So it's a misconception; it's not reality that I've been told.
In your example of the waste the would fit in a pop can, how much energy would still be stored in there that we hope, be it by the Moltex design that might solve some of that, or future technology that could recycle that waste? The ultimate, great thing about nuclear is that you might get more energy out of that pop can.
What per cent of energy is removed from that pop can through the first pass through it?