Japanese reactor crisis

[Medusa]

These are some figures that talk about how much of a material you would need to insulate against radiation in case of a nuclear attack. Not sure if this is the same type of radiation as would leak from the reactors (and probably not because a blast is much more aggressive than a leak)

This is for a blast, and not a leak. I think that radiation carried on a jet stream would probably act much differently than a blast (a blast acting with force versus carried radiation floating on the wind)

But just to give an idea:

Steel: 21 cm (0.7 feet)
Rock: 70-100 cm (2-3 ft)
Concrete: 66 cm (2.2 ft)
Wood: 2.6 m (8.8 ft)
Soil: 1 m (3.3 ft)
Ice: 2 m (6.6 ft)
Snow: 6 m (20-22 ft)