They're in the US: https://www.energy.gov/em/moab-uranium-mill-tailings-remedia...
https://en.wikipedia.org/wiki/List_of_countries_by_uranium_p...
Moreover the more we obtain uranium (prospecting, mining, milling...), the more we add to the associated carbon footprint. Therefore a sustained growth of installed nuclear capacity will lead us to exploit mines at always lowering ore grades => more emissions.
Scientific studies are clear: M. Lenzen ("between 10 and 130 g CO2-e/kWhel, with an average of 65 g") and E. Warner et G. Heath ("9 to 110 g CO‐eq/kWh by 2050")...
https://www.researchgate.net/publication/222817608_Life_cycl...