Calvert Cliffs Nuclear Power Plant - Overview

Overview

The plant, owned and operated by CENG, a joint venture between Exelon and Électricité de France, has two 2700 megawatt thermal (MWth) Combustion Engineering Generation II two-loop pressurized water reactors. Each generating plant (CCNPP 1&2) produces approximately 850 megawatt electrical (MWe) net or 900 MWe gross. Each plant's electrical load consumes approximately 50 MWe. These are saturated steam plants (non-superheated) and are approximately 33% efficient (ratio of 900 MWe gross/2700 MWth core). Only the exhaust of the single high pressure main turbine is slightly superheated by a two stage reheater before delivering the superheated steam in parallel to the three low pressure turbines. Unit 1 uses a General Electric designed main turbine and generator, while Unit 2 uses a Westinghouse designed main turbine and generator. The heat produced by the reactor is returned to the bay, which operates as a cooling heat-sink for the plant.

Unit 1 went into commercial service in 1975 and Unit 2 in 1977. The total cost of the two units was approximately 766 million USD.

Unit 1 had its two steam generators replaced in 2002 and its reactor vessel closure head replaced in 2006, while unit 2 had its two steam generators replaced in 2003, and its vessel closure head replaced in 2007.

The water around the plant (see lower-right-center of photograph) is a very popular place for anglers. Unit 1 & 2 each takes in bay water (from the fenced-in area) to cool its steam driven turbine condensers plus other bay-water–cooled primary and secondary system heat exchangers. The bay water is pumped out at a nominal flow rate of 1.2 million gallons per minute (75,000 L/s) per unit (Unit 1 and 2) for each steam turbine condenser. The water is returned to the bay no more than 12 °F (6.7 °C) warmer than the bay water. Unlike many other nuclear power plants, Calvert Cliffs did not have to utilize water cooling towers to return the hot water to its original temperature. As the water comes out very quickly and creates a sort of artificial rip current, it can be a dangerous place to fish. CCNPP 3 will only need about 10% of the bay cooling water volume needed for Unit 1 and 2 combined. The increase in fish and shellfish impingement and entrainment will be less than 3.5% over Unit 1 and 2 existing conditions.

In February 2009, Calvert Cliffs set a world record for pressurized water reactors (PWRs) by operating 692 days non-stop. In addition, Unit 2's capacity factor in 2008 was a world-record high of 101.37 percent.