The nuclear power stations that have been built before are the ones that shouldn't be considered. Using the criteria that only installed designs should be considered means that there will be no advancements in nuclear plant designs. I'd like to see a modern LFTR plant put into operation. There has never been a commercial one of those built and the last test model that was run didn't have a turbine attached so it just made heat and naught else.
For nuclear power to be viable, there has to be improvements made to the designs with preference for ones that can "burn down" existing nuclear waste that has been generate thus far with the old designs.