Re: airborne U

["William F Miller"<MILLERWF@inel.gov>]

A good reference for Uranium work is the "Health Physics Manual of Good
Practices for Uranium Facilities" prepared for DOE by the INEL in June of
1988.  EGG-2530, UC-41, Contract DE-AC07-76IDO1570,  Bryce Rich, Chairman.





Vincent.King@DOEGJPO.COM on 23/07/97 02:25:46 PM

Please respond to radsafe@romulus.ehs.uiuc.edu


To:   radsafe@romulus.ehs.uiuc.edu
cc:    (bcc: William F Miller/MILLERWF/LMITCO/INEEL/US)
Subject:  Re: airborne U




     Mike
     The DAC values in 10 CFR 835 are based primarily on the methodology
     and annual limits on intake found in International Commission on
     Radiological Protection Publication 30.  There are other, more
     readable sources of information, however (try Internal Radiation
     Dosimetry, edited by Otto G. Raabe, published by HPS from the 1994
     Health Physics Summer school).
     In general, you're thinking is correct.  Inhalation of insoluble
     chemical (e.g., class Y) forms of alpha emitters will result in higher
     lung doses than will moderately soluble forms (class W).
     For both class W and class Y uranium, the lung dose (after applying
     the ICRP tissue weighting factor) is a more significant contributor to
     the committed effective dose equivalent (CEDE) to the whole body than
     is the dose from any other tissue or organ, consequently the CEDE is
     higher for class Y uranium.
     For plutonium, however, the weighted dose to bone surfaces outweighs
     the lung dose contribution.  And since more soluble forms of plutonium
     more readily dissolve in body fluids and become available for
     deposition in the bone, the dose to the whole body increases for the
     more soluble form (even though the lung dose decreases).
     Note that, while it is correct that chemical toxicity of pure U-238
     outweighs radiological risks because of it's extremely low specific
     activity, the radiological dose (at least as far as regulatory limits
     are concerned) from more insoluble forms of natural uranium and from
     enriched uranium may outweigh the chemical concerns. It's best to
     evaluate both risks and determine which limit is more restrictive as
     solubility decreases and enrichment increases.
     Vincent King, CHP
     vincent.king@doegjpo.com
     \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\




     July 23, 1997
     Dear Mike:
     Calculation of radiological risks from pure U-238 is meaningless since
     the actual risk depends on the chemical toxicity of uranium in the
     kidney not in the bone or lung, although both the bone and lung can be
     a reservoir of this potentially toxic element.
     Otto
     ***************************************************** Prof. Otto G.
     Raabe, Ph.D., CHP
     [President, Health Physics Society, 1997-1998] Institute of Toxicology
     & Environmental Health (ITEH)
     (Street address: Old Davis Road)
     University of California, Davis, CA 95616 Phone: 916-752-7754     FAX:
     916-758-6140 E-Mail: ograabe@ucdavis.edu
     ******************************************************
______________________________ Reply Separator
_________________________________
Subject: airborne U
Author:  mcnaught@lanl.gov (Mike McNaughton) at Internet
Date:    7/23/97 12:51

I am comparing the hazards of W and Y class airborne U-238, using the
derived air concentrations in 10CFR835 appendix A. Can anyone shed some
light on these?
For Pu-239, W class is 3 times as hazardous as Y class, presumably because
with Y class, some is cleared from the lung before it is deposited on the
bone.
However, for U-238, Y class is 15 times as hazardous as W class. This must
imply that the critical organ for Y class U-238 is the lung.
Is there a document that explains the logic of the derived air
concentrations in 10CFR835? Thanks, mike
"Shlala gashle" (Zulu greeting, meaning "Stay safe")
mike (mcnaught@LANL.GOV)