I'm dubious about the assertion that nuclear energy research has been held back decades , or at all for that matter. Really, the issue with nuclear still seems to be affordability both Vogtle and Sumner seem awfully pricey and continue to have issue with being built in a timely manner--adding even more to the cost. Really, wind, solar and CC NG plants seem the way to go right now in the US (along with efficiency). Maybe there will be a breakthrough in Nuclear, maybe there will one in battery storage, but right now those should be the big three.
By the late early 80s, many new plants had been cancelled and that industry sort of went stagnant until I believe 2012 or 2013 when a few new ones were approved. Past that, where was the government funding for new research and incentives for the private sector? Where were all the new plants? Where was/is all the new testing and new R&D? If you're saying R&D never stopped, then where are the fruits of that research? I need examples because I'm talking about large-scale operations that would be present were nuclear energy a vibrant, growing industry, as it would have had govt properly supported it and public opinion not been so stupidly ignorant on it.
If there is no demand and no incentives or funding, then the private sector's interest in nuclear energy goes down. The US Govt was researching MSRs like 40 years ago until they scrapped it, and only recently has it gotten interest and actual development in China. That design is one of the safest but most technologically complicated at the moment, and if we had put half as much effort into it as we have solar, then 40 years of that and we'd probably have at least rudimentary but operational versions those plants today.
I actually do think Solar and other clean energy sources are more viable now, but I still think irrational and ignorant public opinion pushed away a very promising candidate for clean energy that we could have maximized use of years ago.