Three Dimensional Simulation of ITER Machine by Using Geant4

International Thermonuclear Experimental Reactor (ITER) is used as a model in this examination. By using dimensional characteristics and materials used in this Tokomak and in order to study some of its parameters, simulation is done by the use of Geant4 code. In order that the results are closer to reality, all the volumes (cylinders, torus and spheres) are defined three-dimensional for the code. With respect to neutrons produced in the plasma because the fusion reaction (D, T), for the neutrons with 14.1 MeV energy that emit isotropically, a torus shaped volume source also is defined for the code. The number of neutrons was obtained at any moment of the time in different parts of the machine. For some important parts, neutron energy spectrum in that part also was obtained. X-rays energy spectrum and prompt gamma inside and outside of the machine are also obtained. The results correspond well with published reports of this field. This paper also tries to show the ability and capability of the Geant4 code to simulate nuclear reactors like ITER.