You can, but it results in non-linear increases in fuel consumption. A nuclear reactor can be run at a high power output continuously without substantial reduct

You can, but it results in non-linear increases in fuel consumption. A nuclear reactor can be run at a high power output continuously without substantial reductions in efficiency. It also allows for infinite range and reduces cost and turnaround time caused by refuelling. Using Ammonia would have none of these benefits, require expensive infrastructure, and involve enormous energy losses.