Reactor's waste heat dissipation in space

[aquitaine]

So, hypothetically if we had a spaceship of some kind using a nuclear fission reactor for power, in order to dump the waste heat into space, how big of a radiator would be needed? How much heat, in watts, can be dumped per square meter of radiator in a vacuum?

 

[Astronuc]

So, hypothetically if we had a spaceship of some kind using a nuclear fission reactor for power, in order to dump the waste heat into space, how big of a radiator would be needed? How much heat, in watts, can be dumped per square meter of radiator in a vacuum?

The size of the radiator depends on the temperature and emissivity of the material.

Eventually all of the heat is radiated to space, which when far enough from a star is at about 4 K. The trade off is between radiator effectiveness (temperature) and thermodynamic efficiency of whatever power conversion system one develops.

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html