[Suicide Junkie]

I was really saddened that Battletech got all the glory over Renegade L. I thought the RL universe to be far more compelling and realistic than a nuclear reactor in a battlemech that didnt vape a city when the mech went boom boom.

Nuclear reactors just don't go up like that unless you're REALLY trying.
Think about it, why would you want to carry around a critical mass of uranium if its not intended to be a bomb? Rather, you just need a small very sub-critical pile, which will power you for years.

Nuclear submarines don't make mushroom clouds when they get torpedoed. They just leak, sink, and spread a little radioactive material at worst.