PNNL

Abstract

Abstract - This paper presents an overview of the dosimetry system, dose equivalent calculation methodology, and QA/QC practices used at the U.S. Department of Energy Hanford site. It describes some of the problems encountered in accurately measuring dose equivalent quantities under a broad range of field conditions that do not necessarily correlate with laboratory calibration conditions and the approach taken to solve these problems. Personnel at Hanford are monitored with a combination of Harshaw model 8825 and 8816 thermoluminescent dosimeters and CR-39? track etch dosimeters. Extremities are monitored using the ICN MeasuRing loaded with a Harshaw XD740 chipstrate TLD. All dosimeters employ LiF:Mg,Ti elements that are read onsite with Harshaw model 8800 and 6600 TLD readers. CR-39? dosimeters are electrochemically etched in non-commercial etch chambers and counted with an automated track counting system developed by Pacific Northwest National Laboratory. Problems with over response of the 8825 with respect to Hp(0.07), under response of the 8825 with respect to Hp(3), and over response of the 8825 with respect to Hp(10) in Hanford's 90Sr/90Y beta radiation fields are discussed. Approaches to measurement of the operational quantities for field conditions and algorithm solutions to the above problems are described. Methods used to calibrate the ring dosimeter for Hanford field conditions together with limitations of the ring dosimeter in measuring Hp(0.07) for extremities, particularly when covered with protective clothing, are also discussed.