ENS 46898
ENS Event | |
|---|---|
21:44 Apr 3, 2011 | |
| Title | 60-Day Optional Notification of Invalid Start of the 'A' Emergency Diesel Generator |
| Event Description | The following event description is based on information currently available. If through subsequent reviews of this event, additional information is identified that is pertinent to this event or alters the information being provided at this time, a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.
This report is being made under 10 CFR 50.73 (a) (2) (iv) (A) for a reportable invalid actuation. On April 3, 2011, at approximately 1444 Mountain Standard Time, Palo Verde Nuclear Generating Station Unit 2 experienced an invalid actuation (start) of the 'A' Emergency Diesel Generator (EDG). EDG 'A' inadvertently started during integrated safeguards surveillance testing to demonstrate that the EDG overspeed trip is not bypassed. Prior to the test, the EDG overspeed governor was actuated, but the butterfly valve was not verified to be fully closed as required. The valve closure actuates a limit switch which activates the interlock that prevents the EDG start following an overspeed trip. The test requires the operator to ensure the butterfly valve is fully closed because it may not fully close as the EDG is not running when it is actuated for the overspeed test. When the demand signal was inserted, the EDG started unexpectedly since the butterfly valve was not fully closed and the limit switch was not engaged. EDG 'A' Train completely actuated in the Emergency Mode and the EDG came up to rated speed and voltage as designed. The supporting 'A' train Essential Spray Pond System, used for engine cooling, was already running prior to the test. The Essential 'A' Train EDG Exhaust Room air handling unit started as required. No damage occurred to the EDG or related equipment as a result of the unplanned actuation. The EDG was secured and the test was successfully re-performed. This report is not considered an LER. The licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1289.48 h53.728 days <br />7.675 weeks <br />1.766 months <br />) | |
| Opened: | Jorge Rodriguez 15:13 May 27, 2011 |
| NRC Officer: | Howie Crouch |
| Last Updated: | May 27, 2011 |
| 46898 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 559262022-04-12T03:45:00012 April 2022 03:45:00
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