Reactivity control rod for core, core of nuclear reactor, nuclear reactor and nuclear power plant

Abstract

In a nuclear reactor in which a primary coolant is contained, the primary coolant moves upwardly from the core by an operation thereof. An annular steam generator is arranged in an upper side of the core into which the upwardly moving primary coolant flows and transfers heat in the primary coolant into water therein to generate a steam. A passage structure defines a coolant passage for the primary coolant to an outside of the core. The heat-transferred primary coolant in the annular steam generator flows downwardly in the coolant passage so as to flow into the core, thereby moving upwardly. A reactor vessel is arranged to surround the coolant passage so as to contain the core, the annular steam generator and the passage means therein.

1 . A nuclear reactor in which a coolant is contained, comprising:
 a core composed of nuclear fuel, said coolant moving upwardly from the core by an operation thereof;   an annular steam generator arranged in an upper side of the core into which the upwardly moving coolant flows and adapted to transfer heat in the coolant into water therein to generate a steam;   a passage structure that defines a coolant passage for the coolant to an outside of the core, said heat-transferred coolant in the annular steam generator flowing downwardly in the coolant passage so as to flow into the core, thereby moving upwardly; and   a reactor vessel arranged to surround the coolant passage so as to contain the core, the annular steam generator and the coolant passage therein.   
   
   
       2 . The nuclear reactor according to  claim 1 , further comprising:
 a core barrel surrounding an outer periphery of the core;   an annular reflector surrounding an outer periphery of the core barrel;   a neutron shield arranged in the coolant passage and surrounding the outer periphery of the core;   an annular solenoid pump arranged in the coolant passage above the neutron shield; and   a guard vessel surrounding an outer periphery of the reactor vessel,   wherein said annular steam generator is arranged to surround an outer periphery of an upper portion of the solenoid pump so that at least lower portion of the steam generator is overlapped to the upper portion of the solenoid pump in an axial direction thereof, and   wherein said core barrel, said annular reflector, said neutron shield and said solenoid pump are contained in the reactor vessel.   
   
   
       3 . The nuclear reactor according to  claim 2 , wherein said steam generator is arranged outside of the solenoid pump at a predetermined space, and wherein, after flowing downwardly in the coolant passage from the annular steam generator, a part of said coolant flows upwardly through the predetermined space between an inner periphery of the steam generator and an outer periphery of the solenoid pump to be sucked from an upper end portion of the solenoid pump, thereby flowing down into the core. 
   
   
       4 . The nuclear reactor according to  claim 3 , wherein said passage structure comprises an inner partition wall surrounding an outer periphery of the core barrel and an outer partition wall arranged to surround an outer periphery of the inner partition wall at a predetermined space, said predetermined space being defined as the coolant passage, said steam generator and the electromagnetic pump are constructed integrally with an upper structure of the nuclear reactor, further comprising a seal structural member interposed between an upper end portion of the inner partition wall and a lower end portion of the electro magnetic pump so as to define the coolant passage. 
   
   
       5 . The nuclear reactor according to  claim 3 , wherein said reactor vessel is arranged to surround an outer periphery of the outer partition wall at an annular space, an upper end portion of said outer partition wall is opened in an upper space of the reactor vessel, further comprising a base plate on which the core is mounted to be supported in a lower portion of the reactor vessel, said base plate being formed at its support portion with a bypass passage, said annular space being communicated through the bypass passage with a lower portion of the core. 
   
   
       6 . The nuclear reactor according to  claim 5 , wherein said steam generator comprises:
 an inner shell arranged inside the reactor vessel;   an outer shell coaxially arranged on an outer peripheral side of the inner shell;   a downcomer tube into which the water enters to flow downwardly through the downcomer tube in the axial direction;   a heat transfer tube communicated with the downcomer tube, into which the water flowing out the downcomer tube enters so that the water flows upwardly through the heat transfer tube in the axial direction, said coolant flowing a shell side of the steam generator so that heat in the coolant is transferred into the water flowing upwardly through the heat transfer tube; and   an intermediate shell provided with an upper end portion and arranged between these inner and outer shells so as to separate the heat transfer tube and the downcomer tube,   said upper end portion of the intermediate shell projecting upwardly from a liquid surface of the coolant in the reactor vessel in a normal operation of the reactor,   said outer shell being formed at its predetermined position with an opening portion, said predetermined position being higher than the liquid surface of the reactor vessel in the normal operation of the reactor.   
   
   
       7 . The nuclear reactor according to  claim 3 , wherein said reactor vessel is arranged to surround an outer periphery of the outer partition wall at an annular space, an upper end portion of said outer partition wall is opened in an upper space of the reactor vessel, further comprising a base plate on which the core is mounted to be supported in a lower portion of the reactor vessel, said annular space being shielded from a lower portion of the core by a support portion of the base plate, and wherein said outer partition wall is formed with a plurality of opening portions at a vicinity of an outlet bottom portion of the steam generator so that the annular space is communicated through the opening portions with the coolant passage. 
   
   
       8 . The nuclear reactor according to  claim 3 , wherein said reactor vessel is arranged to surround an outer periphery of the outer partition wall at an annular space and an upper end portion of said outer partition wall is opened in a vicinity of an outlet portion of the steam generator. 
   
   
       9 . The nuclear reactor according to  claim 3 , wherein said steam generator comprises a heat transfer tube in which the water flows so that the coolant flowing in the steam generator performs the heat exchanging operation with the water flowing through an heat exchange portion of the heat transfer tube, said heat transfer tube having one of a single or double tube structure, said heat exchange portion of the heat transfer tube being formed into a substantially helical shape. 
   
   
       10 . The nuclear reactor according to  claim 7 , wherein said heat transfer tube has the double tube structure with an inner tube and an outer tube surrounding an outer periphery of the inner tube at a predetermined gap in which an inert gas is sealed, further comprising a detection unit adapted to detect a leakage in both of the inner and outer tubes of the heat transfer tubes. 
   
   
       11 . The nuclear reactor according to  claim 3 , wherein said steam generator comprises an inner shell arranged inside the reactor vessel and formed with an opening portion at a position higher than a liquid surface of the primary coolant in the reactor vessel, said opening portion of the inner shell being communicated with a cover gas space in the reactor vessel. 
   
   
       12 . The nuclear reactor according to  claim 6 , wherein said inner shell is provided with a lower end portion providing an outlet portion of the primary coolant in the steam generator, said lower end portion of the inner shell being arranged at a position lower than a lower end portion of the outer shell and that of the intermediate shell. 
   
   
       13 . The nuclear reactor according to  claim 3 , further comprising a detecting unit that detects a peculiar change in flow rate due to a pressure rise of a shell side of the steam generator according to a change in a current of the electromagnetic pump and a control unit that performs a control for stopping an operation of the electromagnetic pump according to a detected signal outputted from the detecting unit. 
   
   
       14 . The nuclear reactor according to  claim 1 , wherein said coolant is a liquid metal made of one of sodium and a heavy metal, said heavy metal being lead or lead bismuth. 
   
   
       15 . A nuclear power plant comprising a nuclear reactor in which a coolant is contained, said nuclear reactor comprising:
 a core composed of nuclear fuel, said coolant moving upwardly from the core by an operation thereof;   an annular steam generator having a plurality of heat transfer tubes and arranged in an upper side of the core into which the upwardly moving coolant flows, said annular steam generator transferring heat in the coolant with water in the heat transfer tubes to generate a steam;   a passage structure that defines a coolant passage for the coolant to an outside of the core, said heat-transferred coolant in the annular steam generator flowing downwardly in the coolant passage so as to flow into the core, thereby moving upwardly; and   a reactor vessel arranged to surround the coolant passage so as to contain the core, the annular steam generator and the passage means therein;   a feed water branch pipe connecting to corresponding to heat transfer tubes;   a steam branch pipe connecting to corresponding to heat transfer tubes, said feed water branch pipe and said steam branch pipe independently penetrating through a reactor container facility;   a first feed water pipe;   a steam pipe, said feed water branch pipe and said steam branch pipe being connected to the first feed water pipe and the steam pipe outside the reactor container facility, respectively;   a steam bypass pipe branching from the steam branch pipe and provided with a steam separator having a bottom portion;   an air conditioner provided for the steam separator via a steam facility pipe thereof; and   a second feed water pipe with a feed-water pump, said bottom portion of the steam separator being connected through the second feed water pipe to the feed water branch pipe.