[ RadSafe ] Contamination..... static electricity, radon progeny and whole body monitors

[parthasarathy k s]

Hi friends,

A few years ago, I was testing a radium tube  for leakage. The leakge was sufficient to make my polyester shirt "active" in a few minutes. I sealed the tube tight in a special steel  tube and send it for disposal. I have to keep away  my shirt for a day to see that the accumulated radon progeny decayed completely. I remember the incident as that was the first time I  removed my shirt and wore a lab coat!

The tube landed in my laboratory  as I was initiating a nationwide program of checking  radium stock in over 65 hospitals in different parts of India. 

We had reason to suspect that the tube is likely to be leaky. We recovered  it---- hold your breath--- from the ashes in a crematorium. The careless hospital staff released the dead body of a patient without removing the intracavitory applicator loaded with five radium tubes (totally 50 mg of radium). All sources were intact except the one I received for further checking in my lab. Because of deplorable safety status in handling radium in Indian hospitals we withdrew the entire stock of radium (about 20 gms)

I had my further contact with static electricity and radon progeny during my doctoral programme in Leeds University. I could  demonstrate the increase in background counting rates of a whole-body monitor due to the accumulation of  radon progeny present in air on the surfaces of whole-body phantoms made of polythene. Covering the phantom with aluminum foil reduced the accumulation; I verified it experimentally.The retention of activity on the phantom surface can affect background stability.It is specially important when the radioactivity to be measured is low, as is the case with mesurement of body potassium. (Those academically inclined may refer to Knowles or write to me personally, I shall provide the references to my papers in Nuc.Instr. Methods in the 90s)

Regards

  K.S.Parthasarathy Ph.D
     
  Raja Ramanna Fellow
  Strategic Planning Group
  Board of Research in Nuclear Sciences
  Department of Atomic Energy
  GN 18, Vikram Sarabhai Bhavan
  Mumbai 400094, INDIA
   
  91+22 25555327 (O)
  91+22 2 5486081(O)
  91+22 2 7706048(R)
  9869016206 ( Mobile)
   
   
  



----- Original Message ----
From: JGinniver at aol.com
To: Kyle.Harness at pgnmail.com; radsafe at radlab.nl
Sent: Friday, 8 September, 2006 11:29:26 PM
Subject: Re: [ RadSafe ] Contamination Monitor and Static Electricity

Hi Kyle,
 
as others have said more information would help.  However I'm a bit  confused 
about the statement "with no confirmed activity after further  
investigation".  My experience with Radon is that you will  find measurable alpha activity 
using hand held portable contamination monitors  if the alarm is due to Radon 
being attracted by static on items or  clothing. Our policy is to hold back the 
item of clothing and re-monitor  after a couple of hours to confirm that it 
has gone, and hence was due to  Radon daughters. As others have said plastic 
hard hats and polyester pants  are favourite for this type of problem, but 
modern polyester fleece jackets are  also common culprits.  Consequently if your 
facility supplies clothing to  personnel to wear they should be supplying cotton 
clothing.  I understand  that some facilities also have problems with fission 
product Noble gases, as  these can also be attracted by static charges on 
clothing.  However this  can also e measured when the individual is checked 
following an alarm in the  Personnel Monitor.
 
Some modern units, (I think the IPM9 from Thermo and the Argos 6 from  
Canberra) have a radon compensation function.  I would suggest that you  contact the 
supplier of your equipment for further advice.
 
Regards Julian
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