Solid core

Introduction

A solid core nuclear reactor is a reactor where the material that supports the fission reaction is in a solid state. This is the kind of reactor that is currently used on earth for power production. For space travel the improvement over conventional chemical rockets is minimal because the exhaust velocity of a thermal rocket is a function of temperature and there is a limit in the temperatures for which materials can remain in a solid state. The maximum possible temperature for a sold core reactor is around 5000 Kelvin.

Performance

Because of the limits in temperature possible for a solid core nuclear thermal rocket, these rockets are only about twice as efficient as chemical rockets in terms of mass fraction. Another factor that limits the performance of nuclear powered rockets is: the weight of the reactor, the cooling system (pumps, pipes radiators) and the crew shielding.

Safety

Before the reactor is shut off it presents a minimal environmental concern to earth and the nuclear material will be incased in a ceramic material to limit contamination to the crash site. However, once the reactor is turned on (hot reactor), it is considerably more toxic and for this reason the environmental protection agency chose an orbit which all nuclear vehicles must reach before turning on the reactor.

Because a hot reactor is considered a considerable pollution risk returning a solid core reactor to earth may not be a justifiable risk. A nuclear save return trajectory could be devised by aiming for the dark side of the moon instead of earth on the return flight. However, the performance gains of a solid core reactor is not sufficient enough to justify this detour.

Designs

See: Triton, Turbo Winds