AbstractAn automatic sensor validation strategy for the five-channel DCN (Deuterium-Carbon-Nitrogen) interferometer installed at ENEA-FTU (Frascati) is presented. The approach proposed is based on a neural model of the observed system, i.e. a model able to emulate the behaviour of a fault-free sensor and on a two-stage fuzzy system able to detect the occurrence of a fault by using a set of suitable indicators. The validation strategy has been implemented and embedded in an interactive software tool installed at FTU.