INDUCTIVE SENSORS FOR DISTANCE MEASUREMENT THROUGH A METALLIC SCREEN: APPLICATION TO THE PRIMARY CONTROL OF A NUCLEAR REACTOR

ABSTRACT

This paper presents an interesting design of magnetic sensors applied to the distance measurement, through a metallic medium 1]. By a detailed physical analysis of this problem, an original modelling for predetermination and optimisation of the performances of this system is achieved, and successfully compared with experimental results. The interest of such a system is demonstrated through two major industrial applications, linked to the control of a pressurised water reactor with enriched uranium. In a first application, the sensor is used to detect the passage of magnetic slots, and provides some informations for incremental counting. This system gives reliable data on the position of the control rods moving up and down into the nuclear reactor. The other application uses the signals given by both elements of a twin sensor and a target with particular geometrical dimensions. A differential measurement between the two sensors gives an analog information on the lateral position of the target, and the system is used to control the positon of water gates located on the coolant circuit.