Etalonnage du systeme Harshaw TLD 4500 du Commissariat general a l'energie atomique

The Harshaw TLD 4500 reader and TLD 100 cards, 2-elements TL in natural LiF (Mg:Tl), object of this paper, constitute, for the Democratic Republic of the Congo, the shackle for individual monitoring system for occupational exposures to external radiation. For the calibration of above dosimetry system, a calibrated Cs-137 gamma irradiator from Isotope Products Laboratories, Valencia CA91355 661-309-1010, was used for irradiating all dosimeters to the same dose of 2mSv. Thus, from repeated measurements, its gamma beam dose rate of 50.025μSv/h was determined with an accuracy of 10% on the irradiation point located at 80 cm. Five best TLD100 standard dosimeters with sensibilities into 99% of the interval of confidence, were generated. These golden cards and the above reference dosimetry enabled through WinREMS software to calibrate the Harshaw TLD 4500 system in order to assess suitably individual doses of radiation workers in Democratic Republic of the Congo. The calibration configuration of Harshaw TLD 4500 was found as follows : the reader calibration factor (RCF=0.0847nC/μSv±1.5%) and the element correction coefficient (ECC=0.05±1.3%). The standard deviations of readout for reader reference Laser light and for the PMTs background were respectively found at 2% against 30% in contrast to the technical performance of the Bicron Hashaw TLD 4500 market. Therefore, other parameters of the system have been remained stable with the time. By comparison to previous calibration configurations undertaken on this same TLD system, we would conclude that Harshaw TLD 4500 system remained still stable and reliable for individual dose measurements of occupational exposures to external radiation in Democratic Republic of the Congo.