Transformers are quite capable of working in either direction.

Your statement about transformers makes little sense within a context of power grids. You start by pushing power into 230 V system, which has a maximum tolerance of around 250V, after that you can damage electrical equipment connected to those line. That alone will limit how much power you can push out into the grid. An then through how many transformers and miles of wires will the electricity you produce go before it reaches high voltage lines, which are needed to transfer power over distances?

On the other hand the nuclear power station turbine generates power with a voltage of 20 KV feeding it to a high voltage transformer, which steps up the voltage to 200KV and is connected directly to the transmission lines.

If I have a, for example, 2kV-to-240V transformer, and I put 240V on the 240V side, how many volts do I get on the 2kV side?

Is there a point to your rhetorical question or do you have troubles understanding the difference between an ideal component vs a real component in a live system?