IMPROVED FRETTING WEAR RESISTANCE SPACER GRID WITH W-TYPE AND M-TYPE SPRING

摘要

A spacer grid with W-type and M-type springs improved in fretting wear resistance is provided to reduce rigidity of the springs by including a parallel unit on a grid surface connection unit. A spacer grid with an M-type spring(64) is supported by a dimple formed on top and bottom portions of the spring to protrude in an opposite direction of the spring. The spring includes a fuel rod contact unit(641) and a grid surface connection unit(642). The fuel rod contact unit includes a depressed surface along a radius of curvature of a nuclear fuel rod. Two projection units(644) are formed on the depressed surface long in a vertical direction. The projection units and the nuclear fuel rod have a plurality of linear contacts. The grid surface connection unit connects the spacer grid and the fuel rod contact unit. The grid surface connection unit is formed in parallel with a spacer grid surface and further includes a parallel unit(643) to control rigidity of the spring according to a length.