Review on the Influence of Excavation Damage Zone (EDZ) on Nuclide Migration

With the development of nuclear power, the disposal and disposal of high-level waste generated by nuclear power plants have also received great attention from the public. After a comprehensive comparison of methods such as transmutation method, dilution method and isolation method, at present, deep geological disposal of high-level radioactive waste is recognized as the best method for nuclear waste at home and abroad. During the construction stage of the repository, due to excavation, the stress in the surrounding rock is redistributed and the surrounding rock is disturbed. The original fissures in the rock mass expand and connect, resulting in new micro-cracks, and the permeability coefficient of the rock mass becomes larger. It is the excavation damaged zone (EDZ). EDZ is located between the engineering barrier of the high-level radioactive waste repository and the remote surrounding rock, and is an important channel for the migration of radionuclides. Groundwater flowing through the deep surrounding rock fissures and the fracture zone of the disturbed layer cause water-rock reaction to change the composition, which affects the release rate and migration parameters of radionuclides in the high-level glass body. It is necessary to obtain large-scale fissures during excavation in the underground laboratory. Rock and disturbed layer fracture zone, establish nuclide release and migration devices, and obtain groundwater intrusion into deep surrounding rock fissures and disturbed fracture zones that lead to the release and migration parameters of high-level radioactive glass nuclide, which is useful for the safety evaluation of the entire geological disposal site. Researchers conducted simulation analysis through experiments and computer software and found that fissure water, Eh-pH, fissure fillings, colloids in the fissures, and humic acid in the fissures in the EDZ zone all affect the migration of nuclide. Carrying out research on the effect of EDZ on the release of nuclide source terms in high-level radioactive waste and studying on the migration behavior of nuclide under deep surrounding rock conditions, and grasping the release law of key nuclides under deep geological conditions and their migration in EDZ areas and fissuring laws and optimizing migration models will provide technical reserves for nuclear in situ migration experiments during the operation phase of underground laboratories, and provide technical support and scientific basis for the site selection, conceptual design and safety evaluation of my country’s high-level radioactive waste repository.