Research On TMD Vibration Reduction Of AP1000 NPPs Shield Factory

The shield factory of AP1000 nuclear power plant is the last safety barrier to prevent nuclear leakage. Earthquake and blast are two main factors that affect the AP1000 shield factory. As is known to all, the intensity and frequency spectrum of the ground motion has great uncertainty. During the service of the nuclear power plant, the nuclear power plant may suffers from earthquake vibration which is exceeds the standard design strength . At the same time, the nuclear power plant is an important infrastructure and has always been the focus of terrorist attacks. Under the seismic or blast effect, the shield factory of AP1000 nuclear power plant may result in failure and cause serious nuclear disasters whose consequences will be unimaginable. So the research on improving the seismic performance and anti-explosion ability of AP1000 nuclear power plant have definite engineering backgrounds and great significance.Taking the shield factory of AP1000 nuclear power plant as the research object and following the geometric characteristics and function demands of the structure, this paper proposed that using TMD(tuned mass damping system) technology to ensure the blast and seismic responses of the structure will be reduce. Based on the shield factory structures of AP1000 nuclear power plant, this paper transforms the upper water tank structure to make it become a TMD system in which using the water tank structure to absorb vibration energy of the shield factory. As a result,the seismic responses of the lower part of the shield factory structures could be reduced. In this paper, the main innovation are as follows:(1) From the perspectives of the theoretical analysis and ANSYS finite element simulation,this research shows the dynamic characteristics and establishes the simplified analysis model of the shield factory structures which has been used to derive the simplified analysis model of the TMD system.(2) This paper taking care of random earthquake in different fields and taking the minimum vertex displacement and acceleration of shield building structures as the optimization goal respectively. The period of TMD system and damping ratio of isolation layer is the parameter that was selected to optimize the TMD systems of the shield factory structures.(3) Based on the relevant specifications of NPPs, under the earthquake effects, this paper compares the seismic responses of the shield building structures with TMD and the current shield building structures from the perspective of the MATLAB program and ANSYS finite element software. The results indicating the shield building structures with TMD have a good seismic performance.This new type of structures has maintained the external antiknock performance of shield building and abandoned the fixed connection between the PCCS inner tank wall and base.Isolation bearings are arranged between the inner cylinder PCCS water tank wall and the base to achieve this new structure. This new type of structure which has clear mechanism, simple structure and reasonable cost is a new structure with strong practicability.