Submarines are encircled by water, that is very good at absorbing heat. Nuclear power stations are also invariably close to a large source of water. There is n

Submarines are encircled by water, that is very good at absorbing heat. Nuclear power stations are also invariably close to a large source of water. There is no such thing on Mars, and that significantly increases the mass and size of your radiators, making it uncompetitive with solar for example, unless the waste heat is needed for something else.