You're going to have to be more specific as to what you call a failure... Closing the Fessenheim plant even though it was in perfect condition, safe, and very useful, just for base politician reasons... is this maybe what you mean?
If you count the MWh/€, the excellent safety records, it's hard to see the failure. Maybe the slow production of an EPR reactor, the giving up on efforts towards 4th-gen reactors?
They might be referring to the fact that France had to import electrical power from Germany last year (which was made with coal and natural gas), because the rivers they used to cool their reactors didn't carry enough water anymore due to a drought.
I am sorry you are not very well informed. The reason France had to import was an extreme abundance of caution: one corrosion case on a safety circuit, not even the main circuit, leading to complete stop and overhaul of all plants having the same design. There are plenty of chemical plants with less paranoia...
Ah, ok, if it that's simple.. only that one tiny bit, not half a dozen reactors showing fatigue and early cracks in primary containment vessels where we can just lower the margins on paper and be safe again.. :)
Basically everything you can find easily by googling.. so hat, their failed maintenance outages failed, their failed (or just too expensive) planning for their future capacities (too much in time and money) and the general concept not being fit for the future on many other aspects.