It's called a lifetime extension. When you build something expensive, you make a conservative estimation for how long it will be operational at minimum, so you can write off your investment in a responsible fashion. Then, at the end of that period, you see if your plant can keep working in a safe and profitable manner, and if it can (gasp) you let it. Of course the "greens" (scare-quotes, since, after all, we're both adults) are against this kind of, hmm, we could call it "re-cycling".