Romanian naval forces carried out a controlled explosion to help redirect vital cooling water from the drought-hit Danube to the country’s last working nuclear ⁠reactor, as neighbouring Hungary ​said it may be able to eke out two more days of power from its only atomic plant.

Hungary and Romania have been forced to shut down nuclear reactors cooled by the Danube for the first time, as record-low water levels deepen fears of an energy crisis across the region. Romania has declared a nationwide state of emergency throughout August stemming from a decline in electricity production after record low Danube river levels led to the shutdown at the Cernavodǎ nuclear plant.

The Danube operation used 180kg of explosives, the Adevărul newspaper reported, to move a large rock restricting the flow of water in a blast that sent a tower of water ⁠into the air. The extraordinary measure underlined the scale of the crisis in Europe, where heat and drought have lowered river levels and raised concerns about water supplies, river transport and power generation.

“Any day past Wednesday or Thursday that the nuclear power plant functions is a gain,” Romania’s defence minister, Radu Miruțǎ, said on Monday. “A day of it functioning is three times more efficient than the costs of this operation.”

Experts said the controlled explosion would allow authorities to build a temporary dam, diverting more water into the channel serving Cernavodǎ’s remaining reactor.

With bothcountry’s sole nuclear plants at reduced ⁠capacity, Hungary and Romania are increasingly relying on expensive power imports as heatwave conditions increase demand for electricity. Both countries use water ​from the Danube as coolant for their reactors.

At Paks, Hungary’s Soviet-era nuclear power station, output has been reduced since Monday. The 44-year-old plant, which normally generates almost half of the country’s electricity, is operating at less than half its capacity. Authorities, who had ‌earlier said they might have to ‌shut Paks as early as Sunday, said it could operate at its reduced capacity until Monday ‌or Tuesday, offering a small reprieve for the power supply.

Hungary’s prime minister, Péter Magyar, said the plant was expected to be fully shut down next week. With the Danube forecast to remain too shallow for the reactors’ cooling systems, the closure could last for several weeks.

“An energy crisis situation could arise beginning Monday,” he posted on X. “Coordinated steps and restraint will be needed to avoid more severe consequences. We are counting on everyone!”

He added: “Today and maybe tomorrow the last turbine producing 240 megawatts can keep working. This is very good news, as the complete shutdown of the plant can be avoided on one of the days with the ‌highest consumption.”

Magyar earlier said voluntary ​cuts in power usage had reduced ​demand by 700MW on Sunday, significantly easing pressure on the grid.

Adding to voluntary cuts by other companies, the pharmaceuticals company Richter said on Mondayit would reduce its electricity consumption by more than 50% in the next three weeks.

In Serbia, record-low Danube levels have pushed the country’s key hydroelectric plant to operate with only 20% of its capacity, prompting the prime minister, Djuro Macut, to preside over an emergency meeting on Monday focusing on energy problems.

Water levels are not expected to rise on the Danube in the coming days or even weeks as no significant rainfall is forecast. The river passes through 10 countries, but in some stretches it has fallen to levels never previously recorded. The retreating river has revealed rocks, shipwrecks, a second world war bomb and the remains of a woolly mammoth.

The prehistoric bones were discovered on the exposed riverbed by a resident of Ryahovo, a village in northern Bulgaria. Experts from the Regional History Museum in the nearby city of Ruse were sent to examine the rare find.

Associated Press and Reuters contributed to this report