Could it put the brakes on research? Yes, it could. In my professional experience with them, Americans are not happy that we developed CANDU. They don't like it. They raise a number of what I consider to be phoney proliferation concerns about it. Would they have all that much interest in pursuing...? There's further research we could do with CANDU. I've talked about enriched fuel. If we had slightly enriched fuel with CANDU, there's amazing stuff we could do with that. Are American competitors interested in seeing us pursue those research avenues? I would say, probably not.
You don't need Donald Trump to come to that conclusion. They've never been all that interested. I don't know that the GOCO has done all that much interesting research into CANDU at all since its inception.
Could they block or halt research that would benefit Canada? Of course they could. I'm not saying they would. There's just no interest south of the border in our fuel technology, and likely very little interest in anything having to do with waste management.