Well actually, we started selling that off to SNC and it's rotting now..

https://www.cbc.ca/news/business/aecl-sold-for-15m-to-snc-la...

at least we still have a few SMR startups like Terrestrial

https://www.terrestrialenergy.com/

There are no military applications to CANDU (heavy water allows it to use less-refined uranium fuel), so I imagine America wouldn't have felt the need to interfere.

Not exactly true...India used plutonium produced by its CANDU reactors for the development of their first nuclear bomb.

http://www.ccnr.org/india_press.html