Mostly fine? https://www.dw.com/en/reports-fessenheim-nuclear-accident-pl... "The reactor had to be shut down by adding boron to the pressure vessel, an unprecedented procedure in Western Europe, according to an expert." By that standard Fukushima ran mostly fine too

I have no idea whether it's even possible to find out how the different reasons have factored into the decision; it might as well just have been due to the age or seismic activity and nothing else...

But, in reality, it was probably a mix of all 3 and some more.

It's more like a mix of solar and wind energy investors with fossil burning energy investors, both benefit from shutting down nuclear reactors. Solar and wind investors just want to have their huge returns with nothing wasted, as each kWh is pretty expensive, but lacking nuclear power most of the energy generation will still go to burning fossils, who will profit massively from it. Happened in other countries too, like Ukraine, which was recently forced to temporary stop some reactors to benefit those two groups and of course make things worse for the climate.

The fundamental reason is electoral calculus. The socialists, and then macronists, needed green votes to get a majority. The safety assessment is perfectly fine.

Germany would be the main country affected, if there were a major "mishap" at Fessenheim. Basically the whole south of Germany would be impacted with large cities like Stuttgart, Augsburg and of course München.

People tend to forget that despite the Chernobyl disaster happening in Ukraine, Bavaria advised their citizens to not eat any mushrooms collected in the woods because wind blew radioactive particles across Europe.