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| Entered date | Event description | |
|---|---|---|
| ENS 50346 | 5 August 2014 22:20:00 | 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.
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). |
| ENS 49174 | 5 July 2013 12:34:00 | On May 22, 2013, at approximately 1134 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 actuation of the Division 1 (outboard) primary containment isolation logic. 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 setpoint), this notification is being made in accordance with 10 CFR 50.73(a)(1) in lieu of a Licensee Event Report. In response to the trip of the 1A RPS M/G, 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 trip was due to a motor fault requiring motor replacement. Replacement of the motor was completed on 5/26/13 and the A RPS bus was restored to its normal power supply on 5/27/13. The licensee has notified the NRC Resident Inspector. |