Slovenia’s Krško nuclear power plant has returned its reactor to 100 per cent power after cooler weather, rainfall and improving conditions on the Sava River eased environmental restrictions that had limited production since early August. The change followed a period when the plant operated under constraints tied to river conditions.
Derating steps as river flows and temperatures shifted
The plant initially cut reactor output to 80 per cent when very low river flows coincided with elevated water temperatures. As conditions improved, output was raised to 90 per cent. The unit then returned to full reactor power on the evening of 18 August.
Grid deliveries remain below typical levels
Electricity supplied to the grid has not yet fully returned to normal. During the afternoon, the plant was delivering approximately 660 MW, compared with more than 700 MW under typical operating conditions.
Cooling-tower use affects electricity output
A portion of the gap is linked to continued use of the cooling-tower system. Some of the plant’s own electricity is being consumed to run cooling infrastructure, which reduces dependence on Sava River water while helping the facility stay within environmental limits.
The episode highlights how extreme summer hydrological conditions can affect nuclear availability in the region. With Krško providing stable generation for both Slovenia and Croatia, partial derating has implications for cross-border electricity balances and wholesale prices.
