Design and development study of gradient composite shielding material for nuclear radiation

In this manuscript, the design process and genetic algorithm coupled with the SuperMC to design the gradient composite radiation shielding material are described. As nuclear radiation penetrates the shielding materials, its energy spectrum and flux change gradually with depth as a result of interaction with material, so composition of materials should also change accordingly for effective shielding that gives the idea of gradient shielding materials. To design the gradient shielding material, the changed leaked source is determined and analyzed at smaller steps along the depth. At each step the composition is adjusted according to changed leaked source that makes the gradation of gradient shielding material. As the step size is smaller, so there are hundreds of input files to be executed, to handle this long computational work, a genetic algorithm was developed that automatically generates the required composition according to leaked source, write the inputs files and execute them on the SuperMC, analyze the outputs, and extract the data to design the whole gradient shielding material. This genetic algorithm coupled with SuperMC takes the base materials, source, mesh size and total thickness as input parameters. As an example, a gradient material based on Polyethylene (C2H4), Tungsten (W) and Boron carbide (B4C) was developed using this algorithm and compared its performance to that of homogenized material and potential layered shielding structures having the same total contents of base materials as that of gradient material. At a thickness of 150 cm, the total dose through the gradient material is about 1250% lower than the total dose through the homogenized material, which shows the better shielding performance of the gradient shielding material. So the gradient composite shielding materials would be particularly important for shielding in mobile compact nuclear applications.