The World Nuclear Association provides this 2019 update on advanced (Gen IV) nuclear technologies. These technologies began development in the 1970s. Their progress has been incredibly slow for political reasons. The engineers and scientists have done wonders, even using just sliderules - no computers. With the lack of backing in Europe and the United States it may take longer for broad implementation of Gen IV nuclear power than to build a European Cathedral in the Middle Ages without the power from fossil fuels. The lack of government backing must be solved first before any real progress will happen.