Abstract: A flexible underwater robot, a control method and a device is provided with at least one movable joint and a control module. A flexible joint module of the movable joint comprises a first connecting plate, a second connecting plate, a first spring, several second springs, several third springs, several first pulling ropes, several second pulling ropes and a pulling module. The first spring, the second springs and the third springs are arranged from inside to outside in sequence with gradually decreased rigidities correspondingly to form a gradual rigidity structure, so that it is more flexible to adjust a posture. When the robot is impacted, it may absorb and release energy to ensure the integrity of the flexible joint module, so that the stability is improved.

Abstract: A bottom nozzle includes a skirt, support blocks, transverse blades and longitudinal blades. The skirt is a hollow structure and a bottom thereof is provided with corner legs which are protruded downwards, a cavity is defined in the hollow structure, the transverse blades are configured in the cavity, the longitudinal blades are configured in the cavity, the transverse blades and longitudinal blades are firmly connected with the skirt, projections of the transverse blades and the longitudinal blades in a level plane are intersectant to form interleaved grids, and the support blocks run through and are fixed on the transverse blades and the longitudinal blades. In such a way, the bottom nozzle forms a three-dimensional gridded water passage, thereby improving the filter capacity and generating small water pressure drop.

Abstract: A new, improved grid spacer for a nuclear fuel assembly is provided, comprising several straps which intersect each other alternatively to form a plurality of grid cells and fuel rods reside in some of the grid cells; the grid spacer further comprises mixing elements set at the corner of the grid cells in which the fuel rods have resided; wherein the mixing element comprises a mixing vane stretching towards the direction of the fuel rod and a flow funnel set on the bended edge of the mixing vane continuously and extending towards adjacent grid cells; the mixing vane and the flow funnel set across two sides of two adjacent grid cells respectively, and the flow funnel introduces the coolant in the grid cell at its side to the mixing vane, then the mixing vane introduces the coolant to the grid cell at its own side.

Abstract: A nuclear core component hold-down assembly includes a hollow spring guide in which an instrumentation insertion channel is formed; a base plate which has a center hole formed through a center thereof, and several water flow holes formed around the center hole; a lower end of the spring guide connecting and mating with an upper end of the base plate, the instrumentation insertion channel communicating with the center hole, and the base plate locating above the adapter plate and pressing against it directly; a hold-down bar slidably mounted on an upper end of the spring guide and locating above the base plate; and a spring element configured between the hold-down bar and the base plate, by which the hold-down bar pushes the base plate to cause the base plate to press against the adapter plate. The structure is stable and reliable.

Abstract: The present invention provides a bottom nozzle filtering device and a debris-preventive bottom nozzle that can be used for a light water reactor (LWR) nuclear fuel assembly. The bottom nozzle filtering device includes a plurality of successively spliced unit plates; a through flow channel is formed between the spliced adjacent unit plates; the flow channel includes a plurality of spaced straight-section flow inlets and straight-section flow outlets, and a flow subchannel communicating; the outlet section of each straight-section flow inlet in the middle splits respectively into two flow subchannels, and the inlet section of each straight-section flow outlet in the middle communicates respectively with the two flow subchannels. The flow direction of the coolant is controlled by the straight-section flow inlet, the straight-section flow outlet, the flow subchannel to prevent unnecessary eddies forming, making the pressure loss effectively controlled and improving the filtering effect.