ENS 41715
ENS Event | |
|---|---|
00:59 May 19, 2005 | |
| Title | Inadvertent De-Energization of 4160 V Safety Related A.C. Bus with Edg Auto Start |
| Event Description | On 5/18/05 at 20:59 the 1A3 4160 V safety related A.C. bus inadvertently de-energized and the 1A Emergency Diesel Generator [EDG] automatically started and loaded onto the bus. The inadvertent de-energization of the 1A3, 4160 V bus appears to have resulted from testing of the 4160 V under voltage relays. Currently, normal power has been restored to the 1A3, 4160 V bus and the 1A Emergency Diesel Generator has been secured.
This notification is being made pursuant to 10 CFR 50.72(b)(3)(iv)(A) to be completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> as a safety systems actuation of the 1A3, 4160 V under voltage relaying and inadvertent start and load of the 1A Emergency Diesel Generator. The licensee notified the NRC Resident Inspector.
On 5/18/05 at 20:59 the 1A3 4,160 KV safety related AC bus inadvertently de-energized and the 1A Emergency Diesel Generator (EDG) automatically started and loaded onto the bus. This event was initiated during the performance of a plant surveillance 1-OSP-100.07, to test the 1A3 4,160 KV Bus Under Voltage Relay. The 1A EDG loaded and carried the 1A3 bus. The 1B3 4,160 KV bus was unaffected and the "B" side power remained energized. This update is to provide the following additional information identified during the follow up investigation. This update is to identify that HVS-1B, Containment Fan Cooler, did not start as expected after the 1A EDG automatically loaded on the 1A3 4,160 KV Bus. The HVS-1A and HVS-1B were both load shed from the bus prior to closure of the 1A EDG output breaker. The HVS-1A did start as expected following closure of the EDG output breaker. The HVS-1B is on the three (3) second load block for the 1A EDG to restart, but did not start. A Root Cause Team has been formed to identify the cause of the initiating event and the auto-start failure of HVS-1B. A Condition Report was generated and a troubleshooting plan has been developed to determine the cause of the initiating event and failure of the HVS-1B to automatically restart. The 1B3 4,160 KV safety related AC bus and associated EDG were not affected by this event and remained operable during and following the event. Troubleshooting for the subject failed equipment is ongoing. The licensee notified the NRC Resident Inspector. The R2DO (Ogle) was notified. |
| Where | |
|---|---|
Saint Lucie  Florida (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+3.63 h0.151 days <br />0.0216 weeks <br />0.00497 months <br />) | |
| Opened: | James Hurchalla 04:37 May 19, 2005 |
| NRC Officer: | Arlon Costa |
| Last Updated: | May 19, 2005 |
| 41715 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 560872022-09-03T02:48:0003 September 2022 02:48:00
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