Neutron shielding materials

Purpose: To improve neutron shielding performance by preventing the atomic density of hydrogen from lowering while exhibiting the characteristics of silicone elastomer. Constitution: A shielding material used is silicone elastomer added with 0.5 to 5 percentage by weight of boron compound. The addition of the boron compound as described above can improve the capacity of absorbing thermal neutrons. Boron compounds to be used are B4C, BN, B2O3, etc. When these compounds are used as a shielding material, the dose rate will suddenly increase if the aforementioned range of percentage by weight is exceeded. Furthermore, the atomic density of hydrogen can be increased by adding polypropylene or hydrogenated titanium to the aforesaid shielding material. In this case, when the quantity of polypropylene added is increased, lowered nonflammability results and also when the quantity of hydrogenated titanium is increased, lowered fluidity before setting results. Therefore, the both additives are added at an appropriate rate. (Horiuchi, T.)