Operating results obtained in a nuclear power plant with a sensor surveillance prototype

Surveillance methods have been validated and specific equipment have been built to measure the response time of sensors from a nuclear power plant protection channel. The reason of the choice of this parameter is twofold: the sensor response time is representative of the sensor physical status and is also part of the overall channel response time. Two surveillance methods are used: noise analysis (by AR or PSD modeling), and loop current step response (for resistance thermometer detectors only). The methods were validated on test facilities and on nuclear power plants. Two test equipments were built and tested on plants. Results are represented and conclusions are drawn on the feasibility of such methods for sensor surveillance