ENS 44737
ENS Event | |
|---|---|
15:45 Dec 20, 2008 | |
| Title | Momentary Loss of 345Kv Offsite Power |
| Event Description | At approximately 1045 hours0.0121 days <br />0.29 hours <br />0.00173 weeks <br />3.976225e-4 months <br /> on Saturday, December 20, 2008, while in a Hot Shutdown condition, Pilgrim Station experienced a momentary loss of all 345kV off-site power to the Startup Transformer (SUT). As a result, the following safety system actuations occurred: automatic Reactor Protection System (RPS) actuation (all control rods were previously inserted), automatic start of both Emergency Diesel Generators (EDG) and loading of their respective emergency buses, automatic actuation of Primary Containment Isolation Systems (PCIS) Groups I, II, VI and Reactor Building Ventilation, manual initiation of the High Pressure Coolant Injection (HPCI) system for reactor pressure control, and manual initiation of the Reactor Core Isolation Cooling (RCIC) system for reactor level control. All systems functioned as designed and expected.
Because power from an off-site source remained available from the 23kV Shutdown Transformer, the criteria for declaration of an Unusual Event were not met (Pilgrim EAL 6.3.2.1). 345kV power was automatically restored to the Startup Transformer via breaker reclose logic. Restoration of normal on-site power to all 4kV buses is complete and efforts to return systems to normal shutdown alignments are in progress. Current plans are in place to maneuver the plant to a Cold Shutdown condition as necessary to support recovery actions. The NRC Resident was on-site at the time of the event and has been notified. There was no threat to the health or safety of the public as a result of this event. The loss of power was caused by a breaker icing in the onsite switchyard. The switchyard breakers were inspected for icing. The licensee notified the State of Massachusetts. |
| Where | |
|---|---|
| Pilgrim Massachusetts (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| LER: | 05000293/LER-2008-007 |
| Time - Person (Reporting Time:+1.37 h0.0571 days <br />0.00815 weeks <br />0.00188 months <br />) | |
| Opened: | R.M. Probasco 17:07 Dec 20, 2008 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Dec 20, 2008 |
| 44737 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Shutdown (0 %) |
| After | Hot Shutdown (0 %) |