[en] In order to eliminate the harm of metal flying debris and the influence of abnormal deformation of cutting position in the process of underwater radial cutting of rod-shaped irradiation test pipe, we developed a rotary extrusion pipe cutting method;In this method, we invented a special cutting device for rotating rod bundle fuel test tube by using servo motor-worm gear drive structure, Linear Variable Differential Transformer (LVDT) displacement sensor control system and considering safety measures. The three-dimensional modeling and simulation analysis show that the device can ensure the radial cutting of the rod bundle test tube, the material at the notch deforms towards the tube, and there is no chip in the whole cutting process, which can ensure the safe underwater cutting of the test tube after irradiation. (authors)

[en] A relaxation test device for the hold-down leaf spring was designed considering the characteristics of the hold-down leaf spring for AFA3G fuel assembly. The reliability of the device is verified by a series of simulation tests. Finally, four groups of different recycled AFA3G fuel assemblies were selected, and the compression force and the deformation of the four compressed plate springs were accurately measured at any position in the whole stroke, using this relaxation test device. The results showed that the repetitive accuracy and the comprehensive accuracy of the device was 0.49% and 1.7%, satisfying the requirement of relaxation test. (authors)