Quick estimate is that it depends on the level of radiation...

Too high, and any long chains compounds that form are destroyed.

A little lower, and you get sub-surface long chain compounds incapable of evolving intelligence.

A little lower still, and you might get cockroaches and cacti (cactuses) (I hope Sir Arthur is right is seeing "bushes" o Mars, but that's just a final hope...)
- still no intelligence -

In the case of a layered water world, teh water could provide shielding from radiation. Perhaps something like octopuses may evolve to intelligence, beneath the water shielding - but oxidizing reactions are impossible there (no fire, and no energy technologies), thus while you might get limited intelligence, you get no advanced intelligence -

EP