JP2004317223A - Control rod driving unit for boiling water reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce electricity cost while enhancing safety by eliminating a housing passing through the bottom of a pressure vessel, which is a reactor primary system pressure boundary, and further downward extending, with respect to a control rod driving unit for driving a control rod in a boiling water reactor. <P>SOLUTION: This new control rod driving unit 22 is built in the pressure vessel by deleting the housing 40. In a lower part of a new control-rod guide tube 25 also serving as a piston cylinder, a submergible motor 103 and a propeller 102 are installed to move the cruciform control rod 10 via a large-diameter speed limiter roundel 124 also serving as a drive piston. As a drive power source, an external power source is supplied by an electric wire 91 or by an optical fiber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control rod driving device for driving a control rod in a boiling water reactor.
[0002]
[Prior art]
FIG. 1 is a schematic view of a conventional control rod driving device (21). A control rod support column (11) and a disk-shaped speed limit umbrella (12) are provided below a cross-shaped control rod (10) composed of a neutron absorber and a structural material. They move up and down together in a cylindrical control rod guide tube (24) filled with water (30) in the tube. Below the control rod guide tube (24) is a housing (40) which extends through the pressure vessel bottom (70) and out of the reactor. In the housing (40), there is a piston cylinder (52) filled with water, and the driving piston (50) moves due to the water pressure difference between the upper driving water (63) and the lower driving water (64), thereby driving the driving piston rod (51). ) To move the cross control rod (10) up and down. To move the drive piston (50) upward, water is sent from the control rod insertion water pipe (61) to the lower drive water (64), and the water of the upper drive water (63) is sent from the control rod drive water inlet / outlet (65). It is activated by lowering the lower driving water (64) pressure below the driving piston (50) than the upper upper driving water (63) pressure by drawing the control rod withdrawing water pipe (62) to a tank outside the pressure vessel. .
The control rod guide tubes (24) stand in a square lattice in the water (35) outside the tubes.
FIG. 2 is a longitudinal sectional view showing an upper portion of the cruciform control rod (10) and a relative arrangement of a fuel rod (110) and a channel box (111) constituting a core. Fuel rod cooling water (113) flows between the fuel rods (110), and leakage cooling water (114) flows between the channel boxes (111). The fuel assembly support fitting supporting the fuel lower tie plate (112), which bundles the fuel rod (110) and the channel box (111), includes a fuel assembly support fitting upper part (121) and a fuel assembly support fitting body. (122). The fuel assembly support body (122) is inside the control rod guide tube (24) and has a lower end closed. The fuel assembly support metal also serves as an introduction path when the cross-shaped control rod (10) enters the core from the control rod guide tube (24). Solid arrows in the figure indicate the flow direction of the cooling water. The fuel assembly support bracket upper part (121) rests on the upper end of the control rod guide tube (24) and supports the fuel assembly support bracket body (122). The cooling water passes from a tube hole (26) formed in the control rod guide tube (24) to a fuel assembly support bracket body (123) through a bracket side hole (123) formed in the fuel assembly support bracket body (122). 122). The cooling water passes in the direction of the solid line arrow in the fracture surface. The core lattice plate (130) is provided to prevent a leak flow from passing between the control rod guide tubes (24) that stand in the forest. FIG. 3 is a plan view of the upper portion (121) of the fuel assembly support bracket. The fuel rod is divided into fuel rod cooling water (113) and leakage cooling water (114) through a fuel rod cooling water passage (116) and a leakage water passage (117).
[0003]
[Problems to be solved by the invention]
A large boiling water reactor has about 160 control rods. Therefore, since about 160 housings (40) penetrate the pressure vessel bottom (70), welding and the like are complicated and the production cost is high. Furthermore, complicated equipment such as about 320 pipes or a pressure storage tank for hydraulic driving is required, and the manufacturing cost is high.
The length of the housing (40) must be at least the same as that of the cruciform control rod (10), and the number of the housings (40) is large.
[0004]
[Means for Solving the Problems]
FIG. 4 is a schematic view of a new control rod driving device (22) of the present invention. The housing (40) penetrating the pressure vessel bottom (70) was eliminated. The upper surface of the fuel assembly support bracket new upper part (125) was made square as shown in FIG. FIG. 7 is a vertical cross-sectional view showing an upper portion of a cross-shaped control rod (10) in the case of a fuel assembly support bracket new upper portion (125) and a relative arrangement of a fuel rod (110) and a channel box (111) constituting a core. As shown in FIG.
As shown in FIG. 4, the propeller (102) is rotated by the submersible motor (103) installed below the control rod new guide tube (25) to create an upward flow, and the flow is made vertical by the rectifying grid (101), and the large diameter speed is increased. Apply pressure under the limiter umbrella (124). The communication pipe (90) filled with water has an upper water port (31) shown in FIG. 4 and a lower water port (32) shown in FIG. 4 and 6 indicate the flow direction of water at the upper water inlet (31) and the lower water inlet (32) of the communication pipe (90) when the cross control rod (10) is moved upward. . The solid line arrows in FIG. 6 indicate the flow direction of the cooling water. The rotation of the propeller (102) sucks the water in the communication pipe (90) from the lower water port (32), and the water in the tube (30) above the large diameter speed limiter umbrella (124) is the upper water port (31). From the communication pipe (90).
The control rod position is set by a control rod fixing device (80) including a latch (81), a latch spring (82), and a suction device (83).
The control rod new guide tube (25) is formed in a square lattice on the control rod new guide tube support plate (71). The control rod new guide tube support plate (71) is supported on the inner surface of the pressure vessel.
The power and signals of the underwater motor (103) and the suction device (83) are taken from outside the pressure vessel by the electric wire (91). The electric wire (91) enters the pressure vessel through a water supply pipe or an emergency cooling system pipe. The case where the electric wire (91) passes through the communication pipe (90) is shown in the fractured surface.
The upper surface of the fuel assembly support bracket new upper portion (125) was made square as shown in FIG. 5 to remove the core lattice plate (130) which was between the conventional control rod guide tubes (24). The arrangement of the adjacent control rod new guide tubes (25) in the planar direction is fixed by the metal spring (151) attached to the new upper part (125) of the fuel assembly support metal, and a leakage flow is generated between them. I did not. The new fuel assembly support bracket includes a new fuel assembly support bracket upper portion (125) and a fuel assembly support bracket body (122) which is the same as that of the related art. FIG. 7 shows a state in a plane direction between adjacent new upper portions (125) of the fuel assembly support bracket.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Eliminate the piping that penetrates the pressure vessel bottom (70), which is the primary system pressure boundary, and installs an electric submersible motor (103) and a propeller (102) in a new control rod guide tube (25) in the pressure vessel. Contains the control rod drive.
It is severe to operate the electric underwater motor (103) in the water of 200 ° C or more, but since the cross-shaped control rod (10) is moved once a month for several seconds, most of the time is spent. This is not a problem because the underwater motor (103) is in a stopped state without power supply. Therefore, even if a large current flows, the temperature of the underwater motor (103) does not rise rapidly, and the temperature of the surrounding water does not exceed 200 ° C.
The propeller (102) is rotated by the submersible motor (103) to draw water in the communication pipe (90) from the lower water inlet / outlet (32) to create an upward flow, and to create a vertical flow by the rectifying grid (101). The vertical flow is transmitted to the large diameter speed limiter umbrella (124) and moves the cruciform control rod (10) upward. The water in the tube (30) above the large diameter speed limiter umbrella (124) is drawn into the communication pipe (90) from the upper water port (31). The large diameter speed limiter umbrella (124) serves as a drive piston, and the control rod new guide tube (25) serves as a cylinder.
In order to set the height position of the cruciform control rod (10) upward, the latch spring (82) contracts due to the force when the large diameter speed limiter umbrella (124) moves upward due to the upward flow by the propeller (102). When the aperture speed limiter umbrella (124) passes upward, the latch spring (82) returns and the latch (81) is inserted under the large aperture speed limiter umbrella (124), and the large aperture speed limiter umbrella (124) does not fall below. Become like
In order to set the height position of the cross-shaped control rod (10) downward, a motor built in the suction device (83) is rotated to make the inside of the control rod fixing device (80) a negative pressure and the latch spring (82). Is released to release the latch (81), whereby the cross-shaped control rod (10) falls by its own weight to the next latch (81). It can also be achieved by rotating the propeller (102) in reverse.
Since the new control rod guide tube (25) stands in a square lattice on the control rod new guide tube support plate (71), there is no load on the bottom of the pressure vessel (70).
If a small hole is made in a part of the control rod new guide tube support plate (71), the inner surface of the pressure vessel bottom (70) can be inspected by an endoscope.
In a boiling water reactor where the purity of water is kept high, electrical insulation is sufficiently maintained.
[0006]
【The invention's effect】
By adopting the new control rod drive unit (22) of the present invention, there is no housing (40) located further below through the pressure vessel bottom (70) as the reactor primary system pressure boundary, so that it is safe. In addition to improving the performance, the processing of the pressure vessel bottom (70) can be simplified, so that the production cost of the pressure vessel bottom (70) is reduced, and if the production cost is reduced, the power generation cost is reduced and the economic efficiency is improved.
The use of the fuel assembly support bracket new upper portion (125) can eliminate the core support plate (130), so that the manufacturing cost of the furnace internal structure can be reduced.
Conventionally, it was difficult to inspect the outer surface of the control rod guide tube (24) and the inner surface of the pressure vessel bottom (70) under the core support plate (130). By removing, the outer surface of the new control rod guide tube (25) and the inner surface of the pressure vessel bottom (70) can be easily inspected visually or by an endoscope, so that safety is improved.
The new control rod guide tube (25) is replaceable, and the pressure vessel bottom (70) also has no housing (40), which facilitates replacement. Therefore, almost all of the large structures of the nuclear reactor can be replaced, and the nuclear power plant does not have a long life. There is no need for the cost of vacant land, and there is no need for an alternative new location, which leads to a reduction in power generation costs.
[0007]
[Other Embodiment 1]
In this embodiment, as a power source for the underwater motor (103) and the suction device (83), a power supply external to the pressure vessel is converted from electricity to light by a conversion element, and a laser is supplied from the outside of the pressure vessel to the underwater motor (103) and suction by an optical fiber. The laser is converted into electricity by the light-to-electricity conversion element.
Optical fibers can transport large amounts of energy without having to consider electrical insulation. The conversion efficiency of light to electricity is about 90%.
By irradiating the iron plate of the rectifying grid (101) with heat without converting the laser to electricity, the water under the large diameter speed limiter umbrella (124) is vaporized and the expansion force of the large diameter speed limiter umbrella (124) is pushed up. Thus, the control rod (10) can be inserted into the core.
[0008]
[Other Embodiment 2]
A storage battery or a fuel cell was used as a drive power source for the underwater motor (103) and the suction device (83).
This eliminates the need for the electric wire (91) penetrating the pressure vessel, thereby increasing safety and facilitating maintenance and inspection.
[0009]
[Other Embodiment 3]
As a power source and an electric signal of the underwater motor (103) and the aspirator (83), the transducer is converted from electricity to ultrasonic waves by a conversion element outside or inside the pressure vessel, and the ultrasonic waves are converted by a transducer made of piezoelectric ceramic, piezoelectric crystal, or magnetostrictive material. To convert to electrical signals.
Since the ultrasonic wave propagates through the water without being attenuated, the electric wire (91) extends at most to the inner surface of the pressure vessel, and the length can be greatly reduced.
Thereby, the electric wire (91) penetrating the pressure vessel can be shortened, so that the safety is enhanced and the maintenance and inspection are facilitated.
[Brief description of the drawings]
FIG. 1 is a schematic view of a conventional control rod driving device (21).
FIG. 2 is a longitudinal sectional view showing an upper portion of a cross-shaped control rod (10) and a relative arrangement of a fuel rod (110) and a channel box (111) constituting a core.
FIG. 3 is a plan view of an upper portion (121) of a conventional fuel assembly support bracket.
FIG. 4 is a schematic view of a new control rod driving device (22) of the present invention.
FIG. 5 is a plan view of a new upper portion (125) of a fuel assembly support bracket of the present invention.
FIG. 6 shows the relative arrangement of the upper part of the cross-shaped control rod (10) when the fuel assembly support bracket new upper part (125) is used, and the fuel rod (110) and the channel box (111) constituting the core. Longitudinal section.
FIG. 7 is a plan view of adjacent new upper portions (125) of the fuel assembly support bracket.
[Explanation of symbols]
10 is a cross-shaped control rod 11 is a control rod support column 12 is a speed limiter umbrella 21 is a control rod drive 22 is a new control rod drive 24 is a control rod guide tube 25 is a control rod new guide tube 26 is a tube hole 30 is a tube Inner water 31 Upper water inlet 32 Lower water inlet 35 Outer tube water 40 Housing 50 Driving piston 51 Driving piston rod 52 Piston cylinder 61 Control rod insertion water piping 62 Control rod drawing water piping 63 Upper The driving water 64 is the lower driving water 65 is the control rod driving water inlet / outlet 70 is the pressure vessel bottom 71 is the control rod new guide tube support plate 80 is the control rod fixing device 81 is the latch 82 is the latch spring 83 is the suction device 90 is the communication pipe 91. The wire 101 is a commutation grid 102, a propeller 103, a submersible motor 110, a fuel rod 111, a channel box 112, and a fuel lower type tray. 113 is fuel rod cooling water 114 is leakage cooling water 116 is fuel rod cooling water passage 117 is leakage water passage 121 is fuel assembly support fitting upper part 122 is fuel assembly support fitting body 123 is metal fitting side hole 124 is large diameter speed limiter The umbrella 125 is a fuel assembly support bracket new upper part 130 is a core support plate 151 is a bracket spring.

Claims (8)

In a boiling water reactor having a cruciform control rod (10), the housing (40) penetrating the pressure vessel bottom (70) is eliminated, and the submersible motor (103) installed below the control rod new guide tube (25) is removed. ), The propeller (102) is rotated to suck the water in the communication pipe (90) from the lower water inlet / outlet (32) to create an ascending flow, and to make it a vertical flow by the rectifying grid (101), under the large diameter speed limiter umbrella (124). , The water (30) in the tube above the large diameter speed limiter umbrella (124) is sucked into the communication pipe (90) from the upper water port (31), and the control rod position is set by the latch (81). A new control rod driving device (22), which is performed by a control rod fixing device (80) including a latch spring (82) and a suction device (83). What is claimed is: 1. A new fuel assembly support bracket for a boiling water reactor, comprising a fuel assembly support bracket new upper part (125) having a square upper surface and a metal fitting spring (151) attached thereto. The power and electric signals of the submersible motor (103) and the suction device (83) according to claim 1 are supplied from outside the pressure vessel by an electric wire (91) introduced into the inside of the pressure vessel through a water supply pipe or an emergency cooling system pipe. It is characterized by the following. A power supply and an electric signal outside the pressure vessel are converted from electricity to a laser by a conversion element as a power supply and an electric signal of the underwater motor (103) and the suction device (83) according to claim 1, and the laser is supplied to a water supply pipe or emergency cooling. It is supplied by an optical fiber introduced into the pressure vessel through the system piping, and is converted into electricity or an electric signal using a light-to-electricity conversion element. The power and electric signals of the submersible motor (103) and the suction device (83) according to claim 1 are converted from electricity to ultrasonic waves by a conversion element outside or inside the pressure vessel, and the ultrasonic waves are made of a piezoelectric ceramic, a piezoelectric crystal, or a magnetostrictive material. It is characterized by being converted into an electric signal using a transducer consisting of In the control rod driving method according to the first aspect, a laser outside the pressure vessel is supplied by an optical fiber introduced into the pressure vessel through a water supply pipe or an emergency cooling system pipe, and the laser is irradiated to the rectifying grid (101) to generate heat. It is characterized by utilizing the expansion force of the generated bubbles. A storage battery or a fuel cell is provided below the control rod new guide tube (25) as a power source for the submersible motor (103) and the suction device (83) in the first aspect. The new control rod guide tube (25) is formed in a square lattice on the control rod new guide tube support plate (71), and the new control rod guide tube support plate (71) is supported on the inner surface of the pressure vessel. I do.

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