The plant is owned and operated by Constellation Energy and has two 2737 megawatt thermal (MWth) Combustion Engineering Generation II two-loop pressurized water reactors.

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.

[citation needed] In February 2009, Calvert Cliffs set a world record for pressurized water reactors (PWRs) by operating 692 days non-stop.

[7] The 2010 US population within 10 miles (16 km) of Calvert Cliffs was 48,798, an increase of 86.4 percent in a decade, according to an analysis of U.S. Census data for msnbc.com.

Residents thought that the Federal Energy Regulatory Commission did not consider the risks could be caused by an attack or an explosion before opening the plant.

[12] Litigation pursuant to the 1970 National Environmental Policy Act led to a 1971 decision by the District of Columbia Court of Appeals requiring the Atomic Energy Commission (succeeded by the NRC in 1974) to consider the environmental impact of building and maintaining such an atomic energy plant.

[14] UniStar Nuclear Energy announced plans to build a unit of the Evolutionary Power Reactor (US-EPR variant) at Calvert Cliffs.

[17] Opponents and supporters of the proposed third reactor at Calvert Cliffs were involved in a series of public hearings before officials of the US Nuclear Regulatory Commission.

In March 2009, Bill Peil of southern Calvert County asked the NRC to deny an emissions permit for the reactor due to health and safety concerns he asserted that the plant posed to the community.

UniStar Nuclear Energy President and CEO George Vanderheyden urged the NRC to approve the air permit application.

[18] In October 2010, Constellation Energy said that it had reached an impasse in negotiations for a federal loan guarantee to build the proposed third reactor.

In April 2011 the NRC stated that UniStar is not eligible to build a third reactor, as it is not a US owned company since Constellation pulled out of the partnership in 2010.

[25] The Calvert Cliffs Nuclear Power Plant consist of two operational reactors, one additional was proposed in 2007 and withdrawn.