Philly-area nuclear plant shuts reactor for repair

LIMERICK, Pa. -- Officials at a nuclear power plant near Philadelphia have taken one reactor offline because of a potential valve problem.

The Mercury of Pottstown reports ( http://bit.ly/QnpsNR) Unit 2 at the Limerick Generating Station was shut down on Friday.

Plant spokeswoman Dana Melia says a slight rise in temperatures indicated a possible malfunction in a main steam valve. She says the valve can be replaced only if the reactor is offline.

Exelon Nuclear shut down Limerick's Unit 1 reactor last week for an electrical problem. The "unusual event" on July 18 fell under the lowest of four emergency classifications.

Unit 1 began operating at full power again earlier this week.

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Read more here: http://www.sacbee.com/2012/07/27/4667886/philly-area-nuclear-plant-shuts.html#storylink=cpy

Exelon shuts Pa. Limerick 1 nuclear power reactor

 July 18 (Reuters) - Exelon Corp shut down the
1,130-megawatt (MW) Unit 1 at the Limerick nuclear power plant
in Pennsylvania early Wednesday following an electrical
disturbance on the non-nuclear side of the plant, the company
said in a release.
    The outage came at a bad time for the power grid: Homes and
businesses in the U.S. Mid-Atlantic are cranking up their air
conditioners amid a brutal heat wave blanketing the region.
    The electrical disturbance caused a loss of power to
generator cooling equipment, the company said. The unit will
remain offline until repairs, inspections and testing are
completed, it said.
    The company said the unit shutdown did not pose any threat
to the public.

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NRC: Despite fault, quake risk not a factor in Limerick relicensing

LIMERICK — Deep in the ground, beneath the poured concrete and reinforced steel of the Limerick nuclear plant’s evaporation towers, lie several sleeping subterranean threats.

The plant’s operators and the regulators of the federal agency that oversees nuclear plants say these threats are likely to stay asleep. 

And even if the Sanatoga fault, the Chalfont fault or the Ramapo fault awoke and shook those landmark towers in an earthquake, it’s unlikely that quake would be severe enough to cause enough damage to the plant to create a disaster.

 That was the conclusion reached by geologists who mapped the local faults in 1974 for Philadelphia Electric Company.Despite improvements in geologists’ understanding of the East Coast earthquake picture — clearly punctuated by last August’s unexpected Virginia tremor felt in several states — that conclusion remains unshaken for both the plant’s current owner, Exelon Nuclear, and the Nuclear Regulatory Commission that oversees the plant.

Further, although newly revised earthquake risk assessments will be a factor in any new nuclear plants licensed by the NRC, they will not be considered when evaluating the 20-year license renewal for Exelon Nuclear’s Limerick Generating Station or any other nuclear plant for that matter.

In the end, it comes down to how risk is calculated.

“It is concluded that movement along the shears could not have occurred later than 500,000 years ago,” reads a July 30, 1974, letter signed by Joseph A. Fischer, a partner at Dames and Moore, and Bernard Archer, a senior geologist for the firm.

“In all probability” the faults have been inactive since 150 million to 200 million years ago, according to the letter that accompanied the green-shaded map showing the Sanatoga fault and Linfield fault zone close to a nuclear power plant.But three independent earthquake experts said recently that they agreed with the Dames and Moore assessment of the earthquake risk being low, but they also all agreed that the operative word here is “probability.”

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Exelon Shuts Down Pennsylvania Nuclear Plant Unit After Power Loss

 Exelon Corp. (EXC) said Thursday that it had to shut down a unit of the Limerick nuclear power plant in Pennsylvania after a power outage that affected plant equipment.

The plant's operators shut down Unit 1 at the plant, in Pottstown, Pa., after the plant's main generator cooling pumps lost electricity, Exelon said in a statement. The operators were still working to determine the cause of the electrical malfunction, which the company said was on the "non-nuclear" side of the plant.

The plant's Unit 2 was operating at full power, the company said.

Each unit has about 1,100 megawatts of capacity and together can serve about 2 million homes.

Limerick Nuclear power plant enters refueling outage

Feb 24, 2012

Exelon Corp. (NYSE: EXC) said more than 2,000 supplemental workers are at the 2,345 MW Limerick Generating Station near Pottstown, Pa., to support the plant’s 2012 refueling outage. Exelon Nuclear employees and supplemental workers will perform over 13,000 outage-related activities, including equipment upgrades, safety inspections and plant improvements.

Major work to be performed includes the replacement of service water piping systems, an integral part of the plant’s cooling systems; installation of new automatic speed drives that supply power to vital systems; and a number of electrical upgrades. Exelon said these activities cannot be performed while Unit 1 is online.

Limerick Unit 2 will continue to generate electricity during the Unit 1 outage.

Units 1 and 2 received their operating licenses from the U.S. Nuclear Regulatory Commission (NRC) in 1984 and 1989.

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Exelon shuts PA Limerick 1 reactor to refuel

Tue Feb 21, 2012 3:36pm EST

"During the outage, trained technicians will be installing new
 adjustable speed drives on Unit 1's massive core circulating
 pumps," Exelon said.

Nearly one-third of the reactor's fuel will be replaced and
workers will perform cabling upgrades on the unit along with
other equipment upgrades, safety inspections and plant
improvements, the company said.