Nuclear reactor equipped with a reactor power distribution monitoring device

Purpose: To enable high-accuracy monitoring of reactor power distribution within a short period of time even when the number of neutron measuring apparatus is considerably decreased. Constitution: Local power monitoring strings are arranged at a rate of one per at least 32 fuel assemblies which constitute a reactor core, and neutron flux measuring apparatus are installed in the strings. First, when a startup command is output, core status data detected by the measuring apparatus are read, and from this reading the neutron flux distribution is calculated through a three-dimensional core simulator. The calculated value is compared with a measured value and the maximum estimated value of the readings of the neutron flux measuring apparatus. Further, using the axial mean distribution of a fudge factor which is a ratio of this value to a measured value, neutron flux distribution in other places where no measuring apparatus are provided is computed, and on the basis of this computed value, the reactor power in all places provided and not provided with the measuring apparatus and the reactor power distribution are computed. (Sekiya, K.)