Development of Aluminum-Based Neutron Absorber Material Containing Gadolinium

Neutron absorber materials are used to prevent the criticality of fuel assemblies in dry casks and spent fuel storage racks. Currently, aluminum/boron carbide metal matrix composite (Al/B4C composite) is used for neutron absorber materials, which can be produced via a powder metallurgy process. In general, neutron absorbing performance (10B areal density) of Al/B4C composite is controlled by boron carbide (B4C) concentration and thickness of the composite. If the thickness is limited by the design, the concentration needs to be increased to ensure the performance. However, this results in reduced ductility of the composite. The addition of another element that has a larger thermal neutron absorption cross section than boron may improve the ductility while keeping the same neutron absorbing performance since the volume fraction of the compound would be lower than using boron alone. Gadolinium was selected as a candidate element because it has a large thermal neutron absorption cross section and has been used in the nuclear industry. Aluminum/gadolinium oxide metal matrix composite (Al/Gd2O3 composite) was manufactured. From the evaluation of this new material, it was found that the amount of particles in the composite could be reduced by using of Gd2O3 instead of B4C when neutron transmission rate is same between Al/Gd2O3 composite and Al/B4C composite. In addition, it was shown that the elongation of the Al/Gd2O3 composite is higher than that of the Al/B4C composite, which has a neutron absorbing performance as high as the developed composite. The aluminum-based neutron absorber material containing gadolinium, which has high neutron absorbing performance and good formability, was developed for spent fuel storage application.