Drive unit for control rods in nuclear reactor - using gear trains which permit rods to fall into reactor if emergency occurs so reactor can be stopped

摘要

A motor uses a worm screw and worm-wheel to rotate a master shaft on which a row of pinions is fixed. Each pinion forms part of a gear train used to move one control rod vertically. In each gear train are satellite wheels meshing with the pinion and with the internal teeth of a ring gear (I) which can rotate on the master shaft. Each gear (I) has external teeth meshing with a toothed rack which moves a control rod vertically. The satellite gears are carried by another gear-wheel (II) which can also rotate on the master shaft. Gear (II) is normally blocked for moving the control rods, but is released in an emergency so all the control rods can fall by gravity into the reactor core to stop the reactor. Drive unit is simple, reliable and inexpensive.