Optimal shielding structure design for a typical 14 MeV neutron source

Optimal shielding structure design plays a guiding role in the implementation of radiation protection engineering. The achievement of the optimal arrangement and thickness ratio for the layers of materials is the key to attaining a light-weight and small-volume shield but with the best shielding effect. In this research, the optimization design method is established by the genetic algorithm combined with the Monte Carlo N-particle code, and a four-layer neutron shield composed of iron (Fe), boron carbon (B 4 C), lead (Pb), and polyethylene (PE) is designed. When setting the total thickness of the shield to 20 cm, different arrangements and thickness combinations of these four layers are calculated. It is shown that the arrangement Fe-PE–B 4 C–Pb is the most radiological optimizing arrangement, and the optimal thickness combination is also obtained. Besides, it seems that the thicker the shield, the higher the requirement for the thickness ratio of Fe and Pb. In order to prove this, an optimal 80 cm thick shield is then designed, and the optimal thickness ratio is also obtained. It is found that the thickness ratio of Fe and Pb should also be increased in order to achieve the best shielding effect.