SOIL STRUCTURE INTERACTION OF NUCLEAR REACTOR BUILDINGS

Abstract

Design of critical facilities such as nuclear power plant requires an accurate and precise evaluation of seismic demands, as any failure of such facilities can cause immense irreversible loss to life and property. Hence, the structural safety of Nuclear Reactor building during expected earthquake motion is of great importance in view of possibility of radiation hazards. These massive structures interact with the surrounding soil, leading to a further modification of the seismic motion at the base. Thus, the structural response may be affected by the interaction with the soil. Also, there will be a feedback from structure into the soil. It is not appropriate to analyse the structure alone. Rather, the total system consisting of the structure and the soil should be analysed. This report presents free vibrational response of a typical reactor building, analysing 3D numerical model with ABAQUS. Fixed base and flexible base analysis is carried out by considering different soil types.Bonded (without slip and separation) and Unbonded models (with slip and separation) of the reactor building were analysed and results were compared. It is found that, with the increase in the stiffness of the soil, the fundamental time period decreases. Slip and separation is also captured in the study with the help of unbonded models, which give comparatively higher tip displacement values. Unbonded models give lower stress at the base of the reactor compared with those obtained using bonded models