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-contact gas heating unit interfaced to an application software package that evaluates and manages generated data. The dosemeter consists of elements that are 240 mg.cm-2 thick and which are symmetrically filtered. The two CaF2:Dy (TLD-200) elements are shielded by 80 mg.cm-2 ABS plastic, 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 4.13. The procedures applied to study the energy response, fading, linearity, uniformity, minimum detectability, reproducibility, reponse dependence on angle of incidence are described, reviewed, and the results presented. The study also included self-irradiation, sensitivity to light and moisture, and performance in actual field conditions. The results demonstrate that this dosemeter satisfies all of the N545-1975 performance requirements. The dose calculation algorithm developed for this dosemeter is outlined and the accuracy of its performance in various pure and mixed fields has been determined. The results are presented and discussed. (author)