ENS Event | |
|---|---|
13:56 Oct 23, 2017 | |
| Title | |
| Event Description | At 0856 [CDT] on October 23, 2017, during the Unit 2 refueling outage, with no fuel in the Reactor Vessel, an unexpected auto start of the Unit 2 Train B Emergency Diesel Generator (D6) occurred when construction electricians inadvertently bumped the plunger for relay 2Sl-20X while working in the relay rack. Relay 2Sl-20X is a slave relay that actuates a light on the control board, starts D6, and starts 22 Residual Heat Removal (RHR) pump on a Safety Injection signal. In this instance, the RHR pump did not start as its control switch was in pull-out. It is expected that the control board light lit for the brief time the relay plunger was depressed, but this could not be confirmed. The D6 actuation resulted in an unexpected annunciator for D6 EMERGENCY GENERATOR SI SIGNAL EMERGENCY START. Operators responded per the alarm response procedure, performed a walk down of running D6 and then performed a shutdown of D6. D6 started and functioned as expected.
There was no impact on public health and safety. This event is being reported as a 60-day telephone notification in accordance with 10 CFR 50.73(a)(2)(iv)(A) as an invalid actuation of an emergency diesel generator. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Prairie Island  Minnesota (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1436.22 h59.843 days <br />8.549 weeks <br />1.967 months <br />) | |
| Opened: | Alex Thornburg 11:09 Dec 22, 2017 |
| NRC Officer: | Steven Vitto |
| Last Updated: | Dec 22, 2017 |
| 53134 - NRC Website
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WEEKMONTHYEARENS 531352017-10-26T01:50:00026 October 2017 01:50:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Cooling Water System ENS 531342017-10-23T13:56:00023 October 2017 13:56:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Emergency Diesel Generator ENS 507022014-10-26T08:40:00026 October 2014 08:40:00 Other Unspec Reqmnt, 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephone Notification of Invalid Actuation of Residual Heat Removal Pump ENS 438342007-10-15T20:02:00015 October 2007 20:02:00 10 CFR 50.73(a)(1), Submit an LER Inadvertent Start of Emergency Diesel Generator D2 2017-10-26T01:50:00 | |