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:
Apr. 13, 1993
Filed:
Sep. 17, 1991
Motoo Aoyama, Mito, JP;
Taro Ueki, Hitachi, JP;
Akinobu Nakajima, Hitachi, JP;
Sadao Uchikawa, Katsuta, JP;
Junichi Yamashita, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A fuel assembly has a plurality of first fuel rods and a plurality of second fuel rods having a shorter length in an axial direction than the first fuel rods. The second fuel rod is loaded with natural uranium in full length of its effective fuel length portion. The fuel assembly has a water rod having a larger horizontal cross sectional area at the upper region than the area at the lower region. The second fuel rods are arranged downward of the upper region of the water rod and adjacent to the lower region of the water rod. The width of the horizontal cross sectional area of the lower region of the water rod is set so as to locate the minimum values of both thermal neutron flux and resonance neutron flux in the horizontal direction of the fuel assembly at an outer side with respect the location of the second fuel rod in the horizontal direction. In accordance with the present invention, the H/U ratio in the axial direction becomes close to the optimum value, and increment of the resonance neutron absorption and flattening of the thermal neutron flux in the horizontal direction are achieved.