The Kozloduy Nuclear Power Plant is a largest nuclear power plant in Bulgaria situated 200 km north of Sofia and 5 km east of Kozloduy, a town on the Danube river, near the border with Romania. It is the country's only nuclear power plant. The construction of the plant began on 6 April 1970.

Kozloduy Nuclear Power Plant currently manages 2 pressurized water reactors with a total output of 1920 MWe. Units 5 and 6, constructed in 1988 and 1993 respectively, are VVER-1000 reactors.

Kozloduy Nuclear Power Plant previously operated four older reactors of the VVER-440/230 design, but under a 1993 agreement between the European Commission and the Bulgarian government, Units 1 and 2 were taken off-line at the end of 2003. A 1995 report by the United States Department of Energy had listed those units among the world's "ten most dangerous reactors". On the 21st of October 2010, licenses for the shutdown reactors were transferred to Bulgaria state radioactive waste enterprise DP RAO, signaling the formal beginning of decommissioning work.

Throughout the 1990s and early 2000s Units 3 and 4, originally licensed for operation until 2011 and 2013, respectively, underwent substantial safety improvements and, after rigorous inspections, received positive reviews from the IAEA in 2002, and from the World Association of Nuclear Operators (WANO) in the following year, concluding that "no technical reasons exist for the early closure of units 3 & 4". Backed by these findings, the government had hoped to convince the European Commission to allow a postponement of the agreed pre-accession shutdown; from a legal and political standpoint, however, this proved untenable. Units 3 and 4 were taken out of operation in the final hours of 2006, immediately prior to the country's accession to the European Union.

82 metric tons of its spent fuel were sent to a repository in Zheleznogorsk, Krasnoyarsk Krai during 2001 and 2002. In 2008, officials at the power plant announced their intention to use CONSTOR storage casks for this purpose.

Prior to the shutdown of units 3 and 4, Kozloduy NPP produced 44% of Bulgaria's electricity supply; as of March 2006, Bulgaria exported about 14% of its electricity production.

Pressure to restart

In January 2009 Bulgaria's president suggested that Unit 3 be restarted in light of the gas dispute between Russia and Ukraine and resulting power shortages in the region.[7] Under the conditions of its Accession Treaty Bulgaria may request temporary derogation from its commitments in the event of serious economic difficulties arising within the first three years of membership in the union.