[ RadSafe ] Re: Utah Board considering banning DU

Brennan, Mike (DOH) Mike.Brennan at DOH.WA.GOV
Thu Jun 11 16:16:52 CDT 2009

Hi, Cary.

Without looking at the output of the decay calculator (my firewall
doesn't like it), I suspect that what you will find is that at some
point you start to get appreciable radon production, with its daughter
products, and that is what drives your app to give you the numbers you
cite.  Now, I think one would be on very, very, very shaky ground
arguing that it is better in any sense to have the radon produced by
that particular amount or uranium out where it can waft into the air and
be breathed, and thus produce actual dose to actual organisms, as
opposed to contained in a way that little if any will ever reach the

Another point worth noting is that NOTHING about turning Unat into DU
causes more uranium to exist than is already present.  It is just that
as DU it is more concentrated and easier to keep isolated from the
environment than it is when the uranium (and its decay products)
contaminate vast quantities of soil and rock.  

Of course, we really aren't talking about much activity per unit mass.
Even using your numbers, in a million years the activity goes from about
0.3 Ci per ton to about 3.0 Ci per ton (it you start with pure metallic
uranium-238).  The biggest hazard remains the possibility of it falling
on you.

-----Original Message-----
From: Cary Renquist [mailto:cary.renquist at ezag.com] 
Sent: Thursday, June 11, 2009 1:04 PM
To: Brennan, Mike (DOH); Mario Bettolo; radsafe at radlab.nl
Subject: RE: [ RadSafe ] Re: Utah Board considering banning DU

Using the WISE uranium decay calculator:
Uranium Decay Calculator

Starting with 1 MBq of depleted natural U:
After ~1 year the total activity goes to ~3 MBq Stays at that level
until ~10,000 - 100,000 years when the Th-230 chain kicks in.
The total activity peaks at ~1,000,000 years at ~13-14 MBq

So, the total activity basically goes up by one order of magnitude after
1 million years.

The good news is that after 10,000,000,000 years they won't have much to
worry about...


Cary Renquist
cary.renquist at ezag.com

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