Romania was working on a dike on Tuesday to divert water from the drought-hit Danube River to its only working nuclear power reactor, while Hungary's prime minister said the sole operating turbine at the Paks nuclear plant was running safely.
The Paks plant in Hungary and Romania's Cernavoda nuclear power plant both use water from the Danube for cooling. Record low river levels have sharply curtailed output, forcing Budapest and Bucharest to increase power imports and urge households and businesses to reduce consumption.
Romanian state-owned nuclear power producer Nuclearelectrica, which normally generates a fifth of the country's electricity needs, shut down one of its two reactors early last week as river levels fell.
At Hungary's Paks plant, three of four turbines have been shut down, leaving the facility operating at just over 10 per cent of capacity. Authorities are closely monitoring Danube water levels in a bid to avoid having to switch off the last remaining unit.
"Around 01:30 we were only a few millimetres away from the full powering down of the Paks nuclear plant but then the decline in the water level stopped and it rose 1.5 centimetres by the morning," Prime Minister Peter Magyar said in a social media post, before heading to Paks, located south of Budapest.
Speaking later in a social media video from the plant, Magyar said, "a potentially significant amount of rain could fall in the Austrian catchment areas sometime around Thursday", although it was not certain the rainfall would reach the Danube.
Romania's state water management agency is building a temporary dike by sinking four rock-filled barges in a branch of the Danube to divert more water towards the Cernavoda plant.
On Monday, the Romanian Navy blew up a rock outcrop to help the water flow before the barges could be submerged. Officials said the embankment should be completed by Wednesday or Thursday.
Nuclearelectrica executive Romeo Urjan told private broadcaster Digi24 that removing the rock obstruction was expected to extend the remaining reactor's operations by about seven days.
In Hungary, voluntary reductions in electricity use by households and more than 300 companies, following a government appeal, have helped lower demand and ease pressure on the national grid. However, Magyar has warned that this week will be critical as hot weather persists.
While the government has not imposed mandatory curbs on industrial power consumption, it has not ruled out doing so if conditions worsen.
Romania has also urged households, businesses and public institutions to cut electricity use. Austrian wood panel maker Kronospan said it will stop some of its Romanian production lines in stages to cut its electricity consumption in half.
Scheduled maintenance and summer shutdowns at carmakers Dacia, owned by France's Renault, and Ford Otosan Romania are also expected to reduce electricity demand.
Elsewhere in the region, Polish grid operator PSE called on power producers to meet their capacity obligations on Tuesday evening to bolster reserve generation as the country grappled with soaring temperatures.
PSE said on Monday that high temperatures and low water levels were constraining some power plants, but added that the system remained well prepared to meet summer demand.
(Reporting by Krisztina Than and Anita Komuves in Budapest, Luiza Ilie in Bucharest, Alan Charlish in Warsaw; Editing by Lincoln Feast and Ros Russell)