1. Xi’an Rare Metal Materials Institute Co., Ltd., Xi’an 710016, China
2. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
3. Northwest Institute for Non-ferrous Metal Research, Xi’an 710016, China
With the increasing number of reactors in China’s nuclear power plants, the generation, transportation and storage of spent fuel have become a serious problem. The closed-loop treatment and recycling of the huge amount of dangerous nuclear spent fuel unloaded is more environmentally friendly and safe than traditional deep burial. Using neutron poison optimized structural materials to manufacture related equipment and instruments, can ensure the safe operation of spent fuel postprocessing. This work investigates the phase diagram of B or Gd added to 316L stainless steel, Ti35, zirconium and other materials commonly used in spent fuel reprocessing. The results show that B and Gd can significantly improve the neutron absorption effect of structural materials, but the chemical properties of B and Gd are far different from those of transition metal. The phase diagram shows that, except for the maximum solid solution of α-Zr is 2.8at% Gd, B and Gd cannot be dissolved in conventional metal alloy systems in large quantities. Forced addition is bound to bring great harm to the mechanical properties or corrosion resistance of the alloy. The cluster model can be adopted to increase the solid solubility of elements that are difficult to be dissolved. Through the manufacturing process of homogeneous precipitation or recombination of B and Gd compound phases and the multialloying of Zr-Gd and Ti-Gd systems, the mutually soluble intermediate phases can be introduced to solve the application bottleneck of neutron poisons B and Gd in spent fuel reprocessing.