Fuel assembly
AssigneeHitachi, Ltd.
InventorsJunichi Yamashita, Toshio Kawai, Michiro Yokomi
Life of this patent
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Abstract
The axial power distribution of a nuclear reactor in a region of high burn-up degrees should desirably be flat. In consideration of the fact that void coefficients have a distribution in the axial direction, a mean infinite multiplication factor in an axially upper region of a reactor core is made lower than a mean infinite multiplication factor in a lower region. Especially, this becomes possible in such a way that a mean enrichment factor of fuel located in the uppr region is made lower than a mean enrichment factor of fuel located in the lower region.
Claims4
A fuel assembly comprising a plurality of fuel rods which, at the initial time of assembly of the fuel rods into the fuel assembly, are (1) new, having not been previously utilized in a nuclear reactor core, and (2) vertically arranged in an axial direction in a manner that the mean infinite multiplication factor of an upper region of the fuel assembly in the core is lower in relationship to the mean infinite multiplication factor of a lower region, whereby said fuel assembly is sufficiently different in said two regions to avoid a power output peak in an upper part of the reactor core in any region of high burn-up degree where the mean burn-up of fuel is higher than 30,000 MWD/T.
Dependencies are inferred from the claim text.