Nuclear power is no longer cool

In recent days, nuclear power plants in France, Switzerland, Hungary, and Romania have had to reduce or suspend their output due to low water levels and high temperatures in rivers used for cooling. This has led to a noticeable decline in electricity generation from these facilities, raising concerns over the reliability of nuclear energy under extreme weather conditions. The issue primarily affects reactors that rely directly on river water for cooling rather than using cooling towers. In Switzerland, the Beznau plant, which operates two units, was temporarily reduced to 50 percent capacity on June 24 after the Aare River reached a temperature of 25 degrees Celsius. It has since been completely shut down. According to Axpo, the operator of the facility, while high temperatures are technically manageable, the shutdown is intended to protect the ecological balance of the river. Regulations require reducing thermal input into the environment when water temperatures exceed certain thresholds, either through lowering production or other measures. Other Swiss nuclear plants, such as Leibstadt and Gösgen, which are equipped with cooling towers, have not yet faced similar restrictions. In France, the Golfech plant was shut down to protect the ecology of the Garonne River, while several other sites including Bugey, Nogent, Chooz, Saint-Alban, and Blayais saw temporary reductions in output. Mycle Schneider, a French nuclear policy analyst based in Paris, noted that this level of production loss earlier in the year is unprecedented. During the heatwave in June, France recorded a record loss of 8.5 gigawatts of available capacity, equivalent to 14 percent of its installed nuclear generating capacity. By early August, cumulative losses for the year had already exceeded four terawatt-hours, representing approximately two percent of total nuclear electricity generated during that period. This situation marks a shift from previous norms. Until recently, production losses due to high temperatures and low water levels were minimal, averaging just 0.3 percent annually since 2000. However, projections suggest that without adjustments to infrastructure, these losses could rise to around 1.5 percent by 2050. To address this, EDF, the French utility company, plans to invest up to 8.7 billion euros by 2040, allocating roughly 600 million euros annually. Technical challenges also play a role in some cases. For example, at the Paks plant in Hungary, the intake pipes of the cooling pumps are insufficient to reach adequate depths given the current low water levels along the Danube. Despite sufficient water availability, the plant has been limited to just twelve percent of its rated capacity. The operator has begun planning to deepen the intake point, though immediate results are unlikely. In Romania, efforts to increase the flow of the Danube to support the Cernavodă nuclear plant included military action. Romanian marine soldiers blasted rocks to redirect more water toward the facility, resulting in a two-centimeter rise in the river’s level. While this measure helped slightly, it highlights the broader challenge of maintaining nuclear operations amid environmental stressors. Meanwhile, in Bulgaria, the Kosloduj plant near the Danube has also been affected by heat and drought, though specific operational impacts remain unclear. These developments underscore the growing vulnerability of nuclear energy to climate-related disruptions, prompting renewed discussions on the need for adaptive strategies and infrastructure upgrades.