ENS 46346
ENS Event | |
|---|---|
22:15 Oct 19, 2010 | |
| Title | Valid Specified System Actuation |
| Event Description | On October 19, 2010, at about 1515 PDT, SONGS Unit 3 RPS channels 'B' and 'D' were tested for maintenance. During this testing, both channels were powered off, which brought in LPD/DNBR [local power density/departure from nucleate boiling] trips on both channels. There are no applicable Technical Specifications required for these RPS channels in Mode 5.
Southern California Edison(SCE) is reporting this occurrence as a valid actuation of RPS in accordance with 10 CFR 50.72(b)(3)(iv)(a). SCE has taken actions to restore both channels 'B' and 'D' of RPS and cleared the RPS trip signal. At the time of this occurrence, Unit 2 was at approximately 100% power and Unit 3 was in a Steam Generator Replacement Outage, Mode 5, shutdown and cooldown with the RCS open, proceeding to Mode 6." The NRC Resident Inspector has been notified.
On October 19, 2010, SCE reported (Event No. 46346) a valid actuation of the Reactor Protection System (RPS) in accordance with 10 CFR 50.72(b)(3)(iv)(A). Upon further review, SCE determined the actuation was invalid and is retracting the notification. Maintenance and surveillance testing was being conducted by Computer Technicians on the Core Protection Calculator [CPC] Channels 'A' and 'D', respectively, following station procedures. De-energizing the CPC channels was expected to bring in an RPS trip signal. The process to disable the control room RPS alarms had not as yet, been completed by the Instrument and Controls group when the CPCs were de-energized by procedure, actuating the RPS logic and causing the control room alarms. The actuation is considered invalid, as the equipment that would have been actuated by the trip safety function was previously de-energized and removed from service for the refueling outage. The Unit 3 reactor was in Mode 5, with the reactor trip breakers open, and control rods inserted. Unit 2 reactor remains at 100% power. The licensee notified the NRC Resident Inspector. Notified R4DO (V.Campbell). |
| Where | |
|---|---|
San Onofre  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-2.1 h-0.0875 days <br />-0.0125 weeks <br />-0.00288 months <br />) | |
| Opened: | Mike Wong 20:09 Oct 19, 2010 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Oct 21, 2010 |
| 46346 - NRC Website
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Unit 3 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 472522011-09-08T22:38:0008 September 2011 22:38:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to a Grid Disturbance ENS 463462010-10-19T22:15:00019 October 2010 22:15:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Valid Specified System Actuation ENS 442732008-06-06T05:56:0006 June 2008 05:56:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Reactor Trip Due to Low Cooling Flow to Main Generator Rectifier ENS 439282008-01-23T22:15:00023 January 2008 22:15:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation One of Two Main Feedwater Pumps Trip ENS 434352007-06-21T05:50:00021 June 2007 05:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Failed Instrument Air Header Leads to Manual Reactor Trip ENS 413682005-02-03T20:27:0003 February 2005 20:27:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Unit Auxiliary Transformer Trip ENS 412092004-11-19T16:07:00019 November 2004 16:07:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Turbine Trip on Main Generator Trip ENS 406642004-04-10T18:50:00010 April 2004 18:50:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip Due to Loss of Both Main Feedwater Pumps 2011-09-08T22:38:00 | |