## 1 Introduction  
In the current seismic design of nuclear power plants (NPPs), the peak ground acceleration (PGA) level of safe shutdown earthquake (SSE) is generally taken to be 0.3 g as a design-basis earthquake. Recently, there have been attempts to increase the PGA level above 0.3 g to enhance the seismic safety of NPPs. Furthermore, after the Fukushima NPP accident, the consideration of the beyond-design-basis earthquake (BDBE) became one of the big issues at the design stage, especially for safety-related nuclear facility components having small seismic margins. In fact, it is true that increasing the value of the SSE level is a big burden for the seismic design of NPPs. There have been many research and development efforts to resolve BDBE issues for the seismic design of NPPs. As one of the hardware approaches to accommodate large earthquakes, seismic isolation design has been studied by many countries for a whole nuclear island building isolation [1,2] or an individual facility component isolation [3,4]. Additionally, seismic energy absorbers such as tuned mass and dampers (TMDs) have been studied for application to seismic fragile piping systems or any other safety-related facilities [5].  
Recently, as one of the approaches against large earthquakes, studies on the new seismic design acceptance criteria for large earthquakes have been actively conducted for the application of nuclear metal components [6; 7; 8; 9]. The main concept of this design criteria provides strain-based design limits to protect the pressure-retaining nuclear metal components against an inelastic strain-induced failure mode. Actually, current design criteria in nuclear codes and standards such as ASME BPVC III [10] and RCC-MR [11] provide the stress-based design limits for the elastically calculated stress values. Therefore, they may not provide adequate limits for actual seismic failure modes in cases when the reversing dynamic plastic responses are significant.  
In the previous studies on the new strain-based seismic design criteria, the feasibility of this approach was investigated for the nuclear pipe and nozzle. The most important thing when applying this approach is to calculate accurate inelastic strain values using inelastic seismic analysis [12; 13]. Then, seismic shaking table tests are inevitably required in order to validate the inelastic seismic analysis method. There has been research on seismic shaking table tests for the piping system [14; 15].  
In this study, the test mockup for simulating the hot leg surge line nozzle, which is known as one of the fragile components in nuclear steam supply systems (NSSS), is designed and tested on a shaking table for two earthquake levels of PGA = 0.3 and 0.6 g. For validation of the inelastic seismic analysis method, the finite element model using the ANSYS program [16] is established with material constitutive equations of the Chaboche kinematic hardening model and the Voee isotropic hardening model for Type 316 stainless steel. Through the investigation of the test results and the comparison of seismic time history responses such as the principal strain and accelerations between the measured data and the inelastic seismic analysis results, the inelastic seismic analysis method for large earthquakes was validated and confirmed to be useful for the seismic design of nuclear metal components.