| 摘要 |
A precision internal tube cutter can sever an upper end portion of a guide thimble inserted and attached within a passageway of a top nozzle adapter plate of an irradiated fuel assembly so as to facilitate reconstitution of the fuel assembly. Further, the upper end portion of the thimble can be cut without producing any burrs, roughness or distortion at the cut end. The cutter includes a body with upper and lower end portions of greater diameter sizes than that of an intermediate portion which interconnects them. A stem extends into an axial bore formed longitudinally through the body. A radial slot is defined within the intermediate body portion. In one embodiment, a pair of slides each with a cutting wheel rotatably mounted thereto are mounted within the slot. A lower conical end of the stem engages the slides and axial movement of the stem will cause radial movement of the slides. The slides are urged toward inward retracted positions by return springs mounted on the intermediate portion of the cutter body. In a second embodiment, the tube cutter incorporates a slidable pin within an eccentric lower bore for actuating a single slide and cutting wheel. However, in both embodiments of the cutter, its body, stem (or pin) and slide or slides are composed of a non-corrosive, anti-galling stainless steel alloy material which adapts the cutter to work for extended periods of time on an irradiated spent fuel assembly submerged in water.
|
