Abstract: A fuel assembly comprises a plurality of fuel rods bundled in grid pattern, a part of the fuel rods containing gadolinium as a burnable poison. At least one of the fuel rod having gadolinium contains gadolinium enriched in at least one kind of isotope of odd mass number more than an isotopic abundance of natural gadolinium. In the enriched gadolinium, a ratio of a content of Gd-155 to that of Gd-157 is 0.1 or less. An average concentration (wt %) G0 of enriched gadolinia is, with M denoting the number of month under rated power operation per one cycle of an equilibrium core, P power density of a nuclear reactor (kw/l unit) and W a sum of isotopic composition, is set in the range shown by the following expression. G0<0.25·P·M/W. Thereby, in the fuel assembly, residual reactivity of a burnable poison at a cycle end can be decreased and thermal performance can be improved.

Abstract: A fishing rod is manufactured by forming a tubular small diameter portion on an outer surface of a rod material. The small diameter portion is formed continuous with and between a pair of walls substantially perpendicular to an axis of the rod material. Then a seat base is formed by placing a pair of dies around the small diameter portion and injecting a heated thermoplastic resin into a cavity (inside space) defined by the dies.