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At 1710 EDT on June 11, 2021, a Technical Specification required shutdown was initiated at Plant Hatch Unit 1. Technical Specification Condition 3.4.4.B unidentified LEAKAGE increase not within limits, was entered due to a greater than 2 gpm increase in unidentified LEAKAGE within the previous 24 hour period in MODE 1. This specification was entered on June 11, 2021, at 1615 EDT with a REQUIRED ACTION to restore leakage increase within limits within 4 hours. This REQUIRED ACTION could not be completed within the COMPLETION TIME; therefore, a Technical Specification required shutdown was initiated, and this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(i). There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

• * * RETRACTION ON 6/17/2021 AT 1309 FROM JASON BUTLER TO JEFFREY WHITED * * *

Upon further review of the leakage rates, it was determined that at 1900 EDT on 6/11/2021 the drywell floor drain unidentified leakage increased greater than 2 gpm within the previous 24 hours while in MODE 1. Technical Specification (TS) 3.4.4.B was entered to reduce leakage increase to within limits within 4 hours. At 2000 EDT on 6/11/2021 unidentified leakage was reduced below the 2 gpm increase within the previous 24 hours due to actions taken to lower reactor power and pressure. Therefore, the TS required shutdown per TS 3.4.4.C was not applicable. Thus Event Report 55303 is being retracted. The NRC resident has been notified of the retraction. Notified R2DO (Miller).

At 1000 EDT on May 1 2020, Operations commenced a shutdown of DC Cook Unit 2 to comply with LCO 3.4.13, Condition B Reactor Coolant System (RCS) pressure boundary leakage. At 0354 EDT on May 1, 2020, Operations detected an estimated 8 gpm Reactor Coolant System leak. The source of the leak could not be identified and Tech Spec 3.4.13, Condition A was entered for unidentified RCS leakage in excess of the 0.8 gpm limit. At 0745 EDT on May 1, 2020, Unit 2 entered LCO 3.4.13, Condition B when the 4-hour limit to complete the required actions of Condition A could not be met. At 0945 EDT on May 1, 2020, Unit 2 entered LCO 3.4.13, Condition B when the 4-hour limit to complete the required actions of Condition A could not be met. At 0945 EDT on May 1, 2020, inspections inside containment identified the leak as pressure boundary leakage from a pressurizer spray line which also requires entry into LCO 3.4.13, Condition B. At 1059 EDT on May 1, Unit 2 was tripped from 15 percent power. All systems functioned normally. This event is reportable under 10 CFR 50.72(b)(2)(i), the initiation of any nuclear plant shutdown required by the plant's Technical Specifications as a 4-hour report and under 10 CFR 50.72 (b)(3)(ii)(A), degraded condition, as an 8-hour report. The NRC Resident Inspector has been notified.

• * * PARTIAL RETRACTION ON 5/15/2020 AT 1442 EDT FROM BUD HINCKLEY TO THOMAS HERRITY * * *

The condition identified in EN #54687, pursuant to 10 CFR 50.72 (b)(3)(ii)(a) has been evaluated, and has been determined not to be RCS pressure boundary leakage. As such, the 8-hour report is being retracted, as it is not an event or condition that results in, 'the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.' The leakage was subsequently determined to be from the tell-tale nipple of a pressurizer spray valve, not from the pressurizer spray line piping as previously reported. The Reactor Coolant Pressure Boundary (RCPB) is formed by the valve body, plug, seat, body to bonnet extension, and bonnet of the pressurizer spray valve. Therefore, the leakage is not RCPB leakage. There is no change to the 4-hour report made under 10 CFR 50.72(b)(2)(i), the initiation of any nuclear plant shutdown required by the plant's Technical Specifications. The NRC Resident Inspector was notified of this retraction. Notified R3DO (Stone).

On 5/22/2019, the 'A' Control Structure Chiller (Div I) tripped due to a loss of (motor control center) MCC 0B136. The 'B' Control Structure Chiller was already inoperable due to Div II (Emergency Service Water) ESW being out of service for planned maintenance. With the loss of Control Structure HVAC System the ability to maintain temperatures in various spaces including relay rooms, Control Room Floor Cooling and Emergency Switchgear rooms was lost. The 'B' Control Structure Chiller was restarted at 0251 EDT and cooling was reestablished to the required areas, however the 'B' chiller is not considered operable at this time. Units 1 and 2 entered (Technical Specification) TS 3.0.3 at 0256 EDT and a controlled shutdown of both units commenced, Unit 2 at 0340 EDT and Unit 1 0350 EDT. This constitutes a TS required shutdown and requires a 4 hour (Emergency Notification System) ENS notification in accordance with 10 CFR 50.72(b)(2)(i). The failure also requires an 8 hour ENS notification in accordance with 10 CFR 50.72(b)(3)(v) due to the loss of a safety function. The licensee needs to restore the 'B' loop of ESW to exit the Limiting Condition of Operation (LCO). The licensee is currently performing a flow surveillance, once complete and assuming the data is acceptable, the licensee will be able to exit the LCO. The units are in a normal electrical lineup. The licensee will be notifying the state of Pennsylvania FEMA Operations Center. The licensee has notified the NRC Resident Inspector.

• * * UPDATE ON 05/22/2019 AT 1302 FROM SCOTT MYRTHEL TO THOMAS KENDZIA * * *

On 5/22/2019 at 0601 EDT Susquehanna Steam Electric Station reported a shutdown had been commenced at 0340 EDT for Unit 2 and 0350 EDT for Unit 1 due to inoperability of both control structure chillers. Power has been restored to MCC 0B136, and at 0901 EDT the 'A' control structure chiller was declared operable and LCO 3.0.3 was exited. Power reduction for both units was halted at 0901 EDT and preparations for power restoration initiated. As of 1255 EDT on 5/22/2019, Unit 1 power is 94% and Unit 2 power is 92%. Notified the R1DO (Arner).

At 0200 Central Daylight Time on 10/21/2018, Browns Ferry Nuclear Plant Unit 3 commenced a reactor shutdown as required by the Technical Requirements Manual Limiting Condition for Operation 3.4.1 Coolant Chemistry Condition D due to conductivity greater than 10 micro mho/cm at 25 degrees Celsius. The required action for this condition is to immediately initiate an orderly shutdown and be in Mode 4 as rapidly as cooldown rate permits. This event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(i). There was no impact on the health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified.

• * * RETRACTION AT 1719 EST ON 12/13/2018 FROM NEEL SHUKLA TO MARK ABRAMOVITZ * * *

ENS Event Number 53678, made on 10/21/18, is being retracted. NRC notification 53678 was made to ensure that the four-hour non-emergency reporting requirements of 10 CFR 50.72 were met when the licensee discovered a condition requiring shut down of a reactor. 10 CFR 50.72 requires a report in accordance with 50.72(b)(2)(i) for any Technical Specifications (TS) required reactor shutdown. NUREG-1022 only specifies TS applicability and makes no mention of a Technical Requirements Manual (TRM) required shutdown. Because the shutdown comes from the TRM and not the TS as discussed in 10 CFR 50.72 and NUREG-1022, an EN was not required. TVA's evaluation of this event notification is documented in the corrective action program. The licensee notified the NRC Resident Inspector. Notified the R2DO (Ehrhardt).

EN Revision Text: GAS VOIDS DISCOVERED IN BOTH TRAINS OF LOW HEAD SAFETY INJECTION On 5/22/2018, while operating at approximately 100 percent power, Ultrasonic Testing of the Beaver Valley Power Station (BVPS) Unit 1 Low Head Safety Injection (LHSI) pump suction piping identified gas voids in excess of the acceptable limit for void volume. Both trains of LHSI were declared inoperable. Technical Specification (TS) 3.5.2 for both trains of the LHSI system was entered along with TS 3.0.3 which requires the initiation of a plant shutdown. Time of TS entry was 12:56 (EDT). Plant shutdown was commenced at 15:56 (EDT) in accordance with plant procedures. At 15:59 (EDT) Train 'A' LHSI was restored to operable status, TS 3.0.3 Action was exited and the power reduction was stopped at approximately 99 percent. At 17:43 (EDT) Train 'B' LHSI was restored to operable status, TS 3.5.2 Actions were exited. This is reportable per 10 CFR 50.72(b)(3)(ii) Unanalyzed Condition, 10 CFR 50.72(b)(3)(v) Event or Condition that Could Have Prevented the Fulfillment of a Safety Function and 10 CFR 50. 72(b )(2)(i) TS Required Shutdown. The NRC Resident Inspector has been notified.

• * * RETRACTION ON 6/21/18 AT 1535 EDT FROM SHAWN KEENER TO RICHARD SMITH * * *

Further engineering evaluation has determined that the gas voids that existed at the time of discovery would not have rendered the LHSI (Low Head Safety Injection) system inoperable if it were required to actuate. The engineering evaluation concluded that filling of the containment sump during a Design Basis Accident would result in a void volume reduction such that the void in the LHSI suction piping would not be large enough to significantly impact the operability of the system. Therefore, the system remained operable but degraded. No TSs (Technical Specifications) were required to be entered and no shutdown was required. As such, all three reporting criteria do not apply and are being retracted. The NRC Resident Inspector has been notified. Notified R1DO (Burritt).

On October 4, 2017, at 0250 hours (EDT), the Perry Nuclear Power Plant commenced a Technical Specification (TS) shutdown by lowering reactor power from 100 percent rated thermal power to 98 percent to comply with TS LCO 3.0.3. Reactor power was further reduced to 82 percent rated thermal power at 0430 hours (EDT). The plant had entered TS 3.0.3 at 0155 hours (EDT) upon loss of MCC (Motor Control Center), Switchgear, and Miscellaneous Electrical Equipment Areas HVAC System train A while train B was removed from service for maintenance. MCC switchgear ventilation train A was declared inoperable based on excessive belt noise and a dropped belt on MCC switchgear supply fan A. This also constitutes a loss of safety function. This event is being reported in accordance with 10 CFR 50.72(b)(2)(i) and 10 CFR 50.72(b)(3)(v)(D). The NRC Resident Inspector was notified.

• * * UPDATE ON 10/04/17 AT 0926 EDT FROM DAN HARTIGAN TO STEVEN VITTO * * *

Due to the loss of both trains of MCC, Switchgear, and Miscellaneous Electrical Equipment Areas HVAC, actions were taken in LCO 3.8.7 for AC and DC Distribution Systems, LCO 3.8.4 for DC Sources, LCO 3.8.1 for AC Sources, and the associated support systems, the High Pressure Core Spray system was also declared inoperable, which is a single train safety system and therefore, an additional loss of safety function. This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(B), 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72 (b)(3)(v)(D). At 0620 hours (EDT) the A train of MCC, Switchgear, and Miscellaneous Electrical Equipment Areas HVAC and High Pressure Core Spray was declared operable and LCO 3.0.3 was exited. The plant was restored to 100% (percent) power at 0804 (EDT). The NRC Resident Inspector was notified. Notified R3DO(Hills).

On February 28, 2017 at 0930 (EST), a containment visual inspection was performed to identify the source of elevated RCS (Reactor Coolant System) leakage. A leak was identified between 13RC6 and 13SS661, 13 RCS hot leg sample isolation valves at 1000 (EST). These valves are manual isolation valves in the reactor coolant hot leg sample line. Leak isolation could not be initially verified and is considered RCS pressure boundary leakage. Salem Unit 1 entered Technical Specification 3.4.6.2a, RCS operational leakage, for the existence of pressure boundary leakage. This event is being reported under the requirements of 10 CFR 50.72(b)(2)(i) for 'The initiation of a plant shutdown required by Technical Specifications' and 10 CFR 50.72(b)(3)(ii)(A) or 'Any event of condition that results in the condition of the nuclear power plant, including its principal safety barriers being seriously degraded.' The unit was placed in mode 3 at 1554 (EST) on 02/28/2017. This condition has no impact on public health and safety. Per Technical Specifications, the unit is proceeding to mode 5. The leak rate at the time of shutdown was 0.33 gpm. This event has no effect on Unit 2. The licensee has notified the NRC Resident Inspector. The licensee will be notifying the Lower Alloways Creek Township, the State of New Jersey and the State of Delaware.

• * * RETRACTION FROM MATT MOG TO HOWIE CROUCH AT 1144 EDT ON 4/14/17 * * *

The purpose of this notification is to retract event report number 52581 made on 2/28/2017 at 1624 (EST). Previously, PSEG notified the NRC that Salem Unit 1 initiated a shutdown required by Technical Specifications (TS) for Reactor Coolant System (RCS) Pressure Boundary Leakage. Subsequent to the initial report, PSEG has determined that the leak occurred in tubing downstream of the design specification break between Safety Related, Nuclear Class 1, Seismic Class1 and Non-Safety-Related, Nuclear Class 2, Seismic Class 2. Therefore, the observed leakage is not RCS pressure boundary leakage as defined in the Salem Unit 1 Technical Specifications and in the tubing design classification specification. At the time of the event, during initial entry into the containment, the volume of steam present and the height of the break above the floor made it difficult to ascertain the location of the steam source with certainty. The initial judgment of RCS Pressure Boundary Leakage was conservative under these circumstances. The plant was taken offline to minimize radiation exposure when personnel operated the isolation valves. Following the shutdown, the leak was isolated. Based on an observed reduction in RCS leak rate and visual verification of leakage isolation, the TS Limiting Condition for Operation (LCO) was exited and the unit remained in Mode 3, Hot Standby, to affect repairs. The condition did not meet the Technical Specification Pressure Boundary Leakage definition of leakage through a non-isolable fault in a RCS component body, pipe wall or vessel wall. The leakage did not impact the ability to shut down the unit and no TS limits were exceeded during this event. Therefore, the plant shutdown to investigate and correct leakage from flawed sample system tubing does not meet the reporting requirements of 10 CFR 50.72 and PSEG is retracting the notifications made under 10 CFR 50.72(b)(2)(i) and 10 CFR 50.72(b)(3)(ii)(A). The NRC Resident Inspector was notified of this retraction by the licensee. Notified R1DO (Jackson).

While operating in MODE 1 at 100 percent rated thermal power and placing Excess Letdown in service for Reactor Coolant System (RCS) leak detection, RCS operational leakage exceeded 1 gpm (gallon per minute) unidentified leakage as identified by performing RCS Water Inventory Balance using the Nuclear Plant Information System Computer. This required the entry into Technical Specification (TS) Limiting Condition of Operation (LCO) 3.4.13 Condition B at 0808 (CDT) on 9/2/16. The associated action is to place the unit into Mode 3 in 6 hours. Trending of containment sump level indicates the leakage is inside containment with the exact location within containment unknown. Containment inspection is being performed to try and identify the source of Reactor Coolant System leakage. NRC Resident Inspector has been notified. Re-alignment of the Letdown System back to its normal arrangement has subsequently reduced RCS leak rate to 0.521 gpm at 0652 CDT on 9/2/16. Unusual or Not Understood - Leak Location is not known at this time. Maximum leak rate recorded was 1.358 gpm. The leak was first discovered at 08/31/16 at 1519 CDT. Safety Related Equipment not operational - Reactor Vessel Level Indicating System (TS 3.3.3).

• * * RETRACTION AT 1101 EDT ON 10/21/2016 FROM LARRY HAUTH TO JEFF HERRERA * * *

Wolf Creek Nuclear Operating Corporation is retracting the 10 CFR 50.72(b)(2)(i) notification based on subsequent review of the event. The calculation of unidentified leak rate which triggered entry into the Mode 3 Required Action Statement was performed immediately after placing RCS Excess Letdown in service. An evaluation of the leak rate calculation determined that the leak rate was invalid due to performance of the RCS water inventory balance during non-steady state operating conditions. This was contrary to the requirements of TS Surveillance Requirement 3.4.13.1, as this test was performed while charging and letdown flows were being stabilized following the alignment of excess letdown. A walk down of the Excess Letdown system while in-service determined no leakage. Subsequent RCS water inventory balances performed with Excess Letdown in service under steady state operating conditions while in Mode 3 at normal operating pressure and temperature determined the maximum calculated unidentified leak rate was 0.675 gpm. After the plant entered Mode 3 a non-RCS pressure boundary leak was identified during equipment walk downs on a seal weld from the reactor vessel head core exit thermocouple nozzle assembly 77. The leakage did not impact the ability to shut down the unit. No TS limits were exceeded during this event. Therefore, the plant shutdown to investigate and correct leakage past the seal weld of a threaded connection does not meet the reporting requirements of 10 CFR 50.72. The NRC Resident Inspector has been notified. Notified the R4DO (Kramer).

At 2342 (EDT), June 30, 2016, the Control Room received panel alarms associated with Safety Features Actuation System (SFAS) Channel 2. Subsequent investigation revealed the alarms were due to a loss of supplied power caused, in part, by a level permissive in the Borated Water Storage Tank (BWST) to be inoperable. With SFAS Channel 1 BWST level transmitter previously declared inoperable for maintenance, the on-shift operating crew did not correctly identify that technical specification (TS) 3.3.5, Condition B applied which is a 6-hour shutdown required action. At 0245, following a duty team call when the condition was re-assessed, the crew entered the proper additional Condition B and correctly identified they were approximately 3 hours into a 6-hour shutdown specification. At 0330 the condition was inappropriately exited on the premise that an operable but degraded situation could be justified. The plant did not initiate a shutdown required by technical specification but, in retrospect, should have initiated and completed a shutdown within 6 hours of 2342.

On July 1 at 1351, the BWST level transmitter for SFAS Channel 1 was repaired and declared operable (and exited TS 3.3.5 Condition B), however, the total time exceeded the 6-hour shutdown action. The plant remained stable throughout this event.  On July 9, 2016, while internally discussing the event among FENOC senior leadership, it was determined that a 4-hour report would have been made if the shutdown was initiated. Hence, this report is retrospective in that a 10 CFR 50.72(h)(2)(i) required report should have been made upon the initiation of any nuclear plant shutdown required by plant's technical specification.

A Licensee Event Report will be provided pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition that was prohibited by the plant's technical specification. The NRC Resident Inspector has been notified. (At 1325 EDT on July 1, it was determined that the justification for SFAS channel 2 BWST level permissive to be operable but degraded could not be supported and reentered TS 3.3.5 Condition B.)

At 2100 hours (EST), on January 23, 2016, the Perry Nuclear Power Plant commenced a reactor shutdown due to unidentified leakage in the drywell. At 2122 hours, drywell unidentified leakage exceeded the Technical Specification 3.4.5.d limit of 'less than or equal to 2 gpm increase in unidentified LEAKAGE within the previous 24 hour period in Mode 1.' The unidentified leakage increased to approximately 3.8 gpm at 2122 hours. Current unidentified leakage is 3.02 gpm. Technical Specification 3.4.5 actions allow 4 hours to reduce the leakage within limits or be in Mode 3 within 12 hours and Mode 4 within 36 hours. The plant is required to be in Mode 3 by 1322 hours on January 24, 2016 and Mode 4 by 1322 hours on January 25, 2016. A drywell entry will be made in Mode 3 to identify the leak source.

This notification is being made due to an expected inability to restore the leakage within limits prior to exceeding the LCO action time. Follow up question from NRC: Event times do not match (2100 versus 2122) - explained downpower was commenced at 2100 with leakage less than TS limit. When Reactor Core flow was reduced, un-identified leakage increased above the TS limit. The Licensee has notified the NRC Resident Inspector.

• * * UPDATE FROM MIKE DOTY TO DANIEL MILLS AT 1123 EST ON 1/24/16 * * *

At 1007 hours, on January 24, 2016 with the plant at 8% power during a feedwater shift to place the motor feed pump in service, reactor level rose to the level 8 scram set point and the Reactor Protection System (RPS) initiated, scramming the reactor. During the scram, all rods fully inserted into the core. Decay heat is being removed via turbine bypass valves to the main condenser. Reactor level control is currently being maintained via feedwater. The plant is stable with cool down and depressurization to Mode 4 to follow. The cause of the rise in feedwater level is under investigation. This notification is being made under 50.72(b)(2)(iv)(B) for a RPS initiation while critical. All safety shutdown systems are available. The electric plant is in its normal shutdown alignment being supplied by offsite power. The licensee has notified the NRC Resident Inspector. Notified R3DO (Cameron). NRR (Morris) and IRD (Gott) were notified via email.

• * * UPDATE FROM DAVID O'DONNELL TO HOWIE CROUCH AT 1915 EST ON 1/24/16 * * *

Following a shutdown required by plant Technical Specifications a small leak was identified coming from the Reactor Recirculation Loop A Pump Discharge Valve vent line. The Recirculation Loop is part of the reactor coolant system making this reportable under 50.72(b)(3)(ii)(A) as a degraded condition. It was subsequently determined to require a plant cool down in accordance with Technical Specification 3.4.5, Action C which requires the plant to be in MODE 4 within 36 hours. Technical Specification 3.4.5 was previously entered for increased unidentified leakage in the drywell. The plant is required to be in Mode 4 by 1322 hours on January 25, 2016. The licensee has notified the NRC Resident Inspector. Notified R3DO (Cameron). NRR (Morris) and IRD (Gott) were notified via email.

Class 1E A/C Unit SGK05A cools safety related electrical train 'A' and was found tripped at 2148 (CDT). As a result, the following supported safety related electrical equipment were declared inoperable: 4.16 KV Bus NB01, 480 Volt Buses NG01 and NG03, 120 volt Instrument AC Inverters and Buses NN11, NN13, NN01 and NN03, 125 VDC Chargers and Buses NK11, NK13, NK01 and NK03. T/S 3.0.3 was entered from T/S 3.8.7 due to two out of four 120 volt AC Inverters (NN11 and NN13) being inoperable. All electrical systems listed above remain available but are declared inoperable due to inadequate room cooling capability. Plant shutdown to mode 5 commenced at 2244 (CDT). No major equipment is out-of-service. All systems have functioned normally. Plant is currently at 99% with power ramping down. Plant must be in mode 3 by 0448 CDT. No compensatory measures have been established. The NRC Resident Inspector has been notified. See EN #51071 for an earlier T/S required shutdown required at 0436 CDT on 5/15/15, due to the same conditions.

• * * UPDATE FROM BRET DAVIS TO VINCE KLCO ON 5/18/15 AT 1600 EDT * * *

For both EN 51071 and 51074, the low lube oil pressure switch tripped the SGK05A unit. Oil pressures were verified to be normal and the SGK05A unit was successfully started. The plant shutdown each time was terminated. A fault in the Electronic Oil Pressure control which monitors the low lube oil pressure switch was identified. A jumper has been installed that bypasses the oil switch while maintenance is being conducted. The unit was declared functional but degraded. Indication of low oil pressure is still provided. The licensee notified the NRC Resident Inspector. Notified the R4DO (Okeefe).