Abstract: A fuel assembly, particularly, a fuel assembly including short-length fuel rods and fuel spacers, is used for a boiling water reactor, which is capable of sufficiently reducing the pressure loss of at least one of the fuel spacers positioned above the upper ends of the short-length fuel rods, irrespective of the arrangement of the short-length fuel rods, and also ensuring the structural strength of the fuel spacer. The fuel assembly includes fuel rods located in a square lattice array, two water rods arranged in a region in which seven of the fuel rods are arrangeable, two fuel spacers for holding the fuel rods and the water rods with mutual intervals kept immovable. Each of the fuel spacers includes cells which are connected to each other and in which the fuel rods are to be inserted, respectively, and a band for surrounding the outermost peripheries of the cells. The short-length fuel rods include four first short-length fuel rods arranged in the outermost peripheral region of the square lattice array.

Abstract: A preventive maintenance method and apparatus for a structural member in a reactor pressure vessel according to the present invention reduce a tensile residual stress on a surface of the structural member by impinging a water jet from a nozzle onto a plane surface of a deflector to thereby change direction of flow of the water jet, and impinging the water jet after being deflected onto the surface of the structural member. This method and apparatus are applicable to a narrow space portion, and can improve a residual stress on the surface of the structural member and can also prevent damage such as stress corrosion cracking.

Abstract: A preventive maintenance method and apparatus for a structural member in a reactor pressure vessel according to the present invention reduce a tensile residual stress on a surface of the structural member by impinging a water jet from a nozzle onto a plane surface of a deflector to thereby change direction of flow of the water jet, and impinging the water jet after being deflected onto the surface of the structural member. This method and apparatus are applicable to a narrow space portion, and can improve a residual stress on the surface of the structural member and can also prevent damage such as stress corrosion cracking.

Abstract: A data processing device having a shutter opening and closing mechanism which operates within a path along which a minidisk MD moves to open a shutter only when it is necessary to open the shutter of the MD. A change-over mechanism for diverting the drive force for loading cassettes to the shutter opening and closing mechanism. A recording medium pushing mechanism is arranged to stop a recording medium from being taken out of the magazine to the carrier when there is a recording medium in the carrier. A recording medium take-in/eject mechanism able to reduce the space occupied, and a carrier mechanism which improves the working efficiency during assembly. This makes it possible to provide a data processing device with improved operating properties.

Abstract: The lower end of each of a plurality of fuel rods is supported by a fuel supporting portion of a lower tie plate. The fuel supporting portion includes a plurality of second coolant paths for supplying a coolant from below the fuel supporting portion to a first coolant path defined above the fuel supporting portion and between the fuel rods. The total cross-sectional area of all the second coolant paths is smaller than the cross-sectional area of the first coolant path.

Abstract: The lower end of each of a plurality of fuel rods is supported by a fuel supporting portion of a lower tie plate. The fuel supporting portion includes a plurality of second coolant paths for supplying a coolant from below the fuel supporting portion to a first coolant path defined above the fuel supporting portion and between the fuel rods. The total cross-sectional area of all the second coolant paths is smaller than the cross-sectional area of the first coolant path.

Abstract: A corrosive environment sensor comprises an elongate metal member having a pair of beam portions, each extending in a length direction between first and second ends of the metal member, and having a crack growth portion formed therein and extending in the length direction of the metal member from a crack starting end toward the second end, wherein the crack starting end is at an intermediate position between the first and second ends of the metal member and is between the pair of beam portions, a changeable load member having an expansible chamber disposed between the beam portion around the first end of the metal member and a means for supplying pressurized fluid to the expansible chamber. The changeable load member applies a load to the crack growth portion and the means for supplying pressurized fluid to the expansible chamber is responsible for ensuring that the displacement of the beam portions is accomplished in such a manner so as to provide a constant stress intensity factor at a crack growing point.

Abstract: A data processing device for holding a plurality of recording medium cassettes has a housing with an aperture to receive and discharge the cassettes. A holding member can receive a cassette that has been inserted through the aperture and deliver the cassette to a storage rack for storing a plurality of cassettes. A shutter can be activated to close the aperture. A moving elevator plate contacts the holding device, the storage rack, and the shutter member to enable the aperture to be opened when the holding member can receive a cassette and to be closed when the holding member has been moved from a position adjacent the aperture.

Abstract: A fuel assembly comprises a plurality of fuel rods, tie plates for holding both ends of these fuel rods, and spacers which support these fuel rods. The spacer comprises a plurality of cells into which the fuel rods are inserted respectively, the adjacent cells being joined to each other at axial ends thereof, whereby a space between these cells being held or retained, and a plurality of loop springs held respectively on the cells. Each of the loop springs has a pair of resilient members which are located within the pair of adjacent cells and which urge the fuel rods in a radial direction, and a pair of connections which connect axial ends of the resilient members to each other. Each of the connections have a passage through which coolant flows axially and which is defined by a closed peripheral wall. The closed peripheral wall is not uniform in thickness. The pair of adjacent cells have at axial end portions of peripheral walls openings for accommodating or receiving the connections of the loop spring.

Abstract: A corrosive environment sensor comprises an elongate member having a pair of elongate beam portions and a crack growth portion formed between the pair of beam portions so as to extend axially, and a wedge inserted between the pair of beam portions, wherein the crack growth portion has width thereof defined by quadratic curves extending axially so as to decrease from an axially intermediate portion of the sensor member to an axially intermediate portion of the crack growth portion and increase from the axially intermediate portion of the crack growth portion toward an end of the sensor member. The quadratic curves each consist of a first circular arc with first radius between the axially intermediate portion of the sensor member and the axially intermediate portion of the crack growth portion and a second circular arc with second radius less than the first radius between the axially intermediate portion of the crack growth portion and around the second end of the sensor member.

Abstract: A non-destructive inspection apparatus includes a magnetic field applying device and a magnetic sensor. The magnetic field applying device is adapted to apply DC and AC magnetic fields to an object to be inspected. Degradation/damage of the object is detected by measuring a magnetic characteristic of the object in a state in which the DC and AC magnetic fields are applied. Also, a non-destructive inspection apparatus includes as a magnetic sensor a plurality of pickup coils and a SQUID(s) connected to the pickup coils and decides the form of a defect of an object to be inspected by producing a difference between outputs of the pickup coils or SQUIDs.

Abstract: A corrosive environmental crack length measuring apparatus including a double-cantilever beam type test piece having a tapered portion in a portion where the crack grows, a slit, and at least two holes, with the test piece being placed within a corrosive environment. Leads inserted in the holes of the test piece to be spot-welded thereto to supply a direct current to the holes. A current polarity switching device is provided with, a stabilized direct current power supply connected with the direct current supplying leads through the current polarity switching device. Potential difference measuring leads are inserted in holes formed in two outer faces of the double-cantilever beam type test piece parallel to a section of a crack growing portion at a plurality of points along the crack growing direction so as to be spot-welded thereto.

Abstract: A fuel assembly, where crystallographic orientations of a channel box are brought into a random distribution; and cladding tubes, spacers and a channel box are made from highly corrosion-resistant, Fe--Ni, zirconium-based alloy, hardened in the (.alpha.+.beta.) phase or .beta.-phase temperature region, has an average discharge burnup level of 50 to 550 GWd/t.

Abstract: A method system for assessing the safety of a rotor of a shrinkage fitted type wherein an opening displacement of a crack is determined an elastic-plastic fracture method and a reduction in shrinkage fitting force is calculated based on the crack opening displacement. The safety of the rotor is assessed based on the reduction in shrinkage fitting force caused to occur by the opening of the crack.