The Study On Damage And Failure Numerical Simulation Of Nuclear Power Plant

The development of Nuclear energy in China has entered into the golden age in recently years. Ensure the safety of nuclear power plant structure is a prerequisite for the development of nuclear power. Earthquake, accident pressure and external shock are important factors during the safety design processing about beyond design basis events of nuclear engineering structure. A reasonable and efficient numerical analysis model and a theoretical study, which mainly involves the static and dynamic analysis, nonlinear analysis, as well as local damage evolution, have important engineering practical significance.As large scale general finite element software, ANSYS, with its powerful function of pre-processing and post-processing, and plenty of analysis model and clear dipartition function, has been approved by Nuclear Regulatory Commission. It is increasingly widespread applied in the field of nuclear engineering mechanics analysis. But the engineer application shows that the nonlinear analysis of ANSYS, especially during the dynamic process, convergence difficulties may occur usually. This disadvantage weighted against the study on the analysis about damage and failure of structure, and consequently, the software applicability of the structural ultimate bearing capacity evaluation has been affected.Based on the above issues, this paper is focused on the numerical simulation about the damage process under internal pressure or external shock, research work is made on the following aspects:(1) Based on the general finite element software ANSYS platform, the paper develop three-dimensional Equivalent-Damage element USER300 with the UPFs secondary development technology. Regard concrete as the heterogeneous quasi brittle material which has nonequivalence of tension and compression characteristic. To simulate the damage evolution corresponding to the tensile and compressive fragment. A case study was done to demonstrate the reliability of USER300 and the compatibility between USER300 and Stand(?) ANSYS element.(2) Based on a dynamic nonlinear iteration technique in the form of increment, the paper developed an equivalent damage numerical model is developed which can consider the composite failure with the UPFs secondary development technology. The model combines the mesoscopic damage evolution mechanism of concrete structure in order to perfect the simulation function of structural failure process. Meanwhile, the applicable scope of nonlinear analysis of ANSYS has been expanded. At last, the reliability and convergence of this method have been verified by the analysis about the static and dynamic damage of three-dimensional structure.(3) Against the reactor building of a 1000 MW Nuclear Power Plant structure, the static and dynamic analysis which under different grade internal pressure and the effect of external events show the applicability of the model proposed in this paper. This method has not only enriched the technology of nuclear structural mechanics analysis, but also shows that the crash-load capacity of the 1000 MW Nuclear Power Plant structure can meet the requirements.To sum up, with ANSYS UPFS technology for secondary development tools, in this paper an Equivalent-Damage model is developed on the element level. This model, which can consider composite failure, involves the dynamic nonlinear iteration technique in the form of increment. The applicable scope of nonlinear analysis of ANSYS has been expanded. This method could be utilized during the bearing capacity analysis process of nuclear power engineer containment vessel, and the achievement can also be reference to practice engineering.