Re: Finger Dosimetry

[BRZGV@ccmail.ceco.com]

     1. The frequency of the read should be based upon the expected rate of 
     dose accumulation and recommedations of the manufacturer due the types 
     of fields your personnel are exposed to.  Look at LLDs/reportable 
     levels as well.  Different materials are available based on your type 
     of fields.  Some values for minimum reportability for finger ring 
     dosimeters might be in the order of 30 mrem for x and gamma rays and 
     40 mrem for energetic betas.  Readings may be skewed if the exposure 
     is from low energy X-rays and beta particles instead of gamma rays.  
     You may need correction factors as determined by the vender based on 
     evaluations of your radiation fields.  Landauer is our current vendor 
     and should be able to provide technical assistance (708-755-7016).  
     
     
     2.a)  The ring should be worn directly against the skin, irregardless 
     of the covering material.
     
     2.b)  At a nuclear power plant, workers are generally working with 
     larger items, so general placement on the best fitting finger with the 
     sensitive area palm-side down is entirely appropriate.
     
     3)  Rings worn under protective gloves seem to work out pretty well.  
     Every once in a while the ring may need a wipe down or the element may 
     need to be taken out of the ring due to contamination in the cracks 
     where the element is inset into the ring.  Gross contamination is 
     found probably <2-3% of all issuances when personnel are frisking out 
     of the immediate work area, and a more sensitive check with our NaI 
     tool monitor sometimes catches a couple when they are remove from the 
     radiologically posted area for shipment to the processing vendor.
     
     4)  As far as regulatory positions, I don't have a specific one to 
     come to mind and don't have a lot of time to research, but you may be 
     able to draw some inferences from the following documents:
     
     INPO 91-014, "Guidelines for Rad Prot. at Nuclear Power Plants."
     
     NRC IE notice 83-59, "Dose Assessment for Workers in Non-Uniform 
     Fields."
     
     INPO REN/OEN-01, "Dosimetry Placement for Steam Generator Workers."
     
     Various NRC HP Position papers should exist.
     
     A rough idea might be to compare general exposure rate information at 
     contact and 12 inches (30 cm) to get a feel for approximate extremity 
     to whole body ratios.  Decide on some ratio of WB/extremity such that 
     worker would not exceed say 1% of SDE limit based upon the workers 
     annual dose.  Apply that generic annual ratio back to specific job 
     cases to determine which specific work tasks would require finger 
     rings and which would not.  This might work as some sort of basis at a 
     nuclear power plant where the work activities are very diverse.  A 
     lab-type facility where the fields are short-ranged and/or 
     sources/beakers being handled by the hand often might require blanket 
     issuance of finger rings to all lab personnel.  
     
     We have our own specific criteria, but it would probably be better to 
     develop your own based upon some of the information sources listed 
     above.
     
     I would also be glad to entertain thoughts from some of our older and 
     wiser HP brethren on the subject
     
     Glen Vickers
     Health Physicist, Nuclear Power Generation
     815-458-2801 ext. 2792
     BRZGV@ccmail.ceco.com


______________________________ Reply Separator _________________________________
Subject: Finger Dosimetry
Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET
Date:    1/18/96 1:22 AM


Dear Radsafer,
     
We are going to establish our own finger dosimetry at the Hong Kong 
University of Science and Technology. Your experience and advices are most 
appreciated on:
     
(1) The frequency of readings
(2) The proper location of the TLD ring. 
     
    (a)underneath gloves or on top of gloves? 
    (b)facing the plam or opposite the plam?
(3) Precautions to prevent contamination.
(4) Is there any standard protocol or guideline?
     
Regards
     
Paul
     
Paul M W Chan, PhD
University Radiation Protection Officer
Hong Kong University of Science and Technology 
IN%"eomwchan@usthk.ust.hk"