Structure optimization of electrical penetration assemblies: Experimental facts and stress field analysis by the finite element method

Abstract

Thermal-mechanical induced stress in glass is critical for the performance of glass-to-metal-type electrical penetration assemblies (EPAs) used in nuclear reactors and is mainly determined by the thermal expansion mismatch between glass and metal and the structural design of the EPAs. Here, from the perspective of structural design, a new strategy for optimizing thermal stress in EPA glass is proposed. A flexible structure is designed to act as a stress buffer layer between glass and metal. The stress field of the EPA is analysed in detail using an improved finite element (FE) model, and the fidelity is verified by stress measurements based on fibre Bragg grating (FBG) technology. The results show that the designed buffer structure can effectively reduce the concentration of von Mises stress and tangential stress in glass. Moreover, the effect of the geometric dimension on the stress field of the EPA is limited. In addition, compression tests and thermal shock tests are employed to evaluate the mechanical strength and service performance, respectively. The flexible structure can enhance the mechanical properties and accident-tolerant capability of EPAs. The findings of this study have important technical implications for the optimization of seal configurations in EPAs.