Your straw man is still too strong for you to push over. Only a small fraction of the arc furnace's power needs to be provided as electricity. A large fraction

Your straw man is still too strong for you to push over. Only a small fraction of the arc furnace's power needs to be provided as electricity. A large fraction of it is a reducing agent like carbon or hydrogen which -- shockingly enough -- can be stored as carbon or hydrogen. Your imagined 30% increase due to idle capital is on top of a 50-80% reduction due to lower energy cost. In industries where energy is the dominant cost, then minor shifts in production methods to do high labour tasks during low energy periods and vice versa will happen regardless of whether nuclear energy is available, because building solar to reduce costs and ignoring the nuclear reactor will still be a cheaper option than buying all of your energy from it. Alternatively the plant does buy the nuclear energy, but only when the sun is not shining because building their own array to use in DC mode costs $10/MWh and the VOM costs of nuclear are $15/MWh. The only out is mandatory payment to a utility or funding it entirely with public money to everyone's detriment.