Say you were to use a pebble bed reactor (Modern aircraft, modern reactor). The reactor is designed in such a way that in case of coolant failure/containment f

Say you were to use a pebble bed reactor (Modern aircraft, modern reactor). The reactor is designed in such a way that in case of coolant failure/containment failure/etc. the pebbles equilibrate at a stable containable temperature, and as such even if you could obliterate the reactor itself, the pebbles wouldn't melt down and as such wouldn't contaminate the environment with radioactive waste. Similarly as the coolant is helium, it is less radioactive in normal use and as such the coolant leak wouldn't be a critical disaster. The pebbles themselves are coated in silicon carbide and as such are probably hard enough that you could use them as impactors against softer targets like, say, tanks. Due to this hardness it is thus unlikely that you would damage a large number of pebbles and hence release a large amount of core material. Disclaimer: I'm not a nuclear scientist, I just think it's freaking cool.