Nuclear is massive-grid-scale base load only in a world that does not need more base load nor massive grid-scale generation. Everything about nuclear is slow, difficult, expensive, dangerous. They are increasingly not handling climate change well. They are decade-scale projects that take a long, long time to become carbon neutral; we cannot wait that long.

* Solar and wind are here to stay and they mean we need fast-reacting spare capacity and storage. Nuclear power plants are very slow to react and because they are so monumentally expensive they have to run at as high capacity as possible, as much as possible. They are strictly base load.

* Siting a nuclear power plant is very difficult just in terms of geology. Siting a nuclear power plant is very difficult grid-wise as well, because they are only cost-effective at massive scale. Super-high-voltage DC transmission systems can help, but they only tack on more to the project cost. You can't just inject gigawatts of power anywhere you want. And it isn't just injection that is the problem. Nuclear power plants that are not producing power need massive amounts of electricity to get things like cooling pumps running or keep them running until everything is up to temperature and you can get the turbines up to temperature and speed. Then there's the matter of needing sufficient cooling - usually done via river, ocean, or lake. Except climate change and other factors are making those sources of cooling increasingly unreliable (for example: invasive species like zebra mussels have made life hell for a lot of power plants)

* Nuclear power plants require lots of highly trained people to design, operate, and maintain. More power plants means more of them. Training them up isn't a short term affair. Solar and wind require far less of all of this. And frankly, I have serious doubts about societal stability in 20-30 years, and nuclear power plants are not even remotely friendly to any sort of societal instability. Not just in terms of security, but upkeep. They have very complex, deep supply chain needs.

* Building nuclear power plants from the start of planning to grid synchronization takes a decade or two, and it then takes another decade or so for the plant to become carbon-neutral in part due to the massive amount of concrete they require. Right now, we need to be reducing carbon footprint as much as possible, as fast as possible. Not causing huge increases in carbon footprint that will only balance out well past catastrophic climate conditions.

* Nuclear reactor containment vessels can only be constructed by a small handful of facilities and their capacity is very limited, and by and large already spoken for. We can't just wave a wand and start building more reactors tomorrow. Or even in the next several years.

* Nuclear waste may be a "solved" problem tech-wise as nuclear power proponents are fond of saying, but reality is that nuclear waste is a huge problem. Even short-term storage is a problem, as demonstrated, again, by Fukashima where fuel cooling ponds caught on fire.

Time and time again we demonstrate that we are not responsible enough to handle nuclear power; we've had numerous military nuclear power disasters; the commercial ones haven't stopped, either. A "1st world" country, arguably one of the most technologically advanced ones around, repeatedly bumbled every aspect of Fukashima, starting with the plant's design, its maintenance and procedures, and the response to the incident. What was Japan's excuse?

How many Mulligans does nuclear power need?

You know what happens when a solar or wind power plant is incompetently designed or run? A bunch of people lose lots of money. You don't end up with thousands of square miles of land uninhabitable. You don't need people with years of training supervising a bunch of solar panels. Maintenance on a wind turbine is a standard-industrial-equipment sort of job, no bunny suits required.

You know what happens when a country with solar or wind power has a government that is full of incompetent suit-stuffing chair-warming morons, or gets taken over by a despot dictator, or has an economic collapse? Nothing.

If you want to look to the future in power grids, look at the iron chemistry liquid batteries that are non-toxic and almost trivial to deploy at electrical substations. They can provide spare capacity at the neighborhood/regional level while helping balance distribution loads and allow those neighborhoods to continue to function in isolation in the event of transmission grid problems.