Depleted uranium

["E.P. Goldfinch" <goldfinch@ntp.org.uk>]

There is another aspect to the inhalation of uranium that I have not seen
mentioned, namely the considerations within the IAEA Regulations for the
Safe Transport of Radioactive Material. Uranium-238 is one of the nuclides
listed in the IAEA regulations with an 'unlimited' A2 value. 'Unlimited'
means that there is no limit on the quantity that can be carried in a Type
A package. The derivation is based upon the assumption that in a 'median'
accident (serious one) no more than 10 mg of dust could physically be
inhaled by any individual in the vicinity. Above that sort of quantity
physical coughing and spluttering would intervene. In general terms, the
'unlimited' boundary occurs when 10 mg would give rise to an effective dose
of 50 mSv and, of course, for DU the dose is much lower. In a combat
situation the general dust level would, no doubt, dilute the DU in the air,
if there is any at a respirable size. On the other hand, exposure on this
basis could be repeated in a combat situation. However, it could be
possible to place an upper conjectural limit on the intake for any
individual. Since the normal daily intake is about 2 micro g, it is not
surprising that U can be found in exposed persons. At the scientific level
the current debate is not whether there have been intakes of DU but whether
there are any effects. As we all recognise, the media view equates intake
with effects!

E.P. Goldfinch


Nuclear Technology Publishing
P.O. Box No 7, Ashford, Kent TN23 1YW, England
File reference: 
Telephone: (+44) (0) 1233 641683
Fax: (+44) (0) 1233 610021
E-mail: goldfinch@ntp.org.uk
Web site:  http://www.ntp.org.uk
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html