Nuclear Aircraft Engine

Designing an aircraft engine which has a nuclear core inside may not seem feasible. However, with careful calculations solutions can be found. In this article I will only focus on the design of the engine. Some of the safety measures related with the engine will be discussed on my next article.

The summary of the idea is to use the heat generated by the nuclear core to drive a fan to suck and heat air to accelerate it to generate thrust. The engine would be started on air with a certain amount of initial ground speed. The nuclear core would be started by natural neutron emitting isotopes. Once the chain reaction starts, the engine would be released together with the plane it is attached to. Initially, this engine would be used on a high endurance surveillance plane. Such autonomous plane would stay aloft for months without refueling. They would only be deployed over the oceans for extra safety.

The engine would work as follows. The nuclear core would only have a single fuel pallet and no control rod or moderator. This simplifies the design and reduces the weight. The nuclear pallet would be surrounded by good heat conducting material such as aluminum alloy. There is no need for a control rod while there would be only a single fuel pallet. The fuel pallet would not be sealed inside a Zirconium casing but housed on a big aluminum casing. This casing also negates the need for the moderator. Part of this casing will have spiraling pipes with a cooling gas inside. This gas would be used to drive a gas turbine which drives the fan of the engine. The gas turbine and the fan would also be made of aluminum alloy for good heat conductivity. This setup would cool the gas inside the spiraling pipe in expense of the reduced efficiency of the gas turbine. The rest of the nuclear core would be surrounded by heat radiating fins. The air sucked by the fan would be heated by the rest of the core which generates the thrust of the engine. In summary, the core would be air cooled. Thermodynamic calculations of the design can be made and minimum air speed and ambient temperature to keep the core temperature under control can be found. The critical part of the design is the closed loop gas turbine. Therefore, it would be made of two independent systems to ensure failsafe operation.

Once started, this engine should keep working to prevent a core melt down. If designed properly, a self-stabilized system can be formed. If the core gets hotter, the fan would spin faster and more air would be sucked. The aft section of the engine would heat the air more to generate more thrust. The higher air speed increases the air-cooling effect on the core. The autonomous plane would adjust its route and altitude to maintain certain air speed and ambient air temperature.