Design of comprehensive diagnosis system in nuclear power plant

Safe operation of a nuclear power plant (NPP) is affected by the following two main factors in addition to the human factors in practice: one is the instruments, namely the condition of the sensors; the other is the systems and components. In this paper, a comprehensive diagnosis system (CDS) for NPP is developed based on these two factors. Thus the developed CDS mainly consists of two continuous parts: firstly it is the monitoring of sensors, and then it is the diagnosis of components and subsystems in a NPP. Based on the verified measurements of sensors, the monitoring results of components and subsystems can be guaranteed. Auto-associative kernel regression (AAKR) and sequential probability ratio test (SPRT) are combined to monitor the condition of sensors. If anomaly is detected, it is to reconstruct the measurements of faulty sensors, and the verified measurements are transmitted to the following step of CDS: the diagnosis of components and subsystems. A qualitative analysis method is applied in the diagnosis of components and subsystems based on the verified sensor measurements. Simulations of fault detection and identification on the sensors and components in reactor coolant system of Qinshan NPP are carried out, and the results demonstrate the effectiveness of the proposed CDS.