| 摘要 |
PROBLEM TO BE SOLVED: To obtain a fuel assembly with improved stability, operation flexibility, and operation characteristics by suppressing the manufacturing cost$ of an MOX fuel (a mixed oxide where a plutonium oxide is mixed into a fuel assembly consisting of a conventional BWR uranium fuel with the uranium oxide as a base material) and at the same time, increasing the amount of loaded plutonium. SOLUTION: In the fuel assembly that is composed of an uranium fuel rod U1 without containing uranium and an uranium fuel rod G1 containing gadolinia and MOX fuel rods P1, P2, and P3 and a water rod W, U1 or G1 is arranged, at least, at one portion of a position adjacent to the water rod W that is not adjacent to a channel box. The U1 and G1 are made of a low-concentration uranium whose uranium 235 concentration of a natural uranium or the like is approximately 1.2 % or less. G1 is arranged at the corner position of the fuel assembly, and G1 or U1 is arranged at a position adjacent to the G1 and a channel box 2. Also, the G1 is provided with a plurality of regions with different uranium concentration in the axial direction.
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