How long does it take to recover from nuclear accident?

Obviously depends on the severity of the accident. In the case of Three Mile Island (1979) there was no reason not to go on running the other unit on site, though the damaged one will never be restarted. In the case of Chernobyl (1986) the damage was so great that the whole site was shutdown, four reactors, and surrounding areas evacuated. This is a permanent result as far as I know.