What natural event caused the French nuclear plant's shutdown?

The correct answer regarding the natural event that caused the French nuclear plant's shutdown is related to a massive jellyfish swarm. This phenomenon is particularly notable in the context of nuclear power plants because jellyfish can clog the cooling systems of these facilities, leading to operational emergencies. Such swarms can occur seasonally and can disrupt the intake of seawater necessary for cooling, forcing plants to temporarily shut down to prevent damage or overheating.

In the case of natural disasters, while earthquakes, tsunamis, and flooding can also pose significant threats to nuclear facilities, they are less common as direct causes for specific shutdowns compared to jellyfish swarms. Earthquakes and tsunamis, relevant in regions like Japan, can lead to broader concerns about structural integrity, while flooding typically impacts infrastructure rather than immediate plant operation without a specific environmental trigger like the jellyfish occurrence. Thus, understanding the unique challenges posed by jellyfish swarms adds an important dimension to the discussions around nuclear safety and environmental interactions.