Seismic Analysis Approach Applied to a Small Size Next Generation Nuclear Reactor

The aim of the paper is to evaluate the behaviour of a Near Term nuclear energy system example with reference to IRIS (International Reactor Innovative and Safety) project. As it is well known the development of new and future-generation nuclear power plant (Gen IV NPP) is strictly related to the sustainability, safety and reliability as well as to the proliferation resistance. In this paper, the safety aspects related to the effects of a severe earthquake (Safe Shutdown Earthquake) as well as to the induced loads are treated by means the Substructure and Time History Approaches, assuming a free field Peak Ground Acceleration equal to 0.3 g as input motion. The analyses and upgrading of the geometry structures with highest probability of criticality are performed on rather complex and detailed 3D finite element (FE) models. The main goals were: the evaluation of the dynamic characteristics of each considered structure, the verification of the load bearing structures in order to obtain a preliminary assessment of the adopted methodological approach and structural models. The analyses results and dynamic response of internal components (e.g. Nuclear Buildings, etc.) seem to confirm the possibility to upgrade the geometry and the performances of the proposed design choices.