JPS6367594A - Fast breeder reactor - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fast breeder reactor whose structure is simplified and compact, and whose mechanical strength is improved.

(Prior Art) A conventional example will be described with reference to FIGS. 6 to 10. 6th
The figure is a sectional view showing the configuration of a tank-type fast breeder reactor, and reference numeral 1 in the figure is a reactor vessel.

A coolant (for example, liquid metal sodium) 2 and a reactor core 3 are housed within the reactor vessel 1 . The reactor core 3 is supported by the reactor vessel 1 via a core support mechanism 4. The reactor core 3 is composed of a plurality of core components 3a (not shown) such as fuel assemblies and control rods. The upper opening 1 a of the reactor vessel 1 is closed by a shielding plug 5 . This shielding plug 5 includes a fixed plug 6 fixed to the reactor vessel 1, a large rotating plug 7 rotatably arranged on the inner circumferential side of this fixed plug 6, and a large rotating plug 7 rotatably arranged on the inner circumferential side of this large rotating plug 7. It is comprised of a medium-rotation plug 8 and a small-rotation plug 9 rotatably placed on the inner circumferential side of the medium-rotation plug 8. A core upper mechanism 10 is installed above the core 3, passing through the medium rotation plug 8. A control rod drive mechanism 11 is installed in this core upper mechanism 10 . Further, a fuel exchange device 12 is disposed passing through the small rotation plug 9. An intermediate heat exchanger 13 and a main circulation pump 14 are disposed between the reactor vessel 1 and the reactor core 3, passing through the fixed plug 6. Further, a cover gas (for example, argon gas) 17 is sealed between the liquid surface of the coolant 2 and the shielding plug 5.

A jack-up device 15 is arranged between the fixed plug 6 and the large-rotation plug 7, between the large-rotation plug 7 and the medium-rotation plug 8, and between the medium-rotation plug 8 and the small-rotation plug 9. lift the large rotation plug 7, medium rotation plug 8, and small rotation plug 9.

Further, a rotary plug drive device 16 is installed in each of the fixed plug 6, large rotation plug 7, and medium rotation plug 8, and these rotation plug drive devices 16 drive the large rotation plug 7, medium rotation plug 8, and small rotation plug. Rotate 9. FIG. 7 is a top view of the tank-type fast breeder reactor shown in FIG. 6, and shows the positional relationship of the above-mentioned equipment.

Next, the configuration of the fuel exchange device 12 will be explained in more detail with reference to FIG. Reference numeral 21 in the figure is a hollow hold-down shaft, and this hold-down shaft 21 passes through the small-rotation plug 9 and is installed in the small-rotation plug 9 so as to be movable up and down. This hold-down shaft 21 is connected to a hold-down drive section 22 attached to the upper surface of the small rotation plug 9.
Driven by. A long tubular hoisting frame 24 is installed on this hold-down drive unit 22 via a door valve 23, and a hoisting machine 25 is installed on this hoisting frame 24. A gripper shaft 26 is inserted into the hold-down shaft 21, and the upper end of the gripper shaft 26 passes through the door valve 23 and reaches into the hoisting frame 24. A sealing mechanism 27 is installed at the connection point between the door valve 23 and the hoisting frame 24 in order to seal the insertion portion of the gripper shaft 26. This seal mechanism 27
Thus, an in-furnace boundary below the door valve 23 is formed. A gripper drive section 28 is provided at the upper end of the gripper shaft 26.
is attached, and the gripper drive unit 28 and the gripper shaft 26 are integrally driven up and down by the hoist 25 via a wire 29.

The gripper shaft 26 has a gripper claw 31 at its lower end, and is capable of being engaged with and detached from a handling head 32 provided at the upper end of the core component 3a of the reactor core 3. The gripper claws 31 are driven by the gripper drive section 28 via an operation rod (not shown) inserted into the gripper shaft 26.

When performing fuel exchange in the above configuration, the large-rotation plug 7, medium-rotation plug 8, and small-rotation plug 9 are lifted by their respective jacking devices 15, and then rotated independently by their respective rotary plug drive devices 16. . Thereby, the refueling device 12 is guided to a desired position in the core 3 (the location where the core component 3a to be replaced is located). Thereafter, the hold-down shaft 21 is lowered by the hold-down drive unit 22 so that its lower end approaches the core component 3a. Then, the gripper drive unit 28 uses the gripper claws 31 to move the handling head 3 of a predetermined core component 3a.
Grasp 2. After that, the gripper shaft 2 is lifted by the hoisting machine 25.
6, the core component 3a is removed from the core 3.
Pull out more.

At this time, the lower end of the hold-down shaft 21 prevents other core components 3a located in the periphery from floating.

Next, the holddown drive shaft 21 is raised by the holddown drive unit 22 to separate its lower end from the reactor core 3. Then, the large-rotation plug 7, medium-rotation plug 8, and small-rotation plug 9 are rotated to move the core component 3a gripped by the gripper claws 31 to a predetermined position in the reactor vessel 1, that is, to the in-reactor relay rack 41 shown in FIG. Move and separate the gripped core component 3a. The above is an overview of the fuel exchange operation. Although it is a core component 3a, specifically, it is a core fuel assembly 40. This is a general term for a wide range of fuel assemblies such as the blanket fuel assembly 42, the movable shield 43, the control rod assembly 44, and the neutron source assembly 45. Furthermore, the area handled within the reactor vessel 1 is wide-ranging, including the in-reactor fuel storage tank 46, the damaged fuel pot 47, and the in-reactor relay rack 48.

The above configuration has the following problems. First, the diameter of the large rotating plug 7 is the diameter of the upper core mechanism 10, or the required reach range 5 of the fuel exchange device, as shown in FIG.
1 (indicated by a dashed line in the figure). Furthermore, the 10th
The figure is a diagram for explaining the dimensional relationship of the shielding plug 5.

The fuel exchange device 12 needs to have a core component 3a located at the center 52 of the reactor, and therefore the radius of the large rotating plug 7 is required to be the minimum size shown below.

r −2Xr, )+Δms+ΔmlI+Δm.

...... (1) However, rL; radius ro of large-rotation plug; radius of core upper mechanism 6m; width of bearing stand for large-rotation plug drive: 6m0; width of bearing stand for medium-rotation plug drive: 6m; (for small-rotation plug drive) bearing stand width) + (radius for fuel exchange device installation) In addition, under these conditions, the required reach range 51 of the fuel exchange device 12
If it does not reach the outer circumference of
)LS
It becomes III.

However, R: Required range radius For example, in the case of a 1 million KWe class nuclear reactor, the radius of the core upper mechanism 10 is approximately 1.5 ms. Large, medium, and small rotating plugs 7.8
．． The bearing stand width of No. 9 is approximately 0.4 m. Therefore, the diameter of the large rotating plug 7 is at least 9 m, making it a fairly large structure. Further, as already explained, the shielding plug 5 has a triple structure, and requires a rotary plug drive device 16 for rotating each independently, a jacking device 15, and a sealing mechanism. The problem is that it becomes large and complicated. This also increases the overall structure of the reactor, and as mentioned above, the shielding plug 5 is of the type 3 rotating plug blade type, and the fixed plug 6 has an opening for the large-rotation plug 7, and the large-rotation plug 7 has an opening for the medium-rotation plug. An opening for the plug 8, the medium rotation plug 8 requires an opening for the small rotation plug 9. Therefore, the rigidity of the shielding plug 5 cannot be said to be high, and there are concerns about mechanical strength.

(Problems to be Solved by the Invention) As described above, with the conventional configuration, there are problems in that the device becomes larger and more complicated, and there are also problems in terms of mechanical strength. The purpose of this invention is to provide a fast breeder reactor that can be made smaller and simpler, as well as having improved mechanical strength.

[Structure of the Invention] (Means for Solving the Problems) That is, the fast breeder reactor according to the present invention includes a reactor vessel for accommodating a coolant and a reactor core, and a single member that closes the upper opening of the reactor vessel. a shielding plug, a core upper mechanism arranged above the reactor core passing through the shielding plug and movable up and down, and a cell installed on the upper surface side of the shielding plug and surrounding the upper part of the core upper mechanism; A core upper mechanism drive device installed in the cell to move the core upper mechanism up and down, and a variable pantograph fuel installed in the cell to penetrate the shielding plug and move core components in and out of the core. The present invention is characterized in that it is equipped with an exchange device.

(Function) In other words, during fuel exchange, the core upper mechanism drive device raises the core upper mechanism to secure a space above the core in which the variable pantograph type fuel exchange device operates. In this state, the variable pantograph refueling device is operated to move core components in and out of the reactor. This eliminates the need for the conventional multi-rotation plug system and allows a single shielding plug. A cell is installed on the upper surface of the shielding plug, and the core upper mechanism, the core upper mechanism drive device, and the variable pantograph type fuel exchange device are housed in this cell, thereby preventing the outflow of radioactive materials from inside the reactor.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4. It should be noted that the same parts as in the prior art are denoted by the same reference numerals and the explanation thereof will be omitted. Reference numeral 101 in the figure is a shielding plug in this embodiment.

This shielding plug 101 is different from the conventional multi-rotation type,
Consists of a single plug. The above shielding plug 10
A cylindrical cell 102 is installed at the center of the cell 1. A variable pantograph refueling device 103, a core upper mechanism 104, and a core upper mechanism driving device 105 are housed within this cell 102. During reactor operation, the lower end of the upper core mechanism 104 is lowered to a position directly above the reactor core 3. At the same time, the variable pantograph type refueling device 103 folds its pantograph so as not to interfere with the upper core machine kW 104. On the other hand, at the time of fuel exchange, the core upper mechanism 104 is raised by a core upper mechanism drive device 105, as shown in FIG. Then, the core components 3a are replaced by the variable pantograph type refueling devices 103, which are arranged in plural units.

The above is a general explanation, but below is the core upper mechanism section upper device 1.
The configuration of 05 will be explained in detail.

FIG. 2 is a front view showing the configuration of the core upper mechanism drive device 105, and reference numeral 111 in the figure is a ball screw. Although only two ball screws 111 are shown in the figure, three or more ball screws 111 are installed (three in this embodiment). Further, its upper end is pivotally supported by a bearing 112 fixed to the ceiling surface of the cell 102, a bevel gear 113 is fixed to its lower end, and its end is pivoted by a bearing 114 fixed to the shielding plug 101. supported. Another bevel gear 115 meshes with the bevel gear 113, and this bevel gear 115 is connected to a lifting drive mechanism 116. On the other hand, a core upper mechanism support plate 117 is attached to the ball screw 111 via a ball nut 118. Then, by driving the lifting drive mechanism 116, the ball screw 11
1, thereby rotating the core upper mechanism support plate 11.
Move 7 up and down. This core upper machine (1 support plate 117
The upper core mechanism 104 is moved up and down by the up and down movement of. Further, an inflatable seal 119 is attached to the penetrating portion of the shielding plug 101 of the core upper mechanism 104. This inflatable seal 119 allows the core upper mechanism 10 to
4 maintains a sealed state at any position when it moves up and down, and particularly prevents sodium vapor from leaking out. This inflatable seal 119 and the cell 102 form a double boundary.

Next, the configuration of the variable pantograph type fuel exchange device 10B will be explained with reference to FIG. Reference numeral 121 in FIG. 3 is a hollow hold-down shaft disposed through the shielding plug 101, and inside this hold-down shaft 121 there is a pantograph opening/closing shaft 122 and a gripper vertical movement drive shaft 1.
23 is inserted. The above pantograph opening/closing shaft 121
Haha linked pantograph arm 124 a, 124
b.

It is connected to the gripper guide tube 125 via 124c. Note that the symbols 135a and 1B5b in the figure.

135c is a ball nut (but ball nut) 13
5c has an opposite thread from the other two), and these ball nuts 135a to 135c move up and down by the rotation of the gripper opening/closing shaft 122, which is a ball screw. As a result, the arms 124a to 124c open and close, and the gripper guide tube 125 moves in parallel. The gripper vertical movement drive shaft 123 has a stroke adjustment mechanism 126
The gripper guide tube 1 is connected to the gripper guide tube 1 via a connecting member 127 having a
25 gripper guide rods 128. An elongated gripper shaft 129 is inserted through the gripper guide tube 125 and connected to the gripper guide rod 128, which is a ball screw, via a ball nut 136. A gripper claw 130 is attached to the lower end of the gripper shaft 129. The gripper claws 130 grip the handling head 32 of the core component 3a.

A pantograph opening/closing drive device 131 and a gripper vertical movement drive device 132 are installed above the hold-down shaft 121, and are connected to the pantograph opening/closing shaft 122 and the gripper vertical movement drive shaft 123, respectively. In addition, a hold-down rotation device 13 is provided on the upper surface of the shielding plug 101.
3 is installed, and this hold down rotation device 13
A door valve 134 is installed above 3. The hold-down rotation device 133 rotates and moves the hold-down shaft 121 up and down.

Variable pantograph type fuel exchange device 103 having the above configuration
As shown in FIG. 4, they are installed at equal intervals at three locations in the circumferential direction. The movable range of each variable pantograph refueling device 103 is indicated by reference numeral 142 in the figure, and the movable range 142 of the three variable pantograph refueling devices 103 allows any core component 3a to be moved in and out.

Also, between each variable pantograph type fuel exchange device 103, there is a
One in-furnace relay rack 41 (this is conventional) and two intermediate relay racks 141 are installed.

This is because, for example, in the case of the variable pantograph type refueling device 103 located at the right end in FIG. After transporting the fuel to another adjacent variable pantograph type fuel exchange device 1
03 to the in-furnace relay rack 41. The number of variable pantograph type fuel exchange devices 103 is not limited to three, but may be two, four or more. Of course, if you can make do with just one, that's fine.

The fuel exchange operation will be explained based on the above configuration.

■First, at the time of starting the fuel exchange operation, the core upper mechanism 1
04 has descended directly above the reactor core 3, and as it is, there is no space for the variable pantograph type refueling device 103 to operate, so first, the above-mentioned core upper mechanism 104 is moved upward and the variable pantograph type refueling device 10 is moved upward.
Start by securing the operating space for step 3. That is, by driving the lifting drive 81 and the ball screw 1
11 to raise the core upper mechanism support plate 117 that supports the core upper mechanism 104 via the ball nut 118. This causes the upper core mechanism 104 to rise, resulting in a state as shown in FIG.

At that time, the storage boundary for radioactive materials is cell 102 i:l.
- formed from Therefore, inflatable seal 1
19 may be in an open state, but in this embodiment, the core upper mechanism 104 is slid in a state in which it is not opened. This creates a double boundary.

In particular, not only should sodium vapor leak out to the outside, but cell 1
Prevent leakage into 02.

■Next, select a variable pantograph refueling device 103 capable of gripping the target core component 3a, rotate the hold-down shaft 121, and configure the selected variable pantograph refueling device 103 for the above-mentioned purpose. Element 3
bring it closer to a. Next, the pantograph arms 124a to 124C are operated to move the gripper guide tube 125 to a position directly above the core component 3a. This is the state shown in FIG.

(2) Next, the gripper guide tube 125 is lowered by the hold-down rotation device 133, and the lower end of the gripper guide tube 125 presses down the core components 3a around the target core component 3a from above.

In this state, the handling head 32 of the core component 3a is gripped by the gripper shaft 129 and the gripper claw 130 and pulled out.

■Next, place the gripped core component 3a on the in-core relay rack 41.
Alternatively, it is transported to the intermediate relay rack 141.

In this embodiment, it is assumed that the storage medium is transported to the intermediate relay rack 141. That is, it is conveyed to the intermediate relay cowl 141 by the rotation of the hold down 121 and the operation of the pantograph arms 124a to 124C. Then, the gripped core component 3a is separated.

The separated core component 3a is accommodated in an intermediate relay rack 141, and then the core component 3a accommodated in this intermediate relay rack 141 is transferred to the in-core relay rack 41 by another variable pantograph type refueling device 103. Transport to.

The operation at this time is similar to the operation described above.

(2) The same operation is then repeated to handle any desired core component 3a.

According to this embodiment, the following effects can be achieved.

■ First, unlike the conventional configuration in which a multi-rotation plug is used to move the fuel exchanger to a desired position, the shielding plug 101 is a single one, and the hold-down shaft 121
rotation and elevation, pantograph arms 124a to 124
Since the configuration is such that any core component 3a can be handled by the operation of C, etc., there is no need for any of the various equipment required when the multi-rotation plug method is adopted, and the configuration can be simplified and the device made more compact. At this time, all the various devices necessary for fuel exchange are arranged around the upper core mechanism 104, so that the above-mentioned compactness can be achieved more effectively.

■Also, the only large opening in the center of the shielding plug 101 is the opening that passes through the core upper mechanism 104. Therefore, when a conventional multi-rotation plug system is adopted, large-rotation plugs, medium-rotation plugs, small-rotation plugs, etc. The mechanical strength is greatly improved compared to the case where openings for plugs are formed individually. This means that the displacement of the upper core mechanism is effectively restricted when an earthquake occurs; for example, the control rod drive mechanism 11
Relative positional displacement between the core 3 and the reactor core 3 can be prevented.

(2) Also, a cell 102 is installed on the top surface of the shielding plug 101, and this cell 102 forms a storage boundary for radioactive materials, so that leakage of radioactive materials during a refueling operation is reliably prevented. Furthermore, the upper core mechanism 1
04 and the inner surface of the opening 101a of the shielding plug 101, an inflatable seal 119 is installed, and this inflatable seal 119 also exerts a sealing function, thereby providing a highly reliable boundary structure. Can be done.

Next, a second embodiment will be described with reference to FIG.

This second embodiment is a cell chamber integrated shielding plug 20 made of steel plate.
1 (in order to increase the rigidity of the shielding plug, a chamber is integrally formed in the upper part). That is, a cell chamber 203 is integrally formed above the shielding plug 201, and a cylindrical cell 202 is integrally formed within this cell chamber 203. The cell 202 has the same function as the cell 102 in the first embodiment. Further, the upper portions of the intermediate heat exchanger 13 and the main circulation pump 14 are accommodated in the cell chamber 203.

The rest of the configuration is the same as that of the first embodiment, and the explanation thereof will be omitted.

Therefore, not only can the same effects as in the first embodiment be achieved, but also a highly rigid structure can be provided.

[Effects of the Invention] As detailed above, according to the fast breeder reactor according to the present invention,
Since there is no need to adopt the multi-rotation plug system as in the past, it is possible to simplify and make the configuration more compact.Furthermore, since it is a single shielding plug and there is no large opening in the center, rigidity can be effectively improved. The effects are great, such as making it possible to increase the

[Brief explanation of the drawing]

1 to 4 are diagrams showing a first embodiment of the present invention,
Figure 1 is a sectional view of a tank-type fast breeder reactor, Figure 2 is a front view of the core upper mechanism drive unit, Figure 3 is a sectional view of a variable pantograph refueling device, and Figure 4 is a variable pantograph refueling device. 5 is a cross-sectional view of a tank-type fast breeder reactor according to the second embodiment, and FIGS. 6 to 10 are diagrams used to explain the conventional example. 6
The figure is a cross-sectional view of a tank-type fast breeder reactor, and Figure 7 is the same as in Figure 6.
8 is a sectional view of the fuel exchange device, FIG. 9 is a sectional view taken along line IX-IX in FIG. 6, and FIG. 10 is a plan view for explaining the dimensional relationship of the rotary plug. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Coolant, 3... Reactor core, 101... Shielding plug, 102... Cell, 10
3...Variable pantograph type fuel exchange device, 104...
- Core upper mechanism, 105... Core upper mechanism drive device. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 4 Figure 50

Claims (5)

[Claims] (1) A reactor vessel that accommodates coolant and a reactor core, a shielding plug made of a single member that closes the upper opening of the reactor vessel, and a shielding plug that is placed above the reactor core so as to pass through the shielding plug and that is arranged vertically and vertically. a core upper mechanism that is movable; a cell that is installed on the upper surface side of the shielding plug and surrounds the upper part of the core upper mechanism; and a core upper mechanism drive device that is installed in this cell and that moves the core upper mechanism up and down; A fast breeder reactor comprising: a variable pantograph refueling device disposed within the cell and penetrating the shielding plug for moving core components in and out of the reactor core. (2) The core upper mechanism drive device includes a core upper mechanism support plate fixed to the core upper mechanism, a ball nut fixed to the core upper mechanism support plate, and a ball screw into which the ball nut is screwed. The fast breeder reactor according to claim 1, further comprising a drive mechanism for rotating the ball screw. (3) The variable pantograph fuel exchange device includes a hollow hold-down shaft that penetrates the shielding plug and is arranged inside the reactor vessel and is rotatable and moves up and down;
A gripper guide tube connected via a pantograph to a pantograph opening/closing shaft disposed within the hold-down shaft; 3. The fast breeder reactor according to claim 1, further comprising a gripper that moves up and down and is connected to a gripper up-and-down drive shaft provided therein. (4) The fast breeder reactor according to claim 1, 2, or 3, wherein the shielding plug has an inflatable seal in a penetrating portion of the core upper mechanism. (5) The shielding plug consists of a shielding plug body that closes the upper opening of the reactor vessel, and a cell chamber that is integrally formed above the shielding plug body, and the cell is integrally formed within this cell chamber. A fast breeder reactor according to claim 1, 2, 3, or 4, characterized in that: