JP7246295B2 - boiling water reactor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling water nuclear reactor, and more particularly to a boiling water nuclear reactor having a core water exclusion device.

In a boiling water nuclear reactor in which a plurality of fuel assemblies are loaded in the core and control rods having a cruciform cross section are inserted between the fuel assemblies, the plurality of fuel rods are densely packed in the channel boxes of the fuel assemblies. A boiling water reactor (hereinafter referred to as a slow spectrum boiling water reactor ) has been proposed (see JP-A-2018-66690). In a boiling water nuclear reactor, during operation, light water, which is cooling water, flows through water gap regions formed between fuel assemblies having square cross sections. Light water rising in the fuel assembly as well as light water rising in the water gap region slows down neutrons produced by fission of fissile material present in the fuel assembly. Moderation of neutrons by light water in the water gap region will reduce the fissile plutonium conversion ratio.

In order to avoid such a decrease in the fissile plutonium conversion ratio, Japanese Patent Application Laid-Open No. 2018-66690 discloses that a control rod having a cruciform cross section inserted between fuel assemblies has a moderation capability higher than that of light water. Control rods having upper halves of followers made of carbon, which is a small substance, are used, and carbon, a substance with a lower moderation capacity than light water, is placed in the water gap region between the fuel assemblies where the control rods are not inserted. A water exclusion plate containing With such a configuration, in JP-A-2018-66690, the water in the water gap region between the fuel assemblies is eliminated to improve the fission plutonium conversion ratio.

Japanese Patent Application Laid-Open No. 2010-14493 also disposes a removable water drain plate in the water gap region between the fuel assemblies.

JP 2018-66690 A JP 2010-14493 A JP-A-5-72366 JP-A-8-29572

JP 2018-66690 and JP 2010-14493 both describe placing a water exclusion plate in the water gap region between the fuel assemblies. Japanese Patent Application Laid-Open No. 2010-14493 describes “removably inserting a water displacement plate into the water gap region”, but both Japanese Patent Application Laid-Open Nos. 2018-66690 and 2010-14493 It does not specifically describe where in the reactor pressure vessel the water displacement plates located in the water gap regions between the fuel assemblies are installed.

It is desirable that the water purge device, which is a water purge plate located in the water gap region between the fuel assemblies, be held in place in the core without movement during seismic events.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a boiling water nuclear reactor in which a water removal device suspended from a grid member of an upper support plate can be prevented from moving horizontally along the grid member.

The feature of the present invention for achieving the above object is that the water removing device is provided in a holding portion, a hanging member attached to the holding portion and extending downward from the holding portion, and provided at the lower portion of the hanging member, It has a water removing member containing a substance with a small deceleration ability, and its holding part is a first movement preventing part and a second movement preventing part provided on the upper surface of the grid member of the upper grid plate from which the water removing device is suspended. and held by the retaining member, the water displacement member being positioned in the water gap region formed between the fuel assemblies immediately below the grid member from which the water displacement device is suspended. It is in.

Since the holding part of the water removing device is arranged between the first movement-preventing part and the second movement-preventing part provided on the upper surface of the grid member of the upper grid plate and held by the grid member, an earthquake occurs. Therefore, when the upper grid plate is swayed causing the retainer to move horizontally along the grid member from which the water removal device is suspended, horizontal movement of the retainer along that grid member is prevented. , the first movement-preventing part and the second movement-preventing part.

ADVANTAGE OF THE INVENTION According to this invention, when an earthquake occurs, it is possible to prevent the water removal device suspended from the lattice member of the upper support plate from moving horizontally along the lattice member.

FIG. 5 is a cross-sectional view taken along line II of FIG. 5, showing a state in which the water exclusion device disposed in the core of the boiling water reactor of Embodiment 1, which is a preferred embodiment of the present invention, is suspended from the upper grid plate; be. 1 is a vertical cross-sectional view of a boiling water reactor of Example 1. FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 4 is a sectional view along IV-IV in FIG. 3; FIG. 3 is a cross-sectional view taken along line VV of FIGS. 1 and 2; FIG. 3 is a sectional view taken along line VI-VI of FIG. 2; FIG. 2 is a perspective view showing the detailed arrangement of fuel assemblies and fuel support fittings arranged in the reactor pressure vessel of the boiling water reactor of Example 1; FIG. 6 is a view taken along line VIII-VIII in FIG. 5; 4 is a cross-sectional view taken along line XI-XI of FIG. 3; FIG. FIG. 10 is an explanatory view showing a state in which the water removal device is removed from the state shown in FIG. 9; FIG. 10 is a vertical cross-sectional view of another example different from FIG. 9 in which the mounting portion of the water removal device is placed on the upper grid plate and prevents movement of the mounting portion along the upper grid plate during an earthquake; be. FIG. 12 is an explanatory diagram showing a state in which the water removal device is removed from the state shown in FIG. 11; 1 is a perspective view of a water exclusion device arranged in the core of the boiling water reactor of Example 1. FIG. FIG. 4 is an explanatory view showing the state of the water removal device descending in the core of the boiling water reactor of Example 1; FIG. 4 is an explanatory view showing the state of the water removal device lowered to near the upper end of the fuel support fitting in the core of the boiling water reactor of Example 1; FIG. 4 is an explanatory view showing the state of the water exclusion device positioned right above between the fuel support fittings in the core of the boiling water reactor of Example 1; FIG. 4 is an explanatory view showing the state of the water exclusion device installed on the upper surface of the upper grid plate with the lower end inserted between the fuel support fittings in the core of the boiling water reactor of Example 1; FIG. 10 is an explanatory view of arranging the double blade guides in each square formed in the upper lattice plate with the water removing device installed on the upper surface of the upper lattice plate; FIG. 10 is an explanatory diagram of a single fuel assembly arranged in each square with a double blade guide arranged in each square formed in the upper lattice plate; FIG. 10 is an explanatory view showing two fuel assemblies arranged in each square with a double blade guide arranged in each square formed in the upper lattice plate; FIG. 7 is an explanatory diagram of the lower end portion of the water exclusion device arranged in the core of the boiling water reactor of Embodiment 2, which is another preferred embodiment of the present invention, arranged between the fuel support fittings. FIG. 7 is an explanatory diagram of the lower end portion of the water exclusion device arranged in the core of the boiling water reactor of Embodiment 2, which is another preferred embodiment of the present invention, arranged between the fuel support fittings. FIG. 3 is an explanatory view showing a water removal device suspended from an upper grid plate and having a lower end supported by a core support plate in a core of a boiling water reactor according to a third preferred embodiment of the present invention; is. FIG. 11 is an explanatory diagram of the lower end portion of the water exclusion device arranged in the core of the boiling water reactor of Example 3, arranged between the fuel support fittings.

Examples of the invention are described below.

A boiling water reactor, which is a preferred embodiment of the present invention, will be described with reference to FIGS. 1 to 13. FIG. The boiling water reactor 1 of this embodiment includes a reactor pressure vessel 2, a core shroud 4, a core 5, a core support plate 6, an upper lattice plate 7, control rods 12 and an internal pump 13, and further , with a water exclusion device 27 shown in FIG. The boiling water reactor 1 is an advanced boiling water reactor in which an internal pump 13 provided in a lower mirror 2A, which is the bottom of the reactor pressure vessel 2, supplies cooling water to the core. ). This advanced boiling water reactor is hereinafter referred to as ABWR.

A boiling water reactor 1 has a reactor pressure vessel 2 containing a core 5 , and a core shroud 4 surrounding the core 5 is provided in the reactor pressure vessel 2 . A core support plate 6 arranged below the core 5 is attached to the inner surface of the core shroud 4 , and an upper lattice plate 7 arranged above the core 5 is also attached to the inner surface of the core shroud 4 . A shroud head 8 that covers the core 5 is attached to the upper end of the core shroud 4 . A plurality of steam separators 9 are attached to the shroud head 8 and extend upwardly within the reactor pressure vessel 2 . A steam dryer 10 is positioned above the steam separator 9 and attached to the inner surface of the reactor pressure vessel 2 .

An annular downcomer 14 surrounding the core shroud 4 is formed between the inner surface of the core shroud 4 and the inner surface of the reactor pressure vessel 2 . A plurality of internal pumps 13 are attached to the lower mirror 2A of the reactor pressure vessel 2 at the position of the downcomer 14 . An impeller 13A of each internal pump 13 is arranged inside the downcomer 14 .

A plurality of control rod drive mechanism housings 16 are arranged inside the internal pump 13 and attached to the reactor pressure vessel 2 through the lower mirror 2A. Each control rod drive mechanism housing 16 extends downward from the lower mirror 2A. Within each control rod drive housing 16 is mounted a control rod drive (not shown). A plurality of control rod guide tubes 15 are arranged below the core 5 within the reactor pressure vessel 2 . Each control rod guide tube 15 is installed at the upper end of the respective control rod drive mechanism housing 16 and extends upward. The upper end of the control rod guide tube 15 reaches the position of the lower end of the fuel support fitting 11 installed on the core support plate 6 . A control rod 12 disposed within each control rod guide tube 15 is coupled to a control rod drive within a control rod drive housing 16 . Control rods 12 in control rod guide tubes 15 are moved up and down by control rod drive mechanisms in control rod drive mechanism housings 16 .

A plurality of through holes 58 are formed in the core support plate 6 as shown in FIG. A fuel support fitting 11 is inserted into each through hole 58 and installed on the core support plate 6 as shown in FIGS. The fuel support fitting 11 has a cross-shaped control rod insertion hole 38 formed in its central portion (see FIGS. 4 and 6). The control rod insertion holes 38 pass through the fuel support fitting 11 in the axial direction of the fuel support fitting 11 . The fuel support fitting 11 forms four cooling water flow paths 43 (see FIG. 4) around the control rod insertion holes 38 . Each cooling water flow path 43 forms an inflow port 39 formed on the side surface of the fuel support fitting 11 and an outflow port 44 formed on the top surface of the fuel support fitting 11 .

The fuel assembly 3 has a channel box 21, a plurality of fuel rods 23, a lower tie plate 22, an upper tie plate 24 and a plurality of fuel spacers 25, as shown in FIG. A lower end of each fuel rod 23 is supported by a lower tie plate 22 and an upper end of each fuel rod 23 is supported by an upper tie plate 24 . These fuel rods 23 are bundled by fuel spacers 25 arranged at a plurality of locations in the axial direction so that gaps of a predetermined width are formed between the fuel rods 23 . The gaps formed between the fuel rods 23 serve as cooling water passages. A tubular channel box 21 having a square cross section surrounds a bundle of fuel rods 23 bundled by fuel spacers 25 . The upper end of the channel box 21 is attached to the upper tie plate 24 by channel fasteners (not shown) (see FIG. 1 of JP-A-5-72366 and FIG. 15 of JP-A-8-29572). This channel fastener is located at one corner of the upper tie plate 24 . A handle 26 is attached to the upper tie plate 24 . The lower tie plate 22 is formed with a cooling water leak hole 38A (see FIG. 8). Spacer pads 36 are attached to the upper ends of each of the two sides of channel box 21 in contact with the channel fasteners.

Each fuel rod 23 uses a mixed oxide fuel (MOX fuel) produced by mixing uranium oxide and plutonium oxide as a nuclear fuel material, and a plurality of fuel pellets made of this MOX fuel are sealed. It is filled in the cladding tube. The length of each fuel rod 23 in the axial direction of the region filled with nuclear fuel material, that is, the active fuel length is 180 cm. The length of the fuel rods 23 used in this embodiment is approximately 370 cm for application to existing boiling water reactors. A gas plenum is formed in the cladding tube of each fuel rod 23 above the upper end of the active fuel length. The active fuel length of the fuel assembly 3 is the same as the active fuel length of the fuel rods 23 .

In the channel box 21, the plurality of fuel rods 23 are densely arranged in an equilateral triangular lattice in the cross section of the fuel assembly 3, as shown in FIG. 1 of JP-A-2018-66690.

The lower tie plate 22 of each fuel assembly 3 loaded in the core 5 is inserted into an outlet 44 of one cooling water passage 43 formed in the fuel support fitting 11 , and each fuel assembly 3 is pushed by the fuel support fitting 11 . Supported. Since four cooling water flow paths 43 are formed in one fuel support fitting 11, four fuel assemblies 3 are supported by one fuel support fitting 11 (see FIG. 7). The upper ends of the four fuel assemblies 3 supported by one fuel support fitting 11 are inserted into one square grid 45 (see FIGS. 4 and 7) formed in the upper lattice plate 7. , supported by the upper grid plate 7 . The upper grid plate 7 is composed of a plurality of grid members 7A as shown in FIG. The four fuel assemblies 3 inserted into one square 45 are fastened by the channel fasteners attached to one of the four corners of the upper tie plate 24 facing each other. The fuel assemblies 3 are held by being pressed against the side surfaces of the four grid members 7A of the upper grid plate 7 facing the grids 45 (see FIG. 14 of Japanese Patent Application Laid-Open No. 8-29572). FIG. 3 shows a state in which four fuel assemblies 3 inserted into one grid 45 are held on each side surface of four grid members 7A of the upper grid plate 7 facing the grid 45. As shown in FIG.

As shown in FIGS. 3 and 5, the control rod 12 has a cruciform cross-section, and four blades extending in all directions from a tie rod (not shown) positioned at the center of the axis. Within each blade is a plurality of neutron absorbing rods (not shown) filled with neutron absorbing material. The control rod 12 is a control rod with a follower, and the follower part existing above the neutron absorbing rod region in which the neutron absorbing rod is arranged contains a substance such as carbon that has a lower moderating ability than light water. The axial length of the neutron absorbing rod region of the control rod 12 is the same as the active fuel length of the fuel assembly 3 . The control rods 12 connected to the control rod driving device are fully inserted into the core 5 when the ABWR boiling water reactor 1 is shut down. That is, the control rods 12 are supported by one fuel support fitting 11 and supported by the upper lattice plate 7 in the water gap regions formed between the four fuel assemblies 3, that is, the water gap regions 42 ( (see Fig. 1). This control rod 12 is inserted into the water gap region 42 through the control rod insertion hole 38 formed in the fuel support fitting 11 (see FIGS. 4, 6 and 7). Note that each control rod 12 does not exist directly below the upper grid plate 7 .

A detailed configuration of the water removing device 27 will be described with reference to FIG. 13 . The water removing device 27 has a pair of plate-like water removing members 28 , a pair of plate-like stopper members 29 , a hanging member 30 , a restraining member 31 , a handle portion 32 , an anti-vibration member 33 and a holding portion 34 . The water removal member 28 and the stopper member 29 contain a substance such as carbon that has a lower moderation capability than light water, which is the cooling water supplied to the core 5 . The suspension member 30 has an upper vertical portion (first suspension portion) 30A, an inclined portion 30B and a lower vertical portion (second suspension portion) 30C. The lower end of the upper vertical portion 30A is connected to the upper end of the inclined portion 30B, and the lower end of the lower vertical portion 30C is connected to the lower end of the inclined portion 30B. The axis of the upper vertical portion 30A and the axis of the lower vertical portion 30C are arranged to be offset in the horizontal direction. The inclined portion 30B is inclined and connects the upper vertical portion 30A and the lower vertical portion 30C, which are horizontally displaced. One end of the handle portion 32 and holding portion 34 is attached to the upper end of the upper vertical portion 30A. A handle portion 32 and a holding portion 34 are arranged in parallel in the horizontal direction and extend from the upper vertical portion 30A directly above the lower vertical portion 30C. A restraining member 31 is arranged in parallel with the upper vertical portion 30A, and the other ends of the handle portion 32 and the holding portion 34 are attached to the restraining member 31 . The spacing S (see FIG. 14) between the opposed side surfaces of the upper vertical portion 30A and the restraining member 31 is the same as the horizontal thickness t (see FIG. 14) of the upper grid plate 7, that is, the grid member 7A.

A pair of stopper members 29 are attached to two side surfaces of the lower vertical portion 30C in the axial direction of the handle portion 32 and the holding portion 34, respectively. A pair of plate-like water removing members 28 are attached to the remaining two side surfaces of the lower vertical portion 30C to which the stopper member 29 is not attached. These plate-like water removing members 28 extend in opposite directions from the lower vertical portion 30C in the axial directions of the handle portion 32 and the holding portion 34, respectively. A plate-like anti-vibration member 33 is attached to the lower end of each of the lower vertical portion 30C and the pair of water removing members 28 . Such anti-vibration members 33 are arranged parallel to the grid member 7A from which the water removing device 27 is suspended, and extend in the longitudinal direction of the grid member 7A.

A pair of plate-like water removing members 28 and a pair of stopper members 29 are suspended by placing the holding portion 34 of the water removing device 27 on the upper surface of the upper grid plate 7, specifically, the corresponding grid member 7A. It is suspended from the upper grid plate 7, ie, grid member 7A, by members 30 (see FIG. 1) and positioned between adjacent fuel assemblies 3 as shown in FIG. By placing the holding portion 34 on the upper surface of the lattice member 7A, the water removal device 27, particularly the water removal member 28 and the stopper member 29 are held at predetermined positions in the core 5. FIG.

When the water removal member 28 and the like are suspended from the upper grid plate 7 by the suspension member 30, the upper vertical portion 30A contacts the side surface of the grid member 7A opposite to the side surface with which the fuel assembly 3 contacts. do. A restraining portion 31A of the restraining member 31, which exists below the holding portion 34, contacts the side surface of the lattice member 7A with which the fuel assembly 3 contacts. Therefore, the lattice member 7A is positioned between the upper vertical portion 30A and the restraint portion 31A.

Since the suspension member 30 has an inclined portion 30B, the lower vertical portion 30C is positioned directly below the upper grid plate 7, and the water removal member 28 is also positioned directly below the upper grid plate 7. become. The water removal member 28 is arranged in a water gap area (first water gap area) 41 (see FIG. 1) existing directly below the upper grid plate 7 among the water gap areas formed between the fuel assemblies. The neutron instrumentation pipe 17 is located directly below the upper grid plate 7 and is present within the water gap region 41 .

A pair of water exclusion members 28 disposed within the water gap region 41 of the water exclusion device 27 are provided on the side of the channel box 21 of each fuel assembly 3 facing away from the control rods 12, as shown in FIG. are arranged to face the A stopper member 29 provided perpendicular to the water discharge member 28 is a water gap region (second water gap region) formed between the fuel assemblies 3 and into which the control rods 12 are inserted, which is different from the water gap region 41 . gap region) 42 and extends to the vicinity of the tip of the blade of the control rod 12 in the horizontal direction.

The heights of the water removing member 28 and the stopper member 29 are equal to or slightly longer than the effective fuel length of the fuel assembly 3 . The water removal member 28 and the stopper member 29 are arranged to face the nuclear fuel material filling region of the fuel assembly 3 .

When the water removing device 27 is suspended from the upper grid plate 7 by the hanging member 30, the anti-vibration member 33 of the water removing device 27 is inserted into the gap formed between the adjacent fuel support fittings 11. be. As shown in FIG. 6, the horizontal width of the gap formed between the adjacent fuel support fittings 11 is the narrowest at the portion where the anti-vibration member 33 is inserted. The lower end of the anti-vibration member 33 contacts the upper surface of the fuel support fitting 11 , and the weight of the water removal device 27 is supported not only by the upper grid plate 7 but also by the fuel support fitting 11 .

Next, the configuration of the lattice member 7A, which is the upper lattice plate 7, on which the holding portion 34 of the water removing device 27 is placed will be specifically described with reference to FIGS. 9 and 10. FIG. As shown in FIG. 10, on the upper surface of the lattice member 7A on which the holding portion 34 of the water removing device 27 is placed, the upper lattice plate 7 has movement blocking portions 59A and 59B, and insertion portions for inserting the holding portion 34 therebetween. Attached, for example by welding, to form 60 . That is, movement blocking portions 59A and 59B are provided on the upper surface of grid member 7A. The holding portion 34 of the water removing device 27 is inserted into the insertion portion 60 from above and placed on the upper surface of the grid member 7A (see FIG. 9). 9, the distance S1 between the movement blocking portion (first movement blocking portion) 59A and the movement blocking portion (second movement blocking portion) 59B is along the grid member 7A of the upper grid plate 7 of the holding portion 34, as shown in FIG. is the same as the width W4 in the horizontal direction. The height of the upper grid plate 7, that is, the grid member 7A is H as shown in FIG.

Instead of the structures shown in FIGS. 9 and 10, the structures shown in FIGS. 11 and 12 may be used. As shown in FIG. 12, this structural example does not have the movement blocking portions 59A and 59B shown in FIG. is formed in The portion of the upper grid plate 7, ie, the portion of the grid member 7A, which forms the opposing side surfaces 62A and 62B of the insertion portion 61, respectively, is a movement blocking portion corresponding to the movement blocking portions 59A and 59B. The holding portion 34 of the water removing device 27 is inserted into the insertion portion 61 from above and placed on the bottom surface 61A of the insertion portion 61 formed in the grid member 7A of the upper grid plate 7 (see FIG. 11). In the insert portion 61, the bottom surface 61A is the top surface of the upper grid plate 7, that is, the grid member 7A. It can be said that the holding portion 34 in the insertion portion 61 is placed on the upper surface of the upper lattice plate 7 . 12, the movement blocking portion (first movement blocking portion) formed by the side surface 62A and the movement blocking portion (second movement blocking portion) formed by the side surface 62B are the same as in FIG. (bottom surface 61A of insertion portion 61). The space S1 between the side surfaces 62A and 62B is the same as the width W4 of the holding portion 34, as shown in FIG. The height from the lower surface of the grid member 7A of the upper grid plate 7 to the bottom surface 61A in this structural example is H, which is the same as the height of the grid member 7A in the structural example shown in FIGS. The height of the grid member 7A shown in FIGS. 11 and 12 is Ha, which is higher than the height H of the grid member 7A shown in FIG.

In the boiling water reactor 1, after starting operation, the control rods 12 inserted in the water gap region 42 are withdrawn by the control rod drive mechanism, and the core 5 becomes critical. Before long, the reactor power is increased to 100%, and the rated operating condition is reached. Cooling water descending in the downcomer 14 is pressurized by the impeller 13A driven by the internal pump 13 and supplied to each fuel assembly 3 . The pressurized cooling water reaches the cooling water passage 43 from the inlet 39 of the cooling water passage 43 formed in each fuel support fitting 11 and is guided into the lower tie plate 22 of the fuel assembly 3 . The cooling water flowing into the lower tie plate 22 rises through cooling water passages formed between the fuel rods 23 in the channel box 21 above the lower tie plate 22 while contacting the fuel rods 23 . This cooling water is heated by the heat generated by nuclear fission of the fissile plutonium contained in the nuclear fuel material present in the fuel rods 23 within the fuel assembly 3, and a part thereof becomes steam.

A gas-liquid two-phase flow containing cooling water and steam is discharged from the fuel assembly 3 and flows into the steam separator 9 . The steam separated from the gas-liquid two-phase flow in the steam separator 9 is further dehumidified in the steam dryer 10 and then supplied through the main steam line 18 to a turbine (not shown). The steam discharged from the turbine is condensed in a condenser (not shown), and the water produced by condensing the steam is supplied as feed water from the condenser to the reactor pressure vessel 2 through the feed water pipe 19. .

The liquid cooling water separated by the steam separator 9 descends through the downcomer 14 and flows into the impeller 13A of the internal pump 13, where it is pressurized by the impeller 13A.

A part of the cooling water supplied into the lower tie plate 22 flows into the water gap regions (water gap regions 41 and 42) formed between the fuel assemblies 3 through the leak holes 38A formed in the lower tie plate 22. Guided up the water gap area. The cooling water rising in the water gap area reaches above the upper grid plate 7 in a non-boiling state. The width W3 of the anti-vibration member 33 of the water removal device 27 in the horizontal direction along the grid member 7A from which the water removal device 27 is suspended is one fuel support facing the water removal member 28 of the water removal device 27. It is shorter than the distance D between the leak holes 38A formed in the respective lower tie plates 22 of the adjacent fuel assemblies 3 supported by the fittings 11 (see FIG. 8). Therefore, since the cooling water flow flowing out from the leak hole 38A is not blocked by the anti-vibration member 33, flow vibration of the water removing member 28 and the anti-vibration member 33 due to the discharged cooling water flow can be suppressed.

A method of arranging the water removal device 27 in the core 5 will be described with reference to FIGS. 14 to 17. FIG. The arrangement of the water removal device 27 in the core 5 is such that, in the new boiling water reactor 1, before the fuel assemblies 3 are loaded into the core 5 in the reactor pressure vessel 2, the existing boiling water In the reactor 1, all the fuel assemblies 3 loaded in the core 5 are removed from the reactor pressure vessel 2 using a refueling machine (not shown) while the operation of the boiling water reactor 1 is stopped. after transfer to a fuel storage pool (not shown). In this embodiment, a method of arranging the water removal device 27 in the core 5 of the existing boiling water reactor 1 will be described.

After the boiling water reactor 1 has been taken out of operation for a certain operating cycle for periodic inspection and replacement of spent fuel, the top of the reactor pressure vessel 2 is removed and loaded into the core 5. All fuel assemblies 3, including spent and non-spent fuel assemblies, are transferred from the reactor pressure vessel 2 to a fuel storage pool (not shown) using a refueling machine (not shown). Spent fuel assemblies and non-spent fuel assemblies are stored in separate areas within the fuel storage pool.

The water removal device 27 , whose handle portion 32 is gripped by the refueling machine, is suspended from the refueling machine, transported into the reactor pressure vessel 2 , and lowered inside the reactor pressure vessel 2 . The lowered water removal device 27 is inserted into one of the grids 45 of the upper grid plate 7 (see FIG. 14). When the inclined portion 30B of the suspension member 30 passes through the grid 45 of the upper grid plate 7, the fuel exchanger is operated so that the water removal device 27 is horizontally positioned on one side of the grid member 7A facing the grid 45. Move toward (see FIG. 15). This horizontal movement brings one side of the upper vertical portion 30A of the hanging member 30 into contact with one side of the grid member 7A (see FIG. 16). At this time, the lower vertical portion 30C is positioned directly below the upper grid plate 7. As shown in FIG. By further lowering the water removing device 27 in this state, the lattice member 7A is inserted between the upper vertical portion 30A and the restraint portion 31A. As the water removing device 27 descends, the holding portion 34 is inserted into the insertion portion 60 formed between the movement blocking portion 59A and the movement blocking portion 59B. Then, the holding portion 34 is placed on the upper surface of the grid member 7A (see FIG. 17). As the water removal device 27 descends, the anti-vibration member 33 is inserted between the adjacent fuel support fittings 11, and the lower end of the anti-vibration member 33 comes into contact with the upper surface of the core support plate 6 (see FIGS. 6 and 17). ).

The operations described above are repeated for a predetermined number of water removal devices 27 to be arranged in the core 5 . When all the predetermined number of water removal devices 27 have been placed in the core 5, the water removal device 27 placement work is completed.

After all the water removal devices 27 have been placed in the core 5, the unused fuel assemblies 3 other than the spent fuel assemblies stored in the fuel storage pool and new fuel assemblies with a burnup of 0 GWd/t Transfer of body 3 to core 5 is initiated. Before starting the transfer of the fuel assemblies 3 to the core 5 , the double blade guides 46 are lowered inside the reactor pressure vessel 2 and inserted into the respective squares 45 formed in the upper lattice plate 7 .

The double blade guide 46 has a pair of blade guide bodies 47 and 48 each having a square cross section and a handle portion 49 . A handle portion 49 is attached to the upper end of each of the blade guide bodies 47 and 48 . Each of the blade guide bodies 47 and 48 has substantially the same shape as the outer shape of the fuel assembly 3, and the axial length of each of the blade guide bodies 47 and 48 is the same as the axial length of the fuel assembly 3. are the same.

Before the double blade guides 46 are first placed in the cells 45 of the upper grid plate 7, none of the cells 45 formed in the upper grid plate 7 have the fuel assemblies 3 inserted therein. The double blade guide 46 is hung from the refueling machine by gripping the handle portion 49 by the refueling machine, and descends in the grid 45 . A pair of blade guide bodies 47 and 48 of the double blade guide 46 are arranged at respective positions where two fuel assemblies 3 are arranged in the direction of one diagonal line of the grid 45 (see FIG. 18), and the blade guides A nose present at the lower end of each of the bodies 47 and 48 is located at the outlet 44 of each of the two cooling water passages 43 formed in the fuel support fitting 11 present in the direction of one diagonal of the square 45 . It is inserted and supported by the fuel support bracket 11 . When the double blade guide 46 is arranged in a certain square 45 formed in the upper lattice plate 7, two orthogonally adjacent side surfaces of one blade guide body 47 of the double blade guide 46 are aligned with the square 45. of the four grid members 7A facing the squares 45 side of the two grid members 7A. Also, the two orthogonally adjacent side surfaces of the other blade guide body 48 of the double blade guide 46 are the square 45 side surfaces of the remaining two lattice members 7A out of the four lattice members 7A. come into contact with The double blade guides 46 are arranged in all the squares 45 formed in the upper grid plate 7 and supported by the corresponding fuel support fittings 11 .

After all the double blade guides 46 have been installed, all the control rods 12 are fully inserted into the core 5 in which no single fuel assembly 3 is loaded (see FIG. 18). Since the double blade guide 46 is installed, the completely inserted control rod 12 is held by the blade guide main bodies 47 and 48 of the double blade guide 46 and is prevented from falling.

After that, the unused fuel assemblies 3 suspended from the refueling machine and the new fuel assemblies 3 with a burnup of 0 GWd/t are sequentially transported one by one from the fuel storage pool into the reactor pressure vessel 2. 4, the blade guide bodies 47 and 48 are loaded one by one in each grid 45 formed in the upper lattice plate 7, at positions where the blade guide bodies 47 and 48 do not exist. The loaded fuel assemblies 3 are supported by fuel support fittings 11 . Further, in the other diagonal direction of the squares 45 passing through the fuel assemblies 3 loaded in the squares 45, to other positions in each square 45 where the blade guide bodies 47 and 48 are not present, the fuel storage pool is transported. The assembled fuel assembly 3 is loaded, and this fuel assembly 3 is also supported by the fuel support bracket 11 (see FIG. 20). After two fuel assemblies 3 are arranged in one diagonal direction in each square 45, all the double blade guides 46 arranged in each square 45 are gripped by the refueling machine and the reactor pressure vessel. 2 is transported outside. Even if the double blade guide 46 is removed, the fully inserted control rod 12 is held by the two fuel assemblies 3 arranged diagonally, so that it is prevented from overturning.

After the double blade guide 46 is removed, two fuel assemblies 3 transported from the fuel storage pool are loaded at each position in each square 45 where the blade guide bodies 47 and 48 were arranged. , are also supported by the fuel support fittings 11 .

Unspent fuel assemblies 3 and new fuel assemblies 3 with a burnup of 0 GWd/t are respectively loaded at predetermined positions in the core 5 .

After the operation of loading the fuel assemblies 3 into the core 5 is completed, the boiling water reactor 11 is started and operated.

In this embodiment, a pair of plate-shaped water removal members 28 of a water removal device 27 are provided in a water gap region 41 in which the control rods 12 are not inserted among the water gap regions formed between the fuel assemblies 3 in the core 5. , the water-to-fuel volume ratio in the core 5 can be reduced, and the fissile plutonium conversion ratio can be improved. Furthermore, a pair of stopper members 29 of the water removal device 27, which are provided at right angles to the water removal member 28, are inserted between the tip of the blade of the control rod 12 and the water removal member 28. Since it is located in the water gap region 42, the water-to-fuel volume ratio in the core 5 can be further reduced, and the fissile plutonium conversion ratio can be further improved.

Further, in this embodiment, since the control rods 12 which are control rods with followers are used, the control rods 12 fully inserted into the core 5 are withdrawn from the core 5 as the boiling water reactor 1 is operated. For example, even if the neutron absorbing rod region of the control rod 12 descends to the lower end of the core 5 in the fully withdrawn state, the control rod There are 12 follower segments. That is, as the control rod 12 is withdrawn, the ratio of the follower portions existing between the nuclear fuel material filling regions of the adjacent fuel assemblies 3 increases. Therefore, the water-to-fuel volume ratio in the core 5 is reduced by the follower portions existing between the nuclear fuel material filling regions of the adjacent fuel assemblies 3, and the fissile plutonium conversion ratio can be further improved. .

Since the water removal device 27 is suspended from the upper grid plate 7, replacement is facilitated. That is, the water removing member 28 and the stopper member 29 of the water removing device 27 are attached to the holding portion 34 placed on the upper surface of the corresponding grid member 7A of the upper grid plate 7 via the hanging member 30. By gripping the handle portion 32 attached to the lowering member 30 with the fuel exchanger, the water removing device 27 can be easily pulled up from the core 5 . Also, by gripping the handle portion 32 of the new water exclusion device 27 with the refueling machine and lowering the new water exclusion device 27 in the reactor pressure vessel 2 and placing the holding portion 34 on the upper surface of the upper grid plate 7, A new water removal device 27 can be easily hung on the upper grid plate 7 .

Since the holding portion 34 of the water removing device 27 is arranged between the movement blocking portion 59A and the movement blocking portion 59B provided on the upper surface of the grid member 7A of the upper grid plate 7, an earthquake occurs and the upper grid plate 7, the side surface of the holding portion 34 facing the movement blocking portion 59A occurs when the first sway that moves the holding portion 34 in the horizontal direction along the grid member 7A on which the holding portion 34 is placed occurs. contacts the side surface 59C of the movement blocking portion 59A facing the insertion portion 60, and the side surface of the holding portion 34 facing the movement blocking portion 59B contacts the side surface 59D of the movement blocking portion 59B facing the insertion portion 60. . Therefore, the movement blocking portions 59A and 59B can block the horizontal movement of the holding portion 34, that is, the upper end portion of the hanging member 30 along the lattice member 7A based on the first swing. can. When the first shaking occurs, the upper end of the suspension member 30 is prevented from moving horizontally along the grid member 7A, so the fuel assembly 3 is removed from the core 5 when replacing the fuel assembly. Therefore, it is possible to prevent the fuel assembly 3 being pulled up from coming into contact with the upper end portion of the suspension member 30 and being damaged.

Further, when the above-described first shaking is caused by an earthquake, the horizontal movement of the pair of stopper members 29 arranged in the water gap region 42 along the grid member 7A is controlled by the water gap region 42 between them. It can be blocked by the two fuel assemblies 3 sandwiching and facing each other, and the horizontal movement of the lower portion of the hanging member 30 can be blocked. The prevention of the horizontal movement of the upper end of the suspension member 30 along the grid member 7A when the first shaking occurs is due to the contact of the water removal member 28 with the neutron instrumentation piping 17. Damage to the mounting pipe 17 can be avoided.

The stopper member 29 has two functions: one is to improve the fissile plutonium conversion ratio, and the other is to prevent the lower portion of the hanging member 30 from moving horizontally along the grid member 7A.

11 and 12 is used instead of the structure shown in FIGS. The side surface 62A of the holding portion 34, which is disposed in the portion 61 and faces the side surface 62A, which is the movement blocking portion corresponding to the movement blocking portion, comes into contact with the side surface 62A. Since the side surface facing the side surface 62B, which is the blocking portion, contacts with the side surface 62B, an earthquake occurs, causing the upper grid plate 7 to move horizontally along the grid member 7A formed with the bottom surface 61A on which the holding portion 34 is placed. Even if the first swing occurs in the direction, the horizontal movement of the holding part 34, that is, the upper end of the suspension member 30 along the grid member 7A based on the first swing, It can be blocked by sides 62A and 62B.

The grid member 7A of the upper grid plate 7, on which the holding portion 34 is placed, is inserted between the upper vertical portion 30A and the restraint member 31, that is, the restraint portion 31A, so that the upper vertical portion 30A of the grid member 7A, Since the restraining portion 31A comes into contact with the side surface facing one grid 45 and the other side surface of the grid member 7A facing the other grid 45, an earthquake occurs and the upper grid plate 7 However, even if a second sway occurs that moves the holding part 34 in a direction perpendicular to the side surface of the grid member 7A on which the holding part 34 is placed, the holding part 34 based on the second sway, that is, Movement of the upper end of the suspension member 30 in the direction perpendicular to the side surface of the grid member 7A can be prevented by the grid member 7A inserted between the upper vertical portion 30A and the restraint portion 31A. In particular, in the water removal device 27, since the restraining portion 31A is provided so as to face the upper vertical portion 30A of the hanging member 30, even when the second shaking occurs, the upper vertical portion 30A and the restraining portion 31A The suspension member 30 is prevented from moving in the direction perpendicular to the side surface of the grid member 7A at the upper end, the suspension member 30 is disengaged from the grid member 7A, and the control rod 12 in which the water removal member 28 exists in the core 5. Alternatively, contact with the fuel assembly 3 and damage to either can be avoided.

Further, since the anti-vibration member 33 is inserted between the adjacent fuel support fittings 11, the movement of the water removal member 28 in the direction perpendicular to the side surface of the water removal member 28 due to the second shaking is suppressed by the vibration. It can be blocked by a pair of fuel support fittings 11 facing the stop member 33 . Since the movement of the lower end of the water removing member 28 in the direction perpendicular to the side surface of the water removing member 28 is blocked by the fuel support fitting 11 , the second shaking causes the lower end of the water removing member 28 to move toward the water removing member 28 . swaying in a direction perpendicular to the side surface of the water removal member 28 to contact the control rod 12 or the fuel assembly 3 and damage either of them.

As described above, movement of the water removal device 27 in the direction perpendicular to the side surface of the grid member 7A on which the holding part 34 is placed due to the second shaking at the time of occurrence of an earthquake is controlled by the grid member 7A and the fuel support fitting. 11 can be blocked.

The holding part 34 is placed on the upper surface of the upper lattice plate 7, and the lower end of the anti-vibration member 33 is brought into contact with the upper surface of the core support plate 6, whereby the water removal device 27 is arranged in the core 5, and the water removal device 27 is mechanically displaced. Since it is not attached to the structural members inside the reactor pressure vessel 2 by any special mechanism, the arrangement of the water removal device 27 in the core 5 and its removal from the core 5 can be easily done by simply gripping the handle portion 32 with the refueling machine. can be done.

Since the lower end of the anti-vibration member 33 of the water removal device 27 is in contact with the upper surface of the core support plate 6 , the load of the water removal device 27 is applied not only to the upper lattice plate 7 but also to the core support plate 6 . The load of the water removal device 27 applied to the core support plate 6 is reduced, and the deformation of the upper grid plate 7 can be reduced.

In the suspension member 30 of the water removal device 27, the upper vertical portion 30A and the lower vertical portion 30C are connected by the inclined portion 30B. can be positioned between the adjacent fuel assemblies 3 directly below the grid member 7A.

Embodiment 2 A boiling water reactor of Embodiment 2, which is a preferred embodiment of the present invention, will be described with reference to FIG. The boiling water reactor of the present embodiment differs from the boiling water reactor 1 of the first embodiment only in the configuration of the water removal device 27 . The configuration of the boiling water reactor of this embodiment other than the water exclusion device 27 is the same as the configuration of the boiling water reactor 1 other than the water exclusion device 27 . Furthermore, the water exclusion device 27 in the boiling water nuclear reactor of this embodiment does not have the pair of stopper members 29 provided in the water exclusion device 27 in the boiling water reactor 1 of the first embodiment. It has a configuration in which the anti-vibration member 33 of the water removal device 27 in the nuclear reactor 1 is replaced with the anti-vibration member 50 shown in FIG.

The anti-vibration member 50 has a first anti-vibration portion 51 and a second anti-vibration portion 52 . The first anti-vibration part 51 is plate-shaped like the anti-vibration member 33 of the water removal device 27 used in the first embodiment, and is attached to the lower ends of the lower vertical part 30C and the pair of water removal members 28. ing. The first anti-vibration portion 51 of the anti-vibration member 50 is arranged parallel to the grid member 7A from which the water removing device 27 used in this embodiment is suspended, and extends in the longitudinal direction of the grid member 7A.

The second anti-vibration portions 52 are provided at both ends of the first anti-vibration portion 51 in the horizontal direction along the lattice member 7A from which the water removal device 27 is suspended. Each second anti-vibration portion 52 is arranged horizontally perpendicular to the side surface of the lattice member 7A from which the water removal device 27 is suspended. The height of the second anti-vibration portion 52 is the same as the height of the first anti-vibration portion 51 . The second steady rest 52 is inserted into the gap formed between the adjacent fuel support fittings 11 . As shown in FIG. 21, the horizontal width G of the gap formed between the adjacent fuel support fittings 11 is the narrowest at the portion where the first anti-vibration portion 51 is inserted. The upper end of each anti-vibration member 50 is attached to the respective lower ends of the pair of water displacement members 28 . The width W1 of the second anti-vibration portion 52 in the direction orthogonal to the side surface of the grid member 7A is wider than the width G described above. The second steady rest 52 is inserted into a gap formed between the adjacent fuel support fittings 11, and is arranged in a gap wider than the narrowest gap having a width G.

Each function of the first anti-vibration portion 51 and the second anti-vibration portion 52 will be described. The width of the gap formed between the adjacent fuel support fittings 11 is the narrowest width G of the gap formed between the adjacent fuel support fittings 11 from the position where the second anti-vibration portion 52 is arranged. decreases towards the part of When the above-mentioned first shaking occurs due to an earthquake, the anti-vibration member 50 is formed in the gap formed between the adjacent fuel support fittings 11 at a portion narrower than the width W1 of the second anti-vibration portion 52. , can be prevented by their fuel support fittings 11 from moving horizontally along the grid member 7A on which the water removal device 27 is suspended. Therefore, even if the first shaking occurs during an earthquake, the lower end of the water removal device 27, that is, the lower end of the water removal member 28, is prevented from moving in the horizontal direction along the lattice member 7A. By blocking the movement of the lower end of the water exclusion member 28 in the horizontal direction along the grid member 7A, damage to the neutron instrumentation piping 17 due to contact of the water exclusion member 28 with the neutron instrumentation piping 17 is prevented. can be avoided.

When the above-mentioned second shaking occurs due to an earthquake, the anti-vibration member 50 inserted into the gap formed between the adjacent fuel support metal fittings 11 and the grid member 7A from which the water removal device 27 is suspended. Movement in the horizontal direction perpendicular to the sides can be prevented by these fuel support fittings 11 . Therefore, even if a second shaking occurs during an earthquake, the lower end of the water removal device 27 is prevented from moving in the direction perpendicular to the side surface of the lattice member 7A.

Note that the horizontal movement of the upper end of the water removal device 27 along the lattice member 7A from which the water removal device 27 is suspended due to the first shaking at the time of the earthquake, and the water removal device due to the second shaking Movement of the upper end of 27 in the horizontal direction perpendicular to the side surface of grid member 7A from which water removal device 27 is suspended can be prevented in the same manner as in the first embodiment.

This embodiment can obtain each effect produced in the first embodiment except for the effect obtained by the stopper member 29 . In this embodiment, since the anti-vibration member 50 has the second anti-vibration portion 52, in this embodiment where the stopper member 29 is not present, the second anti-vibration portion 52 causes a second shaking during an earthquake. However, it is possible to prevent the lower end of the water removing device 27 from moving in the direction perpendicular to the side surface of the grid member 7A. Further, in the anti-vibration member 50, the outer side surface of the second anti-vibration portion 52 provided at both ends of the first anti-vibration portion 51 in the horizontal direction along the lattice member 7A from which the water removal device 27 is suspended. Since the width between them is shorter than the distance D between the leak holes 38A formed in the respective lower tie plates 22 of the adjacent fuel assemblies 3, the flow of cooling water flowing out of the leak holes 38A is blocked by the anti-vibration member 50. Therefore, the flow vibration of the water removing member 28 and the anti-vibration member 50 due to the discharged cooling water flow can be suppressed.

Embodiment 3 A boiling water reactor of Embodiment 3, which is a preferred embodiment of the present invention, will be described with reference to FIGS. 23 and 24. FIG. The boiling water reactor of this embodiment uses a water exclusion device 53 instead of the water exclusion device 27 used in the boiling water reactor 1 of the first embodiment. The configuration of the boiling water reactor of this embodiment other than the water exclusion device 53 is the same as the configuration of the boiling water reactor 1 other than the water exclusion device 27 .

The configuration of the water removing device 53 will be described with reference to FIG. 22 . The water removal device 53 has a configuration in which the anti-vibration member 33 of the water removal device 27 in the boiling water reactor 1 is replaced with the anti-vibration member 54 shown in FIG. That is, the structure of the water removal device 53 other than the anti-vibration member 54 is the same as the structure of the water removal device 27 in the boiling water reactor 1 of the first embodiment, except for the anti-vibration member 33 .

The anti-vibration member 54 has a first anti-vibration portion 55 and a second anti-vibration portion 56 . The first anti-vibration part 55 is plate-like, like the anti-vibration member 33 of the water removing device 27 used in the first embodiment, and is attached to the lower ends of the lower vertical part 30C and the pair of water removing members 28, respectively. ing. The first anti-vibration portion 55 of the anti-vibration member 54 is arranged in parallel with the grid member 7A directly below the grid member 7A from which the water removal device 53 is suspended, and extends horizontally along the grid member 7A. there is A pair of second steady rests 56 are also arranged in parallel with the grid member 7A directly below the grid member 7A from which the water removal device 53 is suspended, and extend horizontally along the grid member 7A. The pair of second anti-vibration portions 56 are connected to both ends of the first anti-vibration portion 55 in the horizontal direction along the lattice member 7A (see FIG. 24), and the pair of second anti-vibration portions 56 are separately attached to respective lower ends of a pair of water displacement members 28 .

A pair of water removing members 28 are arranged directly below the grid member 7A from which the water removing device 53 is suspended. In this state, the lower end portions of the anti-vibration member 54, that is, the first anti-vibration portion 55 and the pair of second anti-vibration portions 56 are inserted between the adjacent fuel support fittings 11, and the pair of second anti-vibration portions Each lower end of the first anti-vibration portion 55 of the anti-vibration portion 56 is in contact with the upper surface of the core support plate 6 . The load of the water removal device 53 is applied not only to the lattice member 7A from which the water removal device 53 is suspended, but also to the core support plate 6 . The lower end of the first steady rest 55 is inserted into the narrowest width G in the horizontal direction of the gap formed between the adjacent fuel support fittings 11 . is inserted into a portion wider than the width G in the horizontal direction of the gap formed between adjacent fuel support fittings 11 (see FIG. 24). The width W2 of the second steady rest 56 in the direction perpendicular to the side surface of the grid member 7A from which the water removal device 53 is suspended is the width of the gap formed between the adjacent fuel support fittings 11 in the horizontal direction. It is wider than the width G of the narrowest portion.

The end surface of each second steady rest 56 having the width W2 in the direction along the grid member 7A from which the water removal device 53 is suspended is the water removal member 28 in the direction along the grid member 7A. Exists at the same position as the end face. Since the pair of second anti-vibration parts 56 are present, the weight of the anti-vibration member 54 of the water removal device 53 is the weight of the anti-vibration member 33 in the first embodiment and the weight of the anti-vibration member 50 in the second embodiment. heavier than

When the above-described first shaking occurs due to an earthquake, the second anti-vibration portion 56 inserted into the gap formed between the adjacent fuel support fittings 11 is formed between the adjacent fuel support fittings 11. The horizontal movement of the anti-vibration member 54 along the grid member 7A from which the water removal device 53 is suspended in the portion of the gap narrower than the width W2 of the second anti-vibration portion 56 It can be blocked by the fuel support fitting 11 . Therefore, even if the first shaking occurs during an earthquake, the horizontal movement of the lower end of the water removal device 53 along the lattice member 7A is prevented. Since the water removing device 53 has a pair of stopper members 29 inserted into the water gap region 42 in the same manner as the water removing device 27 used in the first embodiment, the anti-vibration member 54 is 1 can be prevented from moving in the horizontal direction along the grid member 7A by the rocking of the fuel assembly 3 by the contact of the pair of stopper members 29 with the fuel assembly 3.

When the above-mentioned second shaking occurs due to an earthquake, the anti-vibration member 54 inserted into the gap formed between the adjacent fuel support fittings 11 and the lattice member 7A from which the water removal device 53 is suspended are removed. Movement in the horizontal direction perpendicular to the sides can be prevented by these fuel support fittings 11 . Therefore, even if a second shaking occurs during an earthquake, the lower end of the water removal device 53 is prevented from moving in the direction perpendicular to the side surface of the lattice member 7A.

Note that the horizontal movement of the upper end of the water removal device 53 along the lattice member 7A from which the water removal device 53 is suspended due to the first shaking at the time of the earthquake, and the water removal device due to the second shaking Movement of the upper end of 53 in a direction perpendicular to the side surface of grid member 7A from which water removal device 53 is suspended can be prevented in the same manner as in the first embodiment.

This embodiment can obtain each effect produced in the first embodiment. Furthermore, in this embodiment, the weight of the anti-vibration member 54 having the pair of second anti-vibration portions 56 is heavier than the weight of the anti-vibration member 33 in the first embodiment and the weight of the anti-vibration member 50 in the second embodiment. A portion of the cooling water supplied into the fuel assembly 3 is discharged into the water gap region through the leak hole 38A formed in the lower tie plate 22, and the cooling water flow collides with the anti-vibration member 54 of the water removal device 53. Also, the flow vibration of the anti-vibration member 54 is suppressed.

Each of the boiling water reactors of Examples 1 to 3, which is an ABWR, has a core structure including a water exclusion device, an upper grid plate 7, etc., and is equipped with a recirculation pump and uses water (cooling water) as a coolant. Eliminates the need for internal pumps in normal Boiling Water Reactors (BWRs) and ABWRs that circulate cooling water by flowing it out of the reactor pressure vessel and back into the downcomer inside the reactor pressure vessel. It may be applied to a highly economical simplified boiling water reactor (ESBWR).

DESCRIPTION OF SYMBOLS 1... Boiling water reactor, 2... Reactor pressure vessel, 3... Fuel assembly, 5... Core, 6... Core support plate, 7... Upper lattice plate 7... Lattice member, 11... Fuel support fitting, 12... Control Rod 21 Channel box 22 Lower tie plate 23 Fuel rod 24 Upper tie plate 27, 53 Water removal device 28 Water removal member 29 Stopper member 30 Suspension member 30A Upper vertical portion 30C Lower vertical portion 31 Restricting member 33, 50, 54 Antivibration member 34 Holding portion 38A Leak hole 41, 42 Water gap region 45 Square 51, 55 First steady rest, 52, 56 Second steady rest, 59A, 59B Movement blocking part, 60, 61 Insertion part, 62A, 62B Side (movement blocking part).

Claims (11)

A reactor pressure vessel, a plurality of fuel support brackets on the core support plate that support the lower ends of the plurality of fuel assemblies loaded in the core in the reactor pressure vessel, and the upper ends of those fuel assemblies a supporting upper grate plate and a plurality of water displacement devices;
The water removing device includes a holding portion, a hanging member attached to the holding portion and extending downward from the holding portion, and a water removing member provided below the hanging member and containing a substance having a lower deceleration capacity than light water. has
The holding portion is arranged between a first movement blocking portion and a second movement blocking portion provided on the upper surface of the grid member of the upper grid plate from which the water removing device is suspended and held by the grid member. ,
A boiling water nuclear reactor, wherein the water exclusion member is disposed in a first water gap region formed between the fuel assemblies immediately below the grid member from which the water exclusion device is suspended. . The upper grid plate has a plurality of grid members forming a plurality of squares having a rectangular cross section into which the upper ends of the plurality of fuel assemblies whose lower ends are supported by the fuel support fittings are inserted. , each cell is surrounded by a plurality of grid members, and the upper end of one side surface of each of the plurality of fuel assemblies inserted into the cell is in contact with the side surface of the grid member. The boiling water nuclear reactor of Claim 1. The lattice member from which the water removal device is suspended is arranged between the suspension member and a restraining member attached to the other end of the holding part opposite to the attachment end of the suspension member. A boiling water nuclear reactor as claimed in claim 1. 4. The boiling water mold of claim 3, wherein said suspension member contacts one side of said grid member from which said water exclusion device is suspended and said restraint member contacts the other side of said grid member. Reactor. The hanging member includes a first hanging portion to which the holding portion is attached, an inclined portion, and a second hanging portion located below the first hanging portion and to which the water removing member is attached. and the inclined portion connects the first suspension portion and the second suspension portion, and is positioned immediately below the grid member from which the water removal device is suspended from the first suspension portion. 5. A boiling water nuclear reactor as claimed in claim 3 or 4, being slanted towards said second suspension. A stopper member containing the substance having a lower moderating ability than light water is arranged in a direction orthogonal to the side surface of the water removal member and attached to the side surface of the water removal member, and the stopper member is attached to the side surface of the water removal member. Boiling water reactor according to any one of claims 3 to 5, arranged in a second water gap region separate from said first water gap region formed between and into which control rods are inserted. 7. Said water displacement device has a vibration damping member attached to a lower end of said water evacuation member, said vibration damping member being disposed between said fuel support fittings placed on said core support plate. The boiling water reactor according to any one of Claims 1 to 3. 8. The boiling water reactor according to claim 7, wherein the lower ends of said anti-vibration members disposed between said fuel support fittings are in contact with the upper surface of said core support plate. The width of the anti-vibration member in the horizontal direction along the grid member on which the water removal device is suspended is supported by one of the fuel support fittings facing the water removal member of the water removal device. 9. A boiling water nuclear reactor as claimed in claim 7 or 8, wherein the distance between leak holes formed in the respective lower tie plates of mating fuel assemblies is less than the distance between them. The anti-vibration member disposed between the fuel support fittings is the widest width of the gap formed between the fuel support fittings in a direction orthogonal to the side surface of the grid member on which the water removal device is suspended. A first anti-vibration portion arranged in a narrowed portion, and the first anti-vibration portion provided at both ends in the horizontal direction along the lattice member, and perpendicular to the side surface of the lattice member in the horizontal direction 10. A boiling water nuclear reactor as claimed in any one of claims 7 to 9, having a second steady rest positioned at the . The length of the second steady rest in the direction orthogonal to the side surface of the grid member is orthogonal to the side surface of the grid member on which the water removal device is suspended in the gap formed between the fuel support fittings. The second anti-vibration part is longer than the width of the narrowest part in the direction to which the anti-vibration part is located. The fuel support fittings face each other across the gap at the portion of the gap where the movement in the horizontal direction along the member is wider than the narrowest portion in the direction perpendicular to the side surface of the grid member. 11. The boiling water nuclear reactor of claim 10 configured to be blocked by.

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