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| Entered date | Event description | |
|---|---|---|
| ENS 49870 | 5 March 2014 01:37:00 | At 1917 hours (CST) on March 4, 2014, the Unit 1B fuel pool radiation monitor spiked high due to an invalid actuation which caused the U1 and U2 reactor building ventilation system to isolate (the control room ventilation system also isolated as designed). The Standby Gas Treatment system was already in operation for a scheduled surveillance as of 1900 hours on March 4, 2014. During the ensuing pressure transient, the Reactor Building differential pressure momentarily went positive. As a result, Secondary Containment was declared inoperable. Given the temporary loss in secondary containment, this event is reportable under 10CFR50.72(b)(3)(v)(C) as an event or condition that could have prevented the fulfillment of a safety function. The NRC Resident Inspector has been notified. After the transient, the reactor building ventilation system was shutdown for scheduled maintenance and the control room ventilation system was returned to its normal configuration. The Standby Gas Treatment system was operating to support planned reactor building ventilation system maintenance. Troubleshooting of the radiation monitor spike is underway. |
| ENS 49135 | 19 June 2013 10:15:00 | Planned breaker maintenance activities will be performed today (Wednesday, June 19, 2013) which will temporarily remove power to the Quad Cities Station TSC. The maintenance will be completed in approximately 2 hours and is scheduled to be worked continuously to minimize out-of-service time. If TSC activation is required during this period, compensatory measures have been established to direct ERO (Emergency Response Organization) members to an alternate location. No other emergency response facilities are impacted by the breaker maintenance. This event is reportable per 10CFR50.72(b)(3)(xiii) since the scheduled maintenance affects an emergency response facility. The NRC Resident Inspector has been notified. |
| ENS 48916 | 11 April 2013 21:10:00 | On April 11, 2013, at 1300 hours, during the performance of On-Line Automatic Depressurization System (ADS) Blowdown Logic Testing, two poor wiring connections were identified (the electrical leads were not properly compressed at their termination point). The electrical leads are associated with the B and C ADS valves. Quad Cities has five ADS valves which can be used to depressurize the Reactor Pressure Vessel under accident conditions. While the solenoids of these valves were actuated successfully during the recent Unit 1 refueling outage (which ended on April 8, 2013), the less than optimum configuration could have prevented the valves from actuating under design basis conditions. The degraded wiring for both valves was restored at 1741 hours (CDT). Given the potential impact on the ADS depressurization function, this event is reportable under 50.72(b)(3)(v)(D) as an event or condition that could have prevented the fulfillment of a safety function. The licensee notified the NRC Resident Inspector.
The purpose of this notification is to retract the ENS Report made on April 11, 2013, at 2110 EDT (ENS Report # 48916). Further evaluation performed by Quad Cities Station confirms the Unit 1, 3B and 3C Automatic Depressurization System (ADS) valves would have performed their safety functions when required. Based on this subsequent evaluation, ENS Report # 48916 is being retracted. Note: On April 11, 2013, at 1741 CDT the degraded wiring for the Unit 1, 3B and 3C ADS valves was repaired and both valves were returned to operable status. The licensee notified the NRC Resident Inspector. Notified R3DO (Orth). |