Performance evaluation of multiple gamma-ray detection instrument by non-destructive measurement of radioactive waste sample

Kochiyama, Mami ; Haraga, Tomoko   ; Kameo, Yutaka ; Takahashi, Kuniaki 

A nondestructive measurement of gamma-ray emitting nuclides has been studied and Multiple gamma-ray Detection Instrument is newly constructed with 4 detection units consisting of Ge and BGO detectors. Compton scattering was decreased by the combination of Ge and BGO detectors. This instrument was applied to the detection of interested nuclides in radioactive waste sample, which contains significant amount of Co-60, and detection limit of the interested gamma-ray emitting nuclides were improved by a factor of 4 to 12 times than single gamma-ray spectrometer. As for Nb-94, the radioactivity determined from measurements using Multiple gamma-ray Detection Instrument in this sample was agreed with that determined by radiochemical analysis within 15%. It was confirmed that the instrument are useful for radioactivity determination of gamma-ray emitting nuclides in radioactive waste.