[ RadSafe ] Neutron Generator regulations

[JPreisig at aol.com]

Hi,
 
     Don't know much about neutron generator  regulations.  Perhaps the 
gentleman who works for Schlumberger could  address the regulation question.
 
    The deuterium on tritium neutron generator produces  something like 15 
MeV neutrons.  The deuterium on
deuterium neutron generator produces something like 2 MeV neutrons.   Such 
generators are commercially available from Schlumberger or perhaps GE  
(Largo, Florida).  Other neutron generator manufacturers are sometimes  given in 
the American Institute of Physics Annual Physics Instrumentation/Supply  
catalog.
Cruise the internet also.  Some neutron generators can produce D/D or  D/T 
reactions.  The voltage/Energy
of D/T ions is something like 20 to 50 keV.  In 1978, a neutron  generator 
from Schlumberger cost $5K.
(just the tube, not the other electronics).  The books by Segre or  Kaplan 
on Nuclear Physics should be helpful.  For the Health Physics of the  
neutrons, see Accelerator Health Physics by Patterson and Thomas or perhaps the  
course notes by Cossairt.
 
    A typical tube works as follows.  The deuterium or  tritium is stored 
in a getter/sorber material such as filament made of zirconium  or uranium.  
A slight voltage is applied to the filament and the D or T gas  is 
emanated.  The gas is D2 or T2 and then usually ionized using a  Penning 
Ion Arrangement.  The ions are then accelerated across the 20 to 50  keV gap, 
and the ions crash into a carbon target (possibly backed by a Titanium  ??? 
disk as I recall).  The neutrons are produced by D,T collisions.   The 
neutron generator tube is under vacuum, and has a main cylindrical body made  of 
glass, or lately, ceramic.
 
    One can detect the neutrons with a remball, Snoopy,  Anderson-Braun, 
Long Counter or perhaps even a Bonner Multisphere Spectrometer  (if one wants 
to see the actual neutron spectrum as a function of energy).   I have sent 
numerous email posts to Radafe about Bonner Multisphere  Spectrometry.  One 
can analyze the Bonner data using BON4/BON5, or other  unfolding codes.  Such 
neutron unfolding codes are available from RSICC  (Radiation Shielding 
Information Center, ORNL, Oak Ridge, Tennessee).   BON4/BON5 has crappy plotting 
software, so you may want to plot the output  flux-density data by hand or 
with Grapher or another plotting code.  LOUHI  and MAXED are some other 
unfolding codes.
 
    The neutron generator can give off a fairly large flux  density at a 
fairly high energy, so the generator tube must be shielded.   At Schlumberger 
(Princeton Junction, New Jersey USA) there a whole neutron  generator test 
building.  Be careful!!!!
 
   If you are building the neutron generator in a glass  cylinder, then it 
is useful to connect the glass to Kovar rings which are welded  to the rest 
of the metal assembly.  The Kovar rings are fused to the glass  cylinder 
using a lathe by a guy with glass-blowing skills.  Using ceramic  envelopes 
might be simpler.
 
   Electronically, the high voltage stage must be isolated  from the 
filament electronics using insulators (ceramics also???).
 
    Questions, just email me.  A schematic of a neutron  generator might be 
found online.  Schlumberger's neutron generator was  called a Minitron.  
The QC Tech at EMR Photoelctric used to fondly refer to  the tubes as a 
Bitchitron.  (They were hard to make and get through  electronic testing.)
 
   These neutron generator tubes go down oilwells in a Sonde  along with 
gamma/XRay detectors.  The neutron generators send out neutrons  into the 
rocks/soil and the photomultiplier tube detects the returning  gamma/XRay 
signals (n, gamma or whatever reaction).  Nowadays I hear the  neutron generators 
are part of Measurement While Drilling (MWD not MWD), in  which such 
measurements are made while the oil well is being drilled.
 
     Regards,   Joe Preisig
 
 
          
 
In a message dated 8/27/2013 4:23:09 P.M. E,astern Daylight Time,  
brees at lanl.gov writes:

What are  the regulations regarding an electronic neutron generator?  
Something  like a D-D fusion type.  It's possible to make one in a reasonably 
well  equipped lab, so if someone did, what licensing and use regulations would 
 apply?
Regulations on an x-ray machine are fairly clear (and they're   MUCH more 
common! - both the machines, and regs!).
I realize that "standard  radiation dose limits" would apply, but most of 
the regulations I see are  associated with the Tritium content of a D-T 
generator, is there anything  special someone would have to do if they made a D-D 
neutron  generator?

And yes, I realize that if it was done in a DOE facility  their rules would 
apply.

Thanks in advance!
Brian  Rees
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