JP2005156198A - Reactor building - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a reactor building which enables reduction in the physical quantities of a framework and which is highly economical. <P>SOLUTION: A communication tube 10 allows a spent fuel pool 2 in the reactor building 9 to communicate with a pool 1 inside a static containment vessel cooling system. The communication tube 10 is positioned at the height, which can secure a depth 12 of water required for the shielding from radiation above a fuel storage rack 13. The pool 1 in the static containment vessel cooling system filled with less water is replenished with pool water in the spent fuel pool 2 by way of the communication tube 10, by operating a heat exchanger 3 in the static containment vessel cooling system in the pool 1, in the static containment vessel cooling system. The replenishment can be stopped at a water level which can secure the depth 12 of water required for the shielding from radiation above the fuel storage rack 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a nuclear power plant nuclear reactor building, and more particularly to a light water cooled nuclear reactor nuclear reactor building.

  A nuclear power plant, which is a nuclear power plant, has a reactor building. In the reactor building, there is a reactor containment vessel that houses the reactor. In the reactor containment vessel, the decay heat generated from the reactor core over a long period of time after the occurrence of the accident A reactor containment vessel cooling device is provided for removal outside the containment vessel.

  Conventional reactor containment vessel cooling devices are mainly used to start the pump and supply cooling water to the cooling target area when an accident occurs. However, dynamic devices such as pumps are aimed at further safety and reliability. A static containment vessel cooling system (hereinafter also referred to as PCCS) that cools the reactor containment vessel statically without the need for a reactor is considered.

  PCCS cools and condenses the reactor steam released from the reactor in the reactor containment in the event of a reactor coolant loss accident (hereinafter also referred to as LOCA), etc., and sets the reactor containment pressure to the design pressure. It is provided for the purpose of maintaining the following, and the atmosphere in the reactor containment vessel can be statically cooled by utilizing the natural force of natural circulation caused by the difference in gravity.

  Major PCCS facilities include a heat exchanger for exchanging heat between the reactor steam discharged from the reactor and the pool water, and a large-scale static containment cooling system pool (hereinafter referred to as the pool water storage pool). , Also referred to as PCCS pool). A technique is known in which the pool and a pool for temporarily storing fuel in use are integrated into a large pool to form a common pool (see, for example, Patent Document 2).

  In addition, the new fuel storage pool that temporarily stores new fuel loaded in the core instead of the spent fuel delivered from the core of the reactor and the PCCS pool can be freely connected and shut off, and the pool can be connected between both pools when communicating. A technique is known in which water is allowed to come and go at the bottom of the pool, and the pool water of the new fuel storage pool is diverted to the pool water of the PCCS pool (for example, see Patent Document 1).

JP-A-6-265673 JP 2000-180582 A

  In nuclear power plants, as well as ensuring safety, demands for reducing construction costs and improving economic efficiency of nuclear power plants are increasing. It is also important to reduce the amount of waste at the time of decommissioning due to environmental considerations.

  From the above viewpoint, it is hoped to reduce the amount of enclosure in the reactor building, but when installing the equipment of static containment cooling system (hereinafter also referred to as PCCS), static containment cooling system A large-scale arrangement space such as a pool (hereinafter also referred to as a PCCS pool) is required in the reactor building, which increases the amount of building materials in the reactor building.

  Therefore, as in the conventional example described in the background art section, the PCCS pool, the new fuel storage pool, and the temporary storage pool for the fuel in use are configured to mutually reuse pool water. Compared with the case where these facilities are installed as an independent system in the reactor building, the arrangement space can be reduced.

  However, in the conventional example in which both pool waters are diverted in this way, when the PCCS is activated, the fuel stored below the pool surface of the spent fuel pool is exposed above the water surface due to evaporation of the pool water, etc. However, there is a concern that radiation from fuel cannot be shielded by pool water. In particular, when the fuel is a spent fuel having a higher radiation level than the new fuel, the situation becomes serious. Therefore, when using the pool water of the PCCS pool and the spent fuel pool, even if the water level drops due to evaporation of the pool water in the PCCS pool during PCCS operation, the minimum water depth required for radiation shielding is secured. It is necessary that the spent fuel being stored is immersed in the pool water of the spent fuel pool and the reaction of the nuclear fuel is suppressed and cooled.

  The present invention has been made in view of the above problems, and it is an object of the present invention to reduce the PCCS pool volume by allowing the spent fuel being stored to be cooled.

  Means for solving the problems of the present invention include a static containment vessel cooling system pool and a spent fuel pool provided therein, and a flow path for guiding water in the spent fuel pool to the static containment vessel cooling system pool. And the opening on the spent fuel pool side of the flow path is provided at a position above the upper end of the fuel storage rack in the spent fuel pool.

  Keeping the spent fuel stored in the spent fuel pool soaked in the pool water and using part of the spent fuel pool water as PCCS cooling water are compatible. The effects of storing and reducing the PCCS pool capacity can be achieved. The effect results in safe spent fuel storage and PCCS pool placement area reduction and reactor building size reduction.

  Radiation from the upper position of the fuel storage rack 13 for storing spent fuel to a height position where the water depth necessary for shielding the radiation from the spent fuel in the spent fuel pool 2 can be secured in the spent fuel pool 2 A connecting pipe 10 inlet with a static containment vessel cooling system pool (hereinafter also referred to as a PCCS pool) 1 is provided at a position where the depth of water depth 12 necessary for shielding is added, and the spent fuel pool is provided through the connecting pipe 10. A part of the pool water of No. 2 is supplied to the PCCS pool 1 and used as cooling water for the static containment vessel cooling system (hereinafter also referred to as PCCS), thereby reducing the arrangement area of the PCCS pool 1 It was.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A nuclear power plant is known as one of nuclear plants. The nuclear power plant has a reactor building 9 shown in FIG. In the central region of the reactor building 9, the reactor containment vessel 5 in the region indicated by the dotted line is constructed. The reactor containment vessel 5 is surrounded by reinforced concrete or steel plate of the reactor building 9 and shielded so as not to leak radiation.

  Inside the reactor containment vessel 5, a pressure vessel 20 containing a core loaded with nuclear fuel is installed on a gantry 21 as a nuclear reactor. The outer periphery of the pedestal 21 is a pressure suppression pool 8, and cooling water is stored in the pressure suppression pool 8 as pool water.

  In the reactor building 9 above the reactor containment vessel 5, a spent fuel pool 2 and a static containment vessel cooling system pool (hereinafter also referred to as PCCS pool) 1 are a common wall made of reinforced concrete. 22 and adjacent to each other at the same height.

  The static containment vessel cooling system (hereinafter also referred to as PCCS) includes the PCCS pool 1 and has the following system configuration. That is, the PCCS heat exchanger 3 is installed at the bottom of the PCCS pool 1. One end of a PCCS steam supply pipe 6 is connected to the fluid intake port of the PCCS heat exchanger 3, and the other end of the PCCS steam supply pipe 6 opens into a dry well 23 in the reactor containment vessel 5. One end of the PCCS condensate discharge pipe 7 is connected to the fluid outlet of the PCCS heat exchanger 3, and the other end of the PCCS condensate discharge pipe 7 opens into the pool water of the pressure suppression pool 8 in the reactor containment vessel. ing.

On the other hand, in the spent fuel pool 2, a fuel storage rack 13 is installed at the bottom, and an area of the installation space of the fuel storage rack 13 is a spent fuel storage area. In the fuel storage rack 13, spent fuel 14 taken out from the core is put in a vertical posture and stored and stored inside the fuel storage rack 13. Above the fuel storage rack 13, when the spent fuel 14 is transferred into the pool by a refueling machine (not shown), the water depth from the water surface necessary to shield the radiation from the spent fuel 14, that is, The depth of the spent fuel pool 2 can be obtained so as to obtain a depth obtained by adding the depth 15 necessary for shielding at the time of fuel transfer and the height 16 of the spent fuel, that is, the vertical length during the spent fuel 14 transfer. The pool surface height is set.

  Therefore, the water depth downward from the height position of the pool water surface 24 of the spent fuel pool 2 is the height 4 of the fuel storage rack, the height 16 of the spent fuel, and the water depth 15 necessary for shielding during fuel transfer. It is the depth exceeding the dimension added. The height position of the pool water surface in the PCCS pool is the same height as the pool water surface 24 of the spent fuel pool.

  On the wall 22 between the spent fuel pool 2 and the PCCS pool 1, a horizontal pipe communicating with both pools is installed as the connecting pipe 10. The installation height of the communication pipe 10 is set to a height that can secure a water depth necessary for shielding radiation from spent fuel being stored above the fuel storage rack 13, that is, a water depth 12 necessary for shielding. The connecting pipes 10 are installed in three places as shown in FIG. 1, and the open end on the right side of each connecting pipe 10 is installed as an inlet for passing pool water from the spent fuel pool 2 to the PCCS pool 1. Open to the spent fuel pool at a height. Similarly, the open end on the left side of each connecting pipe 10 opens to the PCCS pool 1 at the installation height of the connecting pipe 10 as an outlet for passing pool water from the spent fuel pool 2 to the PCCS pool 1.

  In this nuclear power plant, the high-temperature and high-pressure steam generated by heating the cooling water in the pressure vessel 20 in the reactor core is installed outside the reactor building 9 through piping not shown from the pressure vessel 20. The turbine that receives the high-temperature and high-pressure steam rotates to drive the generator and generate power.

  In the reactor containment vessel 5 of the power plant, high-temperature and high-pressure steam leaks from the pressure vessel 20 and the piping leading to the pressure vessel 20 into the dry well 23 to cause a reactor coolant leakage accident (hereinafter also referred to as LOCA). If it occurs, the temperature in the reactor containment vessel 5 becomes higher and higher than usual. In this case, the atmosphere containing high-temperature and high-pressure steam in the dry well 23 enters the PCCS heat exchanger 3 through the PCCS steam supply pipe 6, and the pool in the PCCS pool 1 that is in contact with the PCCS heat exchanger 3. Cooled with water and condensed. The steam condensed in the PCCS heat exchanger 3 becomes condensed water and is discharged into the pressure suppression pool 8 through the PCCS condensed water discharge pipe 7. As a result, the high temperature and high pressure state in the reactor containment vessel 5 is relaxed and safety is maintained.

  While the condensation of the high-temperature and high-pressure steam by the PCCS heat exchanger 3 is repeated, the pool water in the PCCS pool 1 is heated by the PCCS heat exchanger 3, and the pool water in the PCCS pool 1 is evaporated and the pool water is evaporated. The water level of the water drops. When the pool water level in the PCCS pool 1 decreases, the pool water in the spent fuel pool 2 flows into the PCCS pool 1 through the connecting pipe 10, and the decrease in the pool water level in the PCCS pool 1 is delayed. Therefore, the mitigating action of the high-temperature and high-pressure state in the reactor containment vessel 5 using the PCCS heat exchanger 3 is maintained for a long time, and safety is maintained for a long time.

  When the pool water in the spent fuel pool 2 flows into the PCCS pool 1 through the connecting pipe 10, the pool water level in the spent fuel pool 2 also decreases, and the water level becomes lower than the opening position of the connecting pipe 10. As a result, the action of the pool water in the spent fuel pool 2 flowing into the PCCS pool 1 through the connecting pipe 10 stops, and the water level drop in the spent fuel pool 2 is indicated by the dotted line in FIG. Stops and maintains at the indicated water level 25. As shown in FIG. 2, the position of the water level 25 is a position where a water depth 12 necessary for shielding radiation can be secured above the fuel storage rack 13. Therefore, the upward leakage of the radiation from the spent fuel stored in the fuel storage rack 13 from the pool water surface is shielded by a water layer having a depth of 12 necessary for shielding, which is dangerous in the reactor building 9. The radiation leakage of the state can be prevented.

  As described above, the pool water in the spent fuel pool 2 can be automatically added to the PCCS pool 1 while achieving radiation leakage from the spent fuel pool 2, so that the size of the PCCS pool 1 can be increased. Long-term safety at the time of LOCA can be ensured without planning.

  Therefore, if the PCCS pool 1 should be enlarged to the area shown by the dotted line in FIG. 1, the PCCS pool 1 is deleted from the PCCS pool placement space reduction range 11 shown by the dotted line in FIG. As a result, the amount of the building in the reactor building 9 can be reduced.

  Further, the radiation radiated from the fuel storage rack 13 toward the PCCS pool 1 is also shielded by the pool water of the PCCS pool 1 adjacent to the spent fuel pool 2, so that the radiation shielding function by the wall 22 is greatly expected. Therefore, the horizontal thickness 26 of the wall 22 can be reduced accordingly. Therefore, the construction amount of the reactor building 9 is further reduced.

  In the present embodiment, in the reactor building 9 in which the PCCS pool 1 shown in FIG. 2 is installed, the connecting pipe is more than the position where the water depth 12 necessary for shielding radiation is secured between the PCCS pool 1 and the spent fuel pool 2. By connecting at 10, it is possible to ensure the safety against the water level drop of the spent fuel pool 2 during the operation of the PCCS, and by using a part of the spent fuel pool water as PCCS pool cooling water. The capacity of the PCCS pool 1 could be reduced. As a result, the PCCS pool 1 arrangement area can be reduced as shown in the PCCS pool arrangement space deletion range 11 in FIG.

  In order to achieve further reduction in the area where the PCCS pool 1 is arranged, after the pool water in the spent fuel pool 2 drops to the state of the water level 25 in FIG. It is necessary to replenish the pool water in the pool 2 into the PCCS pool 1 through the communication pipe 10. For this purpose, the height of the communication pipe 10 shown in FIG. 2 is set to a position where the water depth 12 necessary for shielding is lowered downward, and the pool water in the spent fuel pool 2 is set at the upper end height of the fuel storage rack 13. The height of the communication pipe 10 is changed so that the water level is maintained in agreement.

  Thus, if the water level of the pool water in the spent fuel pool 2 is maintained at the upper end height of the fuel storage rack 13, the fuel being stored in the fuel storage rack 13 is immersed in the pool water. In addition to maintaining the cooled state, the neutron emitted from the fuel is also decelerated, and the state in which the nuclear reaction of the fuel can be prevented from reaching a critical state can be maintained. Therefore, even when the PCCS pool 1 is downsized, the fuel storage state can be maintained as safely as possible while maintaining the PCCS operation period as long as possible.

  The field of application of the present invention is in a reactor building of a nuclear power plant.

It is the figure which showed the planar arrangement | positioning of the spent fuel pool and the PCCS pool in the reactor building by the Example of this invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... PCCS pool, 2 ... Spent fuel pool, 3 ... PCCS heat exchanger, 4 ... Fuel storage rack height, 5 ... Reactor containment vessel, 6 ... PCCS steam supply pipe, 7 ... PCCS condensate discharge pipe, DESCRIPTION OF SYMBOLS 8 ... Pressure suppression pool, 9 ... Reactor building, 10 ... Connecting pipe, 11 ... Arrangement space reduction range of PCCS pool, 12 ... Water depth required for shielding, 13 ... Fuel storage rack, 14 ... Spent fuel, 15 ... Fuel Depth required for shielding during transportation, 16 ... height of spent fuel.

Claims (6)

  A static containment vessel cooling system pool and a spent fuel pool are provided therein, a flow path for guiding water in the spent fuel pool to the static containment vessel cooling system pool is provided, and the spent fuel pool in the flow path is provided. A reactor building in which a side opening is provided at a position above the level of the upper end of the fuel storage rack in the spent fuel pool.   The reactor building according to claim 1, wherein the opening is provided at a position higher than a minimum pool water surface necessary for shielding radiation from fuel stored in the fuel storage rack.   3. The reactor building according to claim 1, wherein the static containment vessel cooling system pool and the spent fuel pool are adjacent to each other in a horizontally overlapping arrangement with a common wall in between. .   The reactor building according to claim 3, wherein the flow path is a through-hole penetrating the wall.   3. The flow path according to claim 1, wherein the flow path guides the water when a position of a water surface in the static containment vessel cooling system pool is lower than a position of a water surface in the spent fuel pool. Reactor building that is the road. In Claim 1, the static containment vessel cooling system heat exchanger installed in the static containment vessel cooling system pool at a position below the pool water surface,
A static containment vessel cooling system steam supply pipe that communicates the static containment vessel cooling system heat exchanger and the dry well so as to supply steam in the dry well to the static containment vessel cooling system heat exchanger; ,
A static containment vessel cooling system that communicates the static containment vessel cooling system heat exchanger and the pressure suppression pool so as to discharge condensed water in the static containment vessel cooling system heat exchanger into the pressure suppression pool. Reactor building with condensate discharge pipe.

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