I think you all have been trolled. Because SF6 is not exclusive to nuclear power generation. It is used in the transformer/switching station behind the turbines. To avoid arc lightning there. Which almost all other power generation is also using in the same way, like in almost all larger switching/substations also. It's the thing to use if you don't want to have arc lightning.

So...in addition to all the CO2 some fossil fueled power plant emits, you have that, and the SF 6. Because behind the turbines they have the same halls with transformers and switching equipment.