Patent Number: 051715163
Section: abstract

A reactor core monitoring system and method wherein: by solving the heterogenous neutron diffusion equation in an infinite lattice consisting only of the fuel segment under consideration of the fuel segments arranged in a reactor core, the local power distribution in infinite lattice and the R factor in infinite lattice used in the critical quality calculation are found beforehand, the neutron diffusion equation is solved by homogenizing each of the fuel segments in a region defined in the core and consisting of the selected fuel segment and the fuel segments surrounding the selected fuel segment. Using this solution, the local power distributions are found by correcting the previously found local power distribution in an infinite lattice consisting only of the selected fuel segment. The R factor for the selected fuel segment is then corrected, and the critical power ratio is determined using this corrected R factor. Control rods of the reactor core are inserted to avoid a boiling transition when the critical power ratio falls below a predetermined threshold.