The way the EU forces the electricity market to operate makes them completely unprofitable. Renewables are always given priority in the market, which results in other power plants operating at a capacity factor of 30-40%. Since nuclear power plants are mostly capital expenditure-intensive, this makes the electricity they produce absurdly expensive.

Because the way how the EU electricity market operates first to supply electric power are the power plants with the lowest operating costs. This are usually renewables and nuclear power plants. Both are capital expensive and cheap in operating costs.

Usually the capacity factor of European nuclear reactors is higher than 60%.

olkiluoto-3 nuclear reactor, had capacity factor 70% in the year 2024: https://world-nuclear.org/nuclear-reactor-database/details/o...

Mochovce-3 had capacity factor 74% in the year 2024: https://world-nuclear.org/nuclear-reactor-database/details/M...

In the U.S. they really try to get maximum from nuclear reactors. https://world-nuclear.org/nuclear-reactor-database/details/W...

That’s just a consequence of how they bid. The marginal cost for a renewable plant is zero. It’s non-zero for nuclear power.

But nuclear power don’t want to shut down since that both increases wear and tear and makes them unable to capture revenue when the prices become higher again.

So they bid negative expecting to eat the losses and let more flexible plant shut down first.