Calvert Cliffs Nuclear Power Plant is located on the western shore of Chesapeake Bay in Maryland. The plant contains two nine hundred megawatt Combustion Engineering Generation II two-loop pressurized water reactors. Unit 1 was put into commercial operation in 1975 with a license to operate until 2014 and Unit 2 was put into operation in 1977 with a license to operate until 2016. Unit 1 was relicensed until 2034 in 2000 and Unit 2 was relicensed until 2036 in 2000. The plant is owned by Constellation Energy Nuclear Group (CENG) which is a joint venture between Exelon Corporation and Electricity of France (EDF), a French energy company.
The population in the NRC plume exposure pathway zone with a radius of ten miles around the plant contains about fifty thousand people. The NRC ingestion pathway zone with a radius of fifty miles around the plant contains almost three million people. The NRC estimates that there is a very low risk of an earthquake that could damage the reactors at the plant.
In 1989, while Unit 1 was shut down for refueling, leaking pressurized heater sleeves had to be replaced which took over a year to accomplish. Unit 2 also had pressurized heater sleeve that leaked and it required over two years to fix those problems after a shut down for refueling in 1989. The NRC was tracking declining performance for months but was unable to force the needed changes until the problems became too serious to ignore.
From 2000 on, operators knew that a roof was leaking whenever it rained but did nothing about the problem for years. Finally, in 2010 electrical equipment was shorted out by the water that came through the roof and one of the reactors shut down automatically. The second reactor automatically shut down because an inoperative protective device had not been replaced due to cost-cutting at the plant.
In 2007, UniStar Nuclear Energy, a company jointly owned by CENG and EDF, launched a proposal to build a third reactor at Calvert Cliffs and the plan began working its way through the licensing process. In 2009, an opponent of the plan to build the new reactor asked the NRC to deny an emissions permit needed for the third reactor. In 2010, CENG sold its stake in the UniStar Nuclear Energy to EDF. In 2011, the NRC said that UniStar could not own a reactor in the United States because it was not a U.S. company.
Calvert Cliffs is another example of poor design/improper construction that required reactors to be shut down for years to remedy. It is also another example of the regulatory impotence of the NRC which saw problems but could not get them fixed until they became serious. The operators knew about a leaking roof for years but did nothing until the leak shut down the reactors. Calvert Cliffs is also the first plant that we have discussed where inoperative safety equipment was not replaced because the operators wanted to save money. Given the history of the operators of this plant, it is probably just as well that the plan to build a third reactor failed.
Photo from Jbs666:
