> For example, Australia has abundant land and great weather; they could probably get by with pure renewables.

Maybe we (Australians) can do 100% renewable. We will see. But even if we never do (and it's not entirely clear how it's possible), it's hard to see a place for nuclear here.

Since you say you follow this closely, you are probably aware one Australia state is at 70% renewables. That's 70% average, over a year. Unlike other places you hear about with a lot of renewables, South Australia has no hydro. Like the rest of Australia SA is pretty flat, so it has no pumped storage either. In fact there is nothing special about SA at all, other than it has no coal or gas, and is at least 500km from anywhere else of note so transmission lines cost a small fortune. It's not an ideal place for renewables, but beggars can't be choosers.

I'd love to say SA hitting 70% was a master stroke of forward planning. It was anything but. You will hear some politicians claim the did it for climate change. Maybe it was, but what they did happened to coincide with taking cheapest option on the table at the time, over and over again. Solar and wind are damned cheap when they are only contributing 10%. Getting to 70% is more expensive, but they already had the natural gas peakers so at each step the options on the table were to import more natural gas, or put up a wind turbine and use less gas. Each % reduction gets asymptomatically more expensive of course. Over provisioning helps, but typically solar drives the price negative during the day now. They claim they will get to 100% in 2027, but without storage I don't have a clue how that's possible without using the transmissions lines to states with coal generators and some creating accounting.

It's possible the current 70% made the grid a unstable. It's hard to know. They did loose power for days, but the proximate causes were some transmission lines were blown over in the worst storm in decades, inter-state interconnects were down for maintenance, and wind turbines tripping out because of the spikes created by the first two. I'd love to say that had been anticipated and they were the victim of delays in building storage, but storage was deemed to be a money losing proposition. Hell, I'd even like to say the engineers stood up and said "we can fix this with a battery", but that didn't happen either. What actually happen is there was a political shit storm over whether the outage was caused by renewables, and the SA government found itself under an enormous amount of pressure to announce a fix. Elon, the masterful dick waving salesman that he is, proclaimed he could fix the issue by installing the world's biggest battery in 100 days - or it was free. It made headlines around the country, and they took him up on it despite the fact that it cost a small fortune and everyone knew it would lose money.

This is how the decision making process has always been. A complete cluster created by special interest groups fighting over their preferred way. It seems everyone hopes to win the fight by yelling at each other, including engineers like yourself. In the end the pollies throw their hands in despair and choosing the easiest option at the time. Everyone, and I do mean everyone including the engineers was wrong about that battery. It made money from the day it was installed. Turns out when a coal fired generator trips out and removes megawatts from the system in a single 50Hz cycle, to the computer controlling that battery that 20 milliseconds looks like an eternity. It can react in microseconds and dump compensating power into the system long enough for a peaker to fire up. And charge a small fortune for doing it. Apparently no one foresaw this, and so no serious grid scale batteries were added. Now everyone has seen they make money new battery installations are springing up like weeds all around the country. Again I'd love to say they are doing it for the climate or for grid stability but no, they are doing it to get on the gravy train. The way we are going about this transition is nothing if not consistent.

Predicting what the end game looks like seems like fools errand to me. 100% renewable seems dubious. But they are at 70% now, so somewhere above 80% seems reasonable by 2030. Maybe they will start building pumped storage by 2050 - stranger things have happened. But using an SMR to fill that 20% gap - that's beyond strange. It's a shitty 20%. You are off most of the time. You have to go from 0 to full peak within an hour or so when the wind stops blowing and the sun ain't shining, and then from full peak back to 0 on a dime. Nuclear might be good at a lot of things, but the one thing it's absolutely hopeless at is load following. Japan having the worlds highest percentage of nuclear is also why Japan has the most pumped storage per unit generation.

The economics aside, nuclear would require a lot of forward thinking and commitment. Clearly when it comes to power generation that hasn't been Australia's strong suite. I don't see it but maybe there is some place in the world that is different. (Who could possibly have thought buying gas from Russia was a good idea?) China would be a good candidate I guess. China does have a 30 year plan for building nuclear. But with the price plummeting on renewables it looks like they've now abandoned it in all but name as they are adding more renewables each year than the nuclear plan called for over it's entire lifetime.