I think the problem is not lack of investment, but how nuclear power plants are built. Experience effects come from people doing a task over and over, learning to do it faster and modifying it so it can be done faster and better. But there's little opportunity for that in nuclear construction. Most workers will not work on many NPPs, and the designs are not easily changed.

It might be better if a string of smaller but identical NPPs were built with overlapping construction timelines, so groups of workers could specialize on one part of the construction of each and switch to the next in line to repeat the process. This would be a kind of assembly line without a factory. But this would require construction of many reactors, which means they'd have to be small. Renewables benefit from having huge opportunity for this kind of pipelining, because individual units are so small.