CONTROL ROD OPERATION MONITORING METHOD AND CONTROL ROD OPERATION MONITORING SYSTEM

摘要

To provide a control rod operation monitoring method capable of improving determination accuracy of a generation of a rod insertion block signal during an operation of a reactor. The four neutron detector assemblies 5A, 5B, 5C, and 5D including a plurality of LPRMs 6 arranged in an axial direction of a core are arranged adjacent to a plurality of insertion selection control rods 4, respectively, which are simultaneously inserted into the core. In neutron flux ratio calculation units 51 which are arranged in each of the four or three neutron detector assemblies 5, ratios (neutron flux ratios B A /A A , C A /A A , and D A /A A ) of an average LPRM signal of the respective LPRMs 6 at positions B, C, and D to an average LPRM signal of the respective LPRMs 6 at a position A which is closest to a control rod insertion end of the core are calculated by a neutron flux ratio calculation device 13A. When the largest neutron flux ratio out of the neutron flux ratios exceeds a set neutron flux ratio, a rod insertion block signal which is generated by a local range rod insertion monitor 11A is output.