"Almost every plan for limiting carbon dioxide output includes keeping old nuclear plants running. But as those plants age, they turn up new problems.
The latest is at a plant owned by Progress Energy in Crystal River, Fla., where a gap was found inside the thick concrete of a containment dome.
The plant had been temporarily shut in late September so workers could replace the aging steam generators — which required them to cut a hole in the dome. (The steam generators at many aging nuclear reactors were intended to last the life of the plant, so no way for swapping them out was designed.)"