After weeks of historically low water levels on the Danube, the river's recovery has allowed operators at Hungary's Paks nuclear power plant to begin reactivating a second turbine. The move marks a cautious step back toward normal operations at the facility, which had been forced to scale back generation during the height of the drought.
At the start of August, the Danube at Paks fell to a record low of minus 134 centimetres, a level that threatened the plant's cooling systems. In response, three of the four reactor units were gradually shut down, leaving only a single turbine online. The reduced output kept the grid supplied but at a fraction of the plant's usual capacity.
Rainfall in the Austrian catchment area has since sent a flood wave downstream, lifting the river by about 19 centimetres at Paks. That modest increase has restored sufficient water pressure for the cold-water channel pumps, which are essential for cooling the condensers. As a result, the second turbine was reconnected to the grid on Monday evening, under strict technical supervision.
Safety first, output second
Nuclear safety remains the overriding priority during the restart, according to plant operators. Before the turbine could be brought back online, engineers had to verify that the condenser vacuum was adequate and that the secondary-circuit water met quality standards. The systems cooling the reactor core and spent fuel pools never stopped operating, even during the low-water period, but they are now being monitored with extra vigilance.
The reactor's thermal output and steam volume are being adjusted gradually, synchronised with the generator's connection to the grid. This step-by-step approach ensures that the equipment is not subjected to sudden stress. Around half a million components are undergoing diagnostics to rule out microscopic defects that could have developed during the prolonged shutdown.
With the second turbine running, the plant's output to the grid will rise from 240 megawatts during the critical period to 500 megawatts. That still falls short of the plant's full capacity, but it provides a significant boost to Hungary's electricity supply as the region grapples with the broader effects of the drought.
The Danube's low water has had wide-ranging consequences across Europe. In Serbia, record-low levels have stranded boats and exposed sandbanks, while in Budapest the riverbed has become an unlikely venue for parties. The drought has also highlighted the fragility of other energy infrastructure, as seen with Poland's coal plants struggling on the Vistula. These events underscore the growing pressure on Europe's water resources, a challenge that the EU is now seeking to address with a resilience plan.
For Paks, the immediate crisis appears to be easing, but the episode serves as a reminder of how dependent nuclear power is on reliable water supplies. As climate change makes extreme weather more frequent, operators across the continent will need to adapt to a future where such disruptions may become more common.
