Stiffness Evaluation of the Welded Connection between Guide Thimbles and the Spacer Grids for 16 × 16 Fuel Assemblies Types, Using the Finite Element Method  

作　　者：Carlos Frederico Mattos Schettino Guilherme Pennachin Sakamiti Joao Carlos Aguiar Gaspar Jflnior 

机构地区：[1]Nuclear Fuel Production, INB--Indfistrias Nucleares do Brasil S.A., Resende 27550-000, Brazil

出　　处：《Journal of Energy and Power Engineering》2014年第9期1583-1589,共7页能源与动力工程（美国大卫英文）

摘　　要：The present work aims to evaluate the increase in the number of spot welds in the 16 × 16 type fuel assembly structure that connects guide thimbles and spacer grids, in order to provide a proper joint for this connection. This new and improved process can provide more stiffness to the whole structure, since the number of spots raised from four to eight. A 3-D geometric model of a guide thimble section was generated in a CAD （computer aided design） program （SolidWorks）. After that, the geometric model was imported to a CAE （computer aided engineering） program （ANSYS Mechanical APDL, Release 14.0）, where the finite element model was built, considering the guide thimble geometry assembled with the spacer grid through the welded connections. Boundaries conditions were implemented in the model in order to simulate the correct physical behavior due to the operation of the fuel assembly inside the reactor. The analysis covered specific loads and displacements acting on the entire structure. The method used to solve this finite element analysis was a linear static simulation in order to perform the connection between a spacer grid cell and a guide thimble section. Hence, four models was evaluated, differing on the spot weld number in the spacer grid and guide thimble connection. The rotational stiffness results of each model were compared. The results acquired from four and eight spot weld were validated with physical test results. The behavior of the structure under the acting force/displacement and the related results of the analysis, mainly the stiffness, were satisfied. The results of this analysis were used to prove that the increasing spot welds number is an improvement in the dimensional stability when submitted to loads and displacements required on the fuel assembly design. This analysis aid to get more information of extreme importance such as, the pursuance to develop better manufacturing process and to improve the fuel assembly performance due to the increasing of the bum-up.

关 键 词：Nuclear energy fuel assembly spacer grid finite element method rotational stiffness. 

分 类 号：TP393.092[自动化与计算机技术—计算机应用技术] TU392.1[自动化与计算机技术—计算机科学与技术]