Local story:
This article from Wednesday talks a bit about the first and second shutdowns earlier this week:Third unplanned shut-down reported at Limerick nuclear plant
Published: Friday, June 03, 2011; Last Updated: Fri. Jun 3, 2011, 12:53pm
By Evan Brandt
LIMERICK -- Less than a day after putting one its two nuclear reactors back on line following two un-planned shut-downs, the other nuclear reactor at Exelon's Limerick Generation station shut down unexpectedly this morning, according to the Nuclear Regulatory Commission.
According to an e-mail from NRC spokesman Neil Sheehan, "Limerick Unit 1 experienced an automatic scram at about 10:15 a.m. today. There were no complications during the shutdown, safety systems responded as expected, and the cooldown of the reactor is proceeding safely."
"The cause of the scram is being investigated by Exelon," Sheehan wrote. "Plant operators were performing a test involving the turbine at the time, but it is unclear at this point if that triggered the shutdown."
It was 5:02 a.m. Sunday that the plant's other reactor, Unit 2, shut down for the first time.
One day later, while completing testing on the system that controls the opening and closing of turbine valves, the turbine tripped offline again, at 11:50 a.m. Monday.
In February, the same reactor, Unit 2, shut down unexpectedly due to problems with systems related to re-circulating pumps. That shutdown lasted for more than two days.
Unit 2 went back on-line Thursday.
Sheehan wrote this morning, "our Senior Resident Inspector went to the plant’s control room immediately after the scram and is independently verifying whether plant operators are following the appropriate steps and procedures. He will continue to gather information on what occurred and the company’s response to it."
Limerick Unit 1 was at 100-percent power when it shut down.
The NRC tracks scrams based on the number of times they happen per 7,000 hours of on-line operation.
"The shutdown would count as a 'hit on Limerick Unit 1’s Performance Indicator for Unplanned Scrams per 7,000 Hours of Online Operation. As of the end of the first quarter of 2011, that indicator stood at 0.8," Sheehan wrote.
(Click here to see NRC's summary of Limerick's performance in this area.)
"Again, a plant has to have more than three unplanned scrams during that 7,000-hour period to receive increased NRC oversight," Sheehan wrote.
A public community information session is planned Wednesday at the power plant from 5 to 7 p.m.
I've lived in the area since 2001 and I'm not overly concerned. I just want to know from our experts here, how typical is this sort of thing in general?Exelon: Limerick Unit 2 Reactor Coming Back Online
The Unit 2 reactor was operating at 3 percent capacity as of early this morning, but is not yet connected to the electrical grid.
By David Powell | June 1, 2011
The Unit 2 reactor at Exelon Nuclear's Limerick Generating Station is back online, the company confirmed this morning.
"The unit is being returned to service," company spokesperson April Schilpp said. A reactor status page maintained by the Nuclear Regulatory Commission (NRC) indicated that the reactor was at 3 percent power early this morning.
Schilpp added that Unit 2's main turbine was still "completely offline" and that the unit is not yet connected to the electrical grid.
The unplanned shutdown early Sunday morning that initially took the unit offline has been attributed to a fault in an actuator on the main turbine's control valve, Schilpp said. Repair crews are in the process of "completely rebuilding" the actuator.
Schilpp said that the turbine is "related to the electrical side" of the power plant and that the type of repairs underway are typical for "any industrial power plant, regardless of the kind of generation."
"Most of our plants operate 100 percent of the time, so there's more wear and tear," Schilpp said.
Schilpp said reports of a "second shutdown" at the plant on Monday described events that were part of the troubleshooting and repair process.
"The unit was already shut down," said Schilpp.
According to Schilpp, an "extremely conservative threshold" for reporting incidents to the NRC resulted in the Monday "scram" appearing in the agency's daily event notification log.
Schilpp could not say precisely when repairs would be completed or when Unit 2 would be reconnected to the electrical grid.
