Patent ID: 6510192
Filing Date: 2003-01-21
Classification: G21C,Y02E

Abstract:
An operation method of a boiling water type nuclear reactor core in which a plurality of fuel assemblies, each enclosed in a channel box, are loaded and a plurality of control rods, each having control blades, are arranged between said channel boxes, characterized in that:long blade control rods, each having control rod blades which extend in four directions and each of which is arranged between channel boxes on a diagonal line of square bundle regions, each square bundle region being formed by a plurality of fuel assemblies; short blade control rods, each having a latitudinal control rod blade length of about one half of the width of each of said square bundle regions and each of which is arranged between said channel boxes in the center of each of said square bundle regions; said long blade control rods each having a latitudinal control rod blade length of about one of said square bundle regions so as to be twice as long as the latitudinal control rod blade length of each of said short blade control rods; and wherein reactivity control during operation and at time of scram is effected by using said short blade control rods arranged between said central channel boxes of said square bundle region.