You should look again how much can be generated with non-recycled and non-breeded uranium.
If we keep insist only proven designs can be produced, we are for in for a short lived transition that won’t last even for the normal lifetime of a reactor. If we stop insisting on proven designs, we are in for discovering some weird new failure mode here and there.
It will still probably be much safer than coal, but nuclear is either extremely limited or way more dangerous than the number indicate.