A reactor powered thermal airship is a fascinating idea! I'm skeptical that it could work though. Some quick web searching suggests that 3 MW burners for hot

A reactor powered thermal airship is a fascinating idea! I'm skeptical that it could work though. Some quick web searching suggests that 3 MW burners for hot air balloons is fairly typical. I'm not sure how light and powerful a reactor could be made, but wikipedia says the Convair NB-36H had a 1 MW air-cooled reactor weighing 16,000kg. That reactor definitely wouldn't work then, too heavy by far and not enough power output. But that was a prototype reactor in the 50s. Also, shielding seems like a big concern even if the reactor can be built light. To stop neutron radiation you need light nuclei like hydrogen, making water or concrete (containing water) popular choices. These are heavy and bulky though, not conducive to airships.