SOME DEVELOPMENTS IN CORE-BARREL VIBRATION DIAGNOSTICS

Diagnostics of core-barrel motion, and notably that of beam mode vibra tions, has been usually performed by two distinct concepts. One strate gy is to perform a qualitative analysis in the time domain, using desc riptors such as vibration trajectory, probability distributions etc. T his approach is rather realistic in the sense that it allows for gener al anisotropic pendular vibrations. The other strategy is to use frequ ency analysis with the goal of quantifying certain vibration propertie s. However, this second approach could so far handle only isotropic an d unidirectional vibrations. In this paper we propose a unification of these two approaches by introducing a model by which general anisotro pic vibrations can be quantified in the frequency domain. However, whe n separating the noise components prior to the frequency analysis, we suggest the use of symmetry properties of the noise in the time domain , based on reactor physics assumptions, as opposed to the earlier meth ods that use statistical independence of the components. Due to the un ified approach, a combination of time and frequency domain analysis me thods can be used for presentation and maximum information extraction. (C) 1998 Elsevier Science Ltd.