| 摘要 |
PROBLEM TO BE SOLVED: To avoid a hard work accompanied by cutting and pealing of conventional plastic deformation member for detaching a locknut after screwing a fuel element end plug in a tie-plate with a locknut utilizing plastic deformation and attain the purpose of detaching only by a recovery operation of the plastic deformation member by pushing a tool. SOLUTION: A fuel element end plug 1 is projected from a path hole of a tie-plate, a locknut 2 is screwed into an end plug male screw la. By pressing and deforming a locknut thin cylinder 2b, a plastic deformation groove thin part 2f is fitted and contacted to the V-shape groove part 1e of the V-shape groove 1d without bottom in the end plug male screw 1a to be tightened state. When the locknut is detached, a tool for detaching inserted in a slit 1f for tool handling opening to the valley part of the V-shape groove 1d without bottom is pushed outward and plastic deformation groove thin part 2e is removed from the V-shape groove 1e and recovered. Only with this process, reverse screwing of the locknut 2 is made possible.
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