Nuclear powered airplanes sound like fun. The US had quite a big programme going - mostly because the Air Force didn't fancy the Navy being the only ones with reactors, but also because of reports that the Soviets were developing something similar. There were two basic designs of engine evaluated, one that just pushed air through the reactor core and one that had a liquid metal heat interchanger. The first was simple, light and spewed enormous amounts of contamination: the second was complex and too heavy to lift itself (and that's before the shielding necessary to stop the crew from glowing). There was even a specialist squad of Marines created to clean up after a crash: I think they called themselves the "Glow In The Dark Boys", but
to me that's just one more reason why joining the Marine Corps would be a bad mistake.
In the end, the Americans found that the Soviets weren't developing anything of the sort and admitted that the darn thing would never fly.
Only the Soviets were - and flew it. They solved the problem of having vast amounts of shielding for the pilots by just not bothering, which saw most of them off in short order.
There's talk of nuclear powered UAVs now, but I can't see the benefits being worth the downside.
R