> Indeed, Canada was also indirectly responsible for many Nuclear weapons proliferation issues in North Korea, India, and Pakistan. Selling small research reactors to emerging economies had long-term consequences.

What does that have to do with how the US can deal with spent fuel? The reactors that consume spent fuel are ordinary power generating reactors rather than small research reactors and the US already has nuclear weapons.

> As a side note, the CANDU are famously bad designs known to develop heavy maintenance costs even to remain operational

The CANDU design is from the 1960s. It's not what you would actually use for a new project, it's an empirical demonstration that reactors that run on spent fuel are a real thing that actually exist rather than merely a theoretical possibility. There are also modern designs under construction in Europe and the same company is partnering with a US company to permanently destroy some of the US government's cold war era plutonium.