Ok... What are you even talking about? Most fusion solutions use the same second stage for power generation as many other power generation solutions. Heating water to spin a turbine. That is the same thing as all coal, natural gas, petroleum, and solar thermal. In a roundabout way you could even say hydro is just generating power from heated water if you abstract it to include the rain cycle that moved the water behind the dam. There is literally 0 "weakening" that is needed to generate power from fusion under the current predominant paradigms that are being researched. Tokomaks and inertial fusion both generate fusion and bleed the excess heat off to boil water. The only method with promise that does not use this method compresses colliding superheated plasma vortex rings in a strong magnetic field to induce fusion causing the plasma's magnetic field to ramp up and push back against the containment field. The flux is captured directly into an electrical current that is shunted into a capacitor bank so it can be slowly discharged into the grid. This last method is the only one that has the potential to overload the grid if some sort of runaway event happens, though I don't see how it would happen as every stage of it is reasonably confined by well-known physics.