Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 52227 | 8 September 2016 14:50:00 | On July 11, 2016, at approximately 0430 CDT, while Unit 1 was operating at 100% power, the 1A Reactor Protection System (RPS) Motor Generator (M/G) set tripped causing a loss of the A RPS bus. This caused the complete actuation of the Division 1 (outboard) primary containment isolation logic. The isolation logic actuation resulted in successful closure of the Division 1 primary containment isolation valves. This was an event that resulted in the actuation of a general containment isolation signal affecting more than one system. However, as this event meets the definition of an invalid actuation (i.e., not a response to an actual plant parameter exceeding a trip set-point), this notification is being made in accordance with 10CFR50.73(a)(2)(iv)(A) in lieu of a Licensee Event Report. In response to the trip of the 1A RPS M/G Set, operators swapped the A RPS bus to the alternate power supply using the applicable response procedure. The containment isolation signal was reset and the systems were restored to their normal lineup. Reactor power was not affected by this event. All safety related equipment controlled by the affected primary containment isolation circuits operated as designed. The 1A RPS M/G Set trip was due to a blown power fuse for the 1A RPS M/G Set. This was the result of worn insulation on one of the generator output leads. The generator output leads were repaired and rerouted to prevent future problems on 07/15/16. Restoration of the normal power supply to the 1A RPS function was completed on 7/19/16. The licensee informed the NRC Resident Inspector. |
| ENS 49973 | 29 March 2014 23:49:00 | This report is being made pursuant to SAF 1.8, 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. During steady state operations on Unit 1 at 1620 (CDT) hrs. on 3/29/14, the Division 3 Core Standby Cooling System (CSCS) Pump Room, SWGR Room, and Battery Room Ventilation failed in such a manner that heat could not be removed from the rooms. These Division 3 systems supply power and cooling water to the High Pressure Core Spray system (HPCS), which is a single-train system. The HPCS system and its associated power supplies were declared inoperable based on long-term temperature considerations. The system remains available due to manual damper adjustments that than can be made per an approved procedure. The licensee will notify the NRC Resident Inspector. |
| ENS 49574 | 22 November 2013 23:59:00 | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. While the 'A' Train of Control Room HVAC was inoperable and out of service for emergent repairs due to a Freon leak, the 'B' Train of Auxiliary Electric Room HVAC became inoperable due to a failure of the Cooler Condenser Fan. The Main Control Room Envelope consists of the Main Control Room and the Auxiliary Electric Equipment Room. Both the Control Room HVAC and the Auxiliary Electric Equipment Room HVAC Systems are required to be Operable in the current Mode. This is a loss of safety function for a system that is intended to mitigate the consequences of an accident and is discussed in Chapter 6 of the UFSAR and is Tech Spec required and is Safety Related. Also, the system, structure, or component (SSC) is inoperable in a required mode in the Tech Spec Applicability and there is no redundant equipment in the same system that is operable. The Required actions of Tech Spec 3.7.5 were entered on 11/22/2013 at 1920 CST when the 'B' train became inoperable. Online Risk remains Green. The station is currently pursuing repairs to both trains. The NRC Resident Inspector has been notified by the licensee. |
| ENS 49080 | 30 May 2013 10:16:00 | On May 30, 2013, at 0900 (CDT), the Exelon LaSalle Station Technical Support Center (TSC) ventilation system was removed from service for planned TSC ventilation system maintenance. The removal of the ventilation system potentially affects the TSC habitability during a declared emergency requiring activation. The Emergency Response Organization (ERO) team has been notified of the maintenance and the possible need to relocate during an emergency. 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 ventilation system is expected to be out of service for approximately 8 hours. This telephone notification is provided in accordance with Exelon Reportability Manual SAF 1.10. 'Major Loss of Emergency Preparedness Capabilities', and 10CFR50.72(b)(3)(xiii). The licensee has notified the NRC Senior Resident Inspector of the issue.
The scheduled TSC ventilation system maintenance is expected to continue for approximately an additional 12 hours. The licensee has notified the Senior Resident Inspector of the issue. The replacement fan belts came off and the cause is being investigated. Notified the R3DO (Orth). |
| ENS 48263 | 31 August 2012 17:50:00 | This report is being made pursuant to 10CFR50.72(b)(3)(v)(D), Event or Condition that could have prevented fulfillment of a Safety Function needed to Mitigate the Consequences of an Accident. During the conduct of the Unit 2 Division 3 High Pressure Core Spray (HPCS) Diesel Generator (DG) air start system receiver blowdown, a low air pressure system alarm was received. Starting air pressure in one of 2 redundant air receiver banks lowered to the point requiring the DG to be declared inoperable per Technical Specifications. This event appears to have been caused by a degraded receiver drain valve. The air system degraded equipment condition has cleared and the DG has been restored to operable status following 42 minutes of inoperability. Although a redundant air bank was fully available and charged, during this time of inoperability the DG was at reduced margin to successfully start if required. Due to this loss of margin and inoperable condition, it has been determined that this failure could potentially affect the safety function of this system, and is being reported as an 8 hour ENS notification. The licensee informed the NRC Resident Inspector. |
| ENS 46638 | 24 February 2011 15:00:00 | A non-licensed employee supervisor had a confirmed positive for alcohol during a random fitness-for-duty test. The employee's access to the plant has been suspended. Contact the Headquarters Operations Officer for additional details. The licensee informed the NRC Resident Inspector and Don Funk of NRC Region III. |