The propulsion itself is the easy part. It’s just hot air. The challenge is that the reactor core gets very hot and you need ceramic materials that can survive temperatures that would melt steel. One of the reasons we gave up on nuclear aircraft was keeping the engines from destroying themselves required materials…

When reading about the flying crowbar in the past, I was always a little shocked that the US deemed it, too cruel during the cold war. I’m thinking the might have been other, more financial, reasons to can the project.