The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 09, 2000
Filed:
Feb. 12, 1998
Junichi Koyama, Hitachi, JP;
Motoo Aoyama, Mito, JP;
Koji Nishida, Hitachiohta, JP;
Junichi Yamashita, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
Each of short-length fuel rods 3 is arranged at a position other than in 3.times.3 corner regions 6 to 9 in such a manner as not to be simultaneously adjacent to a water rod 5 and others of the short-sized fuel rods. Gd fuel rods 4 are arranged at positions excluding the outer periphery, and the number of those of the Gd fuel rods 4 adjacent to the short-length fuel rods 3 is one-half or less the total number of the Gd fuel rods. At a transverse cross-section of a region upward from upper ends of the short-sized fuel rods 3, the amount of burnable poison contained in a polygonal region 10 whose vertexes are located at centers of those of the first fuel rods 3 arranged at the outermost layer is smaller than the amount of burnable poison outside the region 10. With this configuration, a critical power can be improved in consideration of both a distribution of the flow of coolant and a distribution of a thermal power in the fuel assembly.