ENS 40484
ENS Event | |
|---|---|
23:30 Jan 27, 2004 | |
| Title | Automatic Reactor Trip |
| Event Description | At 1730, 1/27/04, Callaway Plant experienced a reactor trip. Auxiliary feedwater actuated as expected to stabilize steam generator levels. All other plant systems responded as expected. At present the cause of the reactor trip is undetermined. Initial indications are that there were no voltage or frequency perturbations on the electrical grid and that the trip signal originated from Callaway's switchyard breaker circuitry. Plant staff is currently engaged in a review of all indications that occurred at the time of the trip and systematically investigating potential problem areas in an effort to identify the cause of the trip.
The licensee also reported that all control rods inserted on the reactor trip, no primary or secondary system relief valves operated, and that reactor temperature is being maintained using steam dump to the condenser. Steam generator water levels are being maintained using auxiliary feedwater. The station electrical system is available and in a normal configuration. The licensee notified the NRC Resident Inspector.
The licensee provided the following information as an update to their initial report: The cause of the reactor trip has been identified as a failed electrical relay in the main generator protection circuitry. The relay is designed to sense a fault in the main electrical generator and trip the generator output breakers. The failed relay was designated as a 321/G relay and provides phase fault backup protection to prevent exceeding thermal limits of the stator windings. After determining the cause of the reactor trip, preparations for a reactor startup are in progress. The licensee will inform the NRC Resident Inspector. Notified R4DO(Johnson). |
| Where | |
|---|---|
Callaway  Missouri (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| Time - Person (Reporting Time:+-1.25 h-0.0521 days <br />-0.00744 weeks <br />-0.00171 months <br />) | |
| Opened: | Eurman Henson 22:15 Jan 27, 2004 |
| NRC Officer: | Bill Gott |
| Last Updated: | Jan 28, 2004 |
| 40484 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |