Nuclear reactor power distribution monitoring system and method including nuclear reactor instrumentation system

A reactor power distribution monitor system for monitoring a power distribution of a reactor core including fuels, in which the fuels in the core are axially divided into a plurality of nodes, said system comprising:

• a plurality of incore nuclear instrumentation assemblies arranged in the core, each of said incore nuclear instrumentation assemblies including a plurality of fixed gamma-ray heat detectors, said fixed gamma-ray heat detectors being arranged in correspondence with predetermined nodes which are selected for gamma-ray heat detector positions in the plurality of nodes;
• a measuring unit configured to measure an operating status in the reactor core as a core condition data;
• a computing device configured to compute a power of each of the nodes of the fuels in the core by the three-dimensional nuclear thermal-hydraulic computing code based on the core condition data transmitted from the measuring unit;
• and
• a computing unit, in a case in which the axially arranged nodes of the fuel are expressed as N in order and one of the nodes of the fuel represents K, configured to compute a gamma heating value of the gamma-heat detector corresponding to the nodes K for each of the incore nuclear assemblies by using power of the nodes K computed by the computing device and powers of adjacent nodes (K−1), (K+1) computed by the computing device, said nodes K surrounding the gamma-heat detector, said adjacent nodes (K−1), (K+1) being axially adjacent to each of the nodes K, and configured to compare the computed gamma heating value of the gamma-heat detector corresponding to the nodes K with actually detected gamma heating values of the gamma-heat detector corresponding to the nodes K so as to correct the power of each of the nodes K according to the compared result.