Radioactive absorbsion.
 

I was reading this Chernobyl article : http://www.grcade.com/viewtopic.php?t=2217

And they said that the soil absorbed a lot more radiation than asphalt.

Anyone have any details on this, cuz it's kinda relevant when moving in a previously nuked area or rather surounding areas...

Time is also a factor offcourse, but what kind of minerals/metals/etc absorbed most radioation over time really intrigued me.

Your thoughts,,,

How's that big concrete cap they dumped on top of it holding up? It occurs to me with all that trapped radioactivity under that cap, it might be very warm under there, which could weaken the concrete.

It's already in need of replacement, apparently it was assessed some years ago and found to be weakening.
This is lifted from the wiki article at http://en.wikipedia.org/wiki/Chernobyl_disaster
"A New Safe Confinement was to have been built by the end of 2005; however, it has suffered ongoing delays and is currently expected to be completed in 2012. The structure will be built adjacent to the existing shelter and then will be slid into place on rails. It is to be a metal arch 105 meters (344.4 feet) high and spanning 257 meters (842.9 feet), to cover both unit 4 and the hastily built 1986 structure."

metal vs stone
 

I understand that metal absorbs far more radiation than dirt ,sand etc ?

I also read that water is an effective barrier to shield radiation ?

Please correct me if I am wrong .

water is an excellant shield for high speed nuetrons thats why most reactors use water as a coolant high densisty poly also stops nuetrons for gamma lead is best but any of the three standards work well Time Distance and shielding