Hungary restarts Paks nuclear reactor after emergency Danube riverbed construction

Reactor restart and capacity ramp-up

Hungary began ramping up power production at the Paks nuclear facility on Saturday evening, 22 August 2026, restarting Reactor 3 after low Danube water levels forced severe capacity cuts. Hungarian Prime Minister Peter Magyar announced on Facebook that the facility is generating approximately 481 megawatts following the reconnection of the unit. The reactivation brought half of the station's total turbine capacity back online, with four of eight turbines currently running. Magyar stated on Sunday, 23 August 2026, that the plant could reach its full 2,000-megawatt operating capacity by Wednesday, 26 August 2026. This timetable moves up the recovery schedule by one or two days compared to earlier government projections, which had anticipated full restoration across all four blocks by 28 August 2026.

Emergency civil engineering on the Danube

The restart was facilitated by rising river water levels alongside emergency hydraulic engineering measures designed to secure cooling water supplies. Consecutive summer heatwaves across the European continent caused water levels in rivers and lakes to decline, severely restricting cooling operations that require high-volume water intake. Near the plant, Hungarian authorities executed emergency riverbed interventions to artificially raise water depths near the cooling water channels. On Saturday, 15 August 2026, workers submerged two 80-meter vessels in the Danube to alter flow conditions. Concurrently, construction advanced on an underwater bottom sill across the riverbed using approximately 150,000 cubic meters of rock. Hungarian Defense Minister Romulusz Ruzsin-Szendi confirmed that military units assisted in the construction, stating that the project represented a critical mission for national security and the ongoing operation of the country.

Grid pressure and voluntary reductions

The hydraulic crisis had previously reduced output at Paks to just over 10% of its total nameplate capacity, bringing the facility close to a complete operational shutdown. Before Reactor 3 was reactivated, only Reactor 2 was generating electricity, operating at a throttled rate of 25% capacity with just two of eight turbines functioning, while three reactors remained shut down. The sharp decline in output from Hungary's primary power source placed severe stress on the national energy network. To compensate for the deficit, Hungary increased electricity imports from neighboring countries. In parallel, government authorities issued appeals to industrial businesses and residential consumers, urging voluntary curbs on power usage during the peak of the supply constraints.

Strategic role of the Paks nuclear plant

The Paks facility, situated in the southern Hungarian town of Paks, was originally constructed with Soviet technology and has generated electricity since 1982. Under normal operating conditions, the four reactor units provide between 40% and 50% of Hungary's total domestic electricity supply. The recent cooling vulnerabilities occurred as Hungary proceeds with the controversial Paks II development project. That expansion project involves constructing two new reactor units on the site under the management of Russian state nuclear entity Rosatom, financed largely through a Russian state loan.