Velocity limiter shear for BWR control rods

    公开(公告)号:US4747995A

    公开(公告)日:1988-05-31

    申请号:US943824

    申请日:1986-12-29

    IPC分类号: G21C19/36 G21C19/00

    摘要: An apparatus for the simultaneous shearing of two sides of the boiling water nuclear reactor control rod. The rotation of the rods at 90 degree rotation and the shearing of the second two sides underwater in a nuclear waste storage pool.In a previous application by A. H. Krieg, Ser. No. 692,849, we have seen the crushing of a BWR control rod for the purpose of reducing nuclear radioactive waste. The control rod however has an end referred to as the velocity limiter end, which is round and bulbous. This end can not be crushed practically, due to its mass. The purpose of this invention is to shear or cut-off the velocity limiter from the rest of the control rod thus having the remaining cruciform crushable. Between the velocity limiter and the rest of the control rod are 2 "D" shaped holes, hereafter refered to as the "D" holes. At this point the control rod is solid and does not contain hollow fins or boron rods.The control rod can therefore be sheared at the "D" hole without concern of polluting the containment pool. At the bottom of the velocity limiter, in its center, is a protrusion which is cylindrical. This protrusion is allowed to stick into a hole in the turntable that rotates the velocity limiter in 90 degree increments for shearing and alignment. At the bottom of the velocity limiter are four ball or wheel like protrusions. These fit into slots in the turntable, and because they are in alignment with the fins, cause the correct positioning of the entire device for shearing. They act as the positioning stop for a rotating device that controls the turning of the control rod. In this manner, it is possible to index the control rod in such a way so that the shearing heads can be activated and carry out their designed function. After the first shearing operation is complete the shearing heads are retracted from the control rod to a sufficient distance to allow rotation. After completion of rotation, the shearing heads are returned to their working position.