[ RadSafe ] Diffusion, Uranium and all that

[parthasarathy k s]

Dear Dr.Preisig,
Thank you very much for the excellent review. I felt like attending one of those memorable lectures of Prof Bill Spiers, Department of Medical Physics, University of Leeds UK in the 70s!
When Elezabeth Rona wrote about Madame Curie and her exploits in Health Physics journal ["Laboratory Contamination in the Early Period of Radiation Research"Health Phys 37(1979):723-7], this writer suggested in a letter to the Editor in Health Physics that veteran scientists must pen their memoirs for the benefit of the younger generation.Health Physics did publish a few.Dr Preisig's review belongs to a different category, equally refreshing none the less.
Best wishes for a happy, productive and prosperous New Year
Parthasarathy 

    On Saturday, 26 December 2015, 9:22, Joseph Preisig <jrpnj01 at gmail.com> wrote:
 

 Dear Radsafe,

    There are a few ways to separate U235 from U238.  Diffusion, laser
separation, use of Accelerators/calutrons etc.  See the internet for
diffusion and laser separation.

      Start with Uranium ore.  Chemically or otherwise, separate the
Uranium from other rock, dirt, impurities.  What you have is Uranium Oxide,
U3O8, or whatever.  For gaseous diffusion, convert the Uranium to UF6 or
whatever.

      For accelerator/calutron separation, refer to the book by Livingston
and Blewett, the internet, or other books.  If one ends up with a bunch of
U235 and a bunch of U238, think about putting the U238 into a reactor and
making Plutonium.  This process is described in Nuclear Physics books by
Kaplan, Segre and so on.  Many nuclear/particle physics grad students
become competent in these accelerator concepts in grad school.  Sometimes,
Grad students from China/Taiwan have copies of fundamental physics graduate
level texts (Goldstein, JD Jackson, Arfken, Matthews and Walker, Schiff,
etc.) that are in paperback form and were printed in China/Taiwan.

    At ORNL during WW2, some accelerators were used to obtain U235.  These
were called Calutrons, and from recent movies I have seen on TV, there were
many Calutrons at ORNL.  Quite an effort.  These calutrons had rather large
beam pipes, perhaps somewhat like heating ducts in your family home.  There
were magnets external to the ducts, some for bending the alleged beam and
some for rather crudely keeping the beam in the beam pipes.  Similar
accelerators to the Calutron might be the Cosmotron at Brookhaven Lab, and
the Zero Gradient Synchrotron at Argonne Lab (USA).  One of  the external
magnets for the Cosmotron used to be outside of the Alternating Gradient
Synchrotron building (BNL).

    Later on, particle accelerators started to have smaller beampipes and
started to use the concept of Alternating Gradients (magnets focused beam
in the horizontal and/or vertical directions as the beam went forward).
The magnets were electromagnets, and not so much Permanent Magnets.  See
Livingston and Blewett about all this, (and weak focusing and strong
focusing).  The Alternating Gradient stuff was developed at Brookhaven Lab,
and possibly also suggested independently by Christofilos.  Alternating
Gradient magnets are used in many serious particle accelerators in many
different countries.  This technology was invented quite a while ago now,
and is in the public domain.

    So, all I will say now is that one could build a modern accelerator
using Alternating Gradients, modern magnets etc. to separate U235 from
238.  It is all quite do-able and there is nothing secret about it.  Such
an accelerator would work better than a Calutron.  Clearly, one is using
the charge to mass ratio to separate U235 from U238.  One can use electric
fields, magnetic fields and/or both to do the separation.  See E and M
books by Lorrain and Corson, Reitz and Milford, Kip etc.  Heck a kid in the
Trenton, NJ area won the Trenton Science Fair by building a mass
spectrometer in the 1970's.  Nothing new here, but it is interesting and
fun.

    Joe Preisig
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