JPS6044889A - Stop device for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a nuclear reactor shutdown device used as a back-up reactor shutdown device for a gas-cooled nuclear reactor.

[Technical background of the invention]

Generally, a gas-cooled nuclear reactor is constructed as shown in FIGS. 1 and 2. That is, numeral 1 in the figure is a nuclear reactor vessel, and a reactor core 2 is accommodated within this reactor vessel 1. In this reactor core 2, graphite blocks are stacked as a moderator, and fuel rods 3 are loaded inside this graphite block.

A coolant such as helium gas flows into the reactor vessel 1 from the inlet pipe 4, passes through the reactor core 2 from above, is heated, and flows out from the outlet pipe 5. The high temperature coolant flowing out from this outlet pipe 5 is then transferred to a heat exchanger 6.
After exchanging heat with the external coolant through the inlet pipe 5, the coolant is returned to the reactor vessel 1 through the inlet pipe 5 by a circulation pump. A control rod guide tube 8 is inserted into the reactor core 3 from above, and a control rod 9 is accommodated in the control rod guide tube 8 so as to be able to move up and down. It is configured to control the output of the reactor core 2 by inserting or withdrawing it into the reactor core 2. And this control rod 9 is the control rod drive mechanism L! is driven by. The control rod drive mechanism 10 includes a wire rope 11 connected to the control rod 9, a drum 12 for winding in and letting out the wire rope 11, and a motor 13 for rotating the drum 12. And this motor 13
The control rod 9 is configured to drive the drum 12, wind in and let out the wire rope 1, and move the control rod 9 up and down. In addition, in such a reactor, the control rod 9 is
A rear reactor shutdown device 14 is provided assuming that the reactor cannot be inserted. Note that the above fuel rod 3. control rod 9
, the control rod drive mechanism, and the backup reactor shutdown device 14, although a plurality of each are actually provided, only one of each is shown in FIG.

The backup reactor shutdown device J4 is the control rod drive mechanism L! The structure and operating principle are different from those of the control rod drive mechanism 10, and the control rod drive mechanism 10 is configured to prevent redundant failures due to causes common to the control rod drive mechanism 10. The details of this back-up reactor shutdown device 14 are constructed as shown in FIG. Reference numeral 15 in the figure indicates a guide tube, which is inserted into the reactor core 2 from above and has an open upper end. A neutron absorbing material storage hole 16 is provided above the guide tube 15, and a neutron absorbing material such as boron carbide (84C, The neutron absorbing material 17 is stored in the form of a small sphere with a diameter of 10 mm or a pellet shape with a diameter of 10 m and a length of 10 cm. In addition, a neutron absorbing material falling port 18 is formed at the bottom of the neutron absorbing material storage hopper 16, and normally the valve body 1
It is blocked by 9.

A connecting rod 2θ is connected to the upper part of this valve body 19, and a driving machine 821 is connected via this connecting rod 20. This drive mechanism 21 includes a drive motor 22;
a gear 23 connected to the gear 23, a gear 2 meshing with the gear 23;
4. This gear screw 25 is connected to this gear 24.
It consists of a connecting plate 27 which is screwed into a screw 25 through a nut 26, and the connecting rod 20 is connected to this connecting plate 27.

In addition, a valve protection tube 3 is provided in the neutron absorbing material storage base 16.
3 is provided, and the valve body 19 moves up and down along this valve body protection tube 33. In the figure, reference numeral 28 indicates an upper limit switch, 29 a lower limit switch, and 30 a bearing.

The backup reactor shutdown device 14 with the above configuration automatically activates the drive motor 22 in response to an emergency activation signal from the reactor safety protection system.
rotates in the normal direction, and the screw 25 rotates in the normal direction via the gears 23 and 24. By the forward rotation of the lug screw 25, the y-lunar screw 25 rises, which causes the connecting plate 27 and the connecting rod 2o and the valve body 19 to rise, causing the connecting plate 27 to come into contact with the upper limit IJ limit switch 28. A signal is output and the drive motor 22 is stopped. Due to the rise of the valve body 19, the neutron absorbing material falling port 18
is opened, and the neutron absorbing material 17 falls into the reactor core 2 via the guide tube 15 due to its own weight. This causes an emergency shutdown of the reactor.

[Problems with background technology]

However, since the neutron absorbing material storage hole 4' l 6 of the neutron absorbing material inlet port 188 is also smaller in diameter, burrs may occur due to interference between the neutron absorbing materials 17 or the neutron absorbing material 17 and the wall surface of the neutron absorbing material inlet port 18, etc. This is not a desirable situation since the fall of the neutron absorbing material 12 is inhibited due to the effect, and as a result, it may take a long time to shut down the reactor.

[Purpose of the invention]

The purpose of the present invention is to reduce the time required for reactor shutdown by suppressing the bridging effect when the neutron absorber falls and allowing the neutron absorber to fall quickly, thereby significantly improving reliability and safety. The object of the present invention is to provide a nuclear reactor shutdown device that can shut down a nuclear reactor.

[Summary of the Invention] That is, the nuclear reactor shutdown device according to the present invention includes a neutron absorbing material storage hole/arm that is provided above a guide tube inserted into a reactor core and houses a neutron absorbing material therein, and a neutron absorbing material storage hole/arm that is provided above a guide tube inserted into a reactor core. 9, a neutron absorbing material falling port formed at the lower part, a valve body that closes the neutron absorbing material falling port by fitting into the neutron absorbing material falling port, and a valve body disposed on the inner peripheral side of the neutron absorbing material storage hole. The valve body protection pipe installed, the blip prevention body deposited on the lower end of the valve body, and the valve body are connected via a connecting rod, and the valve body is reciprocated in the vertical direction within a predetermined range in response to an emergency activation signal. It is equipped with a drive mechanism that moves the neutron absorbing material and drops it into the reactor core, and the valve body can be reciprocated in the vertical direction, and the blip prevention body can be reciprocated in the vertical direction accordingly, so it can absorb neutrons. It prevents the blip effect of materials from occurring, and even if a blip effect occurs, it is destroyed, the neutron absorbing material falls quickly, and the reactor can be stopped within a short time, significantly improving reliability and safety. can be done.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5. In the figure, 101 is a nuclear reactor vessel, and a reactor core 102 is accommodated within the reactor vessel 101 . In this core 102, graphite blocks are stacked as a moderator, and fuel rods 103 are loaded in the graphite blocks. A coolant such as helium gas flows into the reactor vessel 10 from an inlet pipe 104, passes through the reactor core 102 from above, is heated, and flows out from an outlet pipe 105. The high temperature cooling water flowing out from the outlet pipe 105 is heat exchanged with an external coolant via a heat exchanger 106, and then sent to the inlet pipe 10 by a circulation pump 107.
5 and then returned into the reactor vessel 101 again. In addition, a control rod guide tube JOB is inserted into the core 102 from above), and a control rod 109 is housed in the control rod guide tube 108 so as to be able to move up and down. It is configured to control the output of the reactor core 102 by inserting or withdrawing it. This control rod 109 is driven by a control rod drive mechanism 110.

The control rod drive mechanism 110 is composed of a wire lobe 111 connected to a control rod, a drum 112 for winding in and feeding out the wire lobe 111, and a motor 113 for rotationally driving the drum 112. The motor 113 drives the drum 112 to wind in and pay out the wire c5-f1xz, and the control rod 10
9 is configured to be raised and lowered.

Further, such a nuclear reactor is provided with a backup reactor shutdown device 114 in case the control rod 109 cannot be inserted. Note that the fuel rod 103. control rod 10
9. Control rod drive mechanism 110 and backup reactor shutdown device 1
Although a plurality of 14 are actually provided, only one of each is shown in FIG.

The backup reactor shutdown equipment J has a structure and operating principle different from those of the control rod drive mechanism 110, so that it will not fail due to the same cause as the control rod drive mechanism 110. It is configured as follows. The details of this back-up reactor shutdown device port are constructed as shown in FIG. Reference numeral 115 in the figure indicates a guide tube, and the core Jθ2
It is inserted into the interior from above and its upper end is open. A neutron absorbing material storage hopper 116 is provided above the guide tube 115 to store the neutron absorbing material. 116
Inside is a neutron absorbing material 11 formed of a neutron absorbing material such as boron carbide (B4C) in the form of particles, such as small spheres with a diameter of 10 mm or pellets with a diameter of 10 mm and a length of 10 mm.
7 is stored. Further, a neutron absorbing material falling port 118 is formed at the bottom of the neutron absorbing material storage hole 4116, and is normally closed by a valve body 119.

A connecting rod 12θ is connected to the upper part of the valve body 119, and a drive mechanism 121 is connected via the connecting rod 120 of the cylinder. The drive mechanism 121' includes a drive motor 122, a gear 123 connected to the drive motor 122, and a gear 123 connected to the drive motor 122.
23, a ball screw 125 connected to the gear 124, and a connection plate 127 screwed to the ball screw 125 via a ball screw 126. The connecting rod 120 is connected to the connecting rod 120 . Further, a valve body protection tube 133 is provided in the neutron absorbing material storage chamber 116, and the valve body 119 moves up and down along this valve body protection tube 113. In the drawing, reference numeral 128 indicates an upper limit switch, 129 indicates a lower limit switch, and 13θ indicates a bearing.

Approximately 10 to 20 from the above upper limit limit, tosui, chi 128
There is a rim and tosui for the operating point below m.

Chi 13 is provided. That is, in response to an emergency activation signal from the reactor safety protection system, the drive motor 122 automatically rotates in the forward direction, and the connection plate 127. The connecting rod 120 and the valve body 119 rise. Raised connection plate 1
21 comes into contact with an upper limit switch 128, and the drive motor 122 rotates in the reverse direction in response to a signal outputted thereby. This allows the connection plate 121. The connecting rod 120 and the valve body 119 are lowered, and the connecting plate 127 comes into contact with the operating point limit switch 131. The signal output at this time causes the drive motor 122 to rotate forward again and connect the connecting plate 127.
° Raise the connecting rod 120 and valve body 119.

Thereafter, the upper limit switch 128 and the operating point limit, tosui, and
It is configured to reciprocate between 31 and 31.

In addition, at the lower end of the valve body 119, there is a burr as a prip prevention body.
A deformation prevention rod 132 is attached. This prip prevention rod 132 is formed into a tape shape and becomes smaller in diameter as it goes downward. This blip prevention rod 132 also reciprocates in the vertical direction like the valve body 119 when the neutron absorber 111 falls. This vertical movement of the blip preventer 132 prevents the occurrence of prips at the neutron absorbing material drop port 118, and also destroys the generated prips to promote the fall of the neutron absorbing material 117.

According to the above configuration, during normal operation of the nuclear reactor, the valve body 119 is fitted into the neutron absorbing material falling port 118 as shown in FIG. 4, so that the neutron absorbing material 117 does not fall. For example, when an emergency activation signal is output from the reactor safety protection system, the drive motor 122 automatically rotates in the forward direction as shown in FIG. Connecting plate 127 and connecting rod 1 via yW-lu screw 125 and sf-luna screw 126.
20 and the valve body 119 rise. and connection plate 127
When the upper limit switch 128 comes into contact with the upper limit switch 128, a signal is output and the drive motor 122 rotates in the reverse direction. As a result, the connecting plate 127, the connecting rod 120, and the valve body 119 are lowered.

And the connection plate 127 is the limit switch 131 for the operating point.
When it comes into contact with the drive motor 12, a signal is output.
2 rotates forward again to raise the connecting plate 127, connecting rod 120, and valve body 119. After that, the neutron absorbing material 117 is completely dropped until the -P lowering completion instruction signal is received.
28 and the operating point limit, tosui, and chi 131. As the valve body 119 moves up and down, the prip prevention*IJ2 also moves up and down in the neutron absorbing material 117 falling from the neutron absorbing material drop port 118, thereby effectively preventing the occurrence of pripping. Yellowtail,
Since the neutron absorbing material 117 can be quickly dropped into the reactor core 102 and the reactor can be stopped within a short time, the reliability and safety can be significantly improved. I can do it.

〔Effect of the invention〕

As described in detail above, according to the present invention, the occurrence of the prip effect of the neutron absorbing material is prevented by the vertical reciprocating movement of the valve body and the accompanying vertical reciprocating movement of the prip prevention body, and Even if a blip effect occurs, it can be destroyed, the neutron absorber can quickly fall, and the reactor can be stopped within a short time, thereby significantly improving reliability and safety.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing conventional examples. Figure 1 is a vertical cross-sectional view showing the schematic configuration of a gas-cooled nuclear reactor, Figure 2 is a vertical cross-sectional view showing details of the reactor shutdown system, and Figure 3 is a vertical cross-sectional view showing the details of the reactor shutdown system. Figure or 5th
The figure shows one embodiment of the present invention. Figure 3 is a vertical cross-sectional view showing the schematic configuration of a gas-cooled nuclear reactor. Figure 4 is a vertical cross-sectional view of a reactor shutdown device showing the state during normal reactor operation. FIG. 5 is a vertical sectional view showing the operating state of the nuclear reactor shutdown device. 102... Core, 115... Guide tube, 116...
Neutron absorbing material storage ho, A', ll'l... Neutron absorbing material, 118... Neutron absorbing material falling port, 119... Valve body, 120... Connecting rod, 121... Drive mechanism, 132...
... Buri, de-prevention rod (buri, de-prevention body), 133...
Valve protection tube. Applicant's agent: Patent Attorney Dosu Hiko Ebu + 1 Zuko 2 Zuko 3 Zusho 113 Zuko 4 Zuko 5

Claims (1)

[Claims] A neutron absorbing material storage hopper provided above a guide tube inserted into the reactor core and accommodating a neutron absorbing material therein, a neutron absorbing material falling port formed at the bottom of this neutron absorbing material storage hopper 4, and this neutron absorbing material A valve body that closes the neutron absorbing material falling port by fitting into the falling port, a valve protecting pipe disposed on the inner peripheral side of the neutron absorbing material storage housing I4, and a valve body protection pipe attached to the lower end of the valve body. and a drive mechanism that is connected to the valve body via a connecting rod and that causes the valve body to reciprocate in the vertical direction within a predetermined range in response to an emergency activation signal, thereby causing the neutron absorbing material to fall into the reactor core. A nuclear reactor shutdown device featuring: