Nuclear diving just CAN looks safe, but in reality from one of (approx.) 200 pipes from fuel pin array at least one will be broken after 5 years of usage, and all outcomes products from chain reaction will go to the storage tank water.
It could be tiny particles, that can subside on your dry suite surfaces, and when you will wear it off, it can come in to you body....
Does not matter, how well reducing radiation from fuel assembles on the distance, because particles of fuel will floating in all water depth.
Also - reducing radiation depends on radiation energy level (MeV) and for high energy nuclones even 10m is nothing...
So - if you have good hat diving suite, and team of supporters on the surface, and unlimited ammount of clean water and
Simple Green 
e.g. - it is much safer, than nuclear diving (IMnHO).
But if I will choice, to have Nuclear or Contaminated diving - I will prefer this one: