Investigation of Shielding for Fast Neutrons Using Polymer Composites with Pb Reinforcement

Abstract

    Manufacturing high-efficiency polymeric materials to moderate fast neutrons by converting them into slow or thermal neutrons. These materials absorb thermal neutrons as well as gamma rays associated with neutrons. Materials of small mass number are used to slow down fast neutrons because neutrons have a high cross-section when they interact with these materials. Materials of high mass number absorb gamma rays. Polyurethane and epoxy were mixed in various ratios to create a blend to serve as neutrons shield, lead (Pb) was then added to the blend at weight percentages of 20%, 30%, 40%, 50%, and 70% to produce a polymer composite.

    Polymeric materials reinforced with lead in various ratios were tested to select the best composite. The Polymeric samples were placed between the neutron source and the detector, and changing their thickness from 1 cm to 10 cm in increments of 1 cm. The neutron count rate for five readings was recorded, and the average was taken. As a result, the relationship between count rate and sample thickness was plotted, the half-value thickness of the shield was determined, the relationship between the logarithm ( ) and the thickness was drawn, the removal cross-section ( ) was determined, as well as, the mean free path of the fast neutron, and these were compared for each sample. This work concluded that the sample containing 20% lead with a thickness of 10 cm and a diameter of 4 cm was the best shielding for absorbing fast neutrons.

    The removal cross-section (∑_R) was analyzed, and the value of half-thickness of the shield, as well as the mean free path of the fast neutron, were determined and compared for each sample.

During the research, it was revealed that a sample containing 20% lead was the best shielding for absorbing fast neutrons.