fully into the core. No emergency plan classification was required per the Emergency Plan. Safety related buses remained powered from offsite power during the event and the offsite power grid is stable. Both emergency diesel generators automatically started on the AFAS-1 and AFAS-2 actuations as designed and are currently running unloaded. This event is being reported as a reactor protection system actuation in accordance with the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) and a specified system actuation in accordance with 10 CFR 50.72(b)(3)(iv)(A). The NRC Senior Resident Inspector has been informed. Unit 1 and 3 are in Mode 1 at 100 percent power. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: Decay heat is being removed to main condenser via automatic steam bypass and B auxiliary feedwater pump. |
| ENS 56539 | 24 May 2023 19:58:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via phone and email: On May 24th, 2023, at approximately 0710 MDT, a non-licensed contract supervisor had a confirmed positive for alcohol during a for-cause fitness-for-duty test. The individual's plant access has been terminated in accordance with station procedures. The NRC Resident Inspector has been notified. |
| ENS 56501 | 2 May 2023 22:41:00 | Palisades | NRC Region 3 | CE | The following information was provided by the licensee via email: At approximately 1500 (EDT) on 5/2/2023, it was determined that the commercial telecommunications capacity was lost to the Palisades Nuclear Plant (PNP) control room and technical support center due to an issue with the telecommunications provider. After discovery of the condition it was discovered that this loss also included the emergency notification system (ENS). Communications link via the satellite phone was tested satisfactorly. In addition, if needed, the satellite phone would be used to initiate call-out of the emergency response organization. The condition did not affect the ENS or commercial telecommunications capabilities at the offsite Emergency Operations Facility. The telecommunications provider has not provided an estimated repair time. PNP will be notifying the NRC resident inspector.
The following information was provided by the licensee via email: This notification is being made to retract event EN 56501 that was reported on May 02, 2023. Based on further investigation, the Emergency Plan and Emergency Implementing Procedures provide an acceptable alternative routine communication system, which is satellite phones, for communicating with Federal, State, and local offsite agencies, that are in addition to the primary commercial telephone system. It was determined that no actual or potential loss of offsite communications capability existed per 10 CFR 50.72(b)(3)(xiii). This is consistent with NUREG 1022, Revision 3, Supplement 1, 'Event Report Guidelines 10 CFR 50.72(b)(3)(xiii),' and NEI 13-01, Revision 0, 'Reportable Action Levels for Loss of Emergency Preparedness Capabilities.' The NRC Decommissioning Inspector has been notified of the retraction. Commercial telecommunications to the plant were restored at approximately 0600 EDT on 5/3/2023. Notified R3DO (Orlikowski) |
| ENS 56487 | 26 April 2023 06:23:00 | Palo Verde | NRC Region 4 | CE | The following information was provided by the licensee via email: On 4/25/2023 at approximately 2315 (MST) it was reported that there was possible sodium hypochlorite actively leaking near the 'A' essential spray pond (ESP). Upon investigation, it was determined that the 'low flow' line of sodium hypochlorite supply to the 'A' spray pond had developed a leak. Sodium hypochlorite had pooled at the leak location and subsequently run down the ESP apron, into the road, and into the storm drain located in the protected area fence. An estimate of approximately 300 gallons of spilled sodium hypochlorite was determined based on the time frame that the sodium hypochlorite was scheduled to start injecting into the 'A' spray pond and the time the leak was isolated. The leak was isolated on 4/25/2023 at approximately 2330. The leak was contained in the storm drain with the storm gates closed, therefore nothing was released offsite. The cleanup effort in progress includes diluting the sodium hypochlorite with domestic service water, collecting it into the storm drain, pumping it to a tank truck, and transporting it to the Palo Verde Water Resources Facility for neutralization. Condition Report 23-04519 was generated to document the leak. The Palo Verde Senior Environmental Scientist was notified and subsequently informed the Environmental Protection Agency (EPA) National Response Center (NRC#1365638) on 4/26/23 at 0005 in accordance with the 91DP-0EN03 Environmental Spill Response (local procedure). The NRC Senior Resident Inspector was also notified. No personnel were injured and no equipment was damaged as a result of the spill. The Palo Verde Fire Department was notified and the area was barricaded off to prevent personnel from entering the area during the cleanup effort. |
| ENS 56468 | 13 April 2023 22:48:00 | Maine Yankee | NRC Region 1 | CE | The following information was provided by the licensee via phone and email: At 1905 (EDT), a security force member discovered what appeared to be a sewage leak along the gravel roadway northwest of the gatehouse entrance. The affected area was approximately 12' X 15'. The water was slowly bubbling up from the ground about 20' along one of our access roads. Large absorbent spill containment barriers were placed at the scene to minimize the incident. Water usage was stopped within our facility, and sewer pumps isolated. The Maine State Department of Environmental Protection (DEP) was notified of the incident (DEP spill # 23-0004705). The area was inspected at approximately 2130 (EDT), and water discharge was no longer observed. Maine Yankee site management is currently in the process of contacting contractors to resolve the issue. The site is safe and secure. The concrete cask heat removal system is operable, and the temperature monitoring system is functional. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee notified Region 1 personnel. |