The why of US policy?
We are burdened with the decisions made so long ago no longer in living memory. Desire to fuel weapons and prevent access by others have produced the toxic result deliberately. No other route is considered appropriate at that time. Its all about bombs thats why its the way it is. Not safe economical energy. Not a consideration. High level waste was a good thing (thought to prevent proliferation). Now we are generations behind in nuclear science due to neglect, deliberate neglect.