JPH0854486A - Control rod drive for fast reactor - Google Patents

Abstract

(57) [Abstract] [Purpose] For a fast reactor equipped with a sealing means that can separate the sodium atmosphere of the reactor from the upper mechanism of the control rod drive device in a high temperature environment when the structure of the reactor vessel is simplified. A control rod drive is provided. A sealing hollow member 15 having an inner peripheral surface surrounding an outer peripheral surface of the extension pipe 11 is provided in an inner and outer communication portion of a reactor vessel which penetrates the extension pipe 11, and a fluid is supplied to a hollow portion of the sealing hollow member 15. A thin wall to which the supply pipe 16 is connected and the inner peripheral portion of the sealing hollow member 15 is expanded by the fluid pressure supplied from the pipe 16 and the sealing material 24 disposed inside thereof is pressure-bonded to the outer peripheral surface of the extension pipe 11. The structure was designated as 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod drive device for a fast reactor, and more particularly, in a high temperature atmosphere due to the simplification of the heat insulation structure of the reactor vessel, the sealing of the inner and outer communicating portions of the reactor vessel through which the extension pipe is penetrated. The present invention relates to a control rod drive device for a fast reactor.

[0002]

2. Description of the Related Art In a fast breeder reactor (hereinafter abbreviated as a fast reactor) that propagates fissionable substances required for nuclear chain reaction by absorbing fast neutrons into nuclear source materials,
The reaction rate of the core is controlled by inserting or extracting a control rod made of a material that absorbs neutrons into or out of the core.

This control rod has upper and lower end portions of a plurality of absorption pins implanted in the trumpet tube supported by a lattice plate, and a grip portion is formed on the upper portion of the trumpet tube. This control rod is gripped by the lower end of an extension tube suspended from the upper part of the reactor vessel, and is inserted or withdrawn in the core region to change the amount of neutron absorption.

When an abnormal situation occurs in the core, control rods are rapidly inserted into the core to stop the nuclear reaction. The rapid insertion of control rods into this core is due to the operation of the control rod drive,
Or by the action of gravity. The control rod driving device must be configured so that the control rod can be completely inserted into the core region for safety during refueling of the nuclear reactor, and in that state, the control rod can be disconnected to move the upper reactor mechanism.

Various types of control rod drive devices have been proposed as the control rod drive device for inserting, pulling out, and separating the control rods, one example of which is described below.

FIG. 4 shows a conventional control rod drive device including a control rod and a core.

In FIG. 4, a cylindrical upper guide tube 33 is inserted into the through hole 32 of the shield plug 31 that closes the upper opening of the nuclear pressure vessel. This upper guide tube 33
Is fixed to the shielding plug 31 at the flange portion 33a. The upper part of the upper guide tube 33 is connected to the housing 34, and the motor 35 is mounted inside the housing 34.

The lower end of the upper guide pipe 33 is immersed in the liquid sodium 36 in the reactor vessel, and an extension pipe 37 is inserted therein. An upper end portion of the extension pipe 37 is connected to an upper connecting mechanism portion 38 for connecting / disconnecting, and a nut connecting member 39 is fixed to an upper portion of the upper connecting mechanism portion 38. A plurality of nuts 40 are fixed on the nut connecting member 39, and each of the nuts 40 has a motor 3
A screw screw 41, which is driven to rotate by 5, is screwed in.

The lower end of the extension pipe 37 has a lower coupling mechanism portion 42.
Is mechanically connected to the handling head 46 above the control rod 45 in the lower guide tube 44 implanted in the core 43.

With the above structure, when the motor 35 is rotated, the screw screw 41 is rotated, the nut 40 and the nut connecting member 39 are moved up and down, and the extension pipe 37 and the control rod 45 connected thereto are also integrated. Move up and down. A mechanical seal 47 is provided in the upper guide pipe 33 near the through hole 32 to allow the extension pipe 37 to move up and down and to separate the sodium atmosphere for the reactor vessel from the upper mechanism of the control rod drive device. Has been. Mechanical seal 47
Is a sealing material such as fluororubber inserted in a compressed state in a gap to be sealed. This mechanical seal 4
A scraper 48 that prevents sodium adhering to the surface of the extension pipe 37 from entering the seal portion is provided in the lower part of the seventh embodiment.

Although not shown, the shield plug 31 has
A complicated heat insulating structure is provided to prevent heat of the core from being transferred to the mechanical seal 47 and the upper mechanism of the control rod drive device above the mechanical seal 47.

[0012]

In the structure of the conventional fast reactor including the control rod and the driving device described above, the structure of the rotary plug is complicated, and the construction cost of the entire fast reactor increases due to the complexity of the structure and the increase in weight. I had to do it. For this reason, it has been attempted to omit the rotary plug itself, use the upper part of the reactor vessel as an end plate, and penetrate the end plate with the control rod drive device and the fuel exchanger.

However, if the structure of the fast reactor is simplified by mounting the main equipment for controlling the reactor on the end plate of the nuclear pressure vessel as described above, the heat insulation structure conventionally provided in the rotary plug is simplified. The devices and members such as the screw screw of the superstructure of the control rod drive device, the connecting structure portion, and the mechanical seal are exposed to a high temperature environment. This temperature rise is expected to reach a high temperature of about 600 ° C., whereas the conventional operating temperature was around 150 ° C.

In the above-mentioned high temperature atmosphere, some conventional control rod drive devices cannot be used as they are. In particular, the mechanical seal that separates the sodium atmosphere in the reactor vessel from the upper mechanism of the control rod drive device has traditionally used fluorocarbon rubber as the sealing material, but the maximum operating temperature of fluorocarbon rubber is approximately Since the temperature is about 200 ° C., at a high temperature near 600 ° C., elasticity or pressure resistance is lost, and the surface pressure of the sealing surface is reduced, or expansion occurs and the extension pipe is excessively tightened to prevent its vertical movement. was there.

Therefore, an object of the present invention is to solve the above problems of the conventional control rod drive device for a fast reactor and to simplify the structure of the reactor vessel, and to control the sodium atmosphere and control of the reactor in a high temperature environment. It is an object of the present invention to provide a control rod drive device for a fast reactor, which is provided with a sealing means capable of separating the upper mechanism of the rod drive device from each other.

[0016]

In order to achieve the above-mentioned object, a control rod drive device for a fast reactor according to claim 1 of the present invention comprises a connecting means having an upper end connected to the drive means and a lower end detachable. In a control rod drive device for a fast reactor in which a control rod is inserted into or withdrawn from a reactor core by an extension pipe connected to the control rod through the extension pipe, the inner peripheral surface is extended to the inner / outer communication part of the reactor vessel. An annular sealing hollow member surrounding the outer peripheral surface of the pipe is provided, a pipe for supplying a fluid is connected to the hollow portion of the sealing hollow member, and the pipe supplies the inner peripheral portion of the sealing hollow member. It is characterized in that it has a thin structure in which the seal material bulged by the fluid pressure and arranged inside thereof is pressed against the outer peripheral surface of the extension pipe.

The control rod drive device for a fast reactor according to claim 2 of the present application is the control rod drive device according to claim 1, wherein the pipe is connected to an external fluid supply source, and a part of the pipe is hollow of the sealing hollow member. A pressure detecting means for detecting the fluid pressure of the portion and a pressure adjusting valve for adjusting the fluid pressure, and the pressure detected by the pressure detecting means and the opening and closing of the pressure adjusting valve of the sealing hollow member It is characterized in that the tightening force on the extension pipe can be controlled.

A control rod drive device for a fast reactor according to claim 3 of the present application is the control rod drive device according to claim 1 or 2, wherein the drive means comprises a motor, and the motor is rotationally driven by the motor. The drive unit includes a screw screw and a nut screwed to the screw screw and fixed directly or indirectly to the extension pipe.

[0019]

The control rod drive device for a fast reactor according to claim 1 of the present application has an annular sealing hollow member whose inner peripheral surface surrounds the outer peripheral surface of the extension tube in the inner and outer communicating portions of the reactor vessel for penetrating the extension tube. Since the hollow member for sealing has a thin structure in which the inner peripheral portion swells due to the fluid pressure, the fluid pressure inside the hollow member can be adjusted by adjusting the fluid pressure inside the hollow member during use in a high temperature environment. The peripheral surface compresses the outer peripheral surface of the extension pipe through the seal material, thereby obtaining sufficient surface pressure for sealing in a high temperature environment and obtaining the optimum tightening force that allows the extension pipe to move up and down. You can

According to the control rod driving device for a fast reactor of claim 2 of the present application, in addition to the structure of the control rod driving device for a fast reactor of claim 1, a pressure for adjusting the supply of the fluid to the sealing hollow member is provided. Since the pressure detecting means for detecting the fluid pressure inside the regulating valve and the sealing hollow member is provided, while the fluid pressure is detected by the pressure detecting means in addition to the function of the control rod drive device according to claim 1. By controlling the opening and closing of the pressure adjusting valve, the tightening force of the sealing hollow member to the extension pipe can be adjusted. As a result, the sodium atmosphere in the reactor vessel and the upper mechanism of the control rod drive device can be isolated by the optimum surface pressure when the extension pipe moves up and down and when it stops.

A control rod drive device for a fast reactor according to claim 3 of the present application is the control rod drive device according to claim 1 or 2, wherein a motor, a screw screw rotationally driven by the motor, and a screw screw are screwed together. In addition, since the drive unit including the nut fixed to the extension pipe is provided, the rotation of the motor can be converted into the vertical movement of the extension pipe via the screw screw and the nut.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control rod drive device for a fast reactor according to the present invention will be described below.

FIG. 1 shows a structure of a control rod drive device for a fast reactor of the embodiment including a core and control rods. In FIG. 1, reference numeral 1 indicates an upper end plate of the reactor vessel,
The upper end plate 1 is provided with a through hole 2 for penetrating the control rod drive device of this embodiment. A cylindrical upper guide tube 4 having a lower end immersed in the liquid sodium 3 of the reactor vessel is fixed to the through hole 2. A motor 6 for driving a control rod, which will be described later, is installed inside the housing 5 above the upper guide tube 4. The drive shaft of the motor 6 is connected to a plurality of screw screws 7 via a power transmission means such as a gear. These screw screws 7 are respectively screwed into nuts 9 fixed on a common nut connecting member 8. The lower end of the nut connecting member 8 is connected to the extension pipe 11 via an upper connecting mechanism 10 that performs a connecting or disconnecting operation. The extension pipe 11 is the upper guide pipe 4
Is suspended from the upper coupling mechanism 10 inside, and its lower end portion is connected to the handling head 14 of the control rod 13 via the lower coupling mechanism portion 12 that performs a separating operation.

At one point in the length direction of the extension pipe 11, a space between the extension pipe 11 and the upper guide pipe 4 is sealed to isolate the sodium atmosphere of the reactor vessel from the upper mechanism of the control rod drive device. An annular sealing hollow member 15 is provided. The hollow portion of the hollow member 15 is connected to an external gas supply source 17 via a pipe 16. The pipe 16 is provided with a pressure gauge 18 for detecting the fluid pressure inside the hollow member 15 and a valve 19 for pressure adjustment.

The hollow member 1 is removed by removing sodium vapor and the like adhering to the extension pipe 11 below the sealing hollow member 15.
A scraper 20 is attached to prevent sodium from entering the No. 1 seal portion.

The control rod 13 is connected to the lower connecting mechanism portion 12 by the handling head 14 and is movably suspended in the lower guide tube 22 which is planted in the core 21.

In the control rod drive device having the above-mentioned structure, when the motor 6 of the drive unit is rotated, the screw screw 7 is rotated and the nut 9 and the nut connecting member 8 screwed onto the screw screw 7 are moved up and down. As the nut 9 and the nut connecting member 8 move up and down, the extension pipe 11 and the control rod 13 connected to the nut 9 and the control rod 13 integrally move up and down. When suppressing the reactivity of the core 21, insert the control rod 13 into the core 21,
On the contrary, when increasing the reactivity of the core 21,
The output of the reactor can be controlled by controlling the rotation of the motor 6 in the direction in which the control rod 13 is pulled out from.

When the reactor is to be stopped urgently, the lower coupling mechanism portion 12 is separated and the control rod 13 is inserted into the reactor core 21 by the action of gravity. In such an operation operation of the control rod 13, the sealing hollow member 15 keeps a predetermined sealing surface pressure under a high temperature environment, and the sodium atmosphere of the reactor and the upper mechanism of the control rod driving device or the outer region of the reactor vessel. And must be isolated. The structure and function of the sealing hollow member 15 will be described in detail below.

FIG. 2 shows an enlarged vertical cross section of the sealing hollow member 15. As shown in the figure, the sealing hollow member 1
5 is formed in a ring shape as a whole, the inside of the annular portion has a hollow structure, and an extension pipe 11 penetrates through a hole at the center of the ring. The portion of the ring facing the extension pipe 11 has a thin structure 23, and the thin structure 23 and the extension pipe 1
A seal material 24 made of expanded graphite or the like that can be used in a high temperature atmosphere is inserted into the space between the two. The sealing material 24 is fixed by a screw 25 and a holding jig 26 so as not to come out even if the extension pipe 11 moves up and down. Further, as described above, the hollow portion of the hollow member 15 is provided with an external gas supply source 17 (not shown) via the pipe 16.
And is configured to allow gas to be press-fitted through the pipe 16.

The pipe 1 is provided in the hollow portion of the sealing hollow member 15.
When gas is injected from 6, the thin structure 23 of the hollow member 15
Bulges inward as shown in FIG. Due to this deformation, the sealing material 24 is pressed against the outer peripheral surface of the extension tube 11, and the surface pressure seals the gap between the extension tube 11 and the upper guide tube 4.

In this case, if the gas pressure inside the hollow member 15 is too large, the tightening force for the extension pipe 11 may become too large and the extension pipe 11 may not be able to move up and down. In order to prevent such a problem, the load pressure of gas on the hollow member 15 is measured by the pressure gauge 18, and when the target set pressure is reached, the pressure control valve 19 is automatically closed. It is possible to optimally control the sliding resistance and the leak amount generated in the seal when the extension pipe 11 is moved up and down. Furthermore, by controlling the pressure control valve 19 to close immediately when the pressure of the gas supply source 17 drops, the gas pressure in the hollow member 15 is maintained and sealed even if the gas supply source 17 fails. It is possible to maintain the seal surface pressure for.

As a fluid to be supplied to the hollow portion of the hollow member, a heat resistant oil or a liquid such as a liquid metal can be used in addition to an inert gas such as argon or nitrogen. When a liquid is used, the gas supply source 17 may be replaced by a fluid storage facility that stores a liquid and supplies a fluid having a constant pressure. When such a fluid storage facility is used, the pressure of the fluid supplied to the hollow member 15 is always kept constant and does not decrease due to mechanical failure.

As the structural member of the hollow member 15, a nickel alloy such as Inconel 718 having excellent high temperature resistance can be used. Further, the pressure gauge 18 is
It goes without saying that an analog pressure gauge and a digital pressure detection sensor may be used.

[0034]

As is apparent from the above description, in the control rod drive device for a fast reactor according to the present invention, the inner peripheral surface bulges due to the pressure of the fluid supplied therein, and the sealing material is pressed against the surface of the extension tube. Since the sodium atmosphere inside the reactor vessel is isolated from the upper mechanism of the control rod drive device or the outside area of the reactor vessel by using the hollow member for sealing, the structure of the reactor vessel is simplified and the sealing part is kept at high temperature. Even when it must be used under the environment, by adjusting the fluid pressure in the hollow member, the sliding resistance and the leak amount of the seal portion can be easily adjusted from the outside so as to be in an optimum state.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the overall configuration of a control rod drive device for a fast reactor according to the present invention.

FIG. 2 is an enlarged vertical sectional view of a sealing hollow member of a control rod drive device for a fast reactor according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a state in which the inner peripheral portion of the sealing hollow member bulges due to internal pressure and the sealing material is pressure-bonded to the outer peripheral surface of the extension tube.

FIG. 4 is a vertical sectional view showing the overall configuration of a conventional control rod drive device for a fast reactor.

[Explanation of symbols]

 4 Upper guide pipe 6 Motor 7 Screw screw 8 Nut connecting member 9 Nut 10 Upper connecting mechanism part 11 Extension pipe 12 Lower connecting mechanism part 13 Control rod 15 Sealing hollow member 16 Piping 17 Gas supply source 18 Pressure gauge 19 For pressure adjustment Valve 21 Core 23 Thin-walled structure 24 Sealant

Claims (3)

[Claims] Claim: What is claimed is: 1. A control rod drive device for a fast reactor, wherein an upper end portion is connected to a driving means, and a lower end portion is connected to a control rod through a detachable coupling means so that the control rod is inserted into or removed from the core. In, in the internal and external communication portion of the reactor vessel that penetrates the extension pipe,
An annular sealing hollow member whose inner peripheral surface surrounds the outer peripheral surface of the extension pipe is provided, a pipe for supplying a fluid is connected to the hollow portion of the sealing hollow member, and the inner peripheral portion of the sealing hollow member is A control rod drive device for a fast reactor, wherein the control rod drive device has a thin-walled structure that swells by a fluid pressure supplied by the pipe and presses a sealing material disposed inside the pipe to the outer peripheral surface of the extension pipe. 2. A pressure detecting means for connecting the pipe to an external fluid supply source, for detecting a fluid pressure in a hollow portion of the sealing hollow member, and a pressure adjusting valve for adjusting the fluid pressure. 2. The pressure detecting means is provided, and the tightening force of the sealing hollow member with respect to the extension pipe can be controlled by the pressure detected by the pressure detecting means and the opening / closing of the pressure adjusting valve. Control rod drive for the fast reactor. 3. The drive means comprises a motor, the motor, a screw screw rotationally driven by the motor, and a nut screwed to the screw screw and fixed directly or indirectly to the extension pipe. 3. A drive unit comprising: and 3.
The control rod drive device for a fast reactor according to.