It is for 300MW.
One could bring in modules and link them together. But then they tried that on the AP1000 to famously disastrous effect, at least at first.
But, the $5 billion here isn't purely an investment in 300 MW of capacity, it's an investment in starting up the nuclear reactor factory that can start churning these things out at $1-2 billion or whatever their goal may be
Also, have to take into consideration the overall operating costs. Nuclear costs significantly more up front but over time costs much less to operate (and is much more predictable) because you don't have to buy and burn natural gas forever
The only cheap nuclear watts come from facilities built a long time ago in a completely different cost environment, and had construction and insurance subsidized by the state.
A standardized reactor design that doesn't need a bespoke training control room at every single site means fewer training staff. It means the same maintenance workers and compliance workers and everyone else can be utilized more because they can cover more facilities instead of just the single site they are certified on and work at
The underlying mechanic here is that cost projections are being used to sell a technology. As such, there is very strong incentive to underestimate the costs. This applies to FOAK plants and to projected experience rates.
This is an historical artifact. When that generating capacity was built, nuclear was the alternative to fossil fuels. It isn't today; renewables are now cheaper and faster to install.
Your argument can be seen as a way to ignore the cost decline of renewables without at first glance doing so.
(As you say, there are hydro-dominated grids with no nuclear, for example Costa Rica, which gets 98% of its electrical energy from renewables.)
Comparing to renewables is a different story - it can be done but it's much more complex (not dispatchable, seasonally variable) but certainly renewables makes sense in some or many places, (and in all places for a portion of the supply). I'm all in favour as long as it is actually done with the intent of getting to zero CO2, and doesn't just stall when it gets to the more difficult part of the transition. So many places get to 50% annual generation as renewable and throw up their hands about the remainder and leave it on coal/oil/natural gas
It's comparing nuclear to alternatives, one of which is natural gas. Others are renewables. One cannot make or justify a decision on nuclear without considering all the alternatives.
Yes it is. So far, we've flushed enough money down the Iran war toilet to pay for ten of these, and there's no end in sight.
The rat, having been caught by the rat catcher, complains there are other, bigger rats. But he's still a rat.
The uneconomical project, having been called out, complains there are other, even more expensive activities. But that doesn't change that the project is too expensive.