In short... decontamination and shielding. Wash off any fallout outside of your shelter, and get to shelter with sufficient mass to shield you from the radiation emmanating from the fallout out side the shelter. It's just the opposite of what we do at the Nuc. plants... got crapped up??? Get a shower, and stay out of the "can" for the rest of the shift... sorry it's not a bit more dramatic, but that's about as good as it gets... if the exposure is too long or too intense, or if the shielding isn't extensive enough, ya get ta cook.

Troy