Comparison of neutron attenuation properties of ferro boron slabs containing 5% natural boron with other high density materials

Abstract

Modeling and designing cost-effective neutron attenuation along with shield volume reduction is a challenging task in fast reactors. It involves reducing the neutron energy and absorbing them with suitable materials. A series of experiments were conducted in the South beam end of Kalpakkam Mini reactor with powders of ferro boron (FeB), ferrotungsten (FeW), boron carbide, slabs of FeB, and mild steel plates to study their neutron attenuation characteristics. In one of the experiments, FeB slab cast with 5% natural boron was used, and neutron attenuation measurements were carried out. The attenuation factors were found over a thickness of 28 cm for the measured reaction rates of 195 Pt (n, n') 195m Pt, 111 Cd (n, n') 111m Cd, 103 Rh (n, n') 103m Rh, 115 In (n, n') 115m In, 180 Hf (n, n') 180m Hf, 63 Cu (n,g) 64 Cu, 23 Na (n,g) 24 Na, 55 Mn (n,g) 56 Mn, and 197 Au (n,g) 198 Au reactions representative of fast, epithermal, and thermal neutron fluxes. A comparative analysis of the neutron attenuation behavior measured with various materials is presented. In case of attenuation of both thermal and fast fluxes, FeB is better than other high density materials such as mild steel and FeW. The outcome of the experimental study is that FeB slab cast with 5% natural boron can be utilized as cost-effective neutron shield in streaming paths in nuclear reactors.