Investigation of control bars used in nuclear reactors by materials

Control rods in nuclear reactors are used to provide criticality of the reactors. Boron, boron compounds, samarium, gadolinium, hafnium, cadmium are used as control rod materials in nuclear reactors because they are elements with high neutron flux cross section. The absorption cross section values of these elements for high-energy photons should also be examined separately. For this purpose, photon absorption cross sections of materials such as boron, boron compounds, samarium, gadolinium, hafnium, cadmium which are used as control bars in nuclear reactors have been obtained from X com photon activity section program for energy values between 0.001-1000 MeV. The change between the energy and the linear absorption coefficient is graphically obtained to determine the energy range of the photoelectric absorption edges. It has been found that the absorption edges are observed around the Z atomic numbers of the elements and that the absorption edge peaks do not occur in the elements with Z <13. In addition, linear absorption coefficients, half-value thicknesses, one-value thicknesses and mean free path values were calculated using mass absorption coefficients. It is observed that the variation in the graph drawn between linear absorption coefficient and energy is exponential. It is found that the change is linear in the graphs drawn between the linear absorption coefficient and the half value. In this study, it was concluded that boron, boron compounds, samarium, gadolinium, hafnium, cadmium elements are not only good neutrons sweating but also at absorbing high energy photons. Key Words: Control bars, nuclear reactor, photon, absorbtion, cross section.