ENS 48400: Difference between revisions
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| event date = 10/11/2012 12:08 PDT | | event date = 10/11/2012 12:08 PDT | ||
| last update date = 10/12/2012 | | last update date = 10/12/2012 | ||
| title = Unit 2 Experienced | | title = Unit 2 Experienced an Automatic Reactor Trip on a 500Kv Line Differential Relay Actuation | ||
| event text = On October 11, 2012, at 1208 PDT, the Diablo Canyon Power Plant Unit 2 500kV line differential relay actuated, resulting in a unit trip. The unit trip actuated the turbine trip. With the turbine tripped and Unit 2 operating above the P-9 50% power permissive, a reactor trip was initiated from the reactor protection system. All plant equipment responded as designed. | | event text = On October 11, 2012, at 1208 PDT, the Diablo Canyon Power Plant Unit 2 500kV line differential relay actuated, resulting in a unit trip. The unit trip actuated the turbine trip. With the turbine tripped and Unit 2 operating above the P-9 50% power permissive, a reactor trip was initiated from the reactor protection system. All plant equipment responded as designed. | ||
Unit 2 is stable at normal operating temperature and pressure. All power transferred to the plant startup source without incident. Condenser vacuum was maintained. The cause of the differential relay actuation is under investigation. Based on personnel observation it appears to have been initiated due to a flashover to ground across the phase 'A' main bank transformer capacitive coupled voltage transformer. | Unit 2 is stable at normal operating temperature and pressure. All power transferred to the plant startup source without incident. Condenser vacuum was maintained. The cause of the differential relay actuation is under investigation. Based on personnel observation it appears to have been initiated due to a flashover to ground across the phase 'A' main bank transformer capacitive coupled voltage transformer. |
Latest revision as of 22:02, 1 March 2018
Where | |
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Diablo Canyon ![]() California (NRC Region 4) | |
Reporting | |
10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
Time - Person (Reporting Time:+-0.4 h-0.0167 days <br />-0.00238 weeks <br />-5.4792e-4 months <br />) | |
Opened: | Michael Quitter 18:44 Oct 11, 2012 |
NRC Officer: | Steve Sandin |
Last Updated: | Oct 12, 2012 |
48400 - NRC Website
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