The Application of Noise Analysis to Find the Miss-Connected LPRM Cables Before Plant Startup

The miss-connected LPRM (Local Power Range Monitor) cables were occasionally found at the BWRs (Boiling Water Reactors) in Japan. These miss-connections were confirmed by visual inspection after the plant shutdown. In 2007, we proposed a method to find the miss-connection by applying noise analysis to LPRM signal data during plant operation. Actually, in 2008, the miss-connection was found by the method during plant operation at a BWR in Japan. It showed the effectiveness of the method. However, it should be more convenient and helpful, if the miss-connection could be found before the plant startup. A new method is proposed here to find the miss-connections before plant startup, that is, before the primary containment vessel is closed after plant startup preparation.