ENS 53409
ENS Event | |
|---|---|
20:03 May 17, 2018 | |
| Title | Emergency Diesel Generators Inoperable |
| Event Description | On May 17, 2018, with the Unit in Mode 4, Clinton Power Station experienced the concurrent inoperability of two Emergency Diesel Generators (DG). This event is being reported as an 8-hour non-emergency notification per 10 CFR 50.72(b)(3)(v) as, 'Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident.'
On May 17, 2018, at 15:03 CDT, it was identified that the Division 2 DG air start receiver isolation valves 1DG160 and 1DG161 were shut. With these valves shut, the Division 2 DG is inoperable. At the time, Division 1 DG was also inoperable for a 4160V 1A1 partial bus outage. The Technical Specification (TS) Actions for TS 3.8.2, AC Sources Shutdown, and TS 3.5.2, RPV Water Inventory Control, were entered as a result of the inoperability of the onsite AC power sources to isolation valves being credited to limit RPV DRAIN TIME. Division 2 DG air receivers were realigned at 15:45 CDT and the Division 2 DG auto start function was restored. Offsite power was available throughout this event and there was no impact to the health and safety of the public or plant personnel. Investigation is ongoing. It has been determined that the air start receiver isolation valves remained closed following system restoration on May 11, 2018. However, the Division 2 DG was not required to be Operable by TS until 00:45 CDT on May 14, 2018 when the Division 1 DG was made inoperable as a result of scheduled plant maintenance. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Clinton  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+2.98 h0.124 days <br />0.0177 weeks <br />0.00408 months <br />) | |
| Opened: | Dale Shelton 23:02 May 17, 2018 |
| NRC Officer: | Steven Vitto |
| Last Updated: | May 17, 2018 |
| 53409 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |