Building Slovakia's Mochovce 3 and 4 nuclear reactors is the longest running nuclear construction project anywhere in Europe. The reactors were designed by the Soviet Union back in the 1970s. Construction began back in 1987 but in 1992, soon after the collapse of the communist regime, it was suspended. Economic studies in 2000 showed the project to be a financial disaster.

In April 2006 Italian utility ENEL bought 66% of the shares in the Slovak energy utility Slovenské elektrárne (SE) during privatisation. In 2008 SE declared its intention to finally complete Mochovce 3 and 4 supported by the country's pro-nuclear government. Construction work on completion of the units was officially launched on November 3, 2008. The units are due to be finished by 2012 and 2013 respectively. The third unit should be connected to the power grid in autumn 2012 and the fourth unit eight months later, in 2013. The units will have an installed capacity of 880 megawatts.

Although operating since the mid 1980s in the Czech Republic, Slovakia and Hungary, four of the same model of reactor as Mochovce 3 and 4 under construction in East Germany were cancelled in 1990 after the German re-unification because the reactors did not meet basic safety standards.

Russia is the only supplier of nuclear fuel for this type of reactor which makes a mockery of the idea that nuclear power provides energy security. An estimated 22 tonnes of spent nuclear fuel is generated by each reactor every year.

The investment required to build Mochovce 3 and 4 is expected to reach 2.775 billion euros. This will devour a massive 77% of SE's investment for new electricity generation 2007 to 2013. Due to the high financial risks for investors, the Slovak government provides generous state aid that is very likely illegal under EU legislation.

In May 2010, Slovenské Elektrárne, (SE) received the final statement of approval from the Environment Ministry for the Environmental Impact Assessment (EIA) for operation of the third and fourth units of the Mochovce nuclear power plant. This was the last step in the EIA process initiated at the end of 2008. The statement released by the Environment Ministry ends the EIA process and is one of the key documents necessary for the Nuclear Supervision Office (UJD) to issue a permit to launch the operation of the third and fourth units after their completion in 2012 and 2013.

In July 2008, the European Commission issued a conditioned opinion on Slovakia's application to build new reactors at Mochovce, provoking indignant reactions from European Parliament MPs and Greenpeace. The opinion recommends, but does not oblige, the project proponent to ensure "an equivalent level of protection as a full containment" and to perform a thorough analysis of the measures needed in an aircraft crash scenario.

On 25 August 2008 Slovak power firm Slovenske Elektrarne (SE) launched a tender to find a builder to finish blocks 3 and 4 of Mochovce NPP. The deadline for final bids is 8 December 2008; construction works on units 3&4 are expected to start on 1 April 2009 and finish by the end of June 2011 (Reuters, 25 August 2008). The tender was won by a consortium with Czech / Russian nuclear engineer Skoda JS and Slovak VUJE.

On 3 November, Slovak Prime Minister Robert Fice officially started construction of the Mochvoce 3,4 power station. Because of the fact that there is no final construction permit as of today, this action rather served as PR exercise.

After heavy pressure from Greenpeace, Slovak NGOs, the Government of Austria and the European Commision, Slovak authorities decided in Summer 2008 that the Mochovce 3,4 project would need a full Environmental Impact Assessment. In early 2009, SE / ENEL started the EIA procedure. The first report was issued in July 2009, when a public participation period started. Public hearings were organised in Bratislava, Vienna (Austria) and Ezstergom (Hungary). The Slovak Ministry of Environment is expected to approve the final EIA report in February 2010.

ENEL issued in the second half of 2010 bonds to finance its investment programmes. It is believed that also the Mochovce 3,4 project will have to be covered by those bonds.