This system constantly monitors signals from the nuclear and non-nuclear
instrumentation, and when necessary takes corrective action. Corrective
action will be either in the form of “fast insertion” of the control
rods, or in the form of reactor “scram.” Fast insertion takes place at a
rate of 15 inches per minute, while a scram is achieved in 1.6 seconds.
Fast insertion consists of moving all control rods to the full down
position at the fastest rate possible through the electromechanical
drives. For reactor “scram,” all rods are driven to full down position
under the force of a net hydraulic pressure of 1,250 psi.