Materials Selection to be used as Shielding of the Neutron Diffractometer

Abstract

The TRIGA Mark-III nuclear reactor has several intrinsic security specifications related with the reactor core and a biological shield provided by the bathtub itself. However, to shield the exposition to gamma rays and thermal neutrons is vital for protecting the workers exposed to ionizing radiation or the incorporation of radioactive materials. For this reason, in this work we present a study for designing the shield for the neutron diffractometer of the nuclear reactor, with sufficient thickness to diminish the neutron flux (4.8x108 n/cm2-s), and simultaneously to allow the reduction of the dose speed. (Correlation between the absorbed dose and the probability that the stochastic effects appear). For considering the shield dimensions it is necessary to select the adequate materials which allow the attenuation of the gamma radiation and the neutron flux in the peripheral of the diffractometer. The shield design proposed is constituted by a polythene mixture, paraffin and boron, (PBP). A statistical analysis of the results, allows establishing the viability of the design proposed, reducing the neutron flux until an 80%.