The trouble there is that, in order to attenuate high-energy radiation like the cosmic rays under discussion, you need something that's either extremely dense or extremely thick, and ideally both - dense so a speeding particle is more likely to hit it instead of zipping past between the atoms, thick so that Bremsstrahlung X-rays get absorbed before they reach human tissue susceptible to ionization injury.
Both of these are physical necessities, and both militate directly against the idea of a light, comfortable radiation-proof suit or dome. They're also not something that can be solved by incremental improvements in materials science - as sensible to imagine that we're just an unknown number of iterations away from main battle tank armor with the mass and density of Styrofoam, and for precisely the same reasons.
I'm completely out of my depth here, but couldn't we develop some kind of force field to do this? I'm thinking something along the lines of a Faraday cage, but for the GCRs.
A magnetic field (Van Allen belt, or analog on other bodies) deflects lighter charged particles better than heavier ones (with a greater mass-to-charge ration). E.g. - helium ions (alpha particles) vs iron nuclei as mentioned in the article.
Otherwise, pure mass over your head is the best defense.
If this really is just a metre down and 80% water it's got to be an attractive target - relatively easy to mine (once surface is cleared, just use heat) and a hollowed out underground structure with 1m of ice above would be an effective radiation shield:
I'm wondering how contaminated are raw materials on planets without a solid magnetosphere. Could it be that most of the water out there is too radio-active for consumption?
So, your biggest problem in a reactor cooling pool is "lead poisoning", eh? :-)
Anyway, worth pointing out that cosmic rays are little groups of neutrons (and adjoining protons). I don't know about the half life of the resulting products, though, or how often a heavy nucleus collides with another nucleus, vs simply bashing through electron bonds.
Light materials are physically impossible (absorption shield will be heavy anyway), but some energy shield that will deflect radiation could be a solution both for colonies and for spaceships.
