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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).

This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) for an event or condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident. The Unit 1 Low Pressure Core Spray (LPCS) Pump Injection System was declared inoperable at 2043 (CDT) due to a loss of corner room area cooling and loss of motor cooling. The common diesel generator cooling water pump received an auto trip signal while being secured. The LPCS pump remained in standby during the event. This condition prevents LPCS, a single train safety system, from performing its design function. This is a reportable condition as an 8 hour ENS notification. The required action of Technical Specifications (TS) 3.5.1, 'ECCS - Operating,' was entered on June 22, 2017 at 2043 CDT when the condition was identified and the LPCS system was determined to be inoperable. Investigation into the cause of the condition is in progress. The Low Pressure Core Spray (LPCS) Pump Injection System was declared operable, and the TS LCO was exited at 2112 CDT.

• * * UPDATE FROM RICHARD IMMKE TO DONALD NORWOOD AT 1518 EDT ON 6/23/2017 * * *

Update to previous ENS notification at 0100 EDT on 6/23/17. The last statement was revised to say the Low Pressure Core Spray System remains Inoperable. The Low Pressure Core Spray (LPCS) Injection System remains inoperable. The licensee notified the NRC Resident Inspector. Notified R3DO (Pelke).

This notification is being provided in accordance with 10CFR 50.72(b)(2)(iv)(B). On February 17, 2017 at 2353 CST, Unit 1 Reactor Automatic Scram signal was received due to Turbine Control Valves Fast Closure. The turbine trip was due to receipt of Level 8 Trip due to a failure of the Feedwater Regulating Valve to Full open. Plant is in a stable condition with reactor pressure being maintained by the Turbine Bypass valves. Reactor water level is being controlled with Feedwater thru the Low Flow Feedwater Regulating Valve. Further investigation into the cause of the event is in progress. All control rods fully inserted, and decay heat is being removed via steam to the main condenser using bypass valves. The licensee has notified the NRC Resident Inspector.

• * * UPDATE FROM BROCK POLLMANN TO HOWIE CROUCH AT 1721 EDT ON 4/14/17 * * *

Upon further review of the event data, it was determined that the Nuclear Station Operator (NSO) had initiated a manual scram, which was followed by a Turbine Control Valve (TCV) fast closure automatic scram when the turbine tripped. The licensee has notified the NRC Resident Inspector. Notified R3DO (Jeffers).

The following was received via fax and phone: This telephone notification is provided in accordance with Exelon Reportabllity manual SAF 1.1 0, 'Major Loss of Emergency Preparedness Capabilities', and 10CFR50.72(b)(3)(xiii). On June 6th 2015 at 12:13 (CDT), it was determined that the onsite Technical Support Center (TSC) Ventilation System Supply Fan belts had failed, resulting in loss of ventilation for the facility. Repairs were not completed within the time required had the TSC needed to be staffed. There is currently no emergency event in progress requiring TSC staffing. If an emergency is declared and the TSC ERO activation is required, the TSC will be staffed and activated unless the TSC becomes uninhabitable due to ambient temperatures, radiological, or other conditions. If relocation of the TSC staff becomes necessary, the Station Emergency Director will relocate the staff to an alternate TSC location in accordance with applicable site procedures. The licensee has notified the Senior Resident Inspector of the issue.

• • • UPDATE PROVIDED BY TODD CASAGRANDE TO NESTOR MAKRIS AT 2305 EDT ON 06/06/2015 ***

After repairs were completed, the TSC ventilation was restored to service at 2300 (EDT) on 06/06/2015. The licensee has notified the NRC Resident Inspector. Notified R3DO (Passehl) via email

LaSalle Station has completed a review of seismic monitor performance. The seismic monitor is currently operable; however, this review identified 6 times in the past 3 years that the seismic monitor was inoperable such that emergency classification at the ALERT level could not be obtained with site instrumentation. The seismic monitor was determined to be inoperable on the following dates:

 1) January 28, 2015
 2) May 28, 2014
 3) January 1, 2014
 4) August 5, 2013
 5) April 17, 2013
 6) April 10, 2012

These unplanned inoperable conditions of the seismic monitor were entered into the LaSalle Corrective Action Program when they occurred. While Exelon procedural direction allowed the use of offsite sources to obtain seismic data when the seismic monitor is incapable of assessing emergency plan Emergency Action Levels (EALs), this was not explicitly referenced in the approved EALs. The loss of assessment capability is reportable to the NRC within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii). This report is required per 10 CFR 50.72(a)(1)(ii) as an event that occurred within 3 years of the date of discovery. The licensee has notified the NRC Resident Inspector.

This notification is being provided pursuant with SAF 1.6 10CFR50.72(b)(2)(iv)(B) and SAF 1.7 10CFR50.72(b)(3)(iv)(A). At 1734 CDT on August 5, 2014, LaSalle Unit 2 automatically scrammed due to an RPS actuation. The MSIVs isolated on a Group 1 signal, the cause is under investigation. The reactor water cleanup system isolated during the transient. The plant is stable with Reactor Pressure Control being maintained by the Reactor Core Isolation Cooling System and SRVs and level being controlled by the Low Pressure Core Spray System. The plant is planned to remain in hot shutdown pending investigation of the trip." The Unit 2 electric plant is in a normal shutdown lineup. All control rods inserted fully on the scram. Unit 1 was not affected by the Unit 2 transient. The licensee notified the NRC Resident Inspector.

• * * UPDATE PROVIDED BY MICHAEL FITZPATRICK TO JEFF ROTTON AT 1650 EDT ON 8/6/2014 * * *

The initial notification to the NRC stated that the reactor water cleanup system had isolated during the transient. The actual status is being corrected to state that the reactor water cleanup pump tripped during the transient. The licensee has notified the NRC Resident Inspector. Notified R3DO (Stone).