Re: Radon Control During Remediation

[huntjb@ornl.gov (Jerry Hunt)]

I need to make a couple of corrections on my earlier statements (below).
The half-life of the 234-U daughter, 230-Th (T=77,000 yrs) is what really
precludes the ingrowth of daughters that lead to radon (thanks to Paul
Frame at ORISE for pointing this out).  The long half life of 234-U does
mean that the depleted uranium is not producing much new 234-U (it is in
the 238-U decay chain).  Also, ~0.2% is the amount of 235-U left in
depleted uranium ("natural" uranium is ~0.7%), not 234-U as indicated
below.  The 234-U would be much smaller since the gaseous diffusion process
has a higher efficiency for it than even 235-U.


           At 02:44 PM 1/8/98 -0600, you wrote:
>Bates--
>
>You shouldn't have much of a radon problem with the DU since the progenitor
>of the radon (226-radium) has been chemically removed before the uranium
>was processed (the reason that mill tailings are such a problem with
>radon).  The nearest parent isotope left after the chemical processing is
>234-U which is mostly stripped away in the gaseous diffusion process (goes
>with the enriched uranium).  The remaining 234-U (~0.2%) has a long enough
>half-life (~250,000 yrs.) to preclude the ingrowth of daughters below 234-U.
>
>Your primary radon problem will probably be with the Colorado soil.
>
>                                  Jerry 
>
>At 09:28 AM 1/8/98 -0600, you wrote:
>>          Hello Radsafers;
>>          
>>          Rocky Flats will shortly begin remediation of an area known as 
>>          Trench 1 (T1) where ~125 drums of depleted uranium (DU) chips 
>>          and lathe coolant were buried from 1954 until 1962.
>>          
>>          The work will involve excavating the drums and stabilizing the 
>>          potentially pyrophoric DU, in place.  All work will be 
>>          performed inside a very large tent to be constructed over the 
>>          site.
>>          
>>          My question concerns the generation of Radon and decay 
>>          products from the DU (primarily U238) during the work. Are 
>>          there any regulatory drivers, etc. to require monitoring 
>>          worker exposure to the Radon products, as would be the case in 
>>          a uranium mine, since the Radon is being generated from 
>>          man-made materials?
>>          
>>          We intend to air-sample and monitor (with CAMs) for uranium.
>>          
>>          Thanks for any input Radsafers might have.
>>          
>>          Bates Estabrooks
>>          bates.estabrooks@rfets.gov  
>>
>
>*******************************************
>Jerry Hunt, CHP
>Office of Radiation Protection
>Oak Ridge National Laboratory
>P.O. Box 2008
>Bldg. 4500-S, MS-6099
>Oak Ridge, TN  37831-6099
>Ph.-(423)576-5117, Mailto:huntjb@ornl.gov
>*******************************************
>

*******************************************
Jerry Hunt, CHP
Office of Radiation Protection
Oak Ridge National Laboratory
P.O. Box 2008
Bldg. 4500-S, MS-6099
Oak Ridge, TN  37831-6099
Ph.-(423)576-5117, Mailto:huntjb@ornl.gov
*******************************************