The verification of the fuel integrity is one of the important challenges in nuclear power plants. Also, the International Atomic Energy Agency (IAEA) monitors and controls the nuclear inventory of member states called safeguard verification. Nowadays, The Gamma Emission Tomography (GET) as a powerful tool use for above-mentioned verifications. In this paper, a GET system was simulated to investigate its feasibility for identifying the partial defect as a type of safeguards verification. The simulation includes three steps: (a) forward problem (calculation of source term and simulation of GET system in MCNPX code), (b) inverse problem (producing cross-sectional image of the fuel assembly from gathered gamma ray recorded in GET system detectors by FBP Algorithm), (c) data analysis (using our new developed algorithm which calculates the relative activity in all rods of the fuel assembly by the cross-sectional image data). It is shown that the mentioned algorithm calculates relative activities with appropriate accuracy.