Nuclear was the best solution in the 70s. If we had built all the plants then, we wouldn't be in our current mess.

Today, the economics don't make any sense. Energy from a fission plant is much more expensive than from renewables+storage, and nuclear plants that are operating often have to be curtailed in summer (when energy need is high) due to a lack of cooling water. The timeline to build a new plant is decades - far too late to make a difference if we started now.

There would also have to be global trust for literally every country to be operating multiple nuclear reactors, which does not exist today and likely never will. The odds that the US simply allows most of Sub-Saharan Africa - currently ruled by a set of characters ranging from (in the State Department's view) dictators to Jihadists - operational control over advanced nuclear technology do not look very strong.