| Traditional thinking for the construction of hot cells where used nuclear fuel is handled simply consists of 4 – 8 foot thick concrete walls to provide the necessary shielding to protect workers. This work considers alternative materials for the construction of the walls and shielding for such facilities in an effort to reduce the thickness of the walls yet afford the same protection as the traditional walls. The materials selected were tungsten carbide and borated polyethylene (5% boron, high density polyethylene 1.4 g/cm3).
Experiments were designed to test the alternative materials, along with concrete and stainless steel, for shielding against gamma-rays and neutrons. The experiments were modeled in MCNP and the data were compared to the MCNP results. There was excellent correlation between the gamma-ray results with computed to experimental ratios of near unity for all shielding setups. There was good correlation with the neutron results with ratios ranging from unity to 1.17. These results allow for modelling to be used to determine the optimal thickness of each material in the shield.
Using MatLab to generate and analyze results the optimal thickness of each alternative materials was found. The concrete and stainless steel thicknesses were held constant at 30 cm and 1.27 cm. The optimal thickness of tungsten carbide was found to be 11 cm and the optimal thickness of the borated polyethylene was found to be 19 cm. The total thickness of the alternative shield is 61 cm which is half of a four foot (122 cm) thick concrete wall.
Key Words: Radiation Shielding, Hot Cell, Pyroprocessing, Gamma-Ray, Neutron, MCNP,
SCALE, Tungsten Carbide, Borated Polyethylene |