Trade.Information

Product Name: ALPHA SURFACE CONTAMINATION

Product Description

System: Electret Ion Chamber 
Surfaces contaminated with alpha activity 
Radiation detected : Alpha 

Operation 

This system is a passive integrating detector system for measurement of alpha-emitting contaminants on surfaces. It consists of a charged Teflon disk (electret), open faced ionization chamber, and electret voltage reader and data logger. When the electret is screwed into the chamber, a static electrostatic field is established and a passive ionization chamber is formed. The chamber is deployed directly on the surface to be measured. Alpha particles emitted from the contaminated surface enter the chamber, ionize the air molecules, the ions are attracted to the charged surface of the electret, and the electret charge originally present gets reduced. The electret charge is measured before and after the exposure with a portable electret voltage reader, and the rate of change of the charge (change of charge divided by the time of exposure) is proportional to the alpha activity on the surface. 

Electret ion chambers (electret +chamber) are inexpensive, simple, passive, with no moving parts or electronic components, unaffected by ambient environmental conditions and can be normally used for several measurements before a need for replacement of the electret. These are essetially windowless detectors. In low-level measurements, a second detector with a Tyvek filter may be deployed in parallel to correct for background response. 

Specificity/Sensitivity: 

This method measures gross alpha contamination. The measurement may be converted to elemental or isotopic concentration ( such as Pu, U or Ra) if the isotopes are known or measured by another method. The lower limit of detection is a function of deployment time: For a 50 cm2 area detector, 53dpm/100cm2, 15dpm/100 cm2, and 8.4dpm/100cm2 with deployment times of 1 hour, 8 hours and 24 hours respectively. A new 200 cm2 area probe improves the sensitivity by a fctor of 4. Applicability for Site Clean up: High surface contamination levels may be measured with a deployment times of a few minutes. Surface alpha activity down to background levels may be quantified with deployment times of 24 hours or more. Due to their small size(1.5 inch tall and 3 inch diameter) these may be deployed in hard- to- access locations. Several hundreds of the detectors can be deployed and analyzed at a time using one measuring/analyzing instrument. 
Cost
Cost of Equipment: $ 4000 to $ 10000 
Consumable cost of detector per measurement: Under $1 

K.E.Meyer et al Utilization of electret ion chambers for characterization of gross alpha emission from indoor surfaces in DOE Methods for Evaluating Environmental and Waste Management Samples . method RA 010, (Steven Goheen, Batelle NothWest Laboratories, Editor) 1994 
Measurement applications include :
Measurement of contaminated surfaces 
Qualifying Measurement for a free release of contaminated sites
Monitoring of pre and post decommissioning/decontamination of contaminated sites 
Surveying large buildings

Company Details

Rad Elec Inc (REI) was incorporated in 1987 to manufacture and commercialize a product researched and developed under a research contract with NYSERDA (New York Energy Research and Development Authority) during 1986 -1987. The product was based on... more