Dynamic Response Analysis of Small Nuclear Reactor Containment under Seismic Excitation

The excellent characteristics of small nuclear reactor, such as modularity, high sensitivity and safety, are attracted much attention. The dynamic characteristics of the containment structure during earthquakes have a significant impact on the safety assessment of small nuclear reactor. The small nuclear reactor containment was used to establish a threedimensional finite element model and simulate nonlinear seismic analysis by ABAQUS code. The frequency, mode shape, acceleration and displacement dynamic characteristics of the small nuclear reactor containment model under the action of earthquakes were simulated, and the first 16 modes and frequencies were compared. The results show that the vibration frequencies of the 1st and 2nd, 3rd and 4th orders of the containment are respectively close and the main vibration direction is horizontal. Also using the ground motions with peaks of 0.2g, 0.3g and 0.4g as the load input, the maximum principal stress distribution diagrams of the prestressed steel strands and the concrete containment structure under the action of three peak accelerations were obtained. The maximum principal stress of the concrete containment is less than the standard value of tensile strength (2.65 MPa), and the maximum principal stress is mainly distributed in the vicinity of the hole of the structure and the bottom of the foundation. The acceleration and displacement response of the containment structure were compared. The evaluation results show that the small nuclear reactor containment structure has good safety under the action of extreme ground motions.