ENS 45367
ENS Event | |
|---|---|
10:11 Sep 20, 2009 | |
| Title | Unplanned Emergency Diesel Auto Start During Surveillance Testing |
| Event Description | This report is being made due to an auto start of the Red Train Emergency Diesel Generator (2K-4A) which was the result of an unplanned loss of power to the Red Train 4160 Volt Electrical Bus (2A3) during surveillance testing. Concurrent with the loss of power, Shutdown Cooling Flow was temporarily lost.
This condition occurred with the unit in Mode 5 during a refueling outage. The Reactor Coolant System (RCS) Pressurizer level was 85 percent and RCS temperature was 139 degrees Fahrenheit. During the momentary loss of power, 2A3 automatically shed its loads as designed. This caused the running Shutdown Cooling Pump (Low Pressure Safety Injection Pump 2P-60A) to secure which resulted in a loss of Shutdown Cooling Flow to the RCS for approximately three and a half minutes. Shutdown Cooling was restored using the applicable Abnormal Operating Procedure. RCS temperature rose approximately five degrees Fahrenheit. During the performance of planned surveillance testing, 2K-4A was unexpectedly auto started. An Offsite Power Transfer Test was being performed to test automatic transfer from Startup 3 Offsite Transformer to Startup 2 Offsite Transformer. The transfer was initiated by momentarily bypassing (jumpering) a relay. When the test was initiated, a slow transfer of the Red Train 4160 Volt Electrical Bus (2A1) occurred instead of the expected fast transfer. The slow transfer of 2A1 resulted in a momentary loss of power, for approximately two seconds, to the Red Train 4160 Volt Electrical Bus (2A3) which is supplied from 2A1. The under voltage condition on 2A3 caused 2K-4A to auto start, as designed. 2K-4A did not power 2A3, since 2A3 was powered from 2A1 after the slow transfer completed. The cause of the slow transfer versus a fast transfer is under investigation. The licensee notified the Arkansas Department of Health and the NRC Resident Inspector. |
| Where | |
|---|---|
Arkansas Nuclear  Arkansas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+3.1 h0.129 days <br />0.0185 weeks <br />0.00425 months <br />) | |
| Opened: | Albert Martin 13:17 Sep 20, 2009 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Sep 20, 2009 |
| 45367 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |