[en] Nuclear material accounting in the spent fuel handling facilities is indispensable to the safeguards, and various measuring methods are used for it. Several nondestructive accounting methods such as gamma-ray spectrometry, neutron counting, calorimetry, K-Edge/KXRF, and so on can be employed in a case of wet processing products without fission products. But if the gamma emitting fission products include in the processing materials, the above-mentioned methods are limited to use of nuclear material accounting. In this study, a gamma/neutron combined system was designed for neutron coincidence counting and gamma isotopic analysis for small spent fuel samples before measuring pyro-processing products