Research On The Fluid Added Mass Of Spent Fuel Storage Racks Under Seismic Condition

The spent fuel storage rack is the important equipment for the nuclear power plant to temporarily store the used fuel assemblies.The spent fuel storage rack is used as anti-seismic Class I equipment.It should be designed to maintain its storage function and will not fall apart,tip,and produce large deformation.Under seismic conditions,due to the fluid-structure interaction effect,the fluid will have a great influence on the movement and self-deformation of the spent fuel storage rack,which immersed in the fluid,and will cause strong nonlinear motion,which may damage the integrity of the its structure.Fluid added mass is the main parameter for studying the fluid-structure interaction effect,and is an important parameter for the structural integrity analysis of spent fuel storage racks.Therefore,in order to realize the long-term safe storage of spent fuel and ensure the safe,continuous and efficient operation of nuclear power plants,it is necessary to carry out research on the fluid-structure interaction characteristics of spent fuel storage racks,especially the study on fluid added mass of spent fuel storage racks under seismic conditions.Although many domestic and foreign scholars have carried out some research on the fluid-structure interaction characteristics of spent fuel storage racks,most of these studies are only for a single rack,and there is few research were carried out on the fluid-structure interaction characteristics among the racks.Because of the high density spent fuel pools,the spent fuel storage racks are closely aligned in an array.The structures around the rack have a great influence on its fluid-structure interaction characteristics.Therefore,fluid-structure interaction characteristics of a single rack cannot accurately reflect the true fluid-structure interaction characteristics of spent fuel storage racks in a spent fuel pool under seismic condition.Moreover,in the previous research,the theoretical calculation formula for the fluid added mass of the spent fuel storage rack was not obtained,which made the analysis for the fluid-structure interaction characteristics of the rack and the structural integrity analysis of the rack very difficult.Therefore,in order to more accurately reflect the fluid added mass among the spent fuel storage racks,and to obtain the theoretical calculation formula of the spent fuel storage rack,this paper takes China Advanced Passive nuclear power plant(CAP 1400)II area spent fuel storage rack as an example to study the fluid added mass under seismic condition.The research is divided into two parts:experimental research and numerical simulation research.Different from the previous experimental research,this paper uses the multi-rack fluid-structure interaction measurement experiment to study the fluid added mass of the rack.Firstly the small-scale rack-rack experimental rig is built to study fluid added mass of CAP 1400 spent fuel storage racks.Then,the experiment for measuring the fluid added mass of medium-scale rack-rack is carried out.The accuracy of measurement results for the rack was verified by these two sets of experiments.And according to the similarity analysis,the fluid added mass of the prototype racks under different gaps is obtained.The experiment also studied the influence of the gap on the fluid added mass of the rack.Finally,the calculation formula of the fluid added mass under different gap sizes was obtained by the potential function theory,which can bring great convenience to the study for the fluid-structure interaction characteristics of the rack and the integrity analysis of the rack.And in the numerical simulation study,this paper developed a set of CFD numerical simulation method for calculating the additional mass of fluids with complex structures.After that,the numerical simulation of the fluid added mass of the spent fuel storage racks was carried out.Through the CFD method,the motion of rack was simplifed to the fluid boundary conditions,and the dynamic mesh technology was used to obtain the fluid added mass.And compared with the experimental results,the correctness of the numerical simulation method was verified.The effect of surrounding structures on the fluid added mass of spent fuel storage racks was also investigated.In this paper,an in-depth experimental and numerical simulation study on the fluid added mass of spent fuel storage rack is carried out.A theoretical calculation formula for the fluid added mass of the rack is proposed.The formula can conveniently calculate the fluid added mass among the racks under any gap according to the structural size of the rack and the gap between the racks.Morever this paper also develops a CFD numerical simulation method for calculating the fluid added mass of fluids with complex structures.These methods can provide fluid-structure ineraction parameter input for the design and analysis of the spent fuel storage racks.At the same time,it also laid the foundation for the localization research of high-density spent fuel storage racks.