Since there are economic, ecological, conceptual and engineering problems, only five Fast-neutron reactors are operational at the moment. Three in Russia, one in India and one in China. Not surprisingly these are countries that also have an interest in producing weapons grade Plutonium, which FNRs are capable of.
https://journals.sagepub.com/doi/10.2968/066003007
https://spectrum.ieee.org/china-breeder-reactor
https://scienceandglobalsecurity.org/archive/sgs15glaser.pdf
https://energypost.eu/slow-death-fast-reactors/
https://sussex.figshare.com/articles/report/

And while nuclear energy production peaked 1996 at 17% and was nowhere near overtaking fossil energy production in it’s 70(!) year long existence, Renewables will overtake fossil fuel power production in 2025, with only minute risks for the biosphere.
https://www.scientificamerican.com/article/renewable-power-set-to-surpass-coal-globally-by-2025/
https://www.renewable-ei.org/pdfdownload/activities/REI_NuclearReport_201902_EN.pdf

So why cling to an outdated technology when there are viable solutions at hand, which are nowhere as complicated and dangerous as nuclear fission? It’s the monetary interest of a dying nuclear industry and its lobbyists.