RE: Gamma surveys (in-situ)

["Ed Waller" <Ed.Waller@uoit.ca>]

My global comment here is that you can never have absolute "assurance" that you have found everything.

 

You can statistically determine an appropriate grid size, set confidence limits, and make sure you have appropriate detection limits for the isotopes you are looking for, etc. Depth of radionuclide distribution (or burial) in the medium is extremely important for surface detection. 

 

Assuming you are looking at radioactive material in soil, there are an infinite number of possibilities of having radionuclide in the soil that can go undetected.  Example: You are asked by a client to clear a site of all anthropogenic radionuclides. What is there is a 55 gallon drum buried at 1 metre filled with tritium radioluminescents? You'll never detect that (with ionizing radiation detection equipment anyway)...you may get it with conductivity survey or ground penetrating radar though. The historical review will help you a lot here.

 

The main point here is that you have to be very careful how you present your results and how you write the report.

 

Ed



	-----Original Message----- 

	From: owner-radsafe@list.Vanderbilt.Edu on behalf of Jay Beckel 

	Sent: Wed 2/11/2004 11:43 AM 

	To: radsafe@list.Vanderbilt.Edu 

	Cc: 

	Subject: Gamma surveys (in-situ)

	

	

	Okay, this is probably a stupid question to most of you, but is there a standard distance between detector and surface being measured?  We have one meter grids and are wanting a kind of secondary reassurance that we've found everything, so we're doing gross gamma counting in addition to all other surveying.  Probe is centered over the square.

	 

	Thanks for any advice!

	Jay



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