[ RadSafe ] Neutron Generator regulations
JPreisig at aol.com
JPreisig at aol.com
Tue Aug 27 16:06:04 CDT 2013
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
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
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
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
And yes, I realize that if it was done in a DOE facility their rules would
Thanks in advance!
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