ENS 46298: Difference between revisions
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| event date = 09/30/2010 19:04 CDT | | event date = 09/30/2010 19:04 CDT | ||
| last update date = 10/01/2010 | | last update date = 10/01/2010 | ||
| title = Standby Diesel Generator Autostart Due | | title = Standby Diesel Generator Autostart Due to Loss of a Switchyard Bus During Maintenance | ||
| event text = At 1904 [CDT] on 9/30/2010, the South Texas Project (STP) North switchyard bus was lost due to a Transmission & Distribution Service Provider (TDSP) human performance error that occurred while performing maintenance on breaker Y-0530. This resulted in a loss of power to Standby transformer 1 which was supplying power to the Unit 1 B Train Engineered Safety Features (ESF) 4160v bus. The B Train Standby Diesel Generator automatically started due to the Loss of Offsite Power (LOOP) on its associated bus. The Mode II (LOOP) ESF loads sequenced onto the bus. All safety related equipment responded as expected. Action (e) of Technical Specification (TS) 3.8.1.1, 'AC Electrical Power Sources', was momentarily entered due to the loss of two independent offsite circuits while the North bus was de-energized. The North bus was de-energized for approximately 5 minutes. Action (a) of Technical specification (TS) 3.8.1.1, 'AC Electrical Power Sources', was entered due to the loss of one independent offsite circuit. All Technical Specification Limiting Condition of operation have been exited at this time. | | event text = At 1904 [CDT] on 9/30/2010, the South Texas Project (STP) North switchyard bus was lost due to a Transmission & Distribution Service Provider (TDSP) human performance error that occurred while performing maintenance on breaker Y-0530. This resulted in a loss of power to Standby transformer 1 which was supplying power to the Unit 1 B Train Engineered Safety Features (ESF) 4160v bus. The B Train Standby Diesel Generator automatically started due to the Loss of Offsite Power (LOOP) on its associated bus. The Mode II (LOOP) ESF loads sequenced onto the bus. All safety related equipment responded as expected. Action (e) of Technical Specification (TS) 3.8.1.1, 'AC Electrical Power Sources', was momentarily entered due to the loss of two independent offsite circuits while the North bus was de-energized. The North bus was de-energized for approximately 5 minutes. Action (a) of Technical specification (TS) 3.8.1.1, 'AC Electrical Power Sources', was entered due to the loss of one independent offsite circuit. All Technical Specification Limiting Condition of operation have been exited at this time. | ||
An 8-hour notification is required for this event due to the valid actuation of safety related equipment as described in 10CFR50.72 (b) (3) (iv) (A). [A notification is required for] any event or condition that results in valid actuation of any of the systems listed in paragraph (b) (3) (iv) (B) of this section, except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. | An 8-hour notification is required for this event due to the valid actuation of safety related equipment as described in 10CFR50.72 (b) (3) (iv) (A). [A notification is required for] any event or condition that results in valid actuation of any of the systems listed in paragraph (b) (3) (iv) (B) of this section, except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation. | ||
Latest revision as of 21:08, 1 March 2018
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+1.52 h0.0633 days <br />0.00905 weeks <br />0.00208 months <br />) | |
| Opened: | Brad Hardt 01:35 Oct 1, 2010 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Oct 1, 2010 |
| 46298 - NRC Website
| |