Two Techniques for the Analysis of the Local Power Range Monitors Readings under BWR Unstable Conditions

As an example of accidental situations in nuclear power plants, we consider the power oscillations that can occur in a boiling water reactor (BWR) nuclear power plant (NPP) under certain circumstances. An interesting problem is to study and characterize these instabilities analyzing the neutronic power signals obtained from the local power range monitors (LPRMs) installed in the reactor core. Several techniques exist to detect and classify the possible oscillations in a BWR. The power decomposition method and the singular system analysis methodology are reviewed and the performance of both techniques is compared analyzing points 9 and 10 of cycle 14 of the OECD Ringhals 1 stability benchmark