Construction of Hungary’s 2,400 MW Paks II nuclear project is continuing while the government reviews parts of its contractual and financial structure, adding another layer of uncertainty around one of Central Europe’s largest energy investments.
Work is most advanced at Unit 5, where preparations for the reactor-building foundation are more than 80 per cent complete following the pouring of more than 18,000 cubic metres of concrete. Remaining foundation works are expected to be completed before winter. Excavation of the nuclear island for Unit 6 is also progressing, with preparations for first concrete planned before the end of 2026.
Manufacturing has moved ahead in parallel. Rosatom has started producing equipment for both VVER-1200 reactors, while the 730-tonne core catcher for the first unit was delivered to the Paks site in 2024. The supply chain also includes companies from France, the US, Germany, Austria, Switzerland, the Netherlands, the Czech Republic, Slovakia and Turkey. Alstom began manufacturing turbines for the project at its Belfort facility in April 2025.
The financing architecture remains one of the most sensitive issues. Paks II is supported by a Russian state loan of up to €10bn. Major changes to existing contracts or replacement of the principal contractor could require renegotiation of that financing, potentially delaying completion.
Environmental resilience has become an additional consideration. Exceptionally low Danube levels have revived questions about cooling-water availability and whether further measures are required to strengthen the plant’s ability to operate during drought conditions. More substantial design changes, including closed-loop cooling, would add cost and could affect the schedule.
Budapest is therefore balancing the high cost of changing a project already deep into construction against longer-term concerns over financing, cooling resilience and security of electricity supply.
