Uptime is calculated by kWh, I.E How many kilowatts of power you can produce for how many hours.

So it's flexible. If you have 4kw of battery, you can produce 1kw for 4hrs, or 2kw for 2hrs, 4kw for 1hr, etc.

Nuclear is steady state. If the reactor can generate 1gw, it can only generate 1gw, but for 24hrs.

So to match a 1gw nuclear plant, you need around 12gw of of storage, and 13gw 2gw of production.

This has come up before. See this comment where I break down the most recent utility scale nuclear and solar deployments in the US. The comentor above is right, and that doesn't take into account huge strides in solar and battery tech we are currently making.

The 2 most recent reactors built in the US, the Vogtle reactors 3 and 4 in Georgia, took 14 years at 34 billion dollars. They produce 2.4GW of power together.

For comparison, a 1 GW solar/battery plant opened in nevada this year. It took 2 years from funding to finished construction, and cost 2 billion dollars.

So each 1.2GW reactor works out to be 17bil. Time to build still looks like 14 years, as both were started on the same time frame, and only one is fully online now, but we will give it a pass. You could argue it took 18 years, as that's when the first proposals for the plants were formally submitted, but I only took into account financing/build time, so let's sick with 14.

For 17bil in nuclear, you get 1.2GW production and 1.2GW "storage" for 24hrs.

So for 17bil in solar/battery, you get 4.8GW production, and 2.85gw storage for 4hrs. Having that huge storage in batteries is more flexible than nuclear, so you can provide that 2.85gw for 4 hr, or 1.425 for 8hrs, or 712MW for 16hrs. If we are kind to solar and say the sun is down for 12hrs out of every 24, that means the storage lines up with nuclear.

The solar also goes up much, much faster. I don't think a 7.5x larger solar array will take 7.5x longer to build, as it's mostly parallel action. I would expect maybe 6 years instead of 2.

So, worst case, instead of nuclear, for the same cost you can build solar+ battery farms that produces 4x the power, have the same steady baseline power as nuclear, that will take 1/2 as long to build.