Method of diagnosing abnormality of reactor core

Purpose: To enable judgement for the unevenness of control rods and erroneous steps by using the temperature measurement data at the coolant exit of a fuel assembly. Method: Correlation data between the factors giving effects on the coolant exit temperature of a fuel assembly, that is, change of the temperature at the coolant exit prepared based on the configuration of the reactor core and the result of the thermohydrodynamic phenomenon and the power of the fuel assembly are used. Further, 3-dimensional reactor core analysis codes for calculating the power of each of the fuel assemblies under a given control rod insertion state are prepared. The correlation data and the analysis codes are combined so as to exactly recognize the reactor core conditions. (Ikeda, J.)