Reliability-Based Design Optimization of Pump Penetration Shell Accounting for Material and Geometric Non-Linearity

The roof slab of the nuclear reactor supports all the components and sub-systems. Roof slab needs to resist the seismic loads in accordance with load-carrying criteria. The static stress analysis of the reactor roof slab reveals that high-stress concentration was present in the pump penetration shell (PPS) which supports the primary sodium pump. This paper presents the assessment of collapse load and optimization of pump penetration shell, through the reliability approach, accounting for material nonlinearity, geometrical nonlinearity and randomness in loading. In addition to that, the load-carrying capacity of PPS was determined considering two different materials, viz., IS2062 and A48P2. The design of experiments (DoE) was formulated considering the flange angle and flange thickness as parameters. An empirical model for load function was formulated from the results of the collapse load obtained for various combinations of design parameters. The above function was used to perform the reliability-based geometry optimization of PPS of the roof slab.