CORE OF LIGHT WATER COOLING REACTOR AND OPERATION METHOD OF THE REACTOR

摘要

PROBLEM TO BE SOLVED: To make the coolant void coefficient negative, increase the conversion ratio and simultaneously flatten the power distribution without much reducing the core height in a core densified for raising the conversion ratio and a core minor actinide is loaded. SOLUTION: A fuel assembly enriched in plutonium and adjacently arranged in a tight-pitch grid is provided. This fuel assembly is constituted of normal fuel assembly formed by bundling normal fuel rods loading core fuel 1 longer than a certain length and short fuel assembly formed by bundling short fuel rods core fuel 1 loading a shorter than the core fuel 1 of the normal fuel assembly and a blanket 2 including nuclear parent material absorbing neutrons and converting them into fissile material. By this, non-uniformity is attained in core radial direction and axial direction and core fuel length in the short length fuel assembly is made 50% or less of the core fuel length of normal fuel assembly.