The nuclear power plant has four large tunnels that collect cooling water from the sea. At the end of August, it is time for those who go to reactor 4 to be emptied of water. Every inch of both walls and ceilings is then covered with mussels. According to the nuclear power plant's press manager, Anna Collin, they are thriving there because the climate is optimal.

Limits inflow

- It is high water flow with large amounts of food that swirls past, it is dark and comfortable temperature if you are mussel. In addition, it is well protected from predators and other external factors, she says.

The lower part of the concrete wall is cleaned with water cannon. Photo: Ringhals

But there is a downside. The mussels reproduce rapidly and when they become too many, they limit the inflow of cooling water to the reactor - a problem that must be addressed.

It takes two days to empty the tunnel on water. Thereafter, the decontamination itself begins. With the help of high-pressure washers, or rather water cannons, the mussels are sprayed from the walls.

Smaller amount this year

- It's actually the same water cannons that merchant ships use against attacking pirates, says Anna Collin.

They are then shuffled away with bulldozers and tractors before being eventually sealed away with tankers.

"In the tunnel, the old unknown seafood smells," says Ringhals press manager Anna Collin. Photo: Ringhals

- Every year, between 800 and 1000 cubic mussels are cleared. To put it into perspective, a bathtub can hold about half a cubic meter, says Anna Collin.

Just this year, the number of mussels has been slightly smaller - between 500 and 600 cubic meters. Everything that is decontaminated is put on compost along with seagrass, jellyfish and the like, which have been sold away in the nuclear power plant's wastewater treatment plant.

Cannot be eaten

- We have been asked if you can eat them instead. But the answer is no. When the tunnel is emptied of water, the mussels start to rot. And we do not engage in food business, says Anna Collin.

Sea tulips also get stuck on the walls. Photo: Ringhals

The cleansing of marine organisms in the tunnels is just one of 3600 work done during the 34-day shutdown of Ringhals 4. The plant will restart on October 1.

P4 Halland was the first to report on mussel remediation.