Not op, but he is probably referring to the costs of building a nuclear power plant in the US which requires a lot of safety systems, concrete, approval process

Not op, but he is probably referring to the costs of building a nuclear power plant in the US which requires a lot of safety systems, concrete, approval process, etc.... the key is that a coal or gas fired power plant would have the same costs of the steam turbine system but the reactor part of the power plant is vastly more complex in terms of controls and safety compared to a gas or coal fired plant. Long story short, because of the reduced complexity in powerplants using fossil fuels, they are inherently cheaper per kilowatt. And therefore the more complex nuclear power plant costs more to setup and takes longer... Thus increasing the overhead and therefore rate at which one must charge for the power to be economical