Patents by Inventor Tomohiko Ikegawa

Tomohiko Ikegawa 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: 20190371481
    Abstract: In view of above problems, an object of the invention is to provide a primary containment vessel venting system having a structure capable of continuously discharging vapor in a primary containment vessel out of the system and continuously reducing pressure of the primary containment vessel without discharging radioactive noble gases to the outside of the containment vessel and without using an enclosing vessel or a power source. In order to achieve the above object, an nuclear power plant of the invention includes a primary containment vessel which includes a reactor pressure vessel, a radioactive substance separation apparatus which is disposed inside the primary containment vessel and through which the radioactive noble gases do not permeate but vapor permeates, a vent pipe which is connected to the radioactive substance separation apparatus, and an exhaust tower which is connected to the vent pipe and discharges a gas, from which a radioactive substance is removed, to the outside.
    Type: Application
    Filed: January 12, 2018
    Publication date: December 5, 2019
    Inventors: Sohei FUKUI, Takahisa MATSUZAKI, Kazuaki KITO, Yoshihiko ISHII, Masataka HIDAKA, Tomohiko IKEGAWA, Katsuki HAMADA
  • Patent number: 10438707
    Abstract: An atomic power plant is provided including a primary containment vessel (PCV) 1, a reactor pressure vessel (RPV) 3, a main steam line 4, two steam safety relief valves (SRVs) 6, a pressure suppression pool (S/P) 8, an SRV exhaust pipe 9 which is connected to a quencher 10, a temperature measuring instrument 12 which measures a temperature inside the quencher 10, an SRV controller 13 which controls opening and closing of the SRVs 6. After a lapse of predetermined time from when the SRV 6 is opened, in a case where it is determined that a temperature detected by the temperature measuring instrument 12 is equal to or smaller than a predetermined threshold value, the SRV controller 13 causes the SRV 6 to which the temperature measuring instrument 12 detecting the temperature leads, to be closed and to be prohibited from being opened.
    Type: Grant
    Filed: January 31, 2017
    Date of Patent: October 8, 2019
    Assignee: Hitachi-GE Nuclear Energy, Ltd.
    Inventors: Kazuaki Kito, Takahisa Matsuzaki, Tomohiko Ikegawa
  • Publication number: 20170229196
    Abstract: [Problem] Provided is an atomic power plant which can be applied to reactors including existing reactors through a simple method and in which a pressure in a primary containment vessel can be restrained from excessively rising in a case where a steam leakage from an exhaust pipe of a stream safety relief valve occurs. [Solution] There are provided a PCV 1, an RPV 3, a main stream line 4, two SRVs 6, an S/P 8, an SRV exhaust pipe 9 which is connected to a quencher 10, a temperature measuring instrument 12 which measures a temperature inside the quencher 10, an SRV controller 13 which controls opening and closing of the SRVs 6.
    Type: Application
    Filed: January 31, 2017
    Publication date: August 10, 2017
    Inventors: Kazuaki KITO, Takahisa MATSUZAKI, Tomohiko IKEGAWA
  • Patent number: 9312034
    Abstract: The invention includes a heat exchanger provided at a position higher than a primary containment vessel; a condensate storage tank disposed below the heat exchanger and above an upper end of a reactor core placed in a reactor pressure vessel; a non-condensate gas discharge line connected to an upper section of the condensate storage tank and to a suppression pool; a second condensate discharge line connected to a position below that section of the condensate storage tank to which a first end of the non-condensate gas discharge line is connected, and to the suppression pool; and a condensate return line connected to a position below that section of the condensate storage tank to which a first end of the second condensate discharge line is connected, and to a side portion of the reactor pressure vessel, the side portion being above the upper end of the core.
    Type: Grant
    Filed: October 22, 2013
    Date of Patent: April 12, 2016
    Assignee: Hitachi-GE Nuclear Energy, Ltd.
    Inventors: Tomohiko Ikegawa, Kazuaki Kito
  • Publication number: 20140112426
    Abstract: The invention includes a heat exchanger provided at a position higher than a primary containment vessel; a condensate storage tank disposed below the heat exchanger and above an upper end of a reactor core placed in a reactor pressure vessel; a non-condensate gas discharge line connected to an upper section of the condensate storage tank and to a suppression pool; a second condensate discharge line connected to a position below that section of the condensate storage tank to which a first end of the non-condensate gas discharge line is connected, and to the suppression pool; and a condensate return line connected to a position below that section of the condensate storage tank to which a first end of the second condensate discharge line is connected, and to a side portion of the reactor pressure vessel, the side portion being above the upper end of the core.
    Type: Application
    Filed: October 22, 2013
    Publication date: April 24, 2014
    Applicant: Hitachi-GE Nuclear Energy, Ltd.
    Inventors: Tomohiko IKEGAWA, Kazuaki KITO
  • Publication number: 20140064433
    Abstract: In a fuel assembly having fuel rods U1 to U4, and P1 not containing gadolinia, and fuel rods G1-G3 containing gadolinia, the concentrations a of gadolinia in nuclear fuel materials A (8 wt % and 10 wt %) satisfy 0.7<a/amax?1.0, the concentrations b of gadolinia in nuclear fuel materials B (5 wt % and 6 wt %) satisfy 0.4<b/amax?0.7, the concentration c of gadolinia in a nuclear fuel material C (2 wt %) satisfies 0<c/amax?0.4, and L(A)/5.0?L(B) and L(B)/5.0?L(C) are satisfied. The gadolinia with concentrations a burns out during the end of cycle, the gadolinia with concentrations b during the middle of cycle, and the gadolinia with a concentration c during the beginning of cycle. L(A) is the total axial length of zones filled with the nuclear fuel materials A in the fuel rods G1-G3, L(B) for materials B in G2 and G3, and L(C) material C in G1.
    Type: Application
    Filed: August 29, 2013
    Publication date: March 6, 2014
    Applicant: Hitachi-GE Nuclear Energy, Ltd.
    Inventors: Naoyuki Nakadozono, Takeshi Mitsuyasu, Tomohiko Ikegawa
  • Patent number: 8363776
    Abstract: A ratio of the number of fuel assemblies loaded on a core to the number of control rod drive mechanisms is 3 or more. The fuel assembly itself contains mixed oxides of a low enrichment concentration uranium oxide containing 3 to 8 wt % in the average enrichment concentration of the fuel assembly, or mixed oxide containing not less than 2 wt %, but less than 6 wt % in the average enrichment concentration of fissile plutonium of. In the burner type BWR core on which the fuel assemblies are loaded, an average weight density of uranium, plutonium and minor actinides is 2.1 to 3.4 kg/L as a conversion at the value of unburned state.
    Type: Grant
    Filed: March 19, 2004
    Date of Patent: January 29, 2013
    Assignee: Hitachi, Ltd.
    Inventors: Renzou Takeda, Motoo Aoyama, Junichi Miwa, Tomohiko Ikegawa, Kumiaki Moriya
  • Publication number: 20130003908
    Abstract: A ratio of the number of fuel assemblies loaded on a core to the number of control rod drive mechanisms is 3 or more. The fuel assembly itself contains mixed oxides of a low enrichment concentration uranium oxide containing 3 to 8 wt % in the average enrichment concentration of the fuel assembly, or mixed oxide containing not less than 2 wt %, but less than 6 wt % in the average enrichment concentration of fissile plutonium of. In the burner type BWR core on which the fuel assemblies are loaded, an average weight density of uranium, plutonium and minor actinides is 2.1 to 3.4 kg/L as a conversion at the value of unburned state.
    Type: Application
    Filed: March 19, 2004
    Publication date: January 3, 2013
    Inventors: Renzou Takeda, Motoo Aoyama, Junichi Miwa, Tomohiko Ikegawa, Kumiaki Moriya
  • Publication number: 20110200155
    Abstract: In order to stably control a nuclear reactor in a short time, so as not to enter an unstable region that is determined by the relationship between the reactor pressure, the reactor power and the subcooling of the core inlet coolant at start-up time, the nuclear reactor system comprises: an power control apparatus for generating a control rod operation signal for operating a control rod, based on the reactor water temperature change rate; a feed water control apparatus for generating a feed water flow rate signal and a discharge water flow rate signals based on the reactor water level signal; and a process computer for performing overall control of the power control apparatus and the feed water control apparatus, wherein the feed water control apparatus has the reactor water temperature change rate setting section for adjusting the reactor water temperature change rate set value based on the variation of the reactor water level signal.
    Type: Application
    Filed: January 13, 2011
    Publication date: August 18, 2011
    Inventors: Atsushi Fushimi, Setsuo Arita, Yoshihiko Ishii, Tomohiko Ikegawa, Shin Hasegawa, Kazuhiko Ishii
  • Publication number: 20100272223
    Abstract: In order to stably control a nuclear reactor in a short time, so as not to enter an unstable region that is determined by the relationship between the reactor pressure, the reactor power and the subcooling of the core inlet coolant at start-up time, the nuclear reactor system comprises: an power control apparatus for generating a control rod operation signal for operating a control rod, based on the reactor water temperature change rate; a feed water control apparatus for generating a feed water flow rate signal and a discharge water flow rate signals based on the reactor water level signal; and a process computer for performing overall control of the power control apparatus and the feed water control apparatus, wherein the feed water control apparatus has the reactor water temperature change rate setting section for adjusting the reactor water temperature change rate set value based on the variation of the reactor water level signal.
    Type: Application
    Filed: January 25, 2007
    Publication date: October 28, 2010
    Inventors: Atsushi Fushimi, Setsuo Arita, Yoshihiko Ishii, Tomohiko Ikegawa, Shin Hasegawa, Kazuhiko Ishii
  • Publication number: 20100195782
    Abstract: A natural circulation boiling water reactor includes a reactor pressure vessel, a chimney including a lattice member and arranged above a core in said reactor pressure vessel, and a plurality of thermocouple extension wire pulling conduits into which at least one temperature detection thermocouple and at least one cable connected to the temperature detection thermocouple are inserted. At least one of thermocouple extension wire pulling conduits is disposed on an upper end surface of the lattice member and is directly mounted to the upper end surface of the lattice member.
    Type: Application
    Filed: April 13, 2010
    Publication date: August 5, 2010
    Inventors: Yoshihiko Ishii, Shiro Takahashi, Setsuo Arita, Atsushi Fushimi, Tomohiko Ikegawa
  • Publication number: 20090052604
    Abstract: A natural circulation boiling water reactor includes a reactor pressure vessel, a chimney including a lattice member and arranged above a core in the reactor pressure vessel, and at least one thermocouple extension wire pulling conduit into which a temperature detection thermocouple and a cable connected to said temperature detection thermocouple are inserted. The thermocouple extension wire pulling conduit is disposed on an upper end surface of the lattice member and mounted to the upper end surface of the lattice member.
    Type: Application
    Filed: October 14, 2008
    Publication date: February 26, 2009
    Inventors: Yoshihiko Ishii, Shiro Takahashi, Setsuo Arita, Atsushi Fushimi, Tomohiko Ikegawa
  • Patent number: 7349518
    Abstract: A ratio of the number of fuel assemblies loaded on a core to the number of control rod drive mechanisms is 3 or more. The fuel assembly itself contains mixed oxides of a low enrichment concentration uranium oxide containing 3 to 8 wt % in the average enrichment concentration of the fuel assembly, or mixed oxide containing not less than 2 wt %, but less than 6 wt % in the average enrichment concentration of fissile plutonium of. In the burner type BWR core on which the fuel assemblies are loaded, an average weight density of uranium, plutonium and minor actinides is 2.1 to 3.4 kg/L as a conversion at the value of unburned state.
    Type: Grant
    Filed: March 16, 2006
    Date of Patent: March 25, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Renzou Takeda, Motoo Aoyama, Junichi Miwa, Tomohiko Ikegawa, Kumiaki Moriya
  • Publication number: 20070201606
    Abstract: A chimney lattice is arranged in a reactor pressure vessel. Thermocouple extension wire pulling conduits inserting a temperature detection thermocouple and a cable connected to the thermocouple are mounted to the upper end of the chimney lattice. By mounting the thermocouple extension wire pulling conduit on the upper end of the chimney lattice, the thermocouple extension wire pulling conduit does not become an obstacle when the fuel assembly is taken out from the chimney. Because the thermocouple extension wire pulling conduit is installed at the upper end of the chimney, the replacement of the thermocouple damaged is easy.
    Type: Application
    Filed: February 26, 2007
    Publication date: August 30, 2007
    Inventors: Yoshihiko ISHII, Shiro Takahashi, Setsuo Arita, Atsushi Fushimi, Tomohiko Ikegawa
  • Publication number: 20060210009
    Abstract: A ratio of the number of fuel assemblies loaded on a core to the number of control rod drive mechanisms is 3 or more. The fuel assembly itself contains mixed oxides of a low enrichment concentration uranium oxide containing 3 to 8 wt % in the average enrichment concentration of the fuel assembly, or mixed oxide containing not less than 2 wt %, but less than 6 wt % in the average enrichment concentration of fissile plutonium of. In the burner type BWR core on which the fuel assemblies are loaded, an average weight density of uranium, plutonium and minor actinides is 2.1 to 3.4 kg/L as a conversion at the value of unburned state.
    Type: Application
    Filed: March 16, 2006
    Publication date: September 21, 2006
    Inventors: Renzou Takeda, Motoo Aoyama, Junichi Miwa, Tomohiko Ikegawa, Kumiaki Moriya