QUESTION: What is the efficiency of a nuclear power plant?
ANSWER : the efficiency of a nuclear power plant is of the order of 30%.
EXPLANATION: This means that 70% of the "atomic" energy produced by the fission of uranium 235 is "wasted" as heat in the cooling towers.
For a 2 GW electric power plant with 1,3 reactors, this corresponds to a thermal loss of the order of 6 GW and an atomic power of 8,6 GW.
These 6 GW are "evacuated" in the cooling towers of French power plants, there is one tower per reactor (you can therefore easily know the number of reactors in a plant by counting the number of towers).
The heating needs of a modern house are roughly (smoothed over the year) 60 W per m2. Or for a house of 100 m2, 6 kW.
The thermal energy "lost" from a single 2-reactor power station therefore corresponds to the heating of a million houses!
Assuming (which is not the case but it is for the image) that this energy was recoverable in the form of cogeneration, 14 16 to nuclear reactors would be enough to heat the whole of France without any consumption of heating or electrical or fuel oil or gas!