Well, they do tend to be designed to be resistant to that kind of thing - and some sorta fancy bunker buster would probably disperse the fissile material anyway. Certainly a big ol' not good, but criticality depends on having enough mass in close proximity, so it's similar to how you can blow up a nuclear missile with an interceptor safely-ish.

Setting an oil facility ablaze is going to be much easier and have worse health effects in the vicinity.