Why Not Nuclear-Powered Aircraft?

Russians and the Americans tried after world war 2 but due to limitations of technology they failed. There were 2 approaches tried 1) Direct drive approach where weight was comparatively less but the radioactive gases were thrown as exhaust hence was deemed unsafe. 2) Indirect drive (lockheed martin worked on this) which drove the steam turbine which ran the rotors but thrust to weight ratio was so less that it was shelved.

Meanwhile there was an internal competition between U.S. airforce and navy for getting a nuclear fueled vehicle that would have unlimited range. This competition ended when Navy got their 1st Nuclear powered submarine.

Also nuclear powered aircraft if crashed in enemy territory or in any other place will attract serious consequences.

Hence NO Nuclear-Powered Aircraft!

I live near the site (AFP 67) where they were developing the nuclear powered aircraft. The site currently is a fenced-off area in the middle of a National Forest. There are still radiation detectors mounted here and there around the area monitoring for who-knows-what since I don't think there are any materials left there, and haven't been for decades. They filled the entrance to the mostly-underground complex with concrete, there's not much to see above ground (and not sure there ever was much in the first place).