JP2544437B

PURPOSE:To enhance the annihilation efficiency TRUW and facilitate control by providing a region containing the TRUW of a control rod into a reactor core. CONSTITUTION:The absorber rod 1 of a control rod contains BC pellets 3 and TRUW pellets 4 in a clad tube 2, and the pellets 3 are loaded at an upper half of the rod 1 to form a neutron absorption region and the pellets 4 are loaded at a lower half of the rod to form TRUW-containing region. Each region has the same length as a core height. By this constitution, the TRUW inserted into the core as a control rod turns into fission products through a fission reaction by neutrons from the reactor core and the pellets 4 are not restricted by a burnup of a fuel assembly because they are independent from the fuel assembly. Therefore, the burnup of the TRUW is improved, a recovery loss is lowered and an annihilation efficiency of TRUW can be increased.