Re: Welcome to California

["Philip Egidi" <phil.egidi@state.co.us>]

There was a protocol developed using downhole 2 x2 NaI detectors for

estimating depth of contamination on UMTRA sites.  Total counts using a

scaler were converted to equivalent radium in soil.  It was used on

thousands of properties in Grand Junction, and on uranium mill cleanups.

 Results varied, most data was fairly representative, but sometimes

underestimated by as much as a factor of 3 (volume of material needed to

be excavated).  The now-defunct Technical Measurements Center at the DOE

facility in Grand Junction published protocols for calibrating the

instruments using the borehole models they had there on-site that

accounted for moisture, self attenuation, etc.  The methodology has a

practical application in the field, recognizing that heterogeneity is a

big factor (the data is only representative of a discrete area of

course).



Phil Egidi

phil.egidi@state.co.us 







>>> <AndrewsJP@AOL.COM> 06/03/02 09:04AM >>>

In a message dated 6/2/02 9:38:42 PM Pacific Daylight Time, 

kerrembaev@yahoo.com writes:





> Have you tried?:

> 

> 1. To estimate activity distribution by driling

> just a "few" holes.

> 

> 2. To establish correlation Depth vs Absorption

> (including self absorption) in the soil /

> Shielding from the soil.

> 

> 3.It could safe some money.... 

> 

> I know it can be done "easily" in the laboratory

> set up, I was wondering if a some one has tried

> that for the large areas monitoring....

> 

> 



I have done it two ways with interesting results.  The first was depth



monitoring for radium near the old US Radium facility in New Jersey. 

In that 

case we monitored the profile of the distribution of gamma activity in



boreholes that were designed to penetrate through the deposited

material in 

the dump areas.  My finding was that the data was not reproducable

because 

most of it was from radon gas finding its way through the coal ash that

was 

also dumped in the same area.  EPA management on the site would not

permit us 

to use the new GeLi detectors newly available because it was not in our



contract so we could not isolate the 0.184 MeV gamma line from the

radium.  

The reports ultimately were used as if the total gamma radiation was

from 

local radium, not just radon.  Boreholes allowed to air for a day or

more 

would 'dry up' as the radon escaped and would not produce the same

results at 

a later time.  Production and the plan, however, required the holes to

be 

drilled, monitored, and filled with clay very rapidly.  My lesson was

to not 

use this for radium.  The contractors lesson was to use the data to dig

up 

the entire community.



On another job, we monitored for thorium spilled on the ground by

sampling 

extensively.  To simplify this work, we began to use a bulb planting

tool to 

make a nice hole in the ground, then measure the spectrum in the hole

with a 

2x2 NaI(Tl) detector.  This data was quickly translated into activity 

concentrations and permitted rapid cleanup of the local contamination

without 

waiting for extended sampling turnaround times.  Sampling was used to

verify 

the in-situ measurements after cleanup was completed.  



John Andrews

Knoxville, Tennessee

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