Nobody knows. A new exploration campaign is running (named 'Nodssum' https://www.myscience.org/news/2025/dechets_radioactifs_une_... ), targeting North-Atlantic zones.
> Is there evidence of the high doses generated, and if so why isn't this on the wikipedia page?
AFAIK it now is forbidden to dump highly dangerous waste in non-negligible amounts in the ocean not because there was some accident, but because experts judged that it may trigger one. An approach is to advocate the "let's do whatever please until something breaks", another one is to think about potential consequences THEN to decide.
> dose from an old dump is higher than that from a fuel fabrication, reprocessing plant or nuclear power station.
Those contexts are way more under human-control than an ocean floor.
> One wonders how they get to conferences.
This is a weird way to describe a real, ancient (and IMHO growing, since Fukushima) controversy.
https://en.wikipedia.org/wiki/Linear_no-threshold_model#Cont...
https://en.wikipedia.org/wiki/Radiation_hormesis#Proposed_me...