Variation of the trip point in the ornl¿-type safety system

In nuclear reactor safety systems electromagnets are often used to connect neutron-absorbing rods to positioning drive units. The currents through these electromagnets can be varied in a continuous or discontinuous manner as a function of the reactor neutron level, the ultimate objective being to enable a trip or scram should an unsafe operating condition be present or imminent. A group of instrument channels, interconnected so as to determine whether the ¿unsafe operating condition¿ exists and, upon such determination, to trip the rods (all with no operator attention), comprise a safety system. One such safety system is the so-called auctioneering array of safety amplifiers, all deriving information from separate channels, and jointly feeding a single common point of interconnection or bus. The state of this bus is determined by the highest bidder (the channel with the highest output voltage). Thus a single channel, detecting an unsafe condition, is able to assume control and eventually shut down the system.