>build 4 nuclear plants for each one we currently have to achieve a 100% decarbonized grid

Uhh, mining and uranium enrichment and transportation all require fossil fuels, and more fossil fuel energy than a fueled nuclear produces in electrical energy. Increasing 4x nuclear plants would increase fossil fuel consumption in the nuclear supply chain.

Nuclear isn't some secret technology you've just discovered thats being suppressed by environmentalists. It literally ended the biggest war ever and was pursued for decades afterwards. Unless you know a secret, if its feasible it would have been done.