JPS5946884A - Reactor shutdown device - 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 invention] The present invention relates to a nuclear reactor shutdown device for a fast breeder reactor.

[Technical background of the invention]

Generally, a liquid metal cooled fast breeder reactor is constructed as shown in FIGS. 1 and 2. That is, in the figure, reference numeral 1 denotes a reactor vessel, and a reactor core 2 is accommodated within this reactor vessel 1, and this reactor core 2 is supported by a core support structure 3. The upper end of the reactor vessel 1 is closed by a shielding glove 4, and a coolant such as liquid sodium is contained within the reactor vessel 1. The low-temperature coolant flows into the lower part of the reactor vessel 1 through the coolant inlet pipe 5, passes through the reactor core 2 from below and is heated, and the high-temperature coolant flows into the reactor vessel 1 through the coolant outlet pipe 6. leaked outside,
It is sent to an intermediate heat exchanger (not shown) where it is heat-converted with a secondary coolant. The coolant, which has become low temperature through heat exchange with the secondary coolant, is again sent to the lower part of the reactor vessel 1 through the above-mentioned coolant inlet pipe 5, and thereafter circulates through this path. Also, in the core 2, there are control rod assemblies Z together with fuel assemblies.
is loaded. Although a plurality of control rod assemblies are actually provided, only one is shown in the figure. This control rod assembly consists of a lower guide tube 8 and a control rod 9 housed in the lower guide tube 8 so as to be vertically movable. An entrance nozzle 10 is protruded from the lower end of the lower guide tube 8.
is inserted into the high-pressure plenum chamber 13 formed between the core support plates 11 and 12, and is prevented from being removed by the pressure of the coolant in this high-pressure plenum chamber 13. It has a hold-down structure. A portion of the coolant in the high-pressure brenum chamber 13 is introduced into the lower guide pipe 8 from the entrance nozzle 1o to cool the neutron absorber 14 housed in the control rod 9. “Furthermore, a dashpot 15 is provided at the bottom of the lower guide pipe 8, and a control rod 9
A dash ram 16 is provided protruding from the lower end. Then, when this control rod 9 descends, d: dash ram 16
is configured to enter the dashpot 15 and provide a buffer. Further, a core upper mechanism 17 is provided passing through the shielding plug.

Reference numeral 18 denotes a joint shell, which is provided to pass through the shielding glove 4. Inside this joint body 18, there are measuring fingers 19...
The tips of these measurement fingers 19... face the upper surface of the core 2, and the tips are equipped with temperature detectors (not shown), etc. The system is configured to measure the temperature of the exiting coolant. Note that these measurement fingers 19 are led out of the reactor vessel 1 through the protection tube 2o and the penetration 2no. Moreover, control rod drive mechanisms 22 . . . are provided in the upper part of this core upper mechanism 17 .

Upper guide tubes 23 are protruded from the lower ends of these control rod drive mechanisms 22 .
is opposed to the upper end of the lower guide tube 8 of the control rod assembly Z that passes through the joint shell 18 and is loaded into the reactor core 2. An outer extension tube 24 is inserted into the upper guide tube 23, and the outer extension tube 24 is configured to be driven up and down by the control rod drive mechanism 22. A plurality of latch fingers 25... are provided at the lower end of this outer extension tube 24, and these latch fins I25... have an enlarged diameter,
The latch fingers 25 are constructed so that the diameter can be reduced freely, and when the diameter is expanded, these latch fingers 25... are used as the handling head 26 of the control rod 9.
This control rod engaged with? is held, and if the diameter is still reduced, the grip with the handling head 26 is disengaged. Furthermore, an inner extension tube 27 is provided within the outer extension tube 24, and the inner extension tube 27 is configured to be moved to the lower stop by the control rod drive mechanism 22. A latch operation section 2 is provided at the lower end of this inner extension tube 27.
8 is provided, and when this latch operating portion 28 enters into the latch fingers 25..., these latch fingers 25...
... expands in diameter and engages with the handling head 26, and when this latch operating portion 28 comes out from inside the latch finger 25..., the latch finger 25... contracts in diameter by its own elastic force, It is configured so that it can be disengaged from the handling head 26.

Therefore, by moving the outer extension tube 24 up and down by the control rod drive mechanism 22 while the latch fingers 25 are engaged with the handling head 26, the control rod 9 can be inserted into the reactor core 2 or The withdrawal is done and the power of the reactor is controlled.

Furthermore, during a scram, etc., the latch fingers 25... and the handling head 26 are released from each other, and the control rods 9 are dropped into the reactor core 2 by gravity, thereby performing a scram of the reactor.

By the way, such a device has a complicated structure, and in the event of an emergency, if the control rod drive mechanism 22... breaks down or the scram signal is not output, the latch finger 25... \There is a possibility that the control rod 9 will not fall into the reactor core 2 because the engagement with the handling head 26 will not be released.

In order to solve this problem, a control rod drive mechanism as shown in FIG. 3 was developed. That is, 23 is an upper guide tube, and inside this upper guide tube 23 is an extension shaft 3.
θ is inserted through the extension shaft 30, and this extension shaft 30 is driven up and down by a control rod drive mechanism. Further, a heat-sensitive expansion body 31 is attached to the lower end of this extension shaft 30. The heat-sensitive expansion body 3 is, for example, a bellows filled with a fluid that expands as the temperature rises, and is configured to expand when the temperature rises. In addition, this heat-sensitive expansion body 3
A latch operating rod 32 is attached to the lower end of 1, and when the heat-sensitive expansion body 3 extends, the latch operating rod 32 descends and comes out from inside the latch finger 25. When the engagement with the no-doling head 26 is released and the heat-sensitive expansion body 31 contracts, the latch operating rod 32 rises and enters the latch fingers 25, expanding the diameter of the latch fingers 25. Let me...
and is configured and configured to engage the handling head 26. Further, a heater 33 for heating the heat-sensitive expansion body 31 is built-in, and this heater 3 is heated from the outside.
The heat-sensitive expansion body 31 can be heated by supplying power to the heat-sensitive expansion body 31. Further, the coolant flowing out from the upper surface of the core is configured to flow around the heat-sensitive expansion body 31 through the flow holes 34 and 35.

In such a device, normally, when the heat-sensitive expansion member 31 contracts, the latch operating rod 32 enters into the two latch fingers 25 and engages the latch fingers 25 and the handle rad 26. shall be. In this state, the extension shaft 30 is moved up and down by the control rod drive mechanism, and the control rod 9 is inserted into or withdrawn from the reactor core to control the reactor. If the control rod 9 is still released during normal operation or scram, power is supplied to the heater 33 from the outside to heat and expand the heat-sensitive expansion body 3, thereby connecting the latch fingers 25... and handling head 26. release the bond. In addition, in the event of an emergency, if the scram signal is not output and the control rods 9 do not fall into the reactor core, the temperature of the reactor will rise excessively and the thermal expansion body 31 will be heated by the coolant. The latch fingers 25... and the handling head 26 are extended, the control rods 9 fall into the reactor core, and the reactor is automatically scrammed without depending on external signals. maintain the health of

[Problems with Background Art] In the above-mentioned device, when the heat-sensitive expandable body 31 is heated by the heater 33 or the coolant, the heat-sensitive expandable body 3 gradually expands. In this case, the latch finger 25...
To disengage the handling head 26, the heat-sensitive expansion body 31 extends by a predetermined stroke, and the latch operating rod 32 is released after it is completely disengaged from the latch fingers 25. Therefore, there is a problem in that the operating time required to release the control rod 9 from being held is long.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to provide a nuclear reactor capable of releasing control rods in a short time by using a heat-sensitive expansion body equipped with a heater. The purpose is to provide a stopping device.

[Summary of the invention]

The present invention includes an extension shaft that is inserted into a reactor vessel and driven up and down by a control rod drive mechanism, and an extension shaft that is provided at the lower end of the extension shaft and is capable of expanding the diameter 1 and contracting the diameter freely, and also moves in the diameter reduction direction by elastic force. A latch finger that engages the handling head of the control rod by being biased and expanded in diameter, and is disengaged from the handling head by contracting in diameter, and a movable member provided inside the latch finger so as to be able to move up and down. a toggle link having one end pivotally connected to the latch finger and the other end pivotally connected to the movable body;
The present invention includes a temperature-sensitive expansion body provided at the lower end of the extension shaft that expands in response to a rise in temperature and presses down the moving body, and a heater that heats the temperature-sensitive expansion body.

Therefore, under normal conditions, the heat-sensitive expansion body is contracted, and in this state, if the other end of the toggle link is positioned slightly above the end, the other end of the toggle link is pivotally connected. Although the movable body tries to move upward due to the elastic force of the latch finger, the movable body comes into contact with the lower end of the heat-sensitive expansion body, and its upward movement is restricted, and the toggle link does not rotate any further. The latch finger is thus enlarged in diameter by these toggle links, and the latch finger and the handling head of the control rod are brought into engagement. When the heat-sensitive expandable body is heated by a heater or a coolant, the heat-sensitive expandable body expands, and the movable body is pushed down. When the movable body is pushed down, the other end of the toggle link moves downward, and when the other end is located below the other end, the movable body is urged downward by the elastic force of the latch finger. Therefore, this moving body is at the lower end of the heat-sensitive expansion body υ
The latch finger is separated and rapidly moves downward by the elastic force of the latch finger, and the toggle link also rotates so that the other end moves downward, and the latch finger rapidly contracts in diameter and is no longer engaged with the no-end ring head. To be released. Therefore, in this case, the stroke of the heat-sensitive expansion body required to release the latch finger is just a small stroke that moves the other end of the toggle link, which is located slightly above one end, to a position below the one end. Therefore, the latch finger can be released in a short time.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 4 to 7. In the figure, 101 is a reactor vessel, and a reactor core 102 is accommodated within this reactor vessel 101, and this reactor core 102 is supported by a core support structure 103.

The upper end of the reactor vessel 101 is closed by a shielding plug 104, and a coolant such as liquid sodium is contained within the reactor vessel 101. The low-temperature coolant flows into the lower part of the reactor vessel 101 through the coolant inlet pipe 105, passes through the lower core 102 and is heated, and the high-temperature coolant flows through the coolant outlet pipe 106 into the reactor. It flows out of the container 101, is sent to an intermediate heat exchanger (not shown), and is heat exchanged with the secondary coolant. Then, the coolant that has become low temperature by exchanging heat with the secondary coolant is the coolant inlet pipe 1 mentioned above.
05 to the lower part of the reactor vessel 101, and thereafter circulates along this path. Further, a control rod assembly 107 is loaded in the core 102 together with a fuel assembly. Although a plurality of control rod assemblies 107 are actually provided, only one is shown in the figure. This control rod assembly 107 includes a lower guide tube 10B and a lower guide tube 10B.
The controller m1oy is housed in the controller B so as to be vertically movable. An entrance nozzle 110 is protruded from the lower end of the lower guide tube 10B, and this entrance nozzle 110 penetrates the core support plates 111 and 112 and is inserted into the high-pressure plenum chamber 113 formed between them. The pressure of the coolant in this high-pressure plenum chamber 113 prevents leakage, which is a so-called hydraulic hold-down structure. A portion of the coolant in this high pressure FVT chamber 113 is supplied to this entrance nozzle 110.
The neutron absorbing material 114 is introduced into the lower guide tube 10B from the inside and is configured to cool the neutron absorbing material 114 housed in the control rod 109. Further, a Darashi pot 115 is provided at the bottom of the lower guide tube 10B, and a dash ram 116 is provided protruding from the lower end of the control rod 109. and,
When this control rod 109 descends, the dash ram I
J 6 Katashpo.

It is configured to enter into the tonneau 15 and provide a buffer. Further, the core upper mechanism 117 is inserted through the shielding plug.
is provided. 118 is a joint shell, and the above-mentioned shield f
2 and 1θ4. This joint body 118
Measurement fins 119... are housed inside, and the tips of these measurement fins 119... face the upper surface of the reactor core 102, and temperature detectors (not shown), etc. are installed at the tips. The coolant is provided and configured to measure the temperature of the coolant exiting the reactor core 102 . Note that these measurement fins f119... are connected to the protection tube 120. It is guided out of the reactor vessel 10 through a penetration 121. Moreover, control rod drive mechanisms 122 . . . are provided above the core upper mechanism 117. From the lower end of these control rod drive mechanisms 122... are upper guide pipes 123...
These upper guide pipes 123 are connected to the joint body 11.
Control rod assembly 1 loaded into core 1θ2 through B
It faces the upper end of the lower guide pipe JOB of 07.

An extension shaft 124 is inserted into the upper guide tube 123, and this extension shaft 124 is connected to the control rod drive mechanism 122...
It is configured to be driven upward T by. Further, a latch member 125 is attached to the lower end of this extension shaft 124.

This latch member 125 has a cylindrical shape, and the lower part thereof is divided into a plurality of parts in the circumferential direction, and is formed with latch fingers 126 that can be expanded and contracted in diameter and have a hook-shaped portion at the tip.

These latch fins f126... are formed.

The latch fingers 126 are urged in the direction of diameter reduction by their own elastic force, and when the diameter is expanded, the control rod 109
It is configured so that it engages with the handling head 127 of the handle head 127, and is disengaged from the handling head J2'l when the diameter is reduced. Further, a heat-sensitive expansion body 128 is attached to the lower end of the extension shaft 124 9 , and this heat-sensitive expansion body 128 is housed in the upper part of the latch member 125 . The heat-sensitive expansion body 128 is, for example, a heat-resistant expandable bellows filled with a fluid that expands as the temperature rises, and is configured to expand and extend downward as the temperature rises. Further, a heater 129 is built in the heat-sensitive expandable body 128, and by supplying power to the heater 129 from the outside and generating heat, the heat-sensitive expandable body 128 is heated and the heat-sensitive expandable body 128 is expanded. It is configured so that it can be done. still,
A movable body 130 is provided within the latch member 125 so as to be movable up and down. In addition, the latch finger 12
There are toggle links 131 in the middle part of 6...
One end of the toggle link 131... is pivotally connected to the lower end of the movable body 130 by the bin 134, and these toggle links 131... The links 131 constitute a toggle mechanism. And the latch finger 126
In the engaged state of..., these toggle links 131...
As shown in FIG. 6, the other end is located above one end by a slight distance d, and
1... causes the latch fins to push apart 126... and engage them with the handling head 127 of the control rod 109.

In this state, the movable body 130 is attached to the latch finger 126.
Although the moving body 1 is urged upward by the elastic force of...
The upper end of the latch finger 126 is in contact with the lower surface Kfi of the heat-sensitive expansion body 128 to restrict upward movement.
・is maintained in an engaged state. Further, a movable body lifting tube 135 is inserted into the upper guide tube 123, and this movable body lifting tube 135 is configured to be driven up and down by the control rod drive mechanism 122. The lower end of this movable body lifting tube 135 is divided into a plurality of pieces in the circumferential direction, and constitutes a hook portion 136 whose lower end is formed into a hook shape. It is inserted into the latch member 125 through a through hole 137 formed on the upper surface of the member 125, and is configured to be able to engage with the upper end of the movable body 130 and pull up the movable body 130. There is. In addition, communication holes 13B and 139 are formed on the side surfaces of the latch member 125 and the movable body pull-up tube 135, and the coolant flowing out from the upper end of the core 102 passes through these communication holes 13B and 139, and the heat-sensitive expansion body 128 It is structured so that it flows around the

Next, the operation of the first embodiment will be explained. During normal operation, as shown in FIG. 6, the other end of the toggle link 131 is located above the other end, and the latch fingers 126 are pushed apart against their elastic force. It is engaged with the handling head 127. In this state, the extension shaft 124 is moved up and down to move the control rod 109 into the core 1.
It is inserted into or withdrawn from θ2 to control the reactor. Next, when separating the control rod 109 during a scram or the like, power is supplied to the heater 129 in response to the scram signal to heat the heat-sensitive expansion body 128. Therefore, the heat-sensitive expansion body 128 expands, pushes down the movable body 130, and pushes down the other end of the toggle link 13. When the other end of these toggle links 13 is pushed down below the one end, the direction in which the movable body 130 is biased by the elastic force of the latch finger 126 is reversed, and this movable body 130
is biased downward. Therefore, this moving body 130 moves away from the lower end of the heat-sensitive expansion body 128 and rapidly moves downward, and the other ends of the toggle links 131... also rapidly move downward, and as shown in FIG. 7, the latch fingers 126... • is reduced in diameter by its own elastic force, and is released from engagement with the handling head 127. Therefore, the control rods 109 fall into the reactor core 102 due to gravity and stop the reactor.

Next, in the unlikely event that a scram signal is not issued, the control rod 109 will not fall. In this case, if an abnormality occurs in the reactor due to such a cause, the temperature of the coolant increases. Therefore, due to the temperature rise of the coolant, the heat-sensitive expansion body 128 is heated and expanded, and the control rod 109 is released from being held in the same manner as described above, and the control rod 109 moves into the reactor core 1.
02 and safely shut down the reactor. In the above case, in order to release the latch fingers 126... and the handling head 127, the moving body 130 must be pushed down by a small distance d by the expansion of the heat-sensitive expansion body 128, and then the latch fingers 126... The moving body 130 rapidly descends due to the elastic force of the latch finger 126.
...is in a released state. Therefore, the latch finger 126
The time required for the release operation is extremely short.

Note that when the latch fingers 126... are engaged with the handling head 127, the lowered moving body 1.70
is pulled up by the moving body lifting tube 124.

Note that the present invention is not limited to the first embodiment described above.

For example, FIG. 8 shows a second embodiment of the present invention. In this second embodiment, a tension spring 140 is tensioned between the tips of the latch fingers 126, and the tension spring 14
0 biases the latch fingers 126 in the diameter reduction direction.

This second embodiment has the same structure as the first embodiment except for the above-mentioned fish body, and the same reference numerals are given to the parts corresponding to those of the first embodiment in FIG. do.

〔Effect of the invention〕

As described above, the present invention includes an extension shaft that is inserted into a reactor vessel and driven up and down by a control rod drive mechanism, and an extension shaft that is provided at the lower end of the extension shaft so that the diameter can be expanded and contracted freely, and the diameter can be reduced by elastic force. A latch finger that engages the handling head of the control rod by being biased in the direction and expands in diameter, and is released from the handling head by contracting in diameter, and this latch fin can freely move up and down inside the latch finger. a moving body provided; a toggle link having one end pivotally connected to the latch finger and the other end pivotally connected to the moving body; and a toggle link provided at the lower end of the extension shaft that expands due to temperature rise and moves the toggle link. It is equipped with a temperature-sensitive expandable body that presses down the body and a heater that energizes the temperature-sensitive expandable body. Therefore, under normal conditions, the heat-sensitive expansion body is contracted, and in this state, if the other end of the toggle link is positioned slightly above the end, the other end of the toggle link is pivotally connected. Although the movable body tries to move upward due to the elastic force of the latch finger, the movable body comes into contact with the lower end of the heat-sensitive expansion body, and its upward movement is restricted, and the toggle link does not rotate any further. The latch finger is thus enlarged in diameter by these toggle links, and the latch finger and the handling head of the control rod are brought into engagement. When the heat-sensitive expandable body is heated by the coolant, the heat-sensitive expandable body expands, and the movable body is pushed down. When the movable body is pushed down, the other end of the toggle link moves downward, and when the other end is located below the end, the movable body is urged downward by the elastic force of the latch finger. Therefore, this moving body is at the lower end of the heat-sensitive expansion body υ
The latch fingers are separated and rapidly moved downward by the elastic force of the latch fingers, and the toggle link is also rotated so that the other end moves downward, and the latch fingers rapidly contract in diameter and are released from the handling head. Ru. Therefore, in this case, the stroke of the heat-sensitive expansion body required to release the latch finger is just a small stroke that moves the other end of the toggle link, which is located slightly above one end, all the way down from the one end. Its effectiveness, such as being able to perform the release action in a short time, is unique to dogs.

[Brief explanation of drawings]

FIGS. 1 and 2 show a conventional example, with FIG. 1 being a longitudinal sectional view of the whole, and FIG. 2 being a longitudinal sectional view of a control rod assembly and a connection portion with a control rod drive mechanism. Further, FIG. 3 is a longitudinal sectional view of a connecting portion between a control rod and a control rod drive mechanism in another conventional example. 4 to 7 show a first embodiment of the present invention, FIG. 4 is a longitudinal sectional view of the whole, and FIG. 5 is a longitudinal sectional view showing the control rod assembly and the connection part with the control rod drive mechanism. , FIG. 6 is a longitudinal cross-sectional view of the connecting portion with the control rod drive mechanism in the engaged state, and FIG. 7 is a vertical cross-sectional view of the connecting portion with the control rod driving mechanism in the released state. FIG. 8 is a longitudinal cross-sectional view of the connection portion with the control rod drive mechanism of the second embodiment. 101... Reactor vessel, 102... Reactor core, 107.
...Control rod assembly, 109...Control rod, 122...
Control rod drive mechanism, 124... Extension shaft, 126... Latch finger, 127... Handling head, 12
8...Thermosensitive expansion body, 129...Heater, 13o...
- Mobile object, 131...Toggle link. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) An extension shaft that is inserted into the reactor vessel and driven up and down by the control rod drive mechanism, and an extension shaft that is provided at the lower end of this extension shaft and that can freely expand and contract in diameter and is attached in the direction of contraction by elastic force. A latch finger that engages with the handling head of the control rod by being forced to expand in diameter and is disengaged from the handling head by contracting in diameter; a toggle link having one end pivotally connected to the latch finger and the other end pivotally connected to the movable body;
A nuclear reactor shutdown device comprising: a temperature-sensitive expansion body provided at the lower end of the extension shaft that expands as a temperature rises to push down the movable body; and a heater that heats the temperature-sensitivity expansion body. (2) The patented device is characterized in that the latch finger is biased in the diameter reduction direction by its own elastic force. (3) The nuclear reactor shutdown device 0 according to claim 1, wherein the latch finger is biased in a diametrical direction by a spring.