Patents by Inventor Junichi Oyama

Junichi Oyama has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5638416
    Abstract: An arrangement of fuel rod support members having dimples and springs is presented to prevent abrasive wear of the fuel rods caused by bouncing of the fuel rods against the supporting members caused by vibrations in a diagonal direction of the support grids. The supporting members are disposed such that dimples are respectively provided on one pair of adjacent walls located on one side of the vibrational direction while springs are respectively provided on adjacent walls located on the opposite side of the vibrational direction.
    Type: Grant
    Filed: December 2, 1994
    Date of Patent: June 10, 1997
    Assignees: Mitsubishi Nuclear Fuel Co., Mitsubishi Jukogyo Kabushiki Kaisha
    Inventors: Junichi Oyama, Akihiro Kato, Masaji Mori, Toshiyuki Kawagoe, Kazuichi Suzuki, Hitoshi Inada, Hiromasa Miyai
  • Patent number: 5515408
    Abstract: A fuel assembly is presented in which a plurality of support grids are disposed along the longitudinal direction of the fuel rods. The straps forming the grid cells of the support grids are provided with mixing vanes for generating turbulent flow of the cooling water passing through the grid cells. In a plan view of the support girds, each of the mixing vanes protrudes inwardly of the grid cells and is disposed along a positive diagonal direction and a negative diagonal direction. This configuration of the mixing vanes are effective in preventing the generation of systematic vibrations in the fuel assembly by canceling the effects of the turbulent flows of the cooling water. The direction of protrusion of the mixing vanes can be in two diagonal directions within one support grid, or it can be unidirectional along either diagonal direction within one support grid.
    Type: Grant
    Filed: December 2, 1994
    Date of Patent: May 7, 1996
    Assignees: Mitsubishi Nuclear Fuel Co., Mitsubishi Jukogyo Kabushiki Kaisha
    Inventors: Junichi Oyama, Akihiro Kato, Masaji Mori, Toshiyuki Kawagoe, Kazuichi Suzuki, Hitoshi Inada, Hiromasa Miyai
  • Patent number: 5475913
    Abstract: A method of assembling a fuel assembly is presented so as to reduce radiation exposure to the assembly workers and to simplify the assembly procedure. Sleeves are pre-attached to an upper nozzle, and the guide pipes are inserted into respective grid cells through the sleeves of the upper nozzle and through the sleeves of the grids. The guide pipes are fixed in place to the sleeves of the upper nozzle and of the grids by bulging. There is no welding step necessary to join any of the assembly components while the assembly is in a semi-assembled condition. Therefore, the method is simple and efficient, and reduces the risk of radiation exposure to the assembly workers.
    Type: Grant
    Filed: April 20, 1994
    Date of Patent: December 19, 1995
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Katsunori Ohuchi, Shunji Ono, Toshiyuki Kawagoe
  • Patent number: 5396526
    Abstract: An apparatus is presented for removing the inner and outer keys from a support grid of a fuel assembly automatically or by mechanical methods. The apparatus removes a line of keys from a loaded assembly inserted into a grid through an opening section of the grid to deflect the springs. Both ends of the keys are engaged with the engaging members, and one set of keys are rotated in one direction while the other set of keys are rotated in the opposite direction. The springs are then released to press on the fuel rods firmly in place between the springs and the dimples in the grid cell. The keys are removed from the grid by clamping or holding the keys and moving the keys together with the clamping/holding device in the key axis direction by operating the driving device until the keys are removed completely from the grid.
    Type: Grant
    Filed: October 21, 1993
    Date of Patent: March 7, 1995
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Katsunori Ohuchi, Junichi Oyama, Masashi Yoshida, Taichi Koiwai, Shuji Yamazaki
  • Patent number: 5359633
    Abstract: In a method of assembling a nuclear fuel assembly, a deflecting jig is inserted into grid cells in each of a plurality of grids. The diameter of the deflecting jig is enlarged to urge a spring of at least one pair of dimples and spring associated with the grid cell to deflect the springs away from the dimple. A plurality of elongated key members are inserted into the grid cells through a plurality of openings defined at intersections between the straps forming walls of the grid cells. Each key member is rotated about its axis to cause hooks of the key member to project from a wall surface of the strap in a direction opposite to the projecting direction of the springs. The key member is then moved in a direction to engage the hooks with the wall surface of the strap. Urging of the spring by the deflecting jig is released to allow the same to be withdrawn from the grid cells and, subsequently, the fuel rods are inserted into the respective grid cells.
    Type: Grant
    Filed: September 29, 1993
    Date of Patent: October 25, 1994
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Kazuichi Suzuki, Akhirio Kato, Hitoshi Inada, Masaji Mori, Hiromasa Miyai, Toshiyuki Kawagoe
  • Patent number: 5313507
    Abstract: An apparatus for attaching a key member to a nuclear fuel assembly grid and detaching the same therefrom is disclosed. The apparatus includes a supply and recovery mechanism, an inserting and removing mechanism, and a rotating mechanism. The supply and recovery mechanism operates to supply the key member to a prescribed position adjacent to the grid and recover the same. The inserting and removing mechanism is disposed between the supply and recovery mechanism and the grid, and operates to insert the key member supplied from the supply and recovery mechanism into the grid and remove the key member from the grid to recover the same to the supply and recovery mechanism. The rotating mechanism is disposed adjacent to the inserting and removing mechanism, and operates to rotate the key member inserted in the grid in a prescribed direction about the longitudinal axis to attach the same to the grid and rotate the same in a direction opposite to the prescribed direction to detach the same from the grid.
    Type: Grant
    Filed: November 5, 1992
    Date of Patent: May 17, 1994
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Katsunori Ohuchi, Junichi Oyama, Akio Sando
  • Patent number: 5303272
    Abstract: The present invention relates to an apparatus for manipulating the springs which hold the fuel rods firmly inside the grid cells of the grids in a nuclear fuel assembly. Conventionally fuel rods are inserted into the grids while the grid springs are in the active position, thus exposing the rods to possibilities of surface scratches and potential problems. The invented automatic apparatus avoids the formation of such surface damage on the fuel rods, by inserting the keys to inactivate the grid springs before inserting the fuel rods into the grids and removing the keys after all the rods are in place. The apparatus thus contributes to efficient manufacturing of the fuel assembly by simplifying the key quantity management operations and other tasks associated with the assembling operations.
    Type: Grant
    Filed: October 21, 1992
    Date of Patent: April 12, 1994
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Akio Sando, Shuji Yamazaki
  • Patent number: 5289515
    Abstract: In a method of assembling a nuclear fuel assembly, a deflecting jig is inserted into grid cells in each of a plurality of grids. The diameter of the deflecting jig is enlarged to urge a spring of at least one pair of dimples and spring, associated with the grid cell to deflect the springs away from the dimple. A plurality of elongated key members are inserted into the grid cells through a plurality of openings defined at intersections between the straps forming walls of the grid cells. Each key member is rotated about its axis to cause hooks of the key member to project from a wall surface of the strap in a direction opposite to the projecting direction of the springs. The key member is then moved in a direction to engage the hooks with the wall surface of the strap. Urging of the spring by the deflecting jig is released to allow the same to be withdrawn from the grid cells and, subsequently, the fuel rods are inserted into the respective grid cells.
    Type: Grant
    Filed: August 15, 1991
    Date of Patent: February 22, 1994
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Kazuichi Suzuki, Akihiro Kato, Hitoshi Inada, Masaji Mori, Hiromasa Miyai, Toshiyuki Kawagoe
  • Patent number: 5274684
    Abstract: The present invention presents a method and an apparatus for assembling a fuel assembly which is free of surface damage on the fuel rod surfaces, and of distortions caused by residual stresses. Such problems are introduced by the method of inserting the fuel rods into the grids, and the sequence of attaching the control rod guiding pipes. In the conventional method, the guiding pipes are attached to the respective grids first and the fuel rods are inserted in the grids while the holding mechanisms (such as spring force against a dimple formed on the grid wall) are active. In the invented assembling method, the sprigs are deactivated first and then the fuel rods are inserted into the grids. Once the assembly is made firm with all the fuel rods in place and fixed firmly to the grids, the control rod guiding pipes are inserted into the grids and the pipes are fixed rigidly to the respective grids.
    Type: Grant
    Filed: October 23, 1992
    Date of Patent: December 28, 1993
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Masashi Yoshida, Akio Sando, Junichi Oyama, Katsunori Ohuchi
  • Patent number: 5263065
    Abstract: The purpose of the present invention is to provide an apparatus which can insert a plurality of hooks into slits of a strap constructing a grid and to hold springs so that the spaces of grid cells are enlarged simultaneously. The enlargement enables insertion of fuel rods into the cells. The apparatus comprises a frame member adapted to attach to the strap along the longitudinal direction thereof, a pair of clamping members engaged the frame member and extending in the longitudinal direction of the strap. Each clamping member can move along the longitudinal direction of the strap. The clamping member has a plurality of projecting hooks arranged in the longitudinal direction of the strap in a spaced relation to one another. The end of the hooks of one of the clamping means are bent toward a longitudinal direction of the strap, while the hooks of another clamping means are bent toward another longitudinal direction of the strap.
    Type: Grant
    Filed: December 23, 1992
    Date of Patent: November 16, 1993
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Taichi Koiwai, Shuji Yamazaki
  • Patent number: 5114668
    Abstract: In a grid in a nuclear fuel assembly for supporting fuel rods, elongated straps intersect with each other to define grid cells. At least one pair of punched sections are formed, in spaced relation to each other, in each of peripheral walls of the respective grid cells. At least one of elongated spring elements is formed in the peripheral wall of each grid cell. Each spring element is formed such that a portion of the peripheral wall of the grid cell between the pair of punched sections bulges and projects into the grid cell. The spring element is capable of being deflected toward the peripheral wall of the grid cell. A pair of projections are formed in the peripheral wall of the grid cell respectively at both longitudinal ends of the spring element such that a pair of portions of the peripheral wall of the grid cell bulge. Both longitudinal ends of the spring element are connected respectively to the pair of projections.
    Type: Grant
    Filed: January 23, 1990
    Date of Patent: May 19, 1992
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Kazuichi Suzuki, Akihiro Kato, Hitoshi Inada, Masaji Mori, Hiromasa Miyai, Toshiyuki Kawagoe
  • Patent number: 5068081
    Abstract: In a method of assembling a nuclear fuel assembly, a deflecting jig is inserted into grid cells in each of a plurality of grids. The diameter of the deflecting jig is enlarged to urge a spring of at least one pair of dimples and spring associated with the grid cell to deflect the spring away from the dimple. A plurality of elongated key members are inserted into the grid cells through a plurality of openings defined at intersections between the straps forming walls of the grid cells. Each key member is rotated about its axis to cause hooks of the key member to project from a wall surface of the strap in a direction opposite to the projecting direction of the springs. The key member is then moved in a direction to engage the hooks with the wall surface of the strap. Urging of the spring by the deflecting jig is released to allow the same to be withdrawn from the grid cells and, subsequently, the fuel rods are inserted into the respective grid cells.
    Type: Grant
    Filed: January 3, 1990
    Date of Patent: November 26, 1991
    Assignee: Mitsubishi Nuclear Fuel Co.
    Inventors: Junichi Oyama, Kazuichi Suzuki, Akihiro Kato, Hitoshi Inada, Masaji Mori, Hiromasa Miyai, Toshiyuki Kawagoe