| 摘要 |
<p>1. A screw and nut mechanism comprising a screw-nut assembly for controlling a nuclear reactor by vertical displacement of a unit absorbing the neutrons in the core of the reactor and fall of the absorbing unit into a position of maximum insertion under the action of its own weight, for emergency stoppage, the absorbing unit being fixed at the lower end of a shaft connected to one of the vertically translationally movable components of the screw-nut assembly (12, 15-16), the other, rotationally movable, component of the screw-nut assembly being capable of being immobilised in translation, and the mechanism comprising, - a motor (4) for driving in rotation the rotationally movable component (15-16) of the screw and nut assembly (12, 15-16), through the intermediacy of a driving element (20, 24) comprising a profiled part intended to engage with a corresponding part of the rotationally movable component (15-16) of the screw-nut assembly (12, 15-16) to unite integrally in rotation the driving element (20, 24) and the component (15-16), and - a grab (5) provided with swivelling fingers (18) for holding in translation the rotationally movable component (15-16) of the screw-nut assembly (12, 15-16) and for controlling the fall of the screw-nut assembly, of the shaft and of the absorbing unit, at the time of the emergency stoppage, the motor (4) and the grab (5) being fixed on a leakproof enclosure (2) communicating with the interior of the reactor and fixed integrally to the cover (1) of the vessel enclosing the core of this reactor, the motor and the grab being arranged at least partly in this enclosure (2), characterised in that the element for driving the rotationally movable component (15-16) consists of an assembly of two jackets (20, 24) mounted telescopically one following the other in the vertical direction and assembled through the intermediacy of a spring (31) which is compressed when the two jackets (20, 24) move telescopically.</p> |
