ENS 47875

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v t e ENS Event
00:36 Mar 25, 2012
Title	Invalid Protection System Actuation During Station Electrical Transient
Event Description	{{#Wiki_filter:The purpose of this report is to provide a telephone notification for an invalid actuation. On March 24, 2012, following the completion of switch yard work, the Control Room received switching orders to open Bus Tie 9-10 Bus 9 disconnect and close Bus Tie 9-10 Bus 10 disconnect. Operations was unaware that a grounding device, installed for personnel protection during the work activities, had not been removed. Consequently, when the Bus Tie 9-10 Bus 10 disconnect was closed the switchyard was grounded resulting in an electrical transient. Protective relaying operated as designed to clear the fault, and there were no injuries. During the electrical transient, the voltage depression tripped the Unit 1 "A" Reactor Protection System (RPS) bus which caused a 1/2 scram and certain protective logic systems to de-energize by design. The following invalid actuations occurred as a result of the loss of power to the RPS bus: partial Group 11 Isolation (Primary Containment); Group III Isolation (Reactor Water Cleanup); Reactor Building Ventilation Isolation; Control Room Ventilation Isolation; and Standby Gas Treatment Initiation. The electrical transient also tripped the Unit 1 ECCS keep�fill pump, resulting in the Core Spray (CS) discharge pressure decreasing to the alarm setpoint. Both CS subsystems were conservatively declared inoperable and entry into Technical Specifications (TS) 3.0.3 occurred at 1936 hours. Subsequent fill and vent activities confirmed no air existed in the discharge headers of the CS subsystems (no loss of safety function) and both subsystems were declared operable with TS 3.0.3 being exited at 2017 hours. Following the electrical transient, the Unit 1 generator was temporarily limited to approximately 90% load due to elevated vibration on Turbine Bearing No. 10. In-plant walk-downs identified no other equipment concerns. Unit 1 returned to full power on April 2, 2012, following confirmation the bearing vibration is acceptable for long-term operation. Unit 2 was in a scheduled refueling outage during the event and was unaffected by the electrical transient. A Root Cause Investigation is ongoing. The licensee notified the NRC Resident Inspector. }}

ENS 47875 +/-
Where
Quad Cities Illinois (NRC Region 3)
Reporting

10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation
Time - Person (Reporting Time:+877.03 h36.543 days <br />5.22 weeks <br />1.201 months <br />)
Opened:	James Cox 13:38 Apr 30, 2012
NRC Officer:	Mark Abramovitz
Last Updated:	Apr 30, 2012
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v • d • e

v t e Emergency Notification System
Quad Cities with 10 CFR 50.73(a)(1), Submit an LER
WEEKMONTHYEAR2012-03-25T00:36:00 [Table view]
[ENS list for Quad Cities]

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