FUEL ASSEMBLY

摘要

PROBLEM TO BE SOLVED: To improve the scram-transient characteristics and stability of a boiling water reactor without lowering the economical efficiency of it. SOLUTION: The percentage of the volume of a deficient region to that in the case where a nuclear fuel material is accommodated all over an active fuel section in all tetragonal lattice positions is set between 3% and 6% inclusive by keeping a fuel assembly where fuel rods are laid out at least a part of tetragonal lattice positions of N rows and N columns equipped with partially deficient fuel rods with deficient regions accommodating no nuclear fuel material which are formed in the range extending downward from the upper end of the active fuel section beyond 1/6 of the active fuel length A. This makes it possible to load more nuclear fuel materials than the loaded volume of a nuclear fuel material of 9 rows and 9 columns (A type) and to improve the scram-transient characteristics such asΔMCPR and stability. Similar effects can also be obtained by forming a deficient region ranging downward from the upper end of the active fuel section beyond 1/6 of the active fuel length in fuel rods of the number between 1/5 and 1/3 inclusive of N2and by other methods. COPYRIGHT: (C)2009,JPO&INPIT