Patent ID: 6744840
Filing Date: 2004-06-01
Classification: G21C,Y02E

Abstract:
An incore monitoring method of a nuclear reactor, comprising performing the following steps in order:(1) measuring neutron flux levels at a plurality of pitch levels corresponding to a plurality of local power range monitor sensors arranged in an axial direction inside a detector assembly installed in the nuclear reactor; (2) performing a power distribution calculation using a three-dimensional simulation to obtain a first calculation of thermal characteristics of a fuel assembly group consisting of fuel assemblies adjacent to the corresponding detector assembly, based on values indicated by the plurality of local power range monitor sensors of the corresponding detector assembly at a first time; (3) performing during a first cycle at least one of (a) adjusting a reactor core flow rate for regulation reactor power and (b) operating control rods in the reactor core for regulation reactor core power; (4) performing during said first cycle and after step (3) a plurality of second calculations of thermal characteristics in which the power distribution calculation is not performed, based on values indicated by the plurality of local power range monitor sensors at second times, subsequent to the first time, and based on the thermal characteristics calculated in the first calculation at the first time; (5) monitoring during said first cycle and after steps (3) and (4), the plurality of thermal characteristics calculated during said first cycle in the plurality of second calculations; (6) performing during a second cycle at least one of (a) adjusting a reactor core flow rate for regulation reactor power and (b) operating control rods in the reactor core for regulation reactor core power; (7) performing during said second cycle and after step (6) said plurality of second calculations of thermal characteristics in which the power distribution calculation is not performed, based on values indicated by the plurality of local power range monitor sensors at third times, subsequent to the first and second times, and based on the thermal characteristics calculated in the first calculation at the first time; and (8) monitoring during said second cycle and after steps (6) and (7), the plurality of thermal characteristics calculated during said second cycle in the plurality of second calculations.