It was in the environment already in the same sense the uranium in coal was also in the environment already.

Maybe the problem is the uranium mine tailings are safely off in some poor country, not in the US where the coal ash would be?

They're in the US: https://www.energy.gov/em/moab-uranium-mill-tailings-remedia...

Most (99% as of 2018) uranium production is outside the US.

https://en.wikipedia.org/wiki/List_of_countries_by_uranium_p...

Very recently: U.S. utilities push White House not to sanction Russian uranium, see https://www.reuters.com/business/energy/exclusive-us-utiliti...

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...

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2051332

The uranium ore was deep underground, not inhaled by nearby residents as wind blew it off the tailings pile.