The earth has only one atmosphere. The political follies of any single nation are of lesser concern. That said, I'd rather not be a cog in the machinery of a nation that is dragging the rest of the world down.
As to your concerns, fuel costs are just a small fraction of the overall cost of financing and operating a nuclear power plant. Reprocessing used fuel and/or breeding fuel from thorium and uranium 238 increases the cost of fuel but it doesn't increase the price of electricity much.
In a fossil fuel power plant as the price of the fuel increases the price of the electricity it produces increases nearly as much. (This does, of course, ignore the environmental costs of fossil fuels that are an existential threat to our civilization.)
Building new nuclear reactors using existing designs is still a good idea even when there are potentially superior designs on the horizon.
To be blunt, we need to face reality. Global warming is getting worse. On one side we have people who refuse to believe that, on the other side we have people who insist renewable energy can support 8 billion people or, at a minimum, significantly postpone the collapse of our civilization.
I'm not going to pretend that nuclear power is going to halt global warming. I do think that maintaining a heavy industrial base using nuclear power instead of fossil fuels will give humanity a lot more room to find the political solutions that will be essential to our own survival and whatever is left of the natural environment we knew.
Solar panels obliterating many square miles of living desert and giant wind farms don't solve any fundamental problems. We've explored their capabilities at gigawatt scales and they've come up short. At the same time I don't begrudge anyone the solar panels on their roof or their super-efficient automobile. Our society really doesn't offer us many ways to reduce our own environmental footprint beyond grinding poverty. The smallest environmental footprint I ever had was living in my broken car in a church parking lot scavenging food out of trash cans. Thankfully I had access to flush toilets connected to a modern sewage treatment plant and clean fresh water. Everyone on earth deserves flush toilets connected to modern sewage treatment systems and clean fresh water. Providing those simple things to eight billion people requires reliable high density energy resources.