Investigating Neutron and Gamma Radiography Techniques and their Comparison using MCNP code

Neutron and Gamma radiography are two important techniques for investigating objects which cannot be observed ordinarily such as the inside body organs including bones, inside part of the fuselage or the nuclear fuel of the reactors. Gamma radiography, which has a longer tradition compared with the neutron radiography, is effective in many ways; however, for analyzing the objects with a hard coverage it does not help. Therefore, neutron radiography is used instead. In fact, due to the different nature of the gamma and neutron beams interaction with the elements, different information is provided which complement both and can be considerably helpful in recognizing and investigating the desired case. As a result, these two kinds of radiographies can be considered as complementary. In this study 11 pieces of 11 different materials (i.e. 238U ,U Nat, 235U ,82pb 47Ag, 29U, 28Ni, Sn 50,C 6, C2H4 and H2O) in the presence of high-energy gamma source (i.e. Cobalt Co60), low-energy gamma mesh (Iridium Ir77) and thermal neutron mesh with the energy (0.025 ev) were simulated using the MCNP technique. The output data were changed into images by MATLAB software. Comparison of the simulated image by the experimental radiography image indicates a reasonable concordance between the two methods. As a result, use of MCNP code in simulating radiography images of sample pieces with a complex geometry can be effective in separating the defective areas.