Re: soil samples

I agree. There are many regulations that define "clean" (e.g. MARSIMM,NUREG-5849 in the US). Typically, regulators need to be involved and approve this definition. What is clean at one site, may not be clean at another. I suggest that the requestor obtain professional consultation on this matter. I am sure that RADSAFER's will flood him with suitable recommendations.

Because gammas were specified, I believe gamma spectroscopy is the analysis of choice. However, the definition of "clean" would have to be established before choosing the analysis method.

Kevin Wright

>From: "John Johnson"

>Reply-To: "John Johnson"

>To: "Brian Stymest" , "radsafe Listserve"

>Subject: Re: soil samples

>Date: Thu, 14 Mar 2002 12:35:46 -0800

>Brian

>In response to your questions

>1.

> >Specific radiochemical techniques to look at H-3,

> > C-14??? I do not expect to see these types of radionuclides in this

>sample.

>You will see H-3 and C-14 in soil because they are produced in air from

>cosmic ray interactions and are globally distributed from bomb tests. RC

>techniques are not very sensitive because they do not seperate out the

>radioactive isotopes. LS counting is the cheapest but again the sensitivity

>is poor. Mass spectroscopy is expensive but the sensitivity is very good.

>2.

> > What activity level is clean?

> >

>A very difficult question! I would say 3 sigma above background. Background

>level can be found in the UNSCEAR reports (UNSCEAR 2000 is available from

>the UNSCEAR's website

>John

>IDIAS, Inc

>4535 West 9th Ave.

>Vancouver, B. C.

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>(604) 222-9840

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