Abstract: A method of monitoring neutron flex detectors in a nuclear reactor in a neural network is provided. The network comprises an input layer which receives a number of input signals corresponding to values of a measured signal at different times and an output layer which is adapted to deliver a number of state signals. The network is taught to identify a number of different trends of the measured signal such that the state signals indicate the trends, by supplying the network with a plurality of input signals which have known state signals. The network is then supplied with input signals which correspond to values of a measured signal taken at different times from a supervised detector. Also, input signals corresponding to values of measured signals taken at different times from a reference detector are supplied to the network. Next, state signals for the supervised detector and for the reference detectors are calculated and whether the supervised detector is defective is determined based on the state signals.