Europe's Heatwave is Forcing Nuclear Power Plants To Shut Down (qz.com)
Europe's heatwave -- which led to wildfires in Greece and Sweden, droughts in central and northern parts, and made the normally green UK look brown from space -- is forcing nuclear plants to shut down or curtail the amount of power they produce, local media reports. From a report: French utility EDF shut four reactors at three power plants on Saturday, Swedish utility Vattenfall shut one of two reactors at a power plant earlier last week, and nuclear plants in Finland, Germany, and Switzerland have cut back the amount of power they produce. Thermal power plants, such as nuclear or coal, use high-temperature steam to turn turbines, which convert heat energy into electricity. In the process, the steam's temperature falls, so it can no longer be used to move the turbine again. [...] Europe's heatwave, however, hasn't just increased air temperatures but also water temperatures.
Nuke plants mostly perform well in hot weather and carry the system when other sources are struggling. A few reactors have to cut back due to heat limits on cooling water. The total percentage of nuclear reduction across the board is less than 10%. Meanwhile, wind power during the recent heat wave was down over 80%. Nuclear was carrying the load. Particularly it was critical in late afternoon and evening when solar fades. There were times when wind production during these critical times dropped below 1% of demand.
https://news.bloombergenvironment.com/environment-and-energy/europes-power-prices-rise-as-heat-wave-saps-wind-from-turbines
https://www.bloomberg.com/news/articles/2018-08-01/scorching-start-to-august-set-to-test-europe-s-power-system