Back in the 1950's the Air Force wanting too build an Atomic powered bomber. The plan was to build a small nuclear reactor to power two jet engines. This small reactor is setting on two railroad flat cars that are side by side. You can see the two 1950's size jet engines on the left end of the reactor.
Some where I have a picture of a small lead covered diesel engine used to move this reactor around on railroad tracks. The problem with the bomber was all the lead needed to protect the crew and weight and size of the reactor. In the 1950's normal jet engine only had the power to lift a plane built out of aluminum, much less lead.
