The Krško nuclear power plant has lifted generation to around 90% of capacity after cooler weather and improved conditions in the Sava river. The increase follows an earlier heat-related production cut that left output at roughly 80%. The reactor began a gradual ramp-up from the evening of 14 August.
River temperature limits under Krško’s environmental permit
Krško’s environmental permit sets requirements for the Sava downstream of the Brezice hydropower plant. It requires the average daily river temperature to stay below 28C. The permit also allows the plant to raise river temperature by no more than 3C.
During the recent heatwave, maintaining these temperature limits became increasingly difficult. While generation was reduced, Krško expanded reliance on cooling towers and other cooling equipment. Water withdrawals from the Sava fell from around 25 cubic metres/second to approximately 8.5 cubic metres/second.
Cooling setup and factors affecting future output
The reactor does not use Sava water in direct contact with the nuclear system. Instead, Sava water is used in the tertiary cooling circuit to remove heat from the condenser. Plant output therefore remains partly dependent on river temperatures, water levels and weather conditions.
The operational constraints tied to summer hydrology have implications for regional electricity balancing. Krško provides electricity equivalent to around 20% of annual Slovenian consumption and 16% of Croatian demand. Lower generation increases the need for alternative supply or wholesale-market purchases, particularly in Croatia.
Croatia supply expectations amid reduced Krško generation
In Croatia, HEP has indicated that shortages can be covered through domestic generation and imported electricity. The summer operating pattern at Krško highlights how nuclear availability can interact with climate-related hydrological constraints. This interaction is expected to matter more for regional power pricing during future heatwaves.
