Alot of people seem to have misconceptions about how exactly "Nuke option" could be done.
What you DON'T do is drop nuke right into oil/gas and detonate.
What you do is dig smaller hole (definitely not going down to where actual oil is), put nuke inside, and calculate payload so that it shifts ground nearby and breaks oil pipe (we're talking about moving kilotons of ground just a bit further then width of the pipe, not blowing a crater). Once that is done you should have leakage stopped completely, or at least reduced enough to stop it with other methods.Actual radiaton is buried many meters under ground by the same blast, so there shouldn' t be any contamination.
That's optimistic scenario, but still, it has almost no risks mentioned by others (blast NEVER touches actual oil and cannot make another hole).