On-line monitoring of a PWR for plant surveillance by noise analysis

Abstract

For the real-time surveillance of the nuclear power plant Borssele (PWR) a large set of dynamic reactor signals has been linked since early 1982 through a special telephone line of 200 km to a mini-computer in the laboratory of the Netherlands Energy Research Foundation (ECN) at Petten, in order to follow these signals and to identify changes in statistical characteristics of the signals (mean values and noise components). During the operation of two fule cycles of the power plant such information has been collected at normal operation, but also several planned occurrences have been followed which is intersting for the diagnostic information. Several experiences have been obtained during two years of continuous operation of the instrumentation system of the power plant and it was also possible to deduce physical parameters of the reactor from on-line analysis. This system has also been used for in-situ tests of reactor safety channel instrumentation both at the start-up and during continuous operation of the reactor. In this paper hardware and software of the on-line reactor monitoring system are described and the computing capabilities of the system will be given. In the coarse of the development of the system, the following operating experiences were obtained: • - Practical experience with the operation of the system and its reliability. • - On-line monitoring of noise power of several plant sensors both for short time intervals and for long time trend information. • - In-situ test of the reactor safety channels, by measuring spectra, response time of the sensors, etc. • - Continuous monitoring of primary system vibrations. • - Continuous monitoring of core physics (and related) parameters through noise analysis such as the core coolant velocity, reactivity effects, local vibration of the in-core instrumentation the core coolant velocity, reactivity effects, local vibration of the in-core instrumentation guide tube and core support barrel (CSB) motions using in-/ex-core neutron detector and core exit thermocouple signals. • - Some experiences obtained from the return information provided from the far distance on-line monitoring system. The system allowed easy diagnostics of a nuclear power plant from a far distance. It may also serve as an emergency data retrieval center in case of need of measurements under special conditions or during an unforeseen event.