A Magneto-Sonic Type Rod Position Monitoring System for Nuclear Power Plants

Current nuclear power plant rod position monitoring systems utilize transducers that operate mainly on electro-magnetic principles. This paper describes a system that utilizes a magneto-sonic transducer operating on a combination of magnetic and sonics techniques. A magnetostrictive sonic torsional delay line provides the time interval-position relationship. The system exhibits continuous resolution, high reliability, and an accuracy of better than ±1% for a rod travel of 150 inches. The transducer has been qualified for nuclear power plant Safety Class IE operation.