[ RadSafe ] Isotopic Concentrations of Uranium Versus U-235Enrichment

Douglas Minnema douglasm at DNFSB.GOV
Fri Dec 5 15:31:33 CST 2008


It's a long story, but I must be brief as I'm recovering from shoulder surgery and only have one hand to type.

In general, the problem is that most of the enriched uranium in the DOE complex was from recycled uranium that had been run through reactors, processing plants, and enrichment plants multiple times.  Since some of the other isotopes tended to follow the U-235 through the enrichment, then one ended up with a potentially wide range of isotopic mixes for any one value of U-235 enrichment.  This was especially an issue with U-234, which was a major constituent of the radiation dose even though it was a minor constituent of the isotopic mix.  Therefore, the handbook could only provide graphs and general examples but couldn't be specific.  But as you can imagine, the U-235 enrichment value was the only "important" value for the DOE at the time.

Doug Minnema

>>> "Leo M. Lowe - SENES Consultants Limited" <llowe at senes.ca> 12/05/08 3:34 PM >>>

DOE-STD-1136-2004 (Guide of Good Practices for Occupational 
Radiological Protection in Uranium Facilities) gives an equation for 
the specific activity of uranium (Ci/g) as a function of U-235 
percent enrichment.   However, it does not provide a parameterization 
of the isotopic abundances. A graph (Figure 2-2) does show the 
percent of the total activity for individual isotopes but I am 
interested in equations for the abundances, rather than having to 
read values off the graph.

Does anyone has a cite for this information  i.e. Bq/g or Ci/g for 
each uranium isotope versus % U-235 mass enrichment (by the gaseous 
diffusion method).

Feel free to respond directly to me.


Leo M. Lowe, Ph.D., P.Phys.

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