Patent ID: 6735267
Filing Date: 2004-05-11
Classification: G21C,Y02E

Abstract:
A fuel assembly comprising a plurality of first fuel rods and a plurality of second fuel rods having a length shorter than a length of the plurality of first fuel rods, said first and said second fuel rods being arranged in a fuel rod array of 10 rows by 10 columns; and a plurality of water rods occupying regions allowing arrangement of 8 fuel rods, said second fuel rods being not arranged in an outermost tier of the fuel rod array, which satisfies the following conditions:B&gE;60, 15&lE;n&lE;20(n: integer), Awr/Ach&lE;0.149, Lp/Lf&gE;11/24, Awr/Ach&gE;(3.00Ã—10âˆ’4Ã—n2+6.00Ã—10âˆ’4Ã—nâˆ’1.2Ã—10âˆ’2)Ã—(Lp/Lfâˆ’1)+1.75Ã—10âˆ’1, and Awr/Ach&lE;(8.63Ã—10âˆ’4Ã—n2âˆ’6.09Ã—10âˆ’2Ã—n+1.33Ã—101)Ã—(Lp/Lfâˆ’8.32Ã—10âˆ’1) where Awr is a total sum of horizontal sectional areas of said water rods, Ach is a horizontal sectional area of a coolant flow passage in a bottom portion of said fuel assembly, Lf is an effective fuel length of said first fuel rods, n is the number of said second fuel rods, Lp is an effective fuel length of said second fuel rods, and B (GWd/t) is an average unloading burn-up.