RE: Welcome to California

["Redmond, Randy (RXQ) " <RXQ@Y12.doe.gov>]

Folks - the man is being sarcastic.



> -----Original Message-----

> From:	Wes Van Pelt [SMTP:wesvanpelt@ATT.NET]

> Sent:	Saturday, June 01, 2002 6:49 PM

> To:	Speercl; BLHamrick@AOL.COM; radsafe@list.vanderbilt.edu

> Subject:	RE: Welcome to California

> 

> Carl,

>  

> The first thing to do is state in detail the question you wish to answer

> by doing a gamma scan over a large area. By your last sentence, it appears

> you want to measure the extent of residual contamination that produces a

> cancer risk of 1 in 1,000,000. This requires dose modeling, including

> ingestion of vegetables grown on the land, drinking water from wells,

> drinking cow's milk, breathing airborne dust, as well as direct gamma

> exposure. But this is quite easy using commonly available environmental

> dose codes. 

>  

> Then just equate radiation dose to cancer risk using the Linear

> Non-Threshold theory. (Please, no flames.)

>  

> The big problem, as I see it, is determining the depth over which the

> residual contamination is spread.  For example, does it go down 4 inches

> of 4 feet? And how is it distributed by depth? The only way I know to

> determine this is to drill holes and analyze the core samples for

> radionuclide concentration and also doing down-hole gamma readings. This

> gets expensive and requires a lot of drill holes.

>  

> Regards,

> Wes

>  

> Wesley R. Van Pelt, PhD, CIH, CHP

> Wesley R. Van Pelt Associates, Inc.

> Consulting in Radiation Safety and Environmental Radioactivity.

> <http://home.att.net/~wesvanpelt/Radiation.html>

> <mailto:wesvanpelt@att.net>

>  

> -----Original Message-----

> From: owner-radsafe@list.vanderbilt.edu

> [mailto:owner-radsafe@list.vanderbilt.edu]On Behalf Of Speercl

> Sent: Friday, May 31, 2002 10:36 PM

> To: BLHamrick@AOL.COM; radsafe@list.vanderbilt.edu

> Subject: Re: Welcome to California

>  

> I am in the beginning stages of starting my own business of performing

> radiation scanning surveys of large land areas.  If I was to perform gamma

> surveys for license termination in California, what would be the "best"

> technology available to perform these surveys?  I know sampling will have

> to be done and can be counted on a HPGe, REGe or the like, but what about

> land area scanning?  Typically in the past 2 x 2 NaI detectors were used,

> and large area plastic scintillator (LAPS) detectors are comparable, but

> the "Best" is . . . .?  I have thought about getting a 4 x 4 x 4 NaI but

> then a 4 x 4 x 16 NaI would be better. . .then four 4x4x16 NaI detectors

> would be better still.  But then this large of a detector array would mean

> I would be averaging a point source over the field of view of the detector

> system . . . I run into the same line of thinking when I try to figure out

> how fast to scan.  I typically take a moving one second count with a LAPS

> using a GPS, but wouldn't a one minute static count be better before

> moving on?  What detector and scanning method is out there that can

> measure gamma emitting radioisotopes to a 1 in a 1,000,000 cancer risk?

>  

>  

> Carl Speer

> Real-time Radiological Services, Inc

> Las Vegas, NV

> 702-639-0066

> www.realtimerad.com <http://www.realtimerad.com>

>  

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