Even the old PWRs can be operationally unproblematic if you do it right. The German Pre-Konvoi and Konvoi fleet had pretty good stats. I'm not sure if Grohnde (shut down in 2021) is still the NPP block with the highest total production (500 TWhr) or if another block managed to lap it. Overall capacity factor of these was around 90 %. The US fleet is similar iirc.
The French fleet has been running around 65-70 % CF for years, pretty bad, but clearly not root caused by the tech branch.
Modern reactor designs are so much better. They are also basically nonexistent because everyone stopped building reactors :(