As it is presently implemented, nuclear energy isn’t sustainable unless it continues to supply only a small fraction of mankind’s total power demand. The reason for this is that if we tried to generate humanity’s total anticipated power demand circa 2100 A.D., about 22 terrawatts (11.2 billion people consuming as much “energy services” as modern Europeans do now), with today’s burner/converter civilian power reactors, we’d burn 100 percent of the world’s “affordable” uranium within about five years.
People championing such a burner/converter reactor-implemented nuclear renaissance do so based upon economic models and wishful thinking rather than geological or technical data. In that respect, they are much like the pied piper of the USA’s Green New Deal movement, Stanford University’s professor Mark Z. Jacobson.
The reason why we haven’t developed a sustainable and renewable nuclear fuel cycle is that "small” and “modular" are about the only “advanced” reactor characteristics that U.S. DOE Office of Nuclear Energy’s leaders have consistently emphasized and supported for the last 15 years or so. That's why we've ended up with inefficient mini-LWRs (NUSCALEs) instead of something able to “save the world.” Hopefully, those leaders will adopt a different paradigm that encourages their worker bees to develop a system that could implement a nuclear-powered “green new deal” for everyone.