The third block of Hungary's sole nuclear power plant came close to being shut down last week as the temperature of the Danube reached extreme levels, Hungarian media reported on August 27. 

The Paks power plant accounts for half of Hungary's electricity production and a third of its consumption. Production in the summer months is generally lower than in the winter period. Since the power units use water directly from the Danube for cooling the turbines, the thermal efficiency of the power units deteriorates as the temperature of the Danube rises. 

Hungarian regulators set a 30 Celsius limit in the temperature of the Danube in the area where water is discharged from the power plant after which the facility must be shut down. According to media reports, also confirmed by the power plant, the temperature was just shy of this ceiling over the weekend. 

The issue has come up in the debate on the expansion of the power plant. The Paks expansion (Paks 2), the largest ever investment in Hungary, will see Russia’s Rosatom build two new reactors for €12.5bn by 2026 and 2027. 

Opponents of the construction say the impact studies did not provide any assurance that the emitted cooling water will not warm the Danube up over the allowed thermal limit. They say it is extremely irresponsible of the authorities to grant a licence to the Paks 2 project when it cannot guarantee that the Danube will not deteriorate.

Critics also argue that the models used by the authorities did not take into account the effects of climate change, the decreasing water flow, and rising temperatures.