Nondestructive Burnup Determination by Gamma-Ray Spectroscopy

A cold fuel assay method has been developed for nondestructive burnup determination by gamma-ray spectroscopy. This method utilizes the product of neutron flux and time as one variable to avoid tedious treatment of neutron flux, resident time, and intermittent type of iteration. No chemical or mass spectroscopic analysis is needed; only the photopeak of ¹³⁷Cs needs to be analyzed. The method has been applied to fuel element No. 25 of the Tsin-Hua open-pool reactor for burnup calculation. A 35-cm³ Ge(Li) detector connected to a 1024 MCA was used.