VIBRATION ISOLATION OF NUCLEAR POWER PLANTS

Abstract

As the seismic requirements for nuclear power plants are steadily increased design techiques may prove inadequate, not only for the protection of the structure , but more importantly for protection of equipment and piping. It is clear that new asesmic design strategy may be developed One such potential asesmic design strategy for nuclear power plant is vibration isolation In this thesis a study of vibration isolation system has been made in which elastomeric bearing and friction plates are introduced between upper and lower raft. The mathematical model of isolation system and effectiveness of this isolation system in reducing the earthquake respose has been studied for nuclear reactor building. A simple mathematical model of reactor building is chosen, which consists of lumped mass system with beam elements.The isolation model consists of neo-prene pads and frictional plates. The foundation model consists of lower raft which in turn is supported by horizontal , verictical and rocking sail springs . Computer program has been developed n to evaluate the earthquake response of the system by using Newmark 's step-by step time intregration scheme. The influence of variation of parameters,such as shear wave velocity of soil,frequency ofisolation system,coefficient of friction and stiffness of the structure on the structural respose of the system has been studied. A comparison of responses in conventional system and isolation systems been made.