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 Start dateReport dateSiteReporting criterionSystemEvent description
ENS 5596224 June 2022 16:57:00Perry10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentCore SprayThe following information was provided by the licensee via telephone: At 1257 EDT on June 24, 2022, it was discovered the Low Pressure Core Spray System (LPCS) was INOPERABLE. At Perry, the Low Pressure Core Spray System is considered a single train system in Modes 1, 2, and 3; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). Inoperability of the Low Pressure Core Spray system was caused by a loss of power to the LPCS Minimum Flow Valve during surveillance activities. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5595522 June 2022 02:40:00McGuire10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentThe following information was provided by the licensee via email: At 2240 on 06/21/2022, it was discovered that both required trains of Control Room Ventilation and Control Area Chilled Water System were simultaneously inoperable; therefore, this condition is being reported as an eight-hour, nonemergency 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: The 'B' train was restored at 2315.
ENS 5590823 May 2022 17:56:00LaSalle10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentThe following information was provided by the licensee via fax: At 1256 CST on 05/23/2022, it was discovered both trains of Control Room Area Ventilation Air Conditioning Systems were simultaneously INOPERABLE. 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). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5590723 May 2022 09:55:00Cooper10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentSecondary containmentThe following information was provided by the licensee via email: On May 23, 2022, at 0455 CST, Cooper Nuclear Station experienced a spike in Secondary Containment differential pressure which exceeded the Technical Specifications Surveillance Requirements 3.6.4.1.1 limit of -0.25 inches of water gauge. Secondary Containment differential pressure restored to Technical Specification limits within two minutes and further investigation is ongoing. This unplanned Secondary Containment inoperability constitutes a condition reportable under 10CFR50.72(b)(3)(v)(C) and (D). The NRC Senior Resident Inspector has been informed.
ENS 5590520 May 2022 14:05:00LaSalle10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentThe following information was provided by the licensee via email: At 0905 CST on 05/20/2022, it was discovered both trains of Control Room Area Filtration and Area Ventilation Air Conditioning Systems were simultaneously INOPERABLE. 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). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5589411 May 2022 22:14:00Fermi10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionThe following information was provided by the licensee via email: During performance of High Pressure Coolant Injection (HPCI) Pump and Valve Operability surveillance in accordance with procedure 24.202.01, the turbine tripped without operator action. The plant was operating in Mode 1 at 10 percent power with the HPCI turbine running in a test mode at 5100 gpm with all surveillance criteria met. The surveillance was near completion at the point where the HPCI turbine is manually tripped. Before the manual trip was performed, the HPCI turbine tripped without operator action. Prior to performance of the surveillance, HPCI was provisionally operable with only satisfactory completion of Post Maintenance Testing (PMT) surveillance remaining to declare HPCI operable. HPCI surveillance testing was performed at low reactor pressure (165 psig) in Mode 2 satisfactorily. Investigation into the cause of this trip is in progress. HPCI has been declared inoperable from the time of release of the surveillance. Reactor Coolant Isolation Cooling (RCIC) was verified to be operable prior to and after the surveillance in accordance with Technical Specifications 3.5.1 condition E.1. This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5587129 April 2022 16:51:00FitzPatrick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionThe following information was provided by the licensee via email: At 1251 EDT on April 29, 2022, while troubleshooting the failure of the High Pressure Coolant Injection (HPCI) Exhaust Drain Pot High Level Alarm to clear, it was discovered that the High Pressure Coolant Injection exhaust line condensate drain system was not functioning as designed to support removal of condensate from the turbine exhaust. This resulted in some water accumulation in the turbine casing. Subsequently, the High Pressure Coolant Injection System was declared inoperable. As a result, this condition is being reported under 10 CFR 50.72(b)(3)(v)(D) as a condition that could have prevented fulfillment of the safety function at the time of discovery.
ENS 5578512 March 2022 05:50:00Turkey Point10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentMain Steam Isolation Valve

The following information was provided by the licensee via email: At 0050 EST on 3/12/22, while shutting down for entry into a scheduled refueling outage, the station discovered that a single Main Steam Isolation Valve (4A MSIV) did not fully close on demand. All other equipment operated as expected. This condition is being reported pursuant to 10 CFR 50.72(b)(3)(v). The NRC Resident Inspector has been notified.

  • * * RETRACTION ON 04/26/22 AT 1422 EDT FROM DAVID STOIA TO BRIAN PARKS * * *

The following information was provided by the licensee via email: On 3/12/2022 at 0656 EDT Turkey Point Unit 4 notified the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) that a single Main Steam Isolation Valve (MSIV) did not fully close when manually demanded from the control room during shutdown of Unit 4 for a refueling outage. Following disassembly and inspection of the MSIV, Florida Power & Light Engineering identified the cause of the deficiency and determined that the valve would have fully seated under its design accident conditions. This notification is a retraction of EN# 55785. The NRC Resident Inspector has been notified of this retraction. Notified R2DO (Miller).

ENS 5578010 March 2022 01:13:00Brunswick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Reactor Core Isolation Cooling
Automatic Depressurization System

The following information was provided by the licensee: At 2013 EST on March 9, 2022, the HPCI System was declared inoperable following evaluation of routine HPCI surveillance testing data indicating that the required response time for reaching rated conditions was not met. Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). The Reactor Core Isolation Cooling (RCIC) System and Automatic Depressurization System (ADS) are operable. There was no impact on the health and safety of the public or plant personnel. Investigation is in-progress to determine the cause. Unit 1 is not affected by this event. Unit 1 is in a refueling outage. The NRC Resident Inspector has been notified.

  • * * RETRACTION ON 05/04/22 AT 1135 EDT FROM CHARLIE BROOKSHIRE TO DAN LIVERMORE * * *

The following information was provided by the licensee via email: At 20:13 EST on March 9, 2022, the HPCI System was declared inoperable following evaluation of routine HPCI surveillance testing data indicating that the required response time for reaching rated flow and pressure was not met. Subsequent to this, it was determined that the required response time was overly conservative for assuring the safety function of the system could be fulfilled. The required response time was revised. The operability determination for this event has been updated indicating that system operability was never lost for this event. There was not a condition that could have prevented the system from fulfilling the safety function. The NRC Resident Inspector has been notified. Notified R2DO (Miller).

ENS 556821 January 2022 17:10:00Columbia10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentService water
Reactor Core Isolation Cooling
High Pressure Core Spray

The Licensee provided the following information via fax: During performance of a surveillance of the High Pressure Core Spray (HPCS) service water system on January 1, 2022, the HPCS system was declared inoperable for performance of the surveillance. During the surveillance, pump discharge pressure and flow were above the action range curve specified in the surveillance. For the given flow rate, pump discharge pressure was too high. This condition prevents declaring the HPCS service water system and HPCS system operable. The HPCS service water and HPCS systems remain inoperable. The station entered Technical Specification (TS) 3.7.2.A and TS 3.5.1.B at 0910 (PST) on January 1, 2022. In accordance with TS 3.5.1.B, the Reactor Core Isolation Cooling (RCIC) system was verified to be operable. TS 3.5.1 Action B provides a 14-day completion time to restore HPCS to an operable status. All other Emergency Core Cooling systems (ECCS) are operable. This event is being reported as an event or condition that could have prevented the fulfillment of a safety function credited for mitigating the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). The HPCS system is a single train system at Columbia. The NRC resident has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee is investigating the cause of the high pump discharge pressure and verifying instrumentation accuracy.

  • * * RETRACTION ON 1/6/22 AT 1715 EST FROM CHASE WILLIAMS TO TOM KENDZIA * * *

This Notification is to retract EN 55682, Unplanned High Pressure Core Spray (HPCS) Inoperability. On 1/1/2022 at (1735 EST), Columbia Generating Station notified the NRC under 10 CPR 50.72(b)(3)(v)(D) of the inoperability of a single train of safety system (HPCS) for performance of the surveillance. During the surveillance pump discharge pressure and flow were above the action range curve specified in the surveillance. Engineering performed an analysis of this event and concluded the HPCS was operable during the event and would have performed its required safety function. The results of initial IST testing of HPCS-P-2 via OSP-SW/IST-Q703 on 01/01/22 resulted in measured parameters falling outside of the acceptable range specified for this pump. Systematic error was suspected as the cause of the failure and the test was reperformed following taking actions to eliminate the suspected systematic errors. The second performance of the test on 01/01/22 resulted in acceptable pump performance. Evidence exists that the initial performance of the test failed due to imprecise averaging techniques due to difficulties in averaging continuously changing values on the test instrument. The second performance of OSP-SW/IST-Q703 should be considered a successful test and the test of record as the systematic error was eliminated and measured parameters are considered valid. The NRC Resident Inspector has been notified. The HOO notified R4DO (Rolando-Otero).

ENS 556192 December 2021 00:47:00Quad Cities10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentAt 1847 CST on December 1, 2021, it was discovered that the HPCI (high pressure coolant injection) system was inoperable. 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). The Unit 1 RCIC (reactor core isolation cooling) system was Operable during this time period. There was no impact on the health and safety of the public or plant personnel. The NRC Resident has been notified. Unit 1 HPCI operability was restored at 2110 CST.
ENS 5559318 November 2021 22:02:00FitzPatrick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionOn November 18, 2021, during the performance of High Pressure Coolant Injection (HPCI) surveillance testing, 23MOV-19 (HPCI PUMP DISCH TO REACTOR INBD ISOL VALVE) did not go open as expected while performing the sensed low water level portion of the test. The ability to manually open 23MOV-19 from the control room was unaffected as such, the HPCI system remained available for use. Failure of 23MOV-19 to open automatically prevents the HPCI system from performing its safety function as such this condition renders HPCI inoperable but available and is being reported as a condition that could have prevented the fulfillment of the safety function of a system needed to mitigate the consequences of an accident per 10CFR50.72(b)(3)(v)(D). HPCI inoperable placed the licensee in a 14-day limiting condition for operation for Tech Spec 3.5.1.c. The NRC Resident Inspector was notified.
ENS 5552918 October 2021 00:30:00Prairie Island10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentEmergency Diesel Generator

At 1930 CDT on 10/17/2021, it was discovered both of the Unit 2 Emergency Diesel Generators were simultaneously INOPERABLE with a requirement to have one OPERABLE train; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10CFR 50.72(b)(3)(v). Offsite power was OPERABLE during this event. There was no impact on the health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified. The cause was corrected and both Emergency Diesel Generators are currently operable.

  • * * RETRACTION ON 12/13/2021 AT 1607 EST FROM CARLOS PARADA TO LLOYD DESOTELL * * *
  • The following information was provided by the licensee via email:

This is a retraction of Event Notification EN55529 in accordance with 10 CFR 50.72(b)(3)(v)(D) made by the Prairie Island Nuclear Generating Plant on October 18, 2021. The original notification stemmed from a loss of power to the non-safety related Unit 2 Emergency Diesel Generator (EDG) starting air compressors. The resulting pressure decay in the EDG starting air receivers led to a decision to declare both EDGs inoperable. A subsequent engineering evaluation has provided reasonable assurance that the Unit 2 EDGs were operable and capable of performing their safety function during the time power was lost. The NRC Resident Inspector has been notified. The HOO notified R3DO (Skokowski).

ENS 5548423 September 2021 18:43:00Limerick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionDuring planned testing of the Unit 1 HPCI (high pressure coolant injection) system, flow controller oscillations occurred which prevented successful completion of the surveillance test. Operators secured Unit 1 HPCI and declared the system inoperable. HPCI inoperable placed the licensee in a 14-day limiting condition for operation that was extended to 30 days after their risk-informed completion time evaluation was done. The licensee has notified the NRC Resident Inspector.
ENS 554519 September 2021 05:33:00Grand Gulf10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentReactor Core Isolation Cooling
High Pressure Core Spray
At 0033 CDT on September 9, 2021, Grand Gulf Nuclear Station (GGNS) was operating at 70 percent power when the High Pressure Core Spray (HPCS) was declared inoperable. The inoperability determination was made due to control room annunciations. In accordance with GGNS Technical Specification 3.5.1.B.1, the Reactor Core Isolation Cooling system was verified to be operable. Troubleshooting is in progress. This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function. The NRC Resident Inspector has been notified.
ENS 554488 September 2021 05:59:00Hatch10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Reactor Core Isolation Cooling
At 0159 EDT on 09/08/2021, the HPCI pump discharge valve failed to reopen during a valve surveillance, resulting in the HPCI system being declared INOPERABLE. HPCI does not have a redundant system; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). Reactor Core Isolation Cooling system and low pressure Emergency Core Cooling Systems were OPERABLE during this time. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5542322 August 2021 09:29:00Fermi10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Emergency Diesel Generator
Reactor Core Isolation Cooling
At 0529 EDT on August 22, 2021, HPCI ((High Pressure Coolant Injection System)) was declared inoperable due to receiving the HPCI Inverter Circuit Failure annunciator. The cause of the annunciator was a fuse failure. The cause of the fuse failure is unknown at this time and is under investigation. Concurrent with the HPCI fuse failure was a similar fuse failure within the Division 2 EDG ((emergency diesel generators)) Load Sequencer which renders the Division 2 EDGs inoperable. Relation to the HPCI issue is unknown and is part of the investigation. The RCIC ((Reactor Core Isolation Cooling System)) was verified operable per Tech Spec 3.5.1 E.1. In addition, offsite circuits were verified operable per Tech Spec 3.8.1.B. Division 1 EDGs remain operable. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. There was no impact on the health and safety of the public or plant personnel. The Senior NRC Resident Inspector has been notified.
ENS 5540311 August 2021 10:34:00Fermi10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Reactor Pressure Vessel

At 0634 EDT on August 11, 2021 (high pressure coolant injection) HPCI was declared inoperable due to a pump flow controller problem. The cause of the controller problem is unknown at this time and is under investigation. (Reactor core isolation cooling) RCIC was verified operable per Tech Spec 3.5.1 E.1. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

  • * * RETRACTION FROM WHITNEY HEMMINGWAY TO KAREN COTTON ON 10/6/2021 AT 1036 EDT * * *

The purpose of this notification is to retract a previous report made on August 11, 2021 (EN 55403). At 0634 EDT on August 11, 2021, an unplanned inoperability of the High Pressure Coolant Injection system (HPCI) was reported pursuant to 10 CFR 50.72(b)(3)(v)(D) by EN 55403. HPCI was declared inoperable due to receipt of an alarm associated with the pump flow controller. The HPCI system operating procedure states that HPCI should be declared inoperable when this alarm is received. The cause of the alarm, a loose transmitter connection, was identified and corrected. Following clearance of the alarm, HPCI was declared operable at approximately 1930 EDT on August 11, 2021. This alarm indicated a fault in the signal from the transmitter to the HPCI flow controller; in this case, the HPCI flow controller would have continuously called for maximum HPCI flow. The controller is configured with a high limiter to prevent an overspeed trip. An engineering evaluation of the event identified that HPCI was capable of performing its required safety functions while this alarm was present. The condition was that the HPCI flow controller would have continuously called for maximum HPCI flow upon HPCI initiation, however operators would be able to manually control HPCI flow upon HPCI initiation. Additionally HPCI would have run until Reactor Pressure Vessel (RPV) level reached Level 8 where it would trip until RPV level decreased to Level 2 then automatically restart. The licensee notified the NRC Resident Inspector. Notified R3DO (Peterson).

ENS 5531116 June 2021 19:50:00Palisades10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentOn 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 555583 June 2021 06:41:00Fermi10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Reactor Core Isolation Cooling
At 0241 (EDT) on June 3, 2021, during performance of a High Pressure Coolant Injection (HPCI) Condensate Storage Tank (CST) level functional surveillance, the HPCI torus suction inboard isolation valve was slow to open during swap of suction from the CST to the Torus. On June 9, 2021, it was determined that as a result of the June 3, 2021, slow swap condition, TS 3.3.5.1 Required Action D.1 to declare HPCI inoperable within 1 hour was applicable due to inoperable CST low level instrumentation channels. At 1817 (EDT) on June 3, 2021, HPCI suction was swapped to the torus, making TS Required Action D.1 no longer applicable. Reactor Core Isolation Cooling (RCIC) was available throughout this condition. At 0900 (EDT) on November 3, 2021, it was determined that an NRC event report due to HPCI inoperability should have been made. This event is being reported as a late 8-hour non-emergency notification pursuant to 10CFR50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. The cause of the slow valve opening was later determined to be corrosion products on contacts of a relay in the CST low level instrumentation logic. On June 4, 2021 at 1451 (EDT), the HPCI CST Level Functional Test was completed Satisfactorily, restoring HPCI Instrumentation to Operable. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5522430 April 2021 03:54:00Peach Bottom10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Reactor Core Isolation Cooling
On 4/29/21 at 2354 (EDT), an alarm was received for U2 HPCI Inverter Power Failure. (It was) identified that the High Pressure Coolant Injection (HPCI) flow controller had lost power due to a failure of an inverter. Without the flow controller, HPCI would not auto start to mitigate the consequences of an accident; thus, HPCI was declared inoperable. All other emergency core cooling systems and reactor core isolation cooling (RCIC) system remain operable. HPCI is a single train system with no redundant equipment in the same system; therefore, this failure is reportable as an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident per 10CFR50.72(b)(3)(v)(d). The NRC Resident has been informed of this notification.
ENS 551289 March 2021 08:13:00Susquehanna10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection
Primary containment
At 0313 EST on March 9th, 2021, during performance of Unit 1 High Pressure Coolant Injection (HPCI) valve exercising, the inboard vacuum breaker isolation valve did not stroke closed as expected, but remained mid-position. The affected penetration of primary containment was isolated by closing the outboard HPCI vacuum breaker isolation valve. This results in an unplanned inoperability of the Unit 1 HPCI system. This is being reported as a loss of an entire safety function condition in accordance with 10CFR50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector. Unit 1 is in a 14-day LCO for Tech Spec 3.5.1(d), HPCI inoperability. Tech Spec 3.6.1.3(a), Containment Penetration Valve, was completed with closing the outboard HPCI vacuum breaker isolation valve. The Units are in a normal offsite power line-up.
ENS 5504623 December 2020 12:53:00LaSalle10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Core SprayAt 0653 CST on 12/23/20, it was discovered the single train of high pressure core spray was inoperable. 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). All other emergency core cooling systems were operable during this time. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. The high pressure core spray is inoperable because the water lake pump tripped. This inoperability puts the licensee in a 14-day limiting condition for operability.
ENS 5504017 December 2020 20:39:00Harris10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentReactor Coolant SystemOn December 17, 2020 at 1539 EST, with Harris Nuclear Plant Unit 1 preparing for entry into Mode 4, the Reactor Coolant System was pressurized greater than 1000 psig for approximately 15 minutes with all three Cold Leg Injection Accumulator Discharge Valves closed. This event is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). Both Low Head and High Head Safety Injection Systems were operable at this time. This condition does not affect the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5500217 November 2020 01:18:00Clinton10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentAt 1918 CST on 11/16/2020, it was discovered both required trains of the Main Control Room Ventilation and Air Conditioning systems were simultaneously inoperable. Due to these inoperabilities, the systems were 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). Subsequent post-maintenance testing demonstrated that the Division 1 Main Control Room Ventilation system was available at the time of the event and was restored to operable status at 2036 CST on 11/16/2020. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5500016 November 2020 10:15:00Limerick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionDuring normal plant start up on Limerick Unit 1, reactor pressure was raised above 200 psig prior to unisolating the Unit 1 high pressure coolant injection system (HPCI) which remained inoperable. Per TS 3.5.1, HPCI is required to be operable in Mode 2 above 200 psig. HPCI has since been restored to operable. The NRC Resident Inspector has been notified.
ENS 549835 November 2020 03:50:00Browns Ferry10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant Injection

At 2150 CST on 11/04/2020, it was discovered that Unit 1 High Pressure Coolant Injection System (HPCI) was INOPERABLE; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v), 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. During performance of 1-SR-3.5.1.7, HPCI Main and Booster Pump Set Developed Head and Flow Rate Test at Rated Reactor Pressure, Unit 1 HPCI was manually tripped by the control room operator due to local report of excessive shaking of the cooling water supply from the booster pump line. There was no impact to the safety of the public or plant personnel. The NRC Resident Inspector has been notified. CR 1650042 documents this condition in the Corrective Action Program. The Unit is in a 14-day LCO 3.5.1(c). The RCIC System is operable.

  • * * RETRACTION FROM MARK ACKER TO HOWIE CROUCH AT 1607 EST ON 12/29/2020 * * *

ENS Event number 54983, made on 11/05/2020 is being retracted. NRC notification 54983 was made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10 CFR 50.72 were met when Unit 1 HPCI was manually tripped by the control room operator due to a local report for excessive shaking of the cooling water supply from the booster pump line. A subsequent engineering evaluation concluded on 11/06/2020 there was reasonable assurance of operability with no additional intrusive maintenance performed and that the condition was bounded by a previous evaluation documented in (Condition Report) CR 1347736. As such, the circumstances discussed in the report did not result in any condition that at the time of discovery could have prevented the fulfillment of the safety function of structures of the system that are needed to mitigate the consequences of an accident. Therefore, this event is not reportable under 10 CFR 50.72(b)(3)(v). TVA's evaluation of this event is documented in the corrective action program. The licensee has notified the NRC Resident Inspector. Notified R2DO (Miller).

ENS 5495419 October 2020 04:13:00Arkansas Nuclear10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident

On October 18, 2020 at 2313 CDT, Arkansas Nuclear One (ANO) discovered that 2VRA-1B (2VSF-9 outside air damper reserve bottle) was below 600 psig. This condition caused the control room envelope to be inoperable in accordance with OP-2104.007 Attachment L. ANO Unit 1 entered TS 3.7.9 Condition B for inoperable control room boundary. ANO Unit 2 entered TS 3.7.6.1 Action D for inoperable control room boundary. A procedurally controlled temporary modification was implemented to install a blank flange on the 2VSF-9 outside air damper. Both Units declared the control room boundary operable at 2358 CDT. The associated control room emergency recirculation fan remains inoperable with the blank flange installed. This is a 7-day shutdown-LCO for both units. The licensee informed the NRC Resident Inspector.

  • * * RETRACTION FROM AARON TOSCH TO HOWIE CROUCH ON 10/24/2020 AT 1657 EDT * * *..

Previously, Entergy notified the NRC that ANO control room envelope was inoperable due to 2VRA-1B (2VSF-9 outside air damper reserve bottle) was below required pressure of 600 psig. After additional engineering evaluation, it was determined the control room boundary remained intact for this condition. As documented in version 2 operability determination for condition report ANO-C-2020-2818, the control room ventilation boundary remained intact for the condition identified and was able to fulfill its function for the required 30-day mission time. In accordance with NUREG-1022, 'Event Report Guidelines 10 CFR 50.72 and 50.73,' a report may be retracted based on a revised operability determination. The CRE remained operable; therefore, this report may be retracted. The NRC Resident Inspector has been informed. Notified R4DO (Pick).

ENS 548804 September 2020 01:48:00River Bend10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentFeedwater
Service water
High Pressure Core Spray
River Bend Station experienced an inadvertent initiation and injection of High Pressure Core Spray (HPCS) at 2048 (CDT) on 9/3/2020 while operating at 92% power. Initial investigation indicates a power supply failure in the Division III trip units which feeds HPCS and Division III Diesel Initiation signals. The Control Room Operator responded to the event by taking manual control of Feedwater Level Control to maintain Reactor Water Level nominal values. The HPCS injection valve was open for approximately 25 seconds before operators manually closed the valve. The manual closure of the injection isolation valve caused the system to be incapable of responding to an automatic actuation signal. The manual override of the injection isolation valve was reset approximately 52 minutes after the event. The HPCS system has remained inoperable. The event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as a condition that caused loss of function of the HPCS System. No radiological releases have occurred due to this event. The Senior NRC Resident Inspector has been notified. These conditions put the unit in a 14-day LCO (3.5.1) for HPCS Inoperability and a 30-day LCO (3.7.1) for one Standby Service Water Pump Inoperable (2C).
ENS 5492322 July 2020 15:30:00Quad Cities10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentOn July 22, 2020, at 1030 CDT, it was discovered that the as-found Unit 2 Oscillation Power Range Monitor (OPRM) Maximum Confirmation Count Setpoint did not match the values in the Quad Cities Unit 2 (Core Operating Limits Report) (COLR) per TS SR 3.3.1.3.3. All Unit 2 OPRMs were declared inoperable. Due to this inoperability, the OPRM system was in a condition that could have prevented the fulfillment of a safety function; therefore, this condition is being reported per 10 CFR 50.72(b)(3)(v)(D). There were no other Technical Specification or safety systems inoperable at the time of this event. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Quad Cities Unit 2 returned their OPRMs to operable on July 23, 2020, at 1210 CDT, following a setpoint adjustment. In addition, during a more recent meeting between station personnel and the NRC resident inspectors, feedback was provided that brought to the station management's attention that they needed to make the required 50.72 notification as a result to this past inoperability.
ENS 5478115 July 2020 12:35:00Watts Bar10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentAt 0835 EDT on July 15, 2020, it was discovered that the main control room (MCR) envelope was inoperable due to a MCR door being found ajar; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The door was closed, restoring the MCR envelope to operable at 0839 EDT. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 547385 June 2020 07:20:00Millstone10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Emergency Ventilation

EN Revision Imported Date : 10/6/2020 CONTROL ROOM BOUNDARY DOOR FAILURE On June 5, 2020, at 0320 (EDT) a loss of control room envelope (CRE) was declared inoperable due to failure of door 204-36-007. The door was repaired at 0322 (EDT), restoring the CRE to operable. The NRC Resident Inspector, state, and local authorities were notified.

  • * * RETRACTION ON 07/09/2020 AT 1443 EDT FROM GERALD A. BAKER TO OSSY FONT * * *

The purpose of this call is to retract a report made on June 5, 2020, NRC Event Number EN54738. NRC Event Report number EN54738 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room envelope boundary door was discovered to not be able to fully close due to the latching mechanism being stuck in the extended position. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) via an 8 hour prompt report 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. Upon further review, MPS2 determined that there was no loss of safety function. An engineering evaluation determined that even with the control room boundary door unable to be fully closed due to the latching mechanism being stuck in, the extended position, control room air in-leakage would not have been sufficient to prevent the control room emergency ventilation system from performing its safety function. Therefore, this condition is not reportable and NRC Event Number EN54738 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Dimitriadis).

  • * * UPDATE FROM MICHAEL GAGNON TO BRIAN P. SMITH AT 1444 EDT ON 10/01/2020 * * *

The purpose of this call is to provide an update to the retraction for a report made on June 5, 2020, NRC Event Number EN54738. The retraction being updated was made on 7/9/2020 at 1443 hours. NRC Event Report number EN54738 describes a condition at Millstone Power Station Unit 2 (MPS2) in which a control room envelope boundary door was discovered to not be able to fully close due to the latching mechanism being stuck in the extended position. The condition was reported to the NRC pursuant to 10 CFR 50.72(b)(3)(v)(D) via an 8 hour prompt report 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 (the Control Room Envelope). A subsequent engineering evaluation of the conditions that existed at the time, determined that the inability of the control room boundary door to fully close due to the latching mechanism being stuck in the extended position did not have an adverse impact upon the ability of the CRE to perform its safety function. The CRE remained operable throughout this event, and the ventilation system would have performed its safety function. Therefore, this condition is not reportable and NRC Event Number EN54738 is being retracted. The basis for this conclusion has been provided to the NRC Resident Inspector. Notified R1DO (Lally).

ENS 5471819 May 2020 17:29:00Watts Bar10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentAt 1329 EDT on May 19, 2020, it was discovered that the main control room (MCR) envelope was inoperable due to a control room envelope (CRE) door being found ajar; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The CRE door was closed, restoring the MCR envelope to operable at 1331 EDT. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 546934 May 2020 21:40:00LaSalle10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Core Spray

This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to mitigate the Consequences of an Accident. A through wall leak was found on piping connected to the Division 3 Diesel Generator (DG) Cooling Water Strainer. This condition has been evaluated and the Division 3 DG Cooling Water System has been declared inoperable. The Division 3 DG Cooling Water System is a support system for the Division 3 Emergency DG and the High Pressure Core Spray System (HPCS). The NRC Resident Inspector has been notified.

  • * * RETRACTION ON MAY 8, 2020 AT 1709 EDT FROM JOE MESSINA TO BRIAN LIN * * *

This update retracts Event Notification #54693, which reported a condition that could have potentially prevented fulfillment of a safety function needed to mitigate the consequences of an accident. An evaluation of the flaw on the piping connected to the Unit 2 Division 3 Diesel Generator (DG) Cooling Water strainer concluded that the system would have remained operable. The High Pressure Core Spray system, supported by the operable DG Cooling Water system, remained operable and capable of performing its safety function. The NRC Resident Inspector has been notified. Notified R3DO (Stone).

ENS 546923 May 2020 21:50:00Nine Mile Point10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentOn 5/3/2020 at 1100 EDT, Operations identified a step change in the Main Control Room ambient noise. The cause of the noise was a rise in vibrations on the Number 11 fan motor of the Main Control Room Ventilation Circulating Fan. Another step change in noise occurred and Operations swapped from the Number 11 fan motor to its redundant Number 12 fan motor, but the noise and vibrations did not improve. The two independent motors are connected to the blower shaft with belts on either end of the shaft. This entire fan and motor assembly is contained within the Main Control Room ventilation ducting and is not visible. At 1118 EDT, Operations shut off the Main Control Room Ventilation Circulating Fan due to Number 11 fan motor vibrations, declared the Main Control Room Air Treatment System inoperable, and entered the Technical Specification 3.4.5.e, 7-day action statement. At 1750 EDT, Maintenance entered the ductwork and informed Operations that the Number 11 fan bearing had catastrophically failed and because of the extent of damage and close physical proximity to the Number 12 fan motor, jeopardized its continued operation. As a result, Operations also declared the Number 12 fan motor inoperable and determined the event was reportable as a loss of safety function per 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.
ENS 5467722 April 2020 14:15:00Hatch10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Coolant InjectionAt 1015 (EDT), on 04/22/2020, while Unit 2 was at approximately 0.4 percent power in MODE 2, reactor pressure was increased to 150 psig while HPCI was INOPERABLE due to not having been placed in standby. HPCI does not have a redundant system; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). ADS (Automatic Depressurization System) and low pressure ECCS (Emergency Core Cooling System) systems were OPERABLE during this time. HPCI was returned to OPERABLE status at 1109 hrs. on 04/22/2020. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
ENS 5466614 April 2020 21:45:00Quad Cities10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Emergency VentilationOn April 14, 2020 at 1645 CDT, the Control Room Emergency Ventilation Air Conditioning (CREV AC) system was declared inoperable when the electrical feed breaker to the Refrigeration Compressor Unit (RCU) was found in a tripped condition. As a result, both units entered Technical Specification 3.7.5 Condition A. Investigation is in progress to determine the cause and corrective actions of the RCU feed breaker trip. The CREV AC system maintains a habitable control room environment and ensures the operability of components in the control room emergency zone during accident conditions. This notification is being made in accordance with 10 CFR 50.72(b)(3)(v)(D) because the CREV system is a single train system, and loss of the CREV AC could impact the plant's ability to mitigate the consequences of an accident.
ENS 5465710 April 2020 07:00:00FitzPatrick10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentOn April 10, 2020, at 0300 (EDT), an oil leak from 23PCV-12, HPCI (High Pressure Core Injection) Trip System Pressure Control Valve (PCV), resulted in the system being declared inoperable. This condition is being reported as a condition that could have prevented the fulfillment of the safety function of a system needed to mitigate the consequences of an accident per 10 CFR 50.72(b)(3)(v)(D). The licensee notified the NRC Resident Inspector.
ENS 5459420 March 2020 15:25:00Quad Cities10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentEmergency Diesel Generator
Residual Heat Removal
On March 20, 2020, at 1025 hours (CDT), Unit 2 MCC (motor control center) 28/29-5 failed to transfer to its alternate feed during surveillance testing. This would result in MCC 28/29-5 being de-energized in the event of a DBA LOCA (design basis accident loss of coolant accident) in which the Unit 1 Emergency Diesel Generator fails to energize Bus 29. Consequently, the LPCI (low pressure coolant injection) Injection Valve (MO 2-1001-29A/B) would not have power to open on the loop selected by LPCI Loop Select. This renders both divisions of the LPCI mode of Residual Heat Removal system inoperable. Technical Specification 3.5.1, Condition E had previously been entered during testing, requiring restoration of LPCI in 72 hours. No other ECCS (emergency core cooling) systems were inoperable at the time of the event. Troubleshooting and repairs are in progress. This event is reportable under 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function. The plant is still in its 72-hr. LCO action statement. The licensee has notified the NRC Resident Inspector and the state of Illinois Emergency Management Agency.
ENS 545071 February 2020 16:50:00Perry10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentCore Spray

EN Revision Imported Date : 3/17/2020 LOW PRESSURE CORE SPRAY INOPERABLE At 1150 EST on 2/1/2020, it was discovered that the Low Pressure Core Spray System was inoperable due to a divisional battery voltage being out-of-specification. Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The Low Pressure Core Spray is a single train safety system in Modes 1, 2, and 3. Low Pressure Core Spray was restored to operable, restoring function at 1230 on 2/1/2020. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

  • * * RETRACTION ON 03/16/2020 AT 1156 EDT FROM JOHN NAKEL TO BETHANY CECERE * * *

On February 01, 2020, event notification (EN-54507) was made to the NRC for Low Pressure Core Spray (LPCS) inoperability. This notification was made due to high DC bus voltages resulting in LPCS being declared inoperable which resulted in a loss of safety function. An Engineering Evaluation Request (EER) was performed to determine an upper limit for DC bus voltage. This EER determined that LPCS could perform its required functions with a voltage increase of up to 150V DC if the duration was not greater than two hours. The elevated voltage was experienced for approximately 59 minutes. The maximum voltage experienced was 147.07V DC. Therefore, LPCS remained operable and no loss of safety function existed. The NRC Resident Inspector has been briefed on the evaluation results and informed of this retraction. Notified R3DO (Hanna).

ENS 544657 January 2020 18:41:00Oconee10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident

At 1341(EST), on 01/07/20, it was discovered all trains of the Chilled Water System were simultaneously Inoperable; therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D). During this event, the Bravo train chiller was operating in a maintenance run and the temporary chiller was available and placed in service promptly to restore the safety function. The control room area cooling safety function was restored at time 1435 (EST) when one required train was declared Operable. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

  • * * RETRACTION ON 1/23/2020 AT 1718 EST FROM JERRY COLLIER TO THOMAS KENDZIA * * *

The purpose of this notification is to retract a previous report made on January 7, 2020, at 1909 EST (EN#54465). A subsequent evaluation determined that the Bravo train chiller, which was running at the time of the event, would be able to perform its safety function and was operable at the time of the event. Therefore, there was no loss of safety function. The NRC Senior Resident Inspector has been notified. Notified R2DO (Coovert).

ENS 544255 December 2019 14:10:00Cooper10 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
The following was received via email from Cooper Nuclear Station: At 0810 (CST), on 12/5/19, Operations personnel discovered BLDG-DOOR-R209, FIRE DOOR BETWEEN CRITICAL SWITCHGEAR ROOMS F & G, was unlatched. The door was immediately latched upon discovery. Based on door logs, the door separating the two critical switchgear rooms was inadvertently left unlatched for approximately 5 minutes. This door is a Steam Exclusion Boundary (SEB) door. It is required to be closed and latched when the Auxiliary Steam Boiler is in service due to Auxiliary Steam piping passing through Critical Switchgear Room 'G'. If a steam line break was to occur with the door unlatched, steam could render both Critical Switchgear busses inoperable. This is being reported under 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, and 10 CFR 50.72(b)(3)(v), Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (B) remove residual heat and to (D) mitigate consequences of an accident. There was no impact on the health and safety of the public or plant personnel. The door closes automatically and appeared to have been left unlatched by the last person passing through. The door was tested and latches as required. The licensee notified the NRC Resident Inspector.
ENS 5441730 November 2019 19:00:00Diablo Canyon10 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
On November 30, 2019, at 1100 PST, with Unit 2 in Mode 4, Operations identified that both trains of containment spray had been removed from service earlier at approximately 0217 hours as part of preparations for a planned Mode 5 entry. The containment spray pumps are required to be operable (along with the containment fan cooler units) in Modes 1 through 4 in accordance with Technical Specification 3.6.6. With both containment spray pumps inoperable, TS 3.6.6 Action F requires the Unit to be shut down in accordance with TS 3.0.3. At 1125 hours, both trains of containment spray were returned to operable and the required actions of TS 3.6.6 and TS 3.0.3 were exited. The five containment fan cooler units remained operable for the duration of the occurrence. This notification is being made in accordance with the requirement of 10 CFR 50.72(b)(3)(v) as an event or condition that could have prevented fulfillment of a safety function, and 10 CFR 50.72(b)(3)(ii) as an event or condition that may have resulted in the plant being in an unanalyzed condition. The NRC Senior Resident Inspector has been notified.
ENS 5440321 November 2019 18:25:00Clinton10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Core Spray

EN Revision Imported Date : 1/13/2020 UNIT 1 HIGH PRESSURE CORE SPRAY INOPERABLE On 11/21/2019, at 1225 CST, as a result of Division 4 DC bus voltage oscillations, bus voltage lowered to less than the required improved technical specification (ITS) voltage of 127.6 VDC. This resulted in declaring High Pressure Core Spray (HPCS) system inoperable per technical specification LCO 3.8.4 and 3.8.9 actions. Division 4 DC bus voltage was restored to greater than 127.6 VDC at 1227 CST. The HPCS system remains inoperable due to Division 4 DC battery charger inoperability. Since HPCS is an emergency core cooling system and is a single train safety system, this condition is reportable under 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector has been notified. Clinton Power Station has implemented required compensatory actions due to the Division 4 DC battery charger and HPCS remaining inoperable.

  • * * RETRACTION ON 1/10/20 AT 1145 EST FROM JACOB HENRY TO KARL DIEDERICH * * *

The purpose of this notification is to retract a previous report made on 11/21/2019 (EN 54403) under 10 CFR 50.72(b)(3)(v)(D). Subsequent to the initial notification, the event and the NRC guidance in NUREG-1022 pertaining to 10 CFR 50.72(b)(3)(v)(D) were reviewed further. The evaluation determined that the Division 4 DC bus voltage oscillations were caused by a degraded but operable charger. The Division 4 battery remained fully charged during the event and its operability was not impacted. Therefore, the HPCS system remained Operable. Under these circumstances, this event does not represent an inoperability of an accident mitigation system under 10 CFR 50.72(b)(3)(v)(D). Therefore, EN 54403 is retracted. The NRC Resident Inspector has been notified. Notified R3DO (Hanna).

ENS 5440121 November 2019 02:44:00Surry10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentFeedwater
Auxiliary Feedwater
At 2144 EST, on 11/20/2019, all three auxiliary feedwater pumps for Unit 2 were declared Inoperable due to check valve leakage causing the turbine driven auxiliary feedwater pump to rotate backwards and subsequently trip. At this time, two of the Unit 1 motor driven auxiliary feedwater pumps were still able to provide cross-tied feedwater in the event of a design basis accident. At 2203 EST, the two motor driven auxiliary feedwater pumps on Unit 2 were declared operable once the discharge isolation valves for the turbine driven auxiliary feedwater pump were closed, thus preventing backflow through the turbine driven auxiliary feedwater pump and ensuring forward flow of the motor driven auxiliary feedwater pumps. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented the fulfillment of a safety function. There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. Unit 2 is in a 72-hour LCO 3.6.F.1 for turbine driven auxiliary feedwater pump inoperability.
ENS 5439116 November 2019 04:53:00Watts Bar10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Emergency VentilationAt 2353 EST on November 15, 2019, a Main Control Room (MCR) alarm was received for low control room positive pressure. At 2355 EST, a Control Room Envelope (CRE) door was found ajar and immediately closed. Technical Specification 3.7.10 Control Room Emergency Ventilation System (CREVS) was declared not met for both trains. Watts Bar Unit 1 and Unit 2 entered Condition B. At 2355 EST on November 15, 2019, the alarm cleared, CREVS was declared operable and LCO 3.7.10 Condition B was exited for both units. 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. See similar EN #54390. The licensee has taken compensatory measures while investigating the cause.
ENS 5439016 November 2019 03:34:00Watts Bar10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Emergency VentilationAt 2234 Eastern Standard Time (EST) on November 15, 2019, a Main Control Room (MCR) alarm was received for low control room positive pressure. At 2236 EST, a Control Room Envelope (CRE) door was found ajar and immediately closed. Technical Specification 3.7.10 Control Room Emergency Ventilation System (CREVS) was declared not met for both trains. Watts Bar Unit 1 and Unit 2 entered Condition B. At 2236 EST on November 15, 2019, the alarm cleared, CREVS was declared operable and LCO 3.7.10 Condition B was exited for both units. 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.
ENS 543716 November 2019 00:11:00Grand Gulf10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentService water
Emergency Diesel Generator
High Pressure Core Spray

On November 5, 2019 at 1811 CST, station service water A and the Division 1 diesel generator (DG) were declared inoperable based on the results of an engineering evaluation of a Class 3 piping leak. This was determined to be a potential inability to fulfill a safety function due to concurrent inoperability of two emergency diesel generators. Division 3 DG was inoperable due to planned maintenance on November 4, 2019 at 0000 CST. This event is being reported an 8-hour non-emergency notification per 10 CFR 50.72 (b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function (Accident Mitigation). Division 3 DG and high pressure core spray have been restored, and the fulfillment of the accident mitigation safety function has been restored. The NRC Senior Resident Inspector has been notified.

  • * * RETRACTION ON 11/11/19 AT 1739 EST FROM GABRIEL HARGROVE TO BETHANY CECERE * * *

This was initially reported under 10 CFR 50.72(b)(3)(v)(D). However, subsequent engineering evaluation determined that the condition did not affect safety system operability. The evaluation determined that the leakage was within allowable limits and piping structural integrity was not challenged at this time nor in the past three years. The Division 1 DG and SSW A were at the time of discovery OPERABLE and EN54371 is being retracted. The licensee will notify the NRC Resident Inspector. Notified R4DO (Drake).

ENS 543641 November 2019 07:16:00Nine Mile Point10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentHigh Pressure Core SprayOn November 1, 2019 at 0316 EDT, Nine Mile Point Unit 2 (NMP2) received Control Room annunciation for HPCS SYSTEM INOPERABLE and inoperable status light indication for TRIP UNITS OUT OF FILE/POWER FAIL. Initial investigation has identified a potential failed 24 vdc power supply which supplies power to the HPCS trip units for system initiation and control. The HPCS system has been declared inoperable per TS 3.5.1 resulting in an unplanned 14 day LCO. All other plant systems functioned as required. NMP2 is currently at 100 percent power in Mode 1. This condition is reportable under 10 CFR 50.72(b)(3)(v)(D) as, 'Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (D) Mitigate the consequences of an accident.' The licensee notified the NRC Resident Inspector.
ENS 5435527 October 2019 21:05:00Quad Cities10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an AccidentControl Room Emergency VentilationOn October 27, 2019, at 1605 CDT, the Control Room Emergency Ventilation (CREV) was declared inoperable due to finding water in the system's Air Filtration Unit (AFU) filter enclosure. Technical Specification 3.7.4, Condition A, was entered which requires the CREV system to be restored to an operable status in seven days. No other systems were out of service at the time this was declared inoperable. The CREV system maintains a habitable control room environment and ensures the operability of components in the control room emergency zone during accident conditions. This notification is being made in accordance with 10 CFR 50.72(b)(3)(v)(D), "Event or Condition That Could Have Prevented Fulfillment of a Safety Function," because the CREV system is a single train system required to mitigate the consequences of an accident. The licensee has notified the NRC Resident Inspector.