Masumi, Ryoji;

Fuel assembly

A fuel assembly attains high burnup and increases reactor shut-down margin when loaded into a reactor core wherein a water gap width on a control rod side and a water gap width on a side opposite to the control rod side are almost equal to each other. The fuel assembly has a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets and also has at least one neutron moderator rod shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly.

• Radio frequency data communications device Automatic vehicle washing apparatus
• Phased beam transducer Prokaryotic expression in eukaryotic cells
• Engine block Printing apparatus and communication apparatus
• Automation of plasma sequestration Ordered packing
• High density MLV contact assembly Fungicidal composition comprising a 2-imidazolin-5-one
• Vehicle rear-suspension system Chelant enhanced photobleaching
• Haemostatic clip holder Long function monitoring apparatus flowheads
• Polymers and processes thereof Window shutter
• Aircraft brake Partial width oven rack
• Solar heat collector Amplification method for polynucleotide assays
• Connecting structure for shelves Fuse holder
• Proportioned piston ring seals Diagnostics for resistance based transmitter
• Circuit breaker Optical component packaging
• Recording liquid Steering column isolator pads
• Microturbomachinery Concrete slab striker
• Crosslinked polyacrylamides containing silyl groups Flexible integrated memory
• Carbon dioxide detector and shield Hydrolyzable and polymerizable vinylcyclopropane silanes
• Small diameter impact boring tool Transmission over packet switched networks
• Evaluated teletherapy source library Insulated terminal assembly
• Water mattress construction Optical sensor module tester
• Injection cartridge Multi-channel position detection system
• Tool holder Portable external tool tray assembly
• Low permeability dryer fabric Non-linear signal processing apparatus
• Headlight for mine vehicle Antifungal triazole ethanol derivatives
• Engine oil draining system Atmometer covering and method
• Spindle cleaning apparatus Futurebus interrupt subsystem apparatus
• Control of scanning velocity modulation Horn switch
• Apparatus for cutting sheet material Semiconductor integrated circuit device
• Thermal transfer imaging process Polyhydro derivatives of 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine
• Image forming apparatus Multifunction fastening apparatus
• Passive peak deflection sensor Syringe, injector and injector system
• Multi-part pressure chuck

What is claimed is:

1. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same; and

at least one neutron moderator rod shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly.

2. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same; and

at least one neutron moderator rod, a center of said at least one neutron moderator rod being shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly.

3. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a fuel bundle having a plurality of fuel rods arranged in a square lattice pattern and at least one neutron moderator rod, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same;

an upper tie plate and a lower tie plate-holding upper end portions and lower end portions of said fuel rods respectively; and

means for fixing a channel box covering said fuel bundle to one corner of said upper tie plate by a channel fastener, a center of said at least one neutron moderator rod being shifted toward said one corner, away from a cross sectional center of the fuel assembly.

4. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a plurality of fuel rods arranged in a square lattice of 10-rows by 10-columns, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same; and

one water rod disposed in an area of 3-rows by 3-columns in said square lattice, a center of said one water rod being shifted toward one corner where a control rod is inserted with respect to a cross sectional center of the fuel assembly.

5. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a fuel bundle having a plurality of fuel rods arranged in a square lattice of 10-rows by 10-columns and one water rod disposed in an area of 3-rows by 3-columns in said square lattice, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same;

an upper tie plate and a lower tie plate holding upper end portions and lower end portions of said fuel rods respectively; and

means for fixing a channel box covering said fuel bundle to one corner of said upper tie plate by a channel fastener, a center of said one water rod being shifted toward said one corner with respect to a cross sectional center of the fuel assembly.

6. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite-side water gap width are almost equal to each other, comprising:

a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same; and

at least one neutron moderator rod shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly so as to cause the distribution of neutron moderators within a cross section to be shifted toward said one corner.

7. A fuel assembly for being loaded into a reactor core wherein a control rod-side water gap width and an opposite side water gap width are almost equal to each other, comprising:

a plurality of fuel rods arranged in a square lattice pattern, each fuel rod being filled with nuclear fuel pellets, distances between adjacent fuel rods in row and column directions are the same; and

at least one neutron moderator rod, a center of said at least one neutron moderator rod being shifted toward one corner where a control rod is inserted, away from a cross sectional center of the fuel assembly so as to cause the distribution of neutron moderators within a cross section to be shifted toward said one corner.