Estimation of sensitivity factor for direct thoron progeny sensors in occupational environments of a reprocessing facility

Direct Thoron progeny sensors are deposition based absorber mounted track detector, which can be used for measuring the long time-averaged progeny concentrations. Extensive measurements had been carried out in the indoor environments using these detector systems. In the present work, the field studies of these dosimeter systems carried out in the ADU Processing areas of Kalpakkam Reprocessing Plant has been reported. Since the sensitivity factor of these dosimeters is dependent on the deposition of progeny particulates on the detector surface, hence the various environmental processes governing the deposition, affect the sensitivity factor, especially the air exchange rates. Since higher air exchange rates are generally maintained in the Thorium processing plants, these dosimeters were first calibrated for the plant environment, and the calibration factor was obtained as 2.5 Tr cm-2d-1 / EETC (Bq m-3). (author)