A Fault Tolerant Multiplexed Control Rod Position Detection and Indication System for Nuclear Power Plants

The majority of Westinghouse nuclear plants placed in service thus far have incorporated a Rod Position Indication system based upon an analog design philosophy. This system, while meeting all functional and accuracy requirements, has proven somewhat cumbersome, particularly in the area of initial field calibration and maintenance. This paper describes a new Digital Rod Position Indication system (DRPI) developed for use with pressurized water reactors. The system is based upon a digital design philosophy and meets all previous design constraints and environmental requirements, Further, fault tolerance, improved accuracy, interference from adjacent rods and the elimination of adjustments and calibration has been provided.