Patents by Inventor Kouji Hiraiwa

Kouji Hiraiwa 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).

  • Publication number: 20180090233
    Abstract: Light water reactor fuel assemblies each comprises: light water reactor fuel rods that extend longitudinally, contain nuclear fuel materials including enriched uranium, and are arranged parallel to each other; and burnable poison containing fuel rods that extend longitudinally, contain nuclear fuel materials whose main component is uranium that is lower in enrichment than the enriched uranium of the light water reactor fuel rods, and burnable poison, and are arranged in a lattice pattern together with the light water reactor fuel rods. The assemblies are arranged parallel to each other and in a lattice pattern. An initial value of a first enrichment of the enriched uranium is set in such a way that the first enrichment of the enriched uranium at an end of each operation cycle is greater than a predetermined value.
    Type: Application
    Filed: September 26, 2017
    Publication date: March 29, 2018
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Kouji HIRAIWA, Rei Kimura, Shungo Sakurai, Rie Aizawa, Goro Yanase, Shinichiro Kawamura
  • Patent number: 8401141
    Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity A0 expressed as A0=a0×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity B0=b0×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/a0) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/a0) and the correlation curve.
    Type: Grant
    Filed: December 29, 2008
    Date of Patent: March 19, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Makoto Ueda, Hironori Kumanomido, Ishi Mitsuhashi, Tsukasa Kikuchi, Kenichi Yoshioka, Tomoharu Sasaki, Kouji Hiraiwa
  • Publication number: 20090252271
    Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity A0 expressed as A0=a0×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity B0=b0×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/a0) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/a0) and the correlation curve.
    Type: Application
    Filed: December 29, 2008
    Publication date: October 8, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Makoto Ueda, Hironori Kumanomido, Ishi Mitsuhashi, Tsukasa Kikuchi, Kenichi Yoshioka, Tomoharu Sasaki, Kouji Hiraiwa
  • Publication number: 20070076839
    Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity Ao expressed as Ao=ao×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity Bo=bo×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/ao) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/ao) and the correlation curve.
    Type: Application
    Filed: May 16, 2006
    Publication date: April 5, 2007
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Makoto Ueda, Hironori Kumanomido, Ishi Mitsuhashi, Tsukasa Kikuchi, Kenichi Yoshioka, Tomoharu Sasaki, Kouji Hiraiwa
  • Patent number: 6925138
    Abstract: The present invention is to provide a reactor core that allows a nuclear plant to continuously operate for a long term period, for example 15 years or longer, without requiring any fuel exchange, reduces the duration and number of maintenance steps involved in regular plant inspections, markedly improves plant availability and economic efficiency, and is effective in terms of nuclear nonproliferation. A plurality of fuel assemblies 103, themselves obtained by arranging fuel rods 100 and water rods 107 in square lattices, are arranged in a square lattice at a certain pitch. The blades 102a of a cross-shaped (cruciform) control rod 102 in a cross section are inserted into four adjacent spaces formed by four fuel assemblies 100 facing each other. A value of 0.
    Type: Grant
    Filed: October 17, 2001
    Date of Patent: August 2, 2005
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Mikihide Nakamaru, Hideaki Heki, Takehiko Saito, Kouji Hiraiwa, Tadashi Narabayashi, Satoru Oomizu, Tsuyoshi Shimoda, Kenji Arai, Shinichi Morooka, Seijiro Suzuki
  • Patent number: 6810099
    Abstract: The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.
    Type: Grant
    Filed: October 17, 2001
    Date of Patent: October 26, 2004
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Mikihide Nakamaru, Hideaki Heki, Takehiko Saito, Kouji Hiraiwa, Tadashi Narabayashi, Satoru Oomizu, Tsuyoshi Shimoda, Kenji Arai, Shinichi Morooka, Seijiro Suzuki
  • Patent number: 6445759
    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.
    Type: Grant
    Filed: October 13, 2000
    Date of Patent: September 3, 2002
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kouji Hiraiwa, Yamato Hayashi, Yasushi Hirano, Jun Saeki, Kazuki Hida, Junko Watanabe
  • Publication number: 20020101951
    Abstract: The present invention provides a boiling water-type nuclear power plant comprising: a passive safety system having depressurization valves and a gravity driven core cooling system as an emergency core cooling system; a passive containment vessel cooling system in which reactor steam released in the containment vessel is cooled by a heat exchanger in a cooling water pool installed in the upper portion of the containment vessel; and a containment vessel flooding system which injects cooling water into a dry well of the containment vessel on an accident; wherein a containment vessel spray cooling system for injecting cooling water into the containment vessel via a pump is further added as a safety system.
    Type: Application
    Filed: October 17, 2001
    Publication date: August 1, 2002
    Inventors: Mikihide Nakamaru, Hideaki Heki, Takehiko Saito, Kouji Hiraiwa, Tadashi Narabayashi, Satoru Oomizu, Tsuyoshi Shimoda, Kenji Arai, Shinichi Morooka, Seijiro Suzuki
  • Publication number: 20020085660
    Abstract: The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.
    Type: Application
    Filed: October 17, 2001
    Publication date: July 4, 2002
    Inventors: Mikihide Nakamaru, Hideaki Heki, Takehiko Saito, Kouji Hiraiwa, Tadashi Narabayashi, Satoru Oomizu, Tsuyoshi Shimoda, Kenji Arai, Shinichi Morooka, Seijiro Suzuki
  • Publication number: 20020080908
    Abstract: The present invention is to provide a reactor core that allows a nuclear plant to continuously operate for a long term period, for example 15 years or longer, without requiring any fuel exchange, reduces the duration and number of maintenance steps involved in regular plant inspections, markedly improves plant availability and economic efficiency, and is effective in terms of nuclear nonproliferation.
    Type: Application
    Filed: October 17, 2001
    Publication date: June 27, 2002
    Inventors: Mikihide Nakamaru, Hideaki Heki, Takehiko Saito, Kouji Hiraiwa, Tadashi Narabayashi, Satoru Oomizu, Tsuyoshi Shimoda, Kenji Arai, Shinichi Morooka, Seijiro Suzuki
  • Publication number: 20020015462
    Abstract: In a nuclear reactor, in-core stability is improved, power density is increased, and an economical natural-circulation reactor (or partial forced-circulation reactor) is achieved. The reactor core has a void reactivity coefficient between −0.07 and −0.03 % &Dgr; k/k/% void fraction. This void reactivity coefficient range is achieved by, for example, the design of the by-pass portion and channel box, the enrichment distribution along the axial direction, the provision of blanket areas, and/or the arrangement of water rods and fuel rods within a channel box.
    Type: Application
    Filed: August 19, 1999
    Publication date: February 7, 2002
    Inventor: KOUJI HIRAIWA
  • Patent number: 6343106
    Abstract: In a nuclear reactor, in-core stability is improved, power density is increased, and an economical natural-circulation reactor (or partial forced-circulation reactor) is achieved. The reactor core has a void reactivity coefficient between −0.07 and −0.03% &Dgr;k/k/% void fraction. This void reactivity coefficient range is achieved by, for example, the design of the by-pass portion and channel box, the enrichment distribution along the axial direction, the provision of blanket areas, and/or the arrangement of water rods and fuel rods within a channel box.
    Type: Grant
    Filed: August 19, 1999
    Date of Patent: January 29, 2002
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Kouji Hiraiwa
  • Patent number: 5416813
    Abstract: A moderator rod provided with a burnable poison and disposed in a fuel assembly of a reactor core comprises an outer tube, an inner tube disposed in the outer tube, the outer and inner tubes constituting a double tube structure between which an annular section is formed, and a burnable poison charged in said annular section. A containing amount of the burnable poison per unit area of the annular section is distributed at least one of peripheral direction and axial direction of the double tube structure of the inner and outer tubes. A fuel assembly of a nuclear reactor comprises an upper tie plate, a lower tie plate, a number of fuel rods supported at their upper ends by the upper tie plate and at their lower ends by the lower tie plate and filled up in their inner spaces with a plurality of fuel pellets, at least one of moderator rods containing burnable poison in various states and a channel box. The moderator has an outer tube and an inner tube disposed coaxially in the outer tube.
    Type: Grant
    Filed: October 28, 1993
    Date of Patent: May 16, 1995
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kouji Hiraiwa, Yoshihira Ando, Koji Hirukawa, Kazuki Hida
  • Patent number: 4968479
    Abstract: A fuel assembly for a nuclear reactor includes a number of fuel rods filled with a fuel material. A water rod having a cross sectional area larger than that of each fuel rod is disposed at substantially the central portion of the fuel assembly. The fuel rods include first fuel rods having a whole effective fuel zone filled with a fuel material throughout the entire length thereof and second fuel rods each having an interposed zone in which enrichment of a fissile nuclide is significantly reduced or the fissile nuclide does not exist at all. The second fuel rods are arranged so as to surround the water rod so that the interposed zones are positioned on an axial level including a portion at which subcriticality is made small at a period in which maintenance of reactor shut-down margine is made difficult during the reactor operation period.
    Type: Grant
    Filed: August 24, 1988
    Date of Patent: November 6, 1990
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shunsuke Ogiya, Mamoru Nagano, Kouji Hiraiwa, Hisao Suzuki, Shouichi Watanabe, Makoto Ueda