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Reference, Questions and Help => Nuke Q&A => Instrument Q&A => Topic started by: OldNuc on Apr 13, 2005, 04:45

Title: Neutron Dosimetry (TLD?)
Post by: OldNuc on Apr 13, 2005, 04:45
What type of dosimetry is primarily used when monitoring personnel for neutron exposure?  Also, can a typical TLD be used to determine neutron exposure?  Thanks much
Title: Re: Neutron Dosimetry (TLD?)
Post by: Already Gone on Apr 13, 2005, 06:32
The older type of neutron dosimeter is the Neutron Track Emulsion film badge.  Like other film badges, it was very accurate, reliable, and a permanent record of exposure.  I don't think these are being used anymore for personnel dosimetry.  Once developed, it shows a number of tracks that can be counted to quantify the exposure.
The Lithium Fluoride TLD is a newer method, if you consider 1960's technology to be "new".  It works much like other TLD's, and looks just like them, except for the shielding in the case. 
There also is an albedo dosimeter - which means that it actually measures the radiation coming OUT of the body after being reflected.  I don't know the exact combination of chips used in this TLD, but I remember that it has to be worn tight against the body to be accurate.  Like most TLD's in use outside the navy, there are multiple different chips and attenuators corresponding to each.
There is also timekeeping - where you just measure the dose rate and multiply it by the time of exposure.  Or, you can just figure out the ratio of neutron dose rate vs. gamma dose rate for the work area and assign a correction factor to the gamma dose to account for the neutrons.
"Primarily" is a broad term, that assumes that one method is used regularly.  But, the people who work with radiation are the type of people who like to reinvent the wheel a lot - not because they are stupid, but because they think they understand the concept of roundness better than anyone else, and you can't talk them into accepting a common method when they can spend so much more time and money developing one of their own that is just about as good.  So, if you can find two nuke facilities using the same dosimeter, they're certainly using them differently.
Title: Re: Neutron Dosimetry (TLD?)
Post by: radgal on Apr 15, 2005, 10:07
Well put BC couldn't said it better myself!
Title: Re: Neutron Dosimetry (TLD?)
Post by: OldNuc on Apr 19, 2005, 07:19
Thank you.  I appreciate the information on Neutron Dosimetry very much.
Title: Re: Neutron Dosimetry (TLD?)
Post by: Weasel on Apr 27, 2005, 10:33
We have a dosimeter at Hanford that is called a combination TLD.  It's a standard TLD with an attached neutron dosimeter.  More information about this can be found here.

Section 5.5 explains in more detail that any one person would care to learn about these dosimeters.
Title: Re: Neutron Dosimetry (TLD?)
Post by: RT@OPG on Oct 31, 2005, 10:40
Is anyone using the neutron version of the MG or Siemens electronic personal dosimeters.  I would be interested in your experiences, we are supposed to be getting some for evaluation to replace our old "Snoopy" with an integrator.  Believe me any salesman's line sounds good after slugging around a Snoopy.

Is anyone using the Ludlum "Percilla" probe with the Eberline E600 ratemeter for neutron dose.  It's still 10% of the weight of the Snoopy.
Title: Re: Neutron Dosimetry (TLD?)
Post by: Kernwerker on Jul 17, 2006, 11:01
Well here in Germany we use mostly Albedos for Neutron detection. And yes Bearcourt The Albedo must be worn the right side (which is noticeable on the dosemeter) because the body acts as a moderator to produce slow Neutrons. And the Albedo has also fairly good gamma detectability Atm we are testing digital Neutron dosemeters at our plant here in Philippsburg, Germany.