Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 51862 | 12 April 2016 07:47:00 | On April 12, 2016, with the reactor at 100 percent power and the mode switch in RUN, Pilgrim Nuclear Power Station entered an unplanned 24-hour Limiting Condition for Operation (LCO) action statement due to both emergency diesel generators (EDG) being inoperable (Technical Specification 3.5.F.1). At 0050 (EDT) this morning, with EDG B out of service for a planned LCO maintenance window, EDG A was declared inoperable due to a 130 drop per minute leak on a line to a jacket water pressure indicator. Repairs to EDG A are underway at this time. The following plant equipment has been verified operable: both 345 Kv transmission lines; 23kV transmission line; Station Blackout EDG. This condition is reportable to the NRC Staff as an Event or Condition that Could Have prevented Fulfillment of a Safety Function (Mitigate the consequences of an accident) under 10 CFR 50.72(b)(3)(v)(D), and requires an 8-hour notification. The licensee has notified the NRC Senior Resident Inspector. The licensee will notify the Commonwealth of Massachusetts. |
| ENS 51087 | 22 May 2015 13:36:00 | On Friday, May 22, 2015 at 1002 EDT, with the Reactor Mode Select Switch in the Start-Up position and the reactor at approximately 3 percent core thermal power, while returning to power from Refueling Outage Number 20, a manual reactor scram was inserted due to degrading main condenser vacuum. The cause of the degraded vacuum is currently under investigation. Following the reactor scram, all rods were verified to be fully inserted and no Emergency Operating Procedure entry conditions existed. All plant systems responded as designed. Currently reactor pressure is being maintained at 400 psig with the Mechanical Hydraulic Control System (turbine by-pass valves). Reactor water level is being maintained in normal bands with the Condensate and Feedwater System. Off-site power is being supplied to the station by the Startup Transformer (normal power supply for shutdown operations). This event had no impact on the health and/or safety of the public. The NRC Resident Inspector is on-site and has been notified. The licensee has notified the Massachusetts Emergency Management Agency. The licensee will be issuing a press release.
The following was provided by the licensee as clarifying information to the first paragraph of the original event notification: As a conservative measure, the operating crew had previously started reducing power from 20 percent core thermal power when it was first noticed that main condenser vacuum was degrading. This was well before any low condenser vacuum alarms were received. During the shutdown, after already securing the main turbine, the operating crew established benchmark values for degrading condenser vacuum for a normal plant shutdown and for a manual reactor scram should vacuum continue to decline to preclude an automatic scram. The licensee notified the NRC Resident Inspector. Notified R1DO (Dwyer). |
| ENS 41799 | 26 June 2005 15:30:00 | The report is being made in accordance with 10 CFR 50.72(b)(3) due to both Emergency Diesel Generators (EDGs) being declared inoperable. (This is a 24-hour LCO.) The EDGs were declared inoperable due to indicated outside air temperature exceeding the established operability limit of 95F for two short periods of time. Indicated outside air temperature went above 95F during the following time frames: 10:55 to 11:00 and 12:15 to 12:20. Indicated outside air temperature subsequently decreased to less than 95F following these spikes. Both EDGs are currently operable. Outside ambient temperatures are continuing to be monitored. Offsite power is available. Further evaluation of this event is ongoing. The licensee notified the NRC Resident Inspector.
The initial report was made in accordance with 10 CFR 50.72(b)(3) due to both Emergency Diesel Generators (EDGs) being declared inoperable. The EDGs were declared inoperable due to indicated outside air temperature exceeding the established operability limit of 95F for short periods of time on 6/26/05. Outside indicated air temperature subsequently decreased to less than 95F following these short timeframes. Both EDGs were operable when the notification was made, and outside ambient temperatures continued to be monitored. Offsite power was available. Further evaluation of this event has been performed. The initial report used temperature indication that was conservative with respect to actual conditions. The evaluation determined that the air temperature outside the EDG Building was a maximum of 91 F on 6/26105. This evaluation was based on other temperature reading taken during the periods of interest. Additionally, further evaluation has determined that both EDGs were not inoperable even at the higher temperatures initially indicated. Therefore, the EDGs were not inoperable during the periods reported and event notification #41799 is retracted. Notified the R1DO (Caruso). The licensee notified the NRC Resident Inspector. |