Application of noise analysis for BWR performance monitoring and monitoring

Abstract

Noise analysis has been used since the mid seventies in order to characterize the operation of the Swedish nuclear power plants. Reactor noise analysis has also been used in performance monitoring of the Boiling Water Reactors Barsebäck 1 and 2, located in southern Sweden. In the beginning reactor noise was addressed as a problem with possible safety implications. Investigations were started in order to characterize and quantify different noise sources. After long experience the safety implications are believed to bee small. However, a possible reduction of the noise has indicated a potential for large economical savings and this has motivated the utility, SYDKRAFT AB, to continue the noise analysis research. Application aspects, looking towards early fault detection systems and diagnostic aids for the operators, has also been of a great interest. As a tool for the noise analysis a powerful interactive identification package, IDPAC, running on a VAX 11/780 was used. Both spectral and parametric methods have been used. Almost ten years of reactor noise data describing both normal and abnormal behaviour has been compiled and analyzed. Specific noise patterns have been extracted and some examples are presented in this paper. In order to achieve a higher reactor controllability, resulting in e.g. shorter start-up times, an extension of the operating area was suggested. By BWR stability monitoring, using the Pressure-Flux transfer function characteristics as a measure, the new operating area was checked and continuous operation permitted. A comparative noise study concerning the in-core neutron flux characteristics of the Barsebäck 1 and 2 was made in 1983. As a result a simple scheme for detection of abnormal boiling was suggested.