The Krško nuclear power plant, which supplies energy to Slovenia and Croatia, has lowered its reactor output to 80%. This is due to rising Sava River temperatures and declining water flow. This development adds to regional concerns about electricity stability in Southeast Europe. Extreme heat and low river levels have already impacted nuclear energy operations in Hungary and Romania.
NEK, the operator of Krško, announced that the power reduction would occur gradually overnight into Thursday, August 6. Further cuts may be needed if environmental conditions remain unchanged or worsen. The plant uses the Sava River for cooling. Strict environmental regulations require that the river’s temperature at the Brežice hydropower plant’s basin does not exceed 28°C. It also must not increase more than 3°C daily.
If these conditions continue, the plant will have to reduce power further to comply with legal limits. Krško previously cut its power for an extended period in 2003, operating at reduced levels for more than 90 days due to similar environmental constraints. NEK confirmed that full-power operations will only resume once river conditions improve.
This year, Krško managed to operate at full capacity during the hot summer months by using cooling towers and other systems to manage thermal discharge into the river. However, recent rising water temperatures have forced the plant to confront the same operational restrictions it faced nearly two decades ago. As the regional energy landscape remains vulnerable to climate challenges, Krško is closely monitoring the situation.
The impact on the energy grid has been widespread in the region. The last reactor at Hungary’s Paks nuclear plant is barely functioning. Romania is struggling to maintain operations at its Cernavodă facility. Krško’s reduced output underscores the growing interplay between climate change and energy infrastructure. This is especially true in countries dependent on river-based cooling for nuclear power.