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| Entered date | Event description | |
|---|---|---|
| ENS 43840 | 12 December 2007 17:02:00 | This 60-day optional telephone notification as allowed by 10 CFR 50.73(a)(1) is being made in lieu of an LER submittal. This notification is made pursuant to the reporting requirements specified in 10 CFR50.73(a)(2)(iv)(A) for an invalid actuation of one of the systems listed in 10 CFR 50.73(a)(2)(iv)(B). On October 14, 2007, at approximately 0200 hours EST with the plant in Mode 5, Refueling, while performing ECCS Start and Load Reject surveillance testing on Emergency Diesel Generator (EDG) 14, the EDG unexpectedly auto-started. Investigation revealed that the auto-start was caused by a faulty test switch. The test switch had been tested multiple times prior to performing the surveillance with no abnormalities noted. EDG 14 is one of two EDG's in Division II of the Onsite Emergency Power system. The EDG responded properly to the auto-start signal. The actuation was complete, in that the EDG started and ran unloaded. The surveillance testing was immediately stopped upon receipt of the inadvertent actuation. In accordance with the EDG operating procedure, the EDG was synchronized, loaded for about an hour, shut down and returned to standby status. Since no actual plant condition existed that required the EDG to auto-start, the actuation was invalid. There were no safety consequences or impact on the health and safety of the public. The event was entered in the corrective action program for evaluation and resolution. The NRC Resident Inspector will be notified of this report. |
| ENS 43850 | 18 December 2007 10:43:00 | The following information is provided as a 60 day telephone notification under 10 CFR 5O.73(a)(l) in lieu of submitting a written LER to report a condition that resulted in an invalid actuation of a 10 CFR 50.73(a)(2)(iv)(B) system. NUREG 1022, Revision 2, identifies the information that is to be reported as discussed below. On October 22. 2007, at 1830 hours, Division 2 of Residual Heat Removal (RHR) was being placed in Shutdown Cooling (SDC) following completion of a SDC outage. The plant was in Mode 5, Refueling. Reactor Protection System (RPS) A was deenergized for maintenance. RPS B was being supplied by the alternate supply because the B RPS Motor Generator was removed from service for maintenance. Upon start of the RHR D pump motor the RPS B Alternate Supply Electrical Protection Assembly (EPA) breakers tripped due to sensed undervoltage. The loss of the power supply to RPS B resulted in the following: A reactor scram (all rods were already fully inserted), RHR SDC outboard valve isolation, trip of the Reactor Water Cleanup System (RWCU), outboard valve isolation of the Torus Water Management System (TWMS). A secondary containment isolation also occurred resulting in a trip of Reactor Building Heating Ventilation and Air Conditioning (HVAC), auto start of Division 2 of Standby Gas Treatment System (SGTS), and shift of the Control Center HVAC system to recirculation mode. All actuations and isolations were as expected for existing plant conditions. The initiation signal was invalid because it did not result in response to an actual plant parameter, nor did it trip as a result of any other requirement for initiation of a safety function. Due to the actuation of equipment in multiple systems that were not removed from service or otherwise prevented from changing states, this event is reportable under 50.73(a)(2)(iv) as an invalid actuation of one of the specified systems. The reactor scram actuation was complete because a half scram was already present due to RPS A being deenergized for maintenance. The Division 2 SGTS system automatically started, secondary containment fully isolated, Reactor Building HVAC system tripped, and the Control Center HVAC fully shifted into the recirculation mode. The following were partial isolations due to loss of RPS B, Division 2: RHR SDC isolation and TWMS isolation. All systems functioned properly in response to the RPS power loss based on refuel outage system configurations. The licensee believes that the cause of the undervoltage was a result of the start of the RHR pump which caused an in-rush current. The licensee is considering a design change, and captured this event in their corrective action program system as CARD 07-26537. The licensee will notify the NRC Resident Inspector. |