Late Sunday, a jellyfish swarm clogged the cooling-water filters at Gravelines, a six-reactor plant on France’s North Sea coast. Four units shut down automatically. It was a bad timing, as two other reactors were already offline for maintenance,

A huge nuclear power station in France has temporarily shut down after a "massive and unpredictable" swarm of jellyfish swam into the cooling system.

Last weekend, a surprising and uncommon issue arose at one of the biggest nuclear power facilities in Europe. It was not a storm, a technical breakdown, or a security threat. Instead, it was an invasion of jellyfish that forced part of the facility to stop operations.