Review of qa\qc aspects of electret ion chambers- manufacturing practices and performance in worldwide inter-comparison exercises in the past eight years

Rad Elec Inc., located in Frederick, MD, USA is the only commercial producer of electret ionchambers (EIC) systems. These are distributed under the brand name of E-PERM, electret-passiveenvironmental radon monitors. Different versions of these are used in various applications, whichinclude: measurement of indoor/outdoor radon, thoron (220Radon), radon flux, radon in water, radiumin soil/building materials, environmental gamma radiation, tritium in air and on surfaces, alphacontamination on surfaces and in soil. The system consists of three major components: electrets,chambers and electret voltage readers. ISO 9002 listed Rad Elec vendors manufacture chambers andreaders. Rad Elec manufactures and certifies the electrets for stability and performance. The strictongoing QA\QC practices in the manufacturing and documentation of QA\QC data is the key thatassures that all Rad Elec-certified electrets have the same stability and calibration characteristics,irrespective of when these were manufactured. The paper reviews the ongoing QA\QC practices in themanufacturing, the type of certificates issued to the customers and contents of 1997 USEPA QA auditreport. Results of blind annual inter-comparison exercises conducted by Environmental MeasurementLaboratory (U.S. Department of Energy) during 1990-1996 are reviewed.