A SYSTEM FOR ENVIRONMENTAL MONITORING

The system described in this paper consists of a reader, multi-element dosemeters. and dose algorithm. The reader is a medium capacity non-c ontact gas heating unit interfaced to an application software package that evaluates and manages generated data. The dosemeter consists of e lements that are 240 mg.cm-2 thick and which are symetrically filtered . The two CaF2:Dy (TLD-200) elements are shielded by 80 mg.cm-2 ABS pl astic, 0.25 mm tantalum and 0.05 mm lead. The two LiF:Mg,Ti (TLD-100) are shielded by the 80 mg.cm-2 ABS plastic only. The response of this system was characterised according to the criteria established in the ANSI Standard N545, Section 4, as modified by NRC Regulatory Guide 4.1 3. The procedures applied to study the energy response, fading, linear ity, uniformity, minimum detectability, reproducibility, response depe ndence on angle of incidence are described, reviewed, and the results presented. The study also included self-irradiation, sensitivity to li ght and moisture, and performance in actual field conditions. The resu lts demonstrate that this dosemeter satisfies all of the N545-1975 per formance requirements. The dose calculation algorithm developed for th is dosemeter is outlined and the accuracy of its performance in variou s pure and mixed fields has been determined. The results are presented and discussed.