The problem is that none of these designs have ever been used to power the grid. Every nuclear project in the recent past has blown by cost and time estimates. Wind and solar are not only cheaper than nukes, they can also be installed much quicker and predictably. Nukes have a place, but we need clean energy now.
Wind and solar are great, but they cannot provide consistent 24 hours base load production. Even with massive battery farms, they cannot replace bas load consistently.
That’s where nuclear needs to be, replacing the base load production currently being handled via coal and natural gas.
The US at least already has enough nuclear to handle base loads when solar and wind are unavailable. Nukes in some contexts are needed, but I believe we have 30% or so nukes in the US. Diverting resources to new nukes is a waste when we could be making carbon fuels unprofitable soon by investing in solar and wind.
But are they in the right places? There’s always loss in power transmission, so you can’t use reactors that are in, say, Illinois, to make up for grid deficits in Alabama (or, not directly). And Texas, being a special snowflake, isn’t tied into the national grid, so they always need their own systems.