From: gherbert@gw.retro.com (George William Herbert)
Newsgroups: alt.war.nuclear,soc.rights.human,soc.culture.usa,
	soc.culture.british
Subject: Re: The Truth about Depleted Uranium
Date: 16 Jan 2001 00:22:21 -0800

bevnsag  <bevnsag@home.com> wrote:
>George William Herbert wrote:
>> Trakar <shardrukar@yahoo.com> wrote:
>> >Trex <officer1248@my-deja.com> wrote:
>> >>Well, uranium is not your everyday normal metal.
>> >
>> >Actually, it is quite common, in low concentrations it is in the air
>> >we breathe, the food we eat, the water we drink, and the soil we walk
>> >upon.
>>
>> To amplify this, there's a critical mass of U-235 (enough to build at
>> least one nuclear bomb out of) in the top ten meters of topsoil and rock
>> of the average american single family home, just due to the natural
>> background concentration of Uranium in crustal rocks and soil.
>
>That's silly.

But nearly true...

>While U is not uncommon in the crust, that seems more than
>a little stretch (that same soil sample would also have to produce some
>hundreds of pounds of U238 to match the U235 fraction) .

Crustal average is 2.7 parts per million Uranium, ranging from
3.7 PPM in granite and derived soils to about 0.6 ppm in basalt.

A house on a 15,000 square foot lot (about 120 feet square) is going
to have a lot surface area of about 1395 square meters.  10 meters deep
is 13,950 cubic meters with a typical density of about 3.0 for rock
and 1.75 or so for soil.  If we assume 2m of soil and 8m of rock
then that's about 4,800 tons of soil and 33,480 tons of rock
for a grand total of around 36,780 tons of material, or 36,780,000 kg.

At crustal average 2.7 PPM, that's about 100 kilos of Uranium,
of which about a third of a kilo is U-235.  I think when I did the
calculation before it was an acre (three times as large an area)
and I assumed granite at a slightly higher average concentration
(4.5? 5? ppm, from another reference), and 25 meters deep not 10,
and got about 5 kilos of U-235.  However, that envelope is missing.
I sit slightly corrected on the depth required, but it's roughly
within an order of magnitude.


-george