Characterization study of high efficiency particulate filters (HEPA) from exhaust system of isotope wing

Isotope Wing of Radiological Laboratories (RLG) is primarily involved in chemical processing and fabrication of reactor produced radioisotopes. These radioisotopes are supplied to various hospitals, industrial units and research institutions of our country. Fabrication of high activity long-lived radioisotopes like ⁶⁰Co, ¹⁹²Ir and ¹³⁷Cs are carried out by BRIT Facility at RLG. Majority of the relatively short-lived radioisotopes are processed by Radiopharmaceuticals laboratories of Isotope Wing. Ventilation system of Isotope Wing is designed to control the movement of airborne radioactive materials. Two stage exhaust filtration is provided for BRIT facility involved in fabrication of high activity sources in hot cells. Radiopharmaceutical laboratories generally handle relatively short-lived radioisotopes in fume hoods, glove boxes and lead shielded production boxes and generally have two stage filtration systems. Apart from Iodine-131, reactor produced ⁹⁹Mo is processed for supply of ^99mTc to various hospitals. Numerous other relatively short lived radio isotopes like ¹⁷⁷Lu, ³²P, ¹⁵³Sm etc are also processed. Characterization of used exhaust HEPA filters was carried out for detection and measurement of various radionuclide's present in the HEPA filter and in estimation of total activity present in the HEPA filter. This paper explains in details about the results of characterization study and detection and measurement of ⁵⁷Co in the HEPA filter along with the ⁶⁰Co which is predominant in the total activity of the HEPA filters. Characterization of filters is effective for compliance with waste disposal criteria