Study on Gray code control rod position indicator

A new control rod position indicator for water reactors, the Gray code control rod position indicator, is introduced in this paper. The indicator consists of a primary winding, several grouped secondary coils and one coding bar, which is composed of m sections of magnetic core and q sections of non-magnetic portions arranged alternately on the longitudinal axis of the rod housing. As the control rod is withdrawn, the coding bar passes the coils and changes their output signals. By picking up and processing the signals, n bits of Gray code, which are related to the rod position, are obtained. Compared with a combination coding rod position indicator, each Gray code indicates a step. Compared with the coil-coding rod position indicator, the Gray code rod position indicator is simpler in structure and more reliable in operation, so it is a good control rod position indicator for water reactors.