JPS595996A - Fuel exchanging 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 the Invention] The present invention relates to a fuel exchange apparatus for exchanging core components within a reactor vessel of a fast breeder reactor.

[Technical background of the invention]

Figure 1 shows a schematic configuration of a fast breeder reactor. A core support part 2 is provided inside a reactor vessel 1, and this core support part 2 contains core components such as core fuel, blankets, and neutron shields. The reactor core 4 is constructed by loading the elements 3... The upper opening of the reactor vessel 1 is shielded by a fixed plug 5 having an eccentric hole and a rotary plug 6 rotatably attached to the eccentric hole of the fixed plug 5.

A core upper mechanism 7 and a fuel combustion conversion equipment rlt8 are attached to the rotating plug 6. The upper core mechanism 7 is provided with a control rod drive mechanism that controls the output of the core 4 by driving the control rods up and down.

In addition, there is a liquid as a coolant inside the reactor vessel 1.
A ram is accommodated, and a space above the liquid level is filled with, for example, argon gas as a cover gas.

Then, the liquid (Jll) ram flows into the lower part of the reactor vessel 1 through the inlet pipe IA, flows upward in the reactor core 4, and flows into the reactor vessel 1 through the inlet pipe IA.
] Piping IB: It is configured to flow out through Ei.

FIG. 2 shows the fuel-burning conversion fjjltt. A guide sleeve 10 is inserted through a portion of the rotary plug 6, and an upper end portion of a guide tube 11 is rotatably supported inside the guide sleeve 10. The lower end of the guide tube 11 is located near the core support part 2 in the reactor vessel I, has an opening 12 on the - side, and is connected to a tubular grit (guide) via fixing members 12A and 12B. 1
3. and the guide tube 11
A fuel handling mechanism 14 is introduced into the reactor vessel 1 throughout.

The fuel handling mechanism 14 includes a tubular connecting portion 15 that is housed inside the guide tube 11 so as to be able to move up and down, and this connecting portion 15.
The gripper mechanism 17 is connected to the lower part of the reactor via a pantograph mechanism 16 and housed in the gripper guide 13 so as to be able to rise and fall freely, and is removed from the guide tube 11 during reactor operation. .

Further, a rotary plug 6 is provided at the upper end of the guide sleeve 10.
A mounting base 18 is connected to the top side of the frame. A reference numeral 19 is attached to the outside of the mounting base 18.

Further, at the upper end of the mounting base 18, a fixed door knob (lube 20) and a cask door valve 21 are stacked to maintain airtightness inside the reactor vessel 1, and a cask housing 22 is mounted on the cask door valve 21. The upper end of the connecting portion 15 is connected to the cask housing 2.
A drive section 23 is provided at the upper end of the connecting section 15 to drive the both front pantograph mechanisms 16 and the gripper mechanism 17. Also, cask housing 22
A hoisting mechanism 24 is provided at the upper end, and the fuel handling mechanism 1 is connected to the hoisting mechanism 24 via a wire 25.
4 is configured to be driven up and down.

Therefore, when replacing the core components 3 loaded in the reactor core 4, the horizontal position of the gripper mechanism 17 is selected by combining the rotation of the rotary plug 6 and the rotation of the guide tube 110,
The drive unit 23 drives the pantograph mechanism 16 and the gripper mechanism 17 to grip a predetermined core component 3, and the hoisting mechanism 24 raises the fuel handling mechanism 14 to lift the predetermined core component 3. Geru. The core components 3 taken out from the core 4 are held in a rack (not shown) arranged around the core 4, and the gripper mechanism 17 is moved horizontally, and a new core component The fuel handling mechanism 14 is lowered by the hoisting mechanism 24, and a new core component 3 is loaded into the core 4.

Also, during reactor operation, the fuel handling mechanism 14 is guided through the air 1.
1) Remove the fuel handling mechanism 14 inside the guide pipe 11.
As shown in FIG. 3, a guide tube plug 26 having a radiation shielding function equivalent to that of the rotary plug 6 is fitted to the zero position, and the guide tube 11 is closed. In addition, in order to remove the fuel handling mechanism 14 from the guide tube 11, first fold the pantograph mechanism 16 using the drive section 23, and after storing the pantograph mechanism 16 and the gripper mechanism 17 inside the guide tube 1,
It is pulled up from the hoisting mechanism 24V and housed in the Cask No.
and transported to the designated storage facility.

[Problems with background technology]

In the conventional fuel exchange apparatus shown in FIGS. 1 to 3, only the upper end of the guide tube 11 is supported by the rotating plug 6, so that the guide tube 11 is moved by the flow of the liquid metal 9 during reactor operation. There was a problem with vibration. Since the guide v11 is a cantilever beam supported at the upper end, such vibration becomes more intense toward the lower end.

Moreover, since earthquakes occur frequently in Japan, it is necessary to fully consider seismic resistance when designing a nuclear reactor plant, and in particular, it is desirable to increase the wall thickness of the guide tube 11 in order to improve its seismic resistance.

However, on the other hand, liquid sodium 9 in the reactor vessel 1
The temperature of the guide tifllK reaches 500℃.
In this case, an axial temperature gradient of the drum occurs at the liquid level of the liquid sodium 9, and the thermal stress in that part becomes extremely large. Therefore, in order to reduce thermal stress, it is desirable that the wall thickness of the guide tube 11 be made thin.

Since the broken guide tube II is displaced in the horizontal direction due to vibrations during reactor operation, alignment work must be performed to align the guide tube 11 to the reference position before starting the replacement work of core components. It was an unnecessary hassle.

[Purpose of the invention]

The present invention was made based on these circumstances, and its purpose is to maintain the integrity of the guide tube by reducing the perturbation of the guide tube left inside the reactor vessel during reactor operation. At the same time, it is possible to reduce the wall thickness of the guide tube to reduce thermal stress, and also to improve the core configuration. ! To provide a fuel exchange device which can eliminate the trouble of aligning a guide tube at the start of fuel exchange.

The fuel exchange device according to the present invention includes a guide tube whose upper end is rotatably supported by a rotary plug that shields the upper part of the reactor vessel, and a gripper mechanism at the lower part of the connecting part housed in the guide tube so as to be able to move up and down. A fuel handling mechanism that is detachable from the guide tube during reactor operation, and a fuel handling mechanism that closes the guide tube and engages the lower end with the core support part during reactor operation. The device is characterized in that it includes a guide tube plug that supports the lower end.

[Embodiments of the invention]

FIG. 4 shows the fuel exchange device 101. A rotating plug 102 that plugs the top of the reactor vessel (not shown)
A guide sleeve 103 extends over a portion of the guide sleeve 103, and the upper end of a guide tube 104 is rotatably supported inside the guide sleeve 103. The lower end of the guide tube 104 is introduced into the liquid sodium 105 housed in the reactor vessel and is located near the core support part 106.
06 is loaded with core components 107 such as core fuel, a blanket, and a neutron shield to form a core 108. In addition, an opening 1] part 109 is provided on one side of the guide tube 104.
is punched, and a tubular gripper guide 111 is attached to a position opposite to this opening 1090 via fixing members 110A and 110B. Then, the fuel handling mechanism 112 is introduced into the reactor vessel through the entire kite tube 104.

The fuel handling mechanism 112 includes a tubular connecting portion 113 that is housed inside the guide pipe 104 so as to be able to rise and fall freely, and a pantograph machine 4 114 that is connected to the gripper guide 111 at the bottom of the connecting portion 113. The gripper mechanism 115 is housed inside the reactor so that it can be raised and lowered, and is removed from the guide tube 104 during reactor operation.

Further, a mounting base 116 is connected to the upper end of the guide sleeve 103 on the upper surface side of the rotary plug 102. The guide tube 1 is provided on the outside of the mounting base 116.
A drive motor 117 that rotationally drives 04 is attached.

Furthermore, a fixed door valve 118 and a cask door valve 119 are stacked on the upper end of the front d-pi mounting base 116 for the purpose of maintaining airtightness during reactor operation, and a cask housing 120 is mounted on the cask door valve 119. are installed in succession.

The upper end of the connecting portion 113 is connected to the cask housing 1.
A drive unit 121 that drives the pan graph mechanism 114 and the gripper mechanism 115 is provided at the upper end of the connecting unit 113. A hoisting mechanism 122 is provided at the upper end of the frozen cask housing 120, and is configured to drive the fuel handling mechanism 112 up and down via a wire 123 by the hoisting mechanism 122.

Therefore, the number of core components 107 loaded in the core 10B is 5! When changing the gripper mechanism 115, the rotation of the rotary plug 102 and the rotation of the guide tube 104 are combined.
The driving unit 121 drives the pantograph mechanism 114 and the gripper mechanism 115 to grip a predetermined core component 107, and the hoisting mechanism 122 raises the fuel composting mechanism 112 and lifts it. Predetermined core components 107 are lifted. Then, the gripper mechanism 115 is moved horizontally again, and the core component 1 is taken out from the core 108.
07 is held in a rack (not shown) placed around the core 108 to grasp the new core component and move the core 10
The fuel handling mechanism 112 is lowered and the new core component 107 is transferred to the core 10 by the hoisting mechanism 122.
Load on 8.

Also, during reactor operation, the fuel handling mechanism 112 is removed from the guide tube 104, and a guide tube having the same radiation shielding function as the rotary plug 102 is installed in the guide tube 104 instead of the fuel handling mechanism 1120, as shown in FIG. The plug 124 is fitted to close the guide tube 104. Note that in order to remove the fuel handling mechanism 112 from the guide tube 104, the pantograph mechanism 114 and the gripper mechanism 115 are housed in the guide tube 104 using the drive section 121, and then the hoisting mechanism 121 is pulled up to remove the cask housing 120.
The fixed door valve 118 and the cask door valve 119 are closed to separate the fixed door valve 118 and the cask door valve 119, and the cask housing 120 is transported to a predetermined storage facility.

As shown in FIG. 5, the guide tube plug 124 has a plug portion 12 having approximately the same length as the thickness of the rotary plug 102.
5, an extension part 126 extending downward from the closure part 125, a retaining part 127 provided at the lower end of this extension part 126, and a chain part 12 provided at the upper end of the closure part 125.
8. The plug portion 125 is in close contact with the inner circumferential surface of the guide tube 104 to maintain airtightness inside the reactor vessel, and the fourth portion 128 is in contact with a rotation transmitting portion 129 provided inside the mounting base 116 from above. Then, the entire guide tube plug 124 is positioned in the vertical direction. The bent engagement part 127 comes into close contact with the inner circumferential surface of the lower end of the guide tube 104, protrudes downward from the guide v104, and engages from above in the retaining hole 130 provided in the core support part 106. .

With the above configuration, Guide '9 will be displayed during reactor operation.
A guide tube plug 124 is arranged inside the guide tube plug 104, and an engaging portion 12 provided at the lower end of the guide tube plug 124
7 is engaged with the retaining hole 130 of the core support part 106, the guide tube 104 is connected to the rotary plug 102 and the core support part 1.
06 is supported at both ends. Therefore, the structure is not easily vibrated even by the flow of liquid sodium 105, and the seismic resistance against earthquakes is also improved and soundness is maintained. Furthermore, since the wall thickness of the guide tube 104 can be reduced, thermal stress can be reduced. Furthermore, since there is no need to increase the diameter of the guide tube 104, there is no disadvantage that the reactor vessel has a large diameter.

In addition, during the core component replacement work, the guide tube Prada 12
4 has been removed, it is not possible to fix the lower end of the guide tube 104. However, due to the shutdown of the reactor operation, the temperature of the liquid sodium 105 has decreased by about 00℃, and the allowable stress of the guide tube 104 has decreased. There is a margin of about aOS.

Moreover, there is no need to consider creep strength, so structure e
It is easy to obtain IT margin.

Further, the guide tube 104 can be positioned in the horizontal direction by engaging the lower end of the guide tube plug 124 with the core support section 106. Therefore, the trouble of aligning the guide tube 104 at the start of core component replacement work can also be eliminated.

Note that the present invention is not limited to the configurations of the above embodiments. For example, the engagement structure between the guide tube plug and the core support body may be reversed from that of the embodiment, and four parts may be provided at the lower end of the guide tube plug, and a convex portion may be provided on the core support side to engage the two parts. good.

〔Effect of the invention〕

As described above in detail based on the embodiments, the fuel exchange device according to the present invention includes a guide tube whose upper end is rotatably supported by a rotating plug that shields the upper part of the reactor vessel, and a guide tube that can be moved up and down within the guide tube. A gripper mechanism is connected to the lower part of the freely housed connecting part, and the fuel handling mechanism is removed from the guide pipe during reactor operation, and the lower end is connected to the core by closing the guide pipe during reactor operation. The invention further includes a guide tube plug that engages with the support portion and supports the lower end of the guide tube, thereby reducing vibrations of the guide tube left in the reactor vessel during reactor operation. This makes it possible to maintain the integrity of the guide tube, reduce the wall thickness of the guide tube, and reduce thermal stress. Furthermore, it is possible to achieve further advantages, such as eliminating the trouble of positioning the guide U at the start of the conversion work of the core components.

[Brief explanation of drawings]

Figures 1 to 3 show the background art; Figure 1 is a sectional view showing the schematic configuration of a fast breeder reactor, Figures 2 and 3 are sectional views of a fuel exchange device, and Figures 4 and 3 are sectional views of a fuel exchange device. FIG. 5 is a sectional view of a fuel exchange device showing one embodiment of the present invention. 101... Fuel exchange device, 102... Rotating plug,
104...Guide! , 1 (75...Liquid sodium, 106...Core support part, 1o7...Core component, 108...Core, 112...Fuel handling mechanism, 1
13... Connecting portion, 115... Gripper mechanism, 124
...Guide tube plug, 127...Engagement part, 13o.
...Holding hole. Applicant's agent Patent attorney Takeshi Suzue Published in Japanese Patent Publication No. 1983-5
99G (6) Age 3 figure Tokukai 5996 (7) Age 5 figure

Claims (1)

[Claims] A nuclear reactor consists of a guide tube whose upper end is rotatably supported by a rotating plug that shields the upper part of the reactor vessel, and a gripper mechanism connected to the lower part of a connecting part housed in the guide tube so as to be able to rise and fall freely. a fuel handling mechanism that is removed from the guide tube during operation; and a guide tube plug that closes the guide tube and supports the lower end of the guide tube by engaging the lower end with a core support part during reactor operation. A fuel exchange device characterized by comprising: