FUEL ASSEMBLY, PELLET, FUEL POWDER, REACTOR CORE, AND METHOD OF CONTROLLING FUEL REACTIVITY

摘要

A fuel assembly with which Flocal can be controlled while sufficiently controlling the reactivity of a uranium fuel before and in the beginning of fuel burning, whereby power peaking in the reactor core can be controlled. The fuel assembly is characterized by being an assembly of fuel rods comprising a uranium fuel having a 235U concentration of 5 wt.% or lower and 0.2-1 wt.% erbia added thereto. The fuel assembly may be characterized in that two or more kinds of fuel rods differing in erbia content are used. Also provided is a method of controlling fuel reactivity characterized by using the fuel assembly to control the fuel reactivity.