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• Equilibrium equations and compatibility equations were conducted respectively to consider coupling effects of subassemblies in SFR. • Calculation for row bowing was performed with the aid of FADAC code in the present study. • Row bowing was analyzed in detail under different geometric parameters for wrapper tube, even core baffle was taken into consideration. • Reaction forces and deflection parameters were obtained by calculation, which are meaningful for safety evaluation and core structural design. Subassemblies in sodium-cooled fast reactor are different from pressurized water reactor in both geometry and assembly arrangement. In sodium-cooled fast reactor, assembly thermal deformation and narrow clearance between adjacent assemblies would cause them contact with each other, and reaction force between neighboring pads would occur. Under that circumstance, assembly deformation would be decided by both thermal load and mechanical load, which means significant coupling effect would lead to more complicated deformation behaviors. Therefore, so as to deeply study such thermal–mechanical coupling effect in reactor core, it is meaningful to conduct theoretical analysis and numerical simulation on such behaviors, which is indispensable for reactor safety analysis and structural design. In the present study, equilibrium equations and compatibility equations were conducted respectively for acquiring deformation parameters of assemblies in the row, which were already implemented into FADAC code and can perform calculation for row bowing. Furthermore, reaction forces and assembly deflections were analyzed in detail. Besides, sensitivity analysis were performed for row bowing calculation, in which wrapper tube thickness, distance across flat for wrapper tube, pad clearance and effects of core baffle were all taken into consideration. The present theoretical research for assembly deformation in SFR is essential for reactor safety and structural design, and will lay a solid foundation for assembly deformation analysis in the whole core. [ABSTRACT FROM AUTHOR]

• The assembly compression test was described, and the section stiffness were given. • The assembly bending test was described, and the bending stiffness were given. • Compared and discussed the data of the IAEA benchmark tests and the XJTU tests. China Fast Reactor (CFR) is under construction, and the section stiffness and bending stiffness of CFR assemblies remain unknown and need to be investigated to support the core restraint system design and reactivity safety assessment. In this study, assembly compression tests were performed with three types of test samples. With the compression load varying from 0 to 6 kN, the compressive deformations were measured and the section stiffness were obtained. In assembly bending tests, there were two types of assemblies considering different spike clearances, and the horizontal loads from 400 N to 1900 N were applicable to the upper-load-pad, lower-load-pad and mid-fissile-region level of the assemblies. Assembly deflections were measured and correlations for the load-deflection ratio were proposed. Comparison of theoretical and experimental bending stiffness were carried out, which indicated that the spike clearance has to be taken into consideration in the assembly deformation analysis codes. [ABSTRACT FROM AUTHOR]