When was the first time an operating nuclear reactor flew on an airplane and what type of reactor and model of airplane were used in this flight?

Answer 1

The Air Force did a little bit of stuff with nuclear-powered aircraft in the 1950s. They built a couple of nuclear-powered J58 turbojets and ran them to nearly-full throttle, but never installed them in aircraft. They also mounted a reactor in a B-36 bomber, but never connected it to the engines. As far as I can tell they didn't put any fuel in the reactor - they just put the reactor vessel in the plane and went flying. In the end, the amount of shielding it would have taken to keep the crew from dying in mid-flight was impossible to put in a flyable aircraft.

In the early to mid 1960s they also talked about building nuclear-powered civil airliners. Back then EVERYTHING was going to be nuclear-powered - cars, trucks, ships, houses...

The Navy had a lot more luck with nuclear reactors. A ship can accommodate the shielding, so several classes of ship have had nuclear power. All our current carriers and subs are nuclear. The Navy also built nine nuclear-powered cruisers to accompany carriers, all of which were decommissioned at the end of the Cold War. There were some nuclear civil ships too - the US, Japan, Germany and the Soviet Union all built nuclear cargo ships, and the Russians built nine nuclear icebreakers. Of all these ships, three cargo ships have been decommissioned, the German-owned one has been converted to diesel power, and six of the nine icebreakers are still in service.