Study On Structural Improvement Design Of PWR FA Hold-down Spring

In order to breakup technology monopoly and develop Nuclear Fuel Assembly(FA)which owned independent intellectual property rights.CGN launched the self-dependent brands Nuclear FA R&D work during the 12 th Five-year Plan period.As an important structural component,the Hold-Down System’s design is the key and difficult points of the whole FA R&D work.This paper introduced the composition and main structure of the Hold-Down system(HDS)used in STEP-12.Based on the design criteria and functional requirements of the HDS,this paper presented a systematic and improved design method of finite element analysis using the commercial Abaqus software,including simplifing geometric model,meshing,setting boundary conditions.Then,the mechanical test of HDS was carried out,and the test results was consistent with the analysis results obtained by abaqus,which proved the correctness of the finite element analysis method.On this basis,this paper study on the number of springs and the thickness of single-spring used in the STEP-12 FA HDS and analysed the different influence on the hold-down force.The analysed results provided a theoretical basis for the design and selection.Finally,this paper presented the STEP-12 FA HDS improved design scheme.The conclusion of this paper could be retained as design basis and the design mentality could be widely used in other design work.