Let's just use RTGs instead! A gram of Polonium-210 produces 140W of heat. It's also an almost entirely alpha emitter, which means that little shielding is requ

Let's just use RTGs instead! A gram of Polonium-210 produces 140W of heat. It's also an almost entirely alpha emitter, which means that little shielding is required. At about a 10% efficiency of an RTG you could effectively get 14W out of a single gram of it. A 737-300 seems to require about 7-10 MW of energy at level flight. Put 1 ton of Pu-238 onto a 737-300 and you can run the aircraft (probably) for 6-7 months without refueling. Okay, you probably need a smaller aircraft, because takeoff takes more energy, but still! While Polonium-210 is incredibly toxic, it does have a half-life of 138 days. If you do have a crash then in <8 years you'd only have about a gram of it left. The main tricky part is that we produce about 100 grams of it a year. But what's a little scaling up for a startup anyway? (I'm sure I made a calculation error here somewhere.)