Review of the finite element models for a structural integrity evaluation of the sodium-cooled fast reactor high temperature piping

We compared the structural analysis feature of finite element (FE) models for the structural integrity evaluation of the sodium-cooled fast reactor (SFR) high temperature piping and to evaluate the structural integrity against the typical duty cycle event. To evaluate the structural integrity of the high temperature piping per ASME Subsection NH rules, the structural analysis should be carried out first by using a 3-dimensional structural model. The object FE models under consideration in this study are pipe element model, 3-D full model, and 3-D simplified model. The pipe element model is based on the 3-D beam element and effective in understanding overall deformation but less favorable to the detailed stress distribution. The 3-D full model consists of solid structure as well as the contained coolant inside the piping structure with the fluid element. The 3-D simplified model consists of structure shape only, but its material properties are recalculated to reflect the coolant weight effect. The loading conditions for the structural analyses are the mechanical load including dead weight and steady state thermal load. From the analysis results, the piping element model shows the smallest stress intensity, and the required time for FE analysis is also the shortest. The 3-D simplified model shows the most conservative stress intensity output but its calculation time is less than the 3-D full model.