STUDY OF THERMO LUMINESCENCE DOSIMETER READER AND GAMMA ATTENUATION IN TLD BADGE

Abstract

The Semi-Automatic TLD Badge Reader TL1010S is a personnel monitoring system, developed & manufactured by Nucleonix Systems is primarily designed to read the TLD card (TL dosimeters) worn by radiation workers. Several Personnel radiation monitoring systems such as photographic films, pocket ionization chambers and thermoluminescent dosimeters (TLD) have been used for the routine evaluation of radiation exposures to personnel. Recently there has been a rapid increase in the use of TLD for personnel monitoring of radiation workers. This Semi-Automatic TLD Badge Reader is primarily designed to read Bhabha Atomic Research Centre (BARC) developed CaSo4 (D4) PTFE disc dosimeter based TLD cards. These cards utilize three dosimeters. The TLD personnel monitoring system essentially consists of two major parts: TLD badge and TLD badge reader. The TLD Badge comprises of a plastic cassette containing a TLD Card made of aluminum with three Teflon TLD discs (13.3mm and 0.8mm thick) that are mechanically clipped on to circular holes (12.0mm) punched on it (52 x 30 x 1mm). Each TLD Card also comprises of a unique punched hole ID which is readout during the acquisition cycle for identifying the wearer of the TLD. The TLD Badge Reader is designed to measure X, Gamma and Beta radiation dose. The metal filter combination (1mm Al + 0.9mm Cu) is provided to reduce the photon energy dependence of the TL discs. The TL badge reader is calibrated such that the TL output of the disc under the metallic filter reads directly the gamma radiation dose. The radiation workers wear the dosimeter & the radiation exposure is estimated on the basis of TL dosimetric reading. Thermoluminescent dosimeters make use of the property of certain materials, which absorb energy when exposed to X, Gamma or Beta radiation. On heating, the absorbed energy is released in the form of visible light. A plot of light intensity emitted against temperature is known as a glow curve.