In 1977 the Romanian Government signed a contract with AECL to build a five unit nuclear power plant in Cernavodă using Canadian CANDU reactor technology. The heavy water reactor design uses heavy water as its neutron moderator and water from the Danube for cooling. Construction started on the five reactors in 1980. Currently the plant has two fully operational reactors and another three reactors that are partially finished. Unit One took 16 years to build, completed in 1996. It produces 705.6 MW of electricity. Unit Two took 27 years to build, achieving initial criticality in 2007 and produces 706 MW of electricity. Unit Three and Unit Four were expected to be operational by the year 2015 and the total electricity production of the units was to be around 1,500 MW. The total cost of the units is expected to be around US$ 6 billion. On 7 March 2008, Nuclearelectrica, ArcelorMittal, CEZ, Electrabel, Enel, Iberdrola and RWE agreed to set up a company dedicated to the completion, commissioning and operation of Units 3 and 4. The company is expected to be registered in May 2008. When four of the five reactors were to be fully functional the Cernavodă Nuclear Power Plant would have produced around 40% of Romania's total electricity needs. In 2002 and 2006, Romania made efforts to complete unit 3 and 4, respectively. The cost estimate put completion of both reactors at EUR 2.5 billion, with seven companies investing into the project, including the state run Societatea Nationala Nuclearelectrica. The six other companies include ArcelorMittal, CEZ, Electrabel, ENEL, Iberdrola, and RWE. With investment from all these companies, unit 3 would be completed in 2014 and unit 4 in 2015. In March 2008, the Romanian government suggested that it might build another four-unit power plant by 2020. The company that operates and maintains the power plant is Nuclearelectrica. 20 January 2011, GDF Suez, Iberdrola and RWE pulled out of the project, following ČEZ which had already left in 2010, citing "Economic and market-related uncertainties surrounding this project, related for the most part to the present financial crisis, are not reconcilable now with the capital requirements of a new nuclear power project". In November 2015 Nuclearelectrica and the China General Nuclear Power Group signed an memorandum of understanding regarding the construction, operation and decommissioning of Cernavoda 3 and 4.
There are also plans for the construction of a second nuclear power plant in Transylvania that will either have 2 reactors of 1,200 MW each or 4 reactors of 600 MW each with an electricity generating capacity of 2,400 MW and will be constructed after 2020. Currently, several locations for this plant are being considered, some on the Someș River. The French company Areva has been mentioned as a possible constructor for the new plant. A March 2008 statement by the head of SNN "Nuclearelectrica" said that up to four more units by 2020 at a new site were proposed, and early in 2009 site selection was still under way. In May it was announced that Târnăveni municipality in Târgu Mureș district of Transylvania, and on the Mureș River in central Romania was favoured, with a site in the nearby Sibiu district on the Olt River as second choice. Three sites on the Someș River in Transylvania have also been mentioned, for 2400 MWe of capacity to be built after 2020. Areva has been approached to contribute to planning, with a view to a second plant being commissioned by 2030.
