Method of handling control rod and control rod handling apparatus
View Patent ↗A control rod grasped by a hook of a grasping equipment is moved down and is positioned at an upper end of a hollow piston of a control rod drive mechanism (CRD) in a state that the control rod is fully withdrawn from a core. Furthermore, the hook is inserted into an opening of a handle of the control rod. The hook is lifted up so as to make contact with the handle. The control rod grasped by the grasping equipment is rotated by a grasping equipment rotation apparatus. A state that gaps formed between joint convexities in a coupling socket of the control rod are positioned right above coupling spud convexities of the hollow piston occurs. At this time, the control rod falls by its own weight and the coupling spud convexities pass through the gaps. A grasping equipment movement apparatus suppresses the falling speed of the control rod. The control rod is rotated at 90° and the control rod and CRD are connected. The time required for connecting the control rod and the hollow piston of the control rod drive mechanism can be shortened even further.
1. A method of handling a control rod for connecting a plurality of coupling spuds that are included in a hollow piston of a control rod drive mechanism installed in a reactor pressure vessel, the coupling spuds having a plurality of first projection projected outward at an upper end portion and being arranged around an upper end portion of the hollow piston to a coupling socket installed at a lower end portion of the control rod, the coupling socket forming a hole portion with one end opened and having a plurality of second projections formed on an inner surface of the hole portion and projected inward, by using a control rod handling a apparatus having a casing, cylinder apparatus attached to the casing, the cylinder apparatus including a cylinder, a piston disposed in the cylinder and a piston rod connected to the piston, a control rod grasping apparatus supported by the piston rod, and a grasping equipment rotation apparatus, comprising steps of:
moving down the control rod held by the control rod grasping apparatus into said reactor pressure vessel together with the control rod grasping apparatus in a state in which the control rod grasping apparatus is supported by the piston rod, and then, positioning the coupling socket at the upper end portion of the hollow piston existing in the reactor pressure vessel;
thereafter, rotating the control rod by the grasping equipment rotation apparatus;
moving down the control rod and the control rod grasping apparatus by their own weights when each gap formed between the second projections adjoining each other in a peripheral direction of the hole portion is positioned right above each of the first projections by rotation of the control rod, and thus, permitting each of the first projections to pass through each of the gaps; and
rotating the control rod in a state that the first projection is positioned above the second projections, positioning the first projection right above the second projections by this rotation of the control rod, and thus, connecting said plurality of coupling spuds to said coupling socket,
wherein the descent of the control rod and the control rod grasping apparatus by the own weights is executed by decreasing lowering speeds of the control rod and the control rod grasping apparatus by descent of the piston of the cylinder apparatus for holding the control rod grasping apparatus.
2. The method of handling a control rod according to claim 1 , wherein the rotation of the control rod is executed by rotating the control rod grasping apparatus.