ENS 51568: Difference between revisions
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| event date = 11/27/2015 04:31 CST | | event date = 11/27/2015 04:31 CST | ||
| last update date = 11/27/2015 | | last update date = 11/27/2015 | ||
| title = Automatic Reactor Scram Following Partial Loss | | title = Automatic Reactor Scram Following Partial Loss of Offsite Power | ||
| event text = At 0431 CST on November 27, 2015, an automatic reactor scram occurred following the trip of the main generator. The generator trip was apparently caused by a partial loss of offsite power, which resulted from a differential ground on the north bus of the local 230 kV switchyard. The ground signal caused the reserve station service line no. 1 to de-energize, which tripped the Division 1 offsite power source to station, as well as the main generator. The plant responded as designed as follows: The Division 1 emergency diesel generator started and tied to the bus restoring Division 1 emergency power. The Division 3 emergency diesel generator started and tied to the bus, restoring power on the Division 3 switchgear. The reactor protection system tripped as designed. Reactor water level was controlled normally with condensate and feed water. A level 3 reactor water level scram signal occurred as expected, and RPV [Reactor Pressure Vessel] water level was restored to normal level band. Reactor pressure was controlled by the bypass valve system, and a normal cool down was initiated. The reactor is being taken to cold shutdown pending an investigation of the event. The loss of power also resulted in a partial loss of normal service water cooling to the plant, and emergency service water cooling automatically initiated per design. At the time of event, the reactor protection system was aligned to the backup power supply, which was momentarily lost. This resulted in multiple system isolations including reactor water clean up, and outboard balance of plant isolations. These isolations were initiated due to loss of offsite power, and all responded as designed. The isolation resulted in a loss of the running decay heat removal pump for the spent fuel pool. The standby pump is available for service and being aligned for service. The plant is currently stable in hot shutdown. Transmission and distribution personnel are currently investigating the ground in the 230 kV switchyard. | | event text = At 0431 CST on November 27, 2015, an automatic reactor scram occurred following the trip of the main generator. The generator trip was apparently caused by a partial loss of offsite power, which resulted from a differential ground on the north bus of the local 230 kV switchyard. The ground signal caused the reserve station service line no. 1 to de-energize, which tripped the Division 1 offsite power source to station, as well as the main generator. The plant responded as designed as follows: The Division 1 emergency diesel generator started and tied to the bus restoring Division 1 emergency power. The Division 3 emergency diesel generator started and tied to the bus, restoring power on the Division 3 switchgear. The reactor protection system tripped as designed. Reactor water level was controlled normally with condensate and feed water. A level 3 reactor water level scram signal occurred as expected, and RPV [Reactor Pressure Vessel] water level was restored to normal level band. Reactor pressure was controlled by the bypass valve system, and a normal cool down was initiated. The reactor is being taken to cold shutdown pending an investigation of the event. The loss of power also resulted in a partial loss of normal service water cooling to the plant, and emergency service water cooling automatically initiated per design. At the time of event, the reactor protection system was aligned to the backup power supply, which was momentarily lost. This resulted in multiple system isolations including reactor water clean up, and outboard balance of plant isolations. These isolations were initiated due to loss of offsite power, and all responded as designed. The isolation resulted in a loss of the running decay heat removal pump for the spent fuel pool. The standby pump is available for service and being aligned for service. The plant is currently stable in hot shutdown. Transmission and distribution personnel are currently investigating the ground in the 230 kV switchyard. | ||
All control rods inserted. The licensee has notified the NRC Resident Inspector. | All control rods inserted. The licensee has notified the NRC Resident Inspector. | ||
Latest revision as of 20:46, 1 March 2018
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-1.13 h-0.0471 days <br />-0.00673 weeks <br />-0.00155 months <br />) | |
| Opened: | Rob Melton 09:23 Nov 27, 2015 |
| NRC Officer: | Dong Park |
| Last Updated: | Nov 27, 2015 |
| 51568 - NRC Website
| |
River Bend with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |