Development of transportable segmented gamma ray scanning system for measuring on site

A transportable segmented gamma ray scanning system (TSGS) for measuring on site has been developed for the purposes of the accounting for and control of nuclear material in plant. The system developed is used for nondestructive assay of the contents of 235U, 239Pu or fission products existing in a great quantity of low density or median density heterogeneous residual, scraps or wastes. The system developed consists of a transmission source, a rotatable scanning plate, a beam shutter, and shielding body, stepping motors and control system, HPGe detector, nuclear electronics and computer. The full scale segmenting and scanning of samples, spectrum data acquiring and processing could be fulfilled automatically. The system was calibrated by using five standard samples of uranyl nitrate (90% 235U). The uncertainty of calibration is ±1%. A homogeneous sample prepared specially was used to test this system. The measurement results for this homogeneous sample were compared with the measurement standard value of controlled-potential coulometer (CPC). The deviation of both results is less than 1.4%.