Another bad effect would be a subtler version of the squib explosion. Take a
drop of water/salt. The heat of the decay, even if not going critical,
evaporates the water. So now you have very small crystals of radioactive salt
floating through the air. The decay products can provide enough momentum to
carry them all over the ship. And once ingested, they cause severe radiation
poisoning.
So if the fuel lines run near inhabited parts of the ship, we need both very good radiation detectors and air filtration systems. Maybe rad film strips surrounding every air circulation intake and outlet?
Just wondering: Are we sure dried out radioactive salt crystals would be small enough to float in the air? I mean, they are a lot denser than regular table salt, aren't they?