ENS 43850
ENS Event | |
|---|---|
23:30 Oct 22, 2007 | |
| Title | Invalid System Actuation |
| Event Description | 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 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br />, 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. |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1354.22 h56.426 days <br />8.061 weeks <br />1.855 months <br />) | |
| Opened: | Rodney Johnson 10:43 Dec 18, 2007 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Dec 18, 2007 |
| 43850 - NRC Website
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WEEKMONTHYEARENS 528592017-03-24T19:48:00024 March 2017 19:48:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation During Testing ENS 511282015-05-24T23:30:00024 May 2015 23:30:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Actuation of Containment Isolation Valves ENS 501122014-03-19T00:30:00019 March 2014 00:30:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Actuation of Containment Isolation Valves ENS 438502007-10-22T23:30:00022 October 2007 23:30:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation ENS 438402007-10-14T07:00:00014 October 2007 07:00:00 10 CFR 50.73(a)(1), Submit an LER Inadvertent Actuation of Emergency Diesel Generator ENS 424282006-02-10T16:20:00010 February 2006 16:20:00 10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuations ENS 408992004-05-30T14:40:00030 May 2004 14:40:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Isolation Valves Due to Partial Loss of 120 Vac Modular Power Unit 2 Loads 2017-03-24T19:48:00 | |