Abstract:
The initial-core economical efficiency is improved by loading the medium enriched fuel in the peripheral or lacing it adjacent to the low enriched fuel and the highly enriched fuel. According to the present invention, in an initial core of a Boiling Water Reactor loaded with at least three types of fuel including highly enriched fuel with a fission-material content of 3.0 wt % or more, medium enriched fuel with a fission-material content of a range from 1.5 wt % or more to less than 3.0 wt %, and low enriched fuel with a fission-material content of less than 1.5 wt %, when a region of an outermost peripheral of a core occupied by the fuel having no face adjoining another fuel in a horizontal direction is defined as an outermost peripheral region, a region outside a line at 80% of a radius of a circumcircle of the core and except for the outermost peripheral region is defined as a peripheral region and the remainder is defined as an inner region, 50% or more of the fuel loaded in the peripheral region is the medium enriched fuel.
Abstract:
Provided is a structure including a first member (2); a second member (3) disposed opposite to the first member (2); and a glass layer (4) disposed between the first member (2) and the second member (3) so as to bond the first member (2) and the second member (3). A glass transition point of the glass layer (4) is lower than a temperature of the glass layer (4) under operation. In the glass layer (4), at least either of ceramic and metallic particles 4b, 4c is dispersed. In a temperature region lower than the glass transition point of the glass layer (4), a thermal expansion coefficient thereof falls in between thermal expansion coefficients of the first member (2) and the second member (3). This allows thermal strain caused within the structure (1) to be reduced when the structure (1) is operated at a higher temperature than a room temperature.
Abstract:
A fuel assembly capable of linearizing change of an infinite multiplication factor of a fuel and flattening excess reactivity while increasing average fissile plutonium enrichment of a MOX fuel, and a reactor loaded with the fuel assembly can be provided. A fuel assembly includes first fuel rods containing Pu and not containing burnable poison, a second fuel rod containing uranium and burnable poison and not containing Pu, a water rod, and a channel box accommodating the first and second fuel rods and the water rod in a bundle. The second fuel rod is disposed on an outermost periphery and/or adjacent to the water rod, of a fuel rod array in a horizontal section, N2
Abstract:
There is provided a core of a boiling water reactor that can be operated without loading a new fuel assembly at an operation cycle before decommissioning. In the core of the boiling water reactor in which multiple fuel assemblies are loaded in a square lattice shape, during the fuel exchange, dispositions of the multiple fuel assemblies loaded into the core are changed without loading a new fuel assembly in the core, based on the number of residence cycles, in the core, of fuel assemblies laterally adjacent and longitudinally adjacent to a fuel assembly having the shortest loading period in core cross section and the number of residence cycles, in the core, of fuel assemblies diagonally adjacent thereto, among fuel assemblies loaded into the core after the fuel exchange without loading a fuel assembly having a shorter loading period than a fuel assembly having the shortest loading period loaded into the core before the fuel exchange in the core after the fuel exchange.
Abstract:
In a fuel assembly, a plurality of fuel rods are arranged in an array of 10 rows and 10 columns in the cross section of the fuel assembly. A flow resistance member is disposed in a central portion in the cross section at upper end portions of partial length fuel rods which are a part of the fuel rods. In the flow resistance member, resistance members are each disposed between ferrules arranged in an array of 6 rows and 6 columns in the diagonal direction of the flow resistance member. Resistance members are each disposed between the ferrules in a peripheral portion of the flow resistance member. By disposing the resistance members, the pressure loss in an inner region in the cross section of the fuel assembly is increased, and the flow rate of a gas-liquid two-phase flow in an outer region surrounding the inner region is increased.