Segmented gamma ray scanning system using HPGe detector for the assay of alpha active waste present in 200 litre drums

A segmented gamma ray scanning system has been developed and set up in Radiochemistry Division for the assay of alpha active waste present in 200 litre drums. A 10% HPGe detector system is used for detection and analysis of special nuclear materials and other radionuclides present in waste packages. A multi gamma ray high intensity source of 152Eu is used for the determination of attenuation correction factors. The attenuation correction factors for all the gamma rays of 152Eu are fitted to a quadratic exponential curve to arrive at the attenuation correction factors for the 129.3, 375.0 and 413.7 keV gamma rays of 239Pu. The attenuation corrected counts per second of the standard drum and unknown drum are used to determine the amount of 239Pu present in the waste drum. The amount of 241Pu is also being estimated using the 208 keV gamma ray. Using this we are able to know whether the waste is from a research reactor grade plutonium or power reactor grade plutonium. This system is now being routinely used to monitor the alpha active waste present in the 200 litre drums. (author)