As far as I know those studies are far from extensive and there is no permanent effort.
> given their apparent potential hazard
The good'ole "who is in charge, who pays?" is at play.
In many nations the nuclear industry just doesn't care (they dumped their waste, and good bye!) or disappeared after a phase-out.
A fair part of those who can pay those studies prefer to pursue their own endeavors (why would they have to work in order to cope with other's boo-boos?), for example the lack of resources available for oceanographers' core missions is well-known.
> Surely Greenpeace
AFAIK obtaining and maintaining a boat isn't easy for them. Doing so for some bathyscaphe (or similar equipment) and all the associated infrastructure and expertise for what nowadays is a mission (showing the bad effects of civilian nuclear) which is vanishing just as its mere subject is, while others (pollution, overfishing...) are more and more difficult, seems 'ambitious' without any very generous dedicated donation (are you interested in giving?).
> does the position not require such evidence
As already stated experts decided nearly 60 years ago to quit dumping waste in the ocean floor (London Convention), this seems sufficient to me.
> disposing of the waste ten+ metres under the sea floor would have been much better.
Maybe, maybe not. It would have been way more expensive.
> work done by Charles D. Hollister
IMHO the nuclear folks liked to be able to dump waste from a barge. Asking them to dig the seabed...
> You mistake my sense of humour;
Indeed, sorry.
> I was referring to the increased radiation dose from flying to/from conferences.
The point is: anyone decides upon hoping in any jetliner, or abstaining from doing so. A nuclear reactor can trigger a major accident which lets no such choice in a huge area, and for quite a while.
If someone lacerates the tattooed arm of someone else and says "hey, you already hurt yourself with this tattoo" I'm ready to bet that most, including any judge, will not support him.