Application of Continuous and Structural ARMA modeling for noise analysis of a BWR coupled core and plant instability event. (January 2015)

• Record Type: Journal Article
• Authors: Demeshko, M.; Dokhane, A.; Washio, T.; Ferroukhi, H.; Kawahara, Y.; Aguirre, C.
• Is Part Of: Annals of nuclear energy. Volume 75(2015:Jan.)
• Page Start: 645
• Page End: 657
• Publication Date: 2015-01
• Subjects: Multivariate AR/ARMA modeling -- Canonical modeling -- Discrete and continuous time signals -- Reactor noise and causality analysis -- BWR stability and dynamics; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2014.08.045
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: We demonstrate the first application of a novel CSARMA method. We analyze the instability occurred in a Swiss BWR plant during power ascension. Benchmarked the results against STP analysis. The CSARMA results are consistent with the background physics and the STP results. The instability was caused by disturbances in the pressure control system. Abstract: This paper presents a first application of a novel Continuous and Structural Autoregressive Moving Average (CSARMA) modeling approach to BWR noise analysis. The CSARMA approach derives a unique representation of the system dynamics by more robust and reliable canonical models as basis for signal analysis in general and for reactor diagnostics in particular. In this paper, a stability event that occurred in a Swiss BWR plant during power ascension phase is analyzed as well as the time periods that preceded and followed the event. Focusing only on qualitative trends at this stage, the obtained results clearly indicate a different dynamical state during the unstable event compared to the two other stable periods. Also, they could be interpreted as pointing out a disturbance in the pressure control system as primary cause for the event. To benchmark these findings, the frequency-domain based signal transmission-path (STP) method is also applied. And with the STP method, we obtained similar relationships as mentioned above. This consistency between both methods can be considered as being a confirmation that the event was caused by a pressure control system disturbance and not induced by the core. Also, it is worth noting that the STP analysis failed to catch the relations among the processes during the stable periods, that were clearly indicated by the CSARMA method, since the last uses more precise models as basis.