TL;DR
Detach Steam Turbine from nuclear production into separate research that is a prerequisite.What?
What I suggest is to allow players to build steam turbines earlier in the game by making them a separate research option with lesser requirements than for nuclear production research they reside in now.Why?
Steam turbine, while being used mainly in nuclear setups, also have a lot of uses in ordinary powerplants as well. It has double the power for aprox. triple the cost and also allows for higher steam temperature, similar to how Assembling Machine 2 costs double for additional 50% crafting speed and allows for fluid handling.Allowing access for steam turbines earlier will give players the option to make their powerplants more powerful on the same footprint (or make them more compact while retaining their power production), and also make transition into nuclear energy feel smoother.