Absorber rod drive for pebble bed reactor - having two motors and combined gear system to change ratio of rotational to linear motion

摘要

A drive for a rotatable and/or axially movable absorber rod for a nuclear reactor comprises a gear assembly (pref not self-locking) can be driven optionally by a first and/or a second drive motor. The output side of the gear assembly acts in the longitudinal direction of the absorber rod, esp. with chains, and the entire gear is rotatable about the longitudinal axis of the rod by means of the second motor. To enable the helically threaded rod to penetrate into the reactor core, it is rotated at a speed higher than that corresponding to the pitch of the threads as it advances. To withdraw it, however, the rotational speed is dropped. By using two separate motors with this arrangement, different combinations of linear speed and rotational speed can be obtained with a single gear unit. If the power supply to the motor fails, the entire rod drops under gravity into the core to shut the reactor down.