RE: Tl-201

[Marty.Bourquin@GRACE.COM]

Since the individual is alarming portal monitors how do you handle 

access of the individual to potentially contaminated areas?

And secondly how do you handle the fact they are "still irradiate their 

TLDs from the inside out"?  Do you keep them out of work for 4-5 weeks?

 

We typically dont find out a person has had TI administered until 

they're on their way out and set off the portals and friskers. (they 

conviently forget to mention it until then).

 

Marty Bourquin

W.R.Grace

Manager EHS, RSO



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

From: mlantz33@CYBERTRAILS.COM [mailto:mlantz33@CYBERTRAILS.COM]

Sent: Monday, August 05, 2002 1:39 PM

To: willim01@mskcc.org

Cc: radsafe@list.vanderbilt.edu

Subject: Re: Tl-201







Matt is absolutely correct.  I just saw two messages that implied that 

we were wrong in telling Kurt Geber that Tl-202 is the cause of the 

portal monitor alarms.  They reasoned that Tl-202 was less than 5% of 

the original activity.  In fact, it is usually less than 2% in the MANY 

cases I have seen  -- ON DAY 1. 



However, at day 60, it is 99% of what the individual has in them.  This 

is simple decay of two radionuclides, one with a short half-life and 

one with a slightly longer half-life. 



We happen to have portal monitors AND whole body counters at our site.  

So, it is very simple to evaluate a portal monitor alarm and show the 

Tl-202 begin to dominate over time.  Therefore, when workers still 

irradiate their TLDs from the inside out, alarm portal monitors, and 

make the assessment of other internal radionuclides difficult to 

separate (past 30 days, as was the original question), it isn't because 

of the Tl-201 that, yes, was 95% of the mix on day 1, it is because of 

the Tl-202. 



Mike Lantz, CHP 



willim01@mskcc.org wrote: 



     Kurt, 



     It is not excessive and someone hit it right on.  It is the 

impurity 

     (Tl202, T1/2 12.2 d) that's hanging around still alarming the 

portals; 

     4 to 5 weeks sounds about right. 



     Obtain a copy of HPS Vol. 61. No.3 pp. 427-430, 1991, Michael 

Stabin 

     and Audrey Schlafke-Stelson for other nuclides and contaminants of 

     interest. 

  



     Matt Williamson 

     Memorial Sloan-Kettering Cancer Center 

     New York, NY  10021 



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