Design and manufacture of composite flexible shield for neutron-gamma mixed fields

In this study, a flexible composite shield with a combination of polyethylene, tungsten and boron carbide has been designed and constructed for neutron-gamma mixed fields. For this purpose, theoretical studies were conducted using the multi-purpose MCNPX Code. According to the results of simulation studies, a multi-purpose composite was constructed using a combination of a solid phase of boron carbide particles with tungsten metal powder and a mixture of different types of soft and hard polyethylene in a laboratory at the center of polymer and petrochemical industry in Iran. The 241Am-Be neutron flux attenuation rate and the cesium gamma flux attenuation were measured for the built shield. The results show that in the polyethylene /boron carbide / tungsten (PE / B4C / w) composite with respect to the micrometric dimensions of the reinforcing particles and the high cross-section of interactions of the radioactive beams with these particles, the composite shield with a much lower thickness than the ordinary shields has higher absorption of gamma and neutron beams. This shield containing 30% of tungsten and boron with a thickness of approximately 0.5 cm, absorbs 90% of the Americium-beryllium neutrons and at the thickness of 2 cm absorbs nearly 40% of the gamma rays of the 137Cs source.