One brand-new reactor pressure vessel was bought from Poland after the Żarnowiec Nuclear Power Plant project was abandoned in 1990.

In November 2005, Hungary's Parliament passed a resolution with overwhelming bipartisan majority to support the lifetime extension.

The power generator made repeated surveys of public opinion on the lifetime extension and concluded that support for the decision hovered near 70%.

[9][10] On 30 March 2009 the National Assembly of Hungary gave its principal consent by votes 330 for, 6 against and 10 abstentions to the preparation works of the possible new units.

On 26 February 2010 the owner state company MVM Group decided the expansion with about 2 trillion Hungarian Forints price.

(Paks II Ltd.) reported on their website that the preparation of the construction site has started including more than 80 service buildings.

The lid on the cleaning machine was winched up at 04:20, but one of the three lifting cables attached to it broke; and it was not finally removed until 16 April.

However a video examination of the damaged fuel elements following the successful removal of the lid caused the rating to be raised to 3 ("serious incident").

An investigation by the Hungarian Atomic Energy Agency concluded that the cause of the incident was inadequate cooling of the fuel elements, which were heated due to the radioactive decay of short-lived fission products.

The investigation proposed that the severe damage probably occurred when the lid was released, causing thermal shock to cladding because of the sudden entry of cool water into the system, and explosive steam production.

[29] One of the interesting results of the investigation was that the Hungarian Atomic Agency had placed too much trust in the technology and knowledge of the French Framatome Company.

The agency did not investigate documentation provided by the company deeply enough, missing a fatal design flaw in the Framatome-designed, produced, and operated cleaning equipment.

The discharge of radioactive gases through the stack continued for several days after the incident, although the Hungarian Atomic Energy Agency determined that the radiation levels adjacent to the plant were only about 10% above normal.

The defect that occurred during the cooling of the block was classified as INES grade 1 (abnormality), although the power plant originally requested a zero rating.

On the morning of 14 July 2016 reactor 1 was automatically shut down due to an equipment malfunction, which did not pose any safety threat.