That doesn't really show anything because it's such a huge mixture and the vast majority is random toxic chemicals, not plain old spent fuel.

I'm not saying I think dumping nuclear waste in the ocean is a good idea (though I am also curious if there's been specific impact studies done on it, if we're talking about very very deep ocean) but I'm pretty sure somalia isn't in the ocean.

They were dumping waste off the coast of Somalia, in the ocean

"Bottom of the ocean" here doesn't mean on the continental shelf.