Accident scenaria and seismic stability of polar crane operating at a nuclear power plant

Abstract

In this study, a universal method is proposed to determine the seismic qualification of the structure of a polar crane, in an accident scenario, for operating at the nuclear power plant (NPP) Kozloduy, which includes preliminary functional analysis and seismic safety analysis. The initial events and event trees connected with the polar crane operation, which are crucial for the NPP safety insurance in case of earthquake accidents, are specified on the basis of the two analyses. The proposed method is the first basic step for seismic qualification of heavy equipment such as a polar crane. The second step is the analysis of the seismic stability of a NPP polar crane structure, based on the use of probability analysis of safety by seismic qualification. The real loading condition of the polar crane structure is determined by the ratio of the total actuation time of the systems for automatic protection and the time for maximal seismic applied load. A practical application of the method is done by using the finite element method to determine the high confidence for low probability of failure criteria and the seismic stability curve for the main beam of the polar crane.