Thanks, once more, to Frances McKie for alerting us to this and who comments:

It keeps coming back to basic things like plumbing, blockages and corrosion…..at Dounreay, they never found a way to stop seaweed blocking their intake pipes…Here it’s jellyfish.

From Reuters yesterday:

Three reactors at ‌France’s Gravelines nuclear power plant were shut down late on Monday due to a massive swarm of jellyfish, triggering preventative measures put in place last year after the entire plant went offline, operator EDF said. The plant in northern France is one of the ​largest in the country and is cooled from a canal connected to the North Sea. ​Its six units produce 900 megawatts of power each, or 5.4 gigawatts in ⁠total. Scientists warn ⁠such events could become more common due to factors including global warming, the arrival of invasive species, habitat loss of predators and over-fishing.

EDF is also grappling with heat-limited nuclear reactors across the country, as a fifth heatwave is ⁠expected ​to grow throughout the week and curtail French nuclear output. One reactor ​in the north has been offline for most of the summer due to low river levels, while another reactor has had ​limited restarts and remained largely offline for most of July. https://www.reuters.com/business/energy/jellyfish-hit-french-nuclear-plant-shuts-down-three-reactors-2026-08-11/

This is by no means a new threat.

In August 2025, we thanked gavinochiltree for:

Four reactors at the EDF French nuke plant at Gravelines have been forced to close down on Sunday and Monday because of a swarm of jelly fish getting into the cooling system. If it had been Hinckley Point, what would be the back up, as we scots are frequently asked about wind. And jelly fish? There are millions around the UK–check out Ayr beach. Fish used to keep them in check by eating them when young, but there ain’t so many fish these days.

and to Dotty for alerting me to this:

A swarm of jellyfish has forced the shutdown of one of the largest nuclear power plants in France after entering the water intake systems used to cool the coastal reactors.

Three reactors at the Gravelines nuclear power plant in northern France shut down automatically late on Sunday, according to the French nuclear company EDF, after the filter drums of the pumping stations became packed with a “massive and unpredictable” swarm of the marine creatures.

The entire nuclear plant, capable of powering about 5m homes, was brought offline when a fourth reactor shut down shortly after the free-swimming invertebrates jammed the power plant, which had already lost its two other reactors for planned summer maintenance work.https://www.theguardian.com/world/2025/aug/11/swarm-of-jellyfish-shuts-nuclear-power-plant-in-france

How common is this problem?

In October 2021:

Scotland’s only working nuclear power plant at Torness shut down in an emergency procedure when jellyfish clogged the sea water-cooling intake pipes at the plant, according to the Scotland Herald this week. Without access to cool water, a nuclear power plant risks overheating. The intake pipes can also be damaged, which disrupts power generation. https://thebulletin.org/2021/10/jellyfish-attack-nuclear-power-plant-again

In February 2015:

Jellyfish and algae have assaulted nuclear power plants in the United States, Canada, Scotland, Sweden, Japan, and France. In Scotland alone, two reactors at the country’s Torness power station had to shut down in a single week when the seawater they used as a coolant was inundated with jellyfish. https://thebulletin.org/2015/02/spineless-attacks-on-nuclear-power-plants-could-increase/

From a report in 2019:

In 1937, they caused a power outage in Brisbane, Australia. And in 1999, they blacked out the Philippine island of Luzon. That plunged 40 million people into darkness, and raised fears of a military coup. Clean-up crews pulled 50 truckloads of jellyfish from the water intake line on a coal-fired power plant. https://www.scienceandthesea.org/program/jellyfish-blackouts

Also in 2019:

Shutdown of Oyster Creek Nuclear Power Plant [USA] Has Surprising Stinging Consequence — Tiny Jellyfish: https://www.nbcphiladelphia.com/news/national-international/oyster-creek-nuclear-power-plant-closing-tiny-stinging-jellyfish-thrive/1993643/

There seems no end to the Internet hits on this:

In 2008, a swarm of jellyfish shut down a nuclear power plant in California, and three years later the same occurred at a plant in Japan. In 2017, jellyfish clogged a power plant in Israel. https://www.vice.com/en/article/jellyfish-keep-attacking-nuclear-power-plants/

I’ll stop there. Will any Scottish reporter ask Scottish Labour how they plan to deal with this?