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Limerick Generating Station
NRC image of Limerick Generating Station, Units 1 & 2.
Country United States
Location Limerick Township, Montgomery County, Pennsylvania
Coordinates 40°13′36″N 75°35′14″W / 40.22667°N 75.58722°W / 40.22667; -75.58722Coordinates: 40°13′36″N 75°35′14″W / 40.22667°N 75.58722°W / 40.22667; -75.58722
Status Operational
Construction began June 19, 1974 (1974-06-19)
Commission date Unit 1: February 1, 1986
Unit 2: January 8, 1990
Construction cost $7.246 billion (2007 USD, Unit 1 only)
Owner(s) Exelon
Operator(s) Exelon
Limerick Generating Station

The Limerick Generating Station in Pennsylvania is located next to the Schuylkill River in Limerick Township, Montgomery County, northwest of Philadelphia. The facility has two General Electric boiling water reactor (BWR) units, cooled by natural draft cooling towers. The two units are capable of producing over 1,200 megawatts of power, which combined would provide electricity to over 2 million households. Exelon Corporation owns and operates this facility. With the exception of refueling outages, Limerick Generating Station always operates at 100% power. The plant is connected to the grid by several 500kv transmission lines.

For critical standby power, Exelon depends on eight Fairbanks Morse 38 8-1/8 diesel engine generator sets that each deliver 3000 kilowatts of power and are capable of achieving rated speed within ten seconds of start.

The cooling towers for the Limerick Generating Station can be seen for miles away in parts of Montgomery, Chester, and Berks counties. On clear days the cooling towers for the Limerick Generating Station can be seen from the One Liberty Observation Deck in Philadelphia.

Surrounding population

The Nuclear Regulatory Commission defines two emergency planning zones around nuclear power plants: a plume exposure pathway zone with a radius of 10 miles (16 km), concerned primarily with exposure to, and inhalation of, airborne radioactive contamination, and an ingestion pathway zone of about 50 miles (80 km), concerned primarily with ingestion of food and liquid contaminated by radioactivity.

The 2010 U.S. population within 10 miles (16 km) of Limerick was 252,197, an increase of 18.7 percent in a decade, according to an analysis of U.S. Census data for The 2010 U.S. population within 50 miles (80 km) was 8,027,924, an increase of 6.1 percent since 2000. Cities within 50 miles include Philadelphia (28 miles to city center).


The site was chosen and plans to build the station were announced in 1969, by the Philadelphia Electric Company (now PECO Energy, a subsidiary of Exelon). It is located approximately one mile south of Sanatoga, PA. Community protests by the Keystone Alliance and other delays pushed the start of construction by the Bechtel Power Corporation to June 1974.

Limerick Unit 1 first attained criticality (began producing nuclear power, at limited capacity) on December 22, 1984 and was certified for commercial operation on February 1, 1986.

Limerick Unit 2 attained criticality on August 1, 1989, and commercial operation began on January 8, 1990.

President George W. Bush visited the Limerick Generating Station in May 2006 to discuss nuclear power and its role in the Advanced Energy Initiative, which he announced at the 2006 State of the Union Address. He toured the facility, including a trip to the control room of the plant.

On October 20, 2014, the Nuclear Regulatory Commission (NRC) granted extensions for Limerick Units 1 and 2 for another 20 years. The units now are licensed to operate until 2044 and 2049 respectively.

Unit 2 of the station was scrammed from 100% power to a shutdown on June 1, 2016, at 9 am. The reactor was shut down due to an electrical fault, causing the stopping of the recirculation pumps. The steam bypass valves that lead to the main condenser were opened and Limerick went through a normal hot shutdown process.

Seismic risk

The Nuclear Regulatory Commission's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Limerick was 1 in 18,868, according to an NRC study published in August 2010. Following the Fukushima Daiichi nuclear disaster in 2011, government regulators announced the plant would undergo further evaluations for seismic activity risk.

A quarry is located nearby which occasionally does blasting; however, this is done with the consent of plant staff.

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