I can reduce the worry. The problem is "easy" to deal with.
First, a little about radiation. For a gross over-simplification think of a pool table setup to go and all the balls neatly in a triangle ready to break - this represents the contrsuct of an atom. Protons, neutrons and eletrons in a tidy little package. Should a stray particle of great speed impact this tidy little package - illustrated in this example by the white ball colliding the triangle on a break - it de-stablises the contents causing high speed particles to release.
The three major types of radiaiton - Alpha, Beta, and Gamma - are commonly ordered by "penetration depth" - long story short, density matters. The more dense an atom is, the more resistence it will pose to the high speed particles. Alpha is moving at the greatest speed, but has the least penetration depth - a few CM of air or a thick sheet of card can provide sufficient shielding. Your skin should be thick enough to stop it(although, it will absorb the damages and likely lead to things like skin cancer) and should require direct contact for long times to cause harm - swallowing it or breathing in a small particle however is likely fatal as it'll allow it to damage something important. Beta has a little more depth penetration going some distance in air a sheet of aluminium foil should be thick enough to absorb it. Gamma going many miles and taking a few inches of lead(denser than 80% of the periodic) to absorb.
Hydrogen, being atomically dense, is an excellent "barrier" - but has several drawbacks like being explosive and difficult to keep aligned in a useful pattern unless under pressure - and historically hydrogen and pressure don't tend to be a good mix. Water contains lots of hydrogen, and is dense as a substance whilst being significantly less volitile - however exposure will decay this to deutrium and reduce the supply of usable water which on the scale of it possibly isn't the most sensible resource to squander. To those thinking of just wrapping up in foil attention should be drawn to "secondary emittence" - to consider the pool table analogy, say the triangle is an aluminium atom... As the white ball(this time representing "cosmic rays") hits it and causes emittence, these would be recorded as X-rays. For something presenting minimal secondary emittences Iron appears to be quite good.
Iron is quite common, with most asteroids being quite heavy in their nickle and iron composition. To seriously entertain mass residence in the stars we'll need to be tapping resources in asteroids anyway - lifting the required mass is unfeasible as this would take thousands of years just to begin assembling pieces, at one launch per day using NASA's new SLS system comming online soon. Taking it from up there using exponentially expanding methods is the only way to get at such in a reasonably timeframe(and we're still talking decades) so naturally create megatonnes of nickle, and iron. Thusly, I personally would be creating an external barrier that clips to the external pressure hull of about five meters thick NiFe - This is largely overspec to requirements, with the nickle/iron composition providing for "sufficient" shielding from radiaiton at 1/5th of this thickness should any make it through the 7½CM of titanium it's skinned in.
I'd be comfortable sitting behind that, in a solar flare.