JPS6275297A - Fast breeder 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 1 The present invention relates to a nuclear reactor structure for a fast breeder reactor.

[Technical Background of the Invention 11 Figure 5 shows a schematic configuration of a fast breeder reactor.
A core consisting of... is constructed on the core support mechanism 3. Further, liquid sodium 4 is contained as a coolant in the reactor vessel 1, and the upper part thereof is covered with an inert gas 5.

The upper opening of the reactor vessel 1 is opened by a shielding plug 6 . The shielding plug 6 includes a fixed plug 7 having a circular hole 7a at an eccentric position and fixed to the reactor vessel 1, and a rotary plug 8 rotatably attached to the circular hole 7a.

The shielding plug 6 is provided with a jack-up device a9 for lifting the rotary plug 8 and a rotary plug drive device 10 for rotating the rotary plug 8.

The rotary plug 8 includes a core upper mechanism 12 that holds the V control rod drive mechanism 11, and a fuel exchange device 13 that exchanges the fuel assembly 2 inside the reactor vessel 1, as shown in FIG. It is installed at an eccentric position relative to 8,
During operation, the upper core mechanism 12 is located at the center of the reactor vessel 1, that is, at the center of the fixed plug.

As shown in FIG. 5, a coolant inflow pipe 14 and a coolant outflow pipe 15 are provided outside the reactor vessel 1. One end of the coolant inflow pipe 14 penetrates the lower part of the peripheral wall of the reactor vessel 1 and is introduced below the core support mechanism 3, and one end of the coolant outflow pipe 15 is connected to the peripheral wall of the reactor vessel 1 to It communicates with the upper part of the core support mechanism 3 inside the reactor vessel 1 .

Furthermore, a guard vessel 16 is provided outside the reactor vessel 1 to protect it, and this guard vessel 16 is provided with protection pipes 17 and 18 that protect the coolant inflow pipe 14 and the coolant outflow pipe 15, respectively. There is. Further, as shown in FIG. 5, an oval hole 19 is provided in a part of the rotary plug 8, and this oval hole 19 is closed with an oval plug 20. Exchange device 1
3 is for installation. FIG. 6 shows the top layout of the shielding plug 6.

FIG. 7 shows the fuel exchange device 13, and the reference numeral 21 in the figure is a hollow hold-down shaft that passes through the oval plug 20 and is attached to the oval plug 20 so as to be rotatable and movable up and down. . This hold-down shaft 21 is driven up and down and rotated by a hold-down drive section 22 attached to the upper surface of the oval plug 20.

A good slit 23 is provided in the axial direction in the part of the hold-down shaft 21 that is introduced into the reactor vessel 1.
A gripper guide tube 24 is vertically disposed in front of the slit 23.

The gripper guide tube 24 is fixed to the hold-down shaft 21 via connecting members 25a and 25b, and also has a slit 26 that is long in the axial direction at a portion of the hold-down shaft 21 that faces the slit 23. There is.

A door valve 27 is disposed on the hold-down drive section 22.
A good tubular hoisting frame 28 is provided via the hoisting frame 28, and a hoisting 129 is installed on the hoisting frame 28.

On the other hand, an elevator pipe 30 is inserted through the hold-down shaft 21 . The upper end of this elevator pipe 30 passes through the door valve 27 and reaches the inside of the hoisting frame 28.
A sealing machine vh31 for sealing the insertion portion of the elevator pipe 30 is provided at the connection point between the hoisting frame 28 and the hoisting frame 28, thereby forming an in-furnace boundary below the door valve 27. A gripper drive unit 32 is attached to the upper end of the elevator pipe 30.
The gripper driving section 32 and the elevator tube 30 are integrally driven up and down by the hoist 29 via a wire 33.

An elongated gripper 34 is inserted into the gripper guide tube 24. This gripper 34 has gripper claws 35 at its lower end.
The gripper claw 35 can be engaged with and detached from a handling head 36 provided at the upper end of the fuel assembly 2. Note that the gripper 34 is connected to the elevator pipe 30 via a link-shaped pantograph arm 37. The pantograph arm 37 is driven by the gripper drive unit 32 via an operating rod (not shown) inserted into the elevator tube 30, whereby the gripper 34 moves up and down inside the gripper guide tube 24, and the gripper claw 35 is configured to be engaged with and disengaged from the handling head 36 of the fuel assembly 2.

When performing fuel exchange in a reactor with the above configuration,
After lifting the rotary plug 8 with the rotary plug lifting machine 9, the rotary plug is driven! It is rotated using the IJ device 10. Then, the hold down drive unit 22 allows the bold down@
21 is rotated and lowered to bring the lower end of the gripper guide tube 24 close to the fuel assembly 2 , and then the gripper driving section 32 grips the handling head 36 of a predetermined fuel assembly 2 with the gripper claws 35 . Thereafter, by pulling up the elevator pipe 30 with the winding J-m 29, the fuel assembly 2 is handled from the core, and the surrounding fuel assemblies 2.2... are lifted up by the gripper guide pipe 29. Prevent at the bottom edge of.

Next, the hold-down shaft 21 is moved upward again by the hold-down drive unit 22 to separate the lower end of the gripper guide tube 24 from the combustion II assembly 2.2, and the rotary plug 8 and the hold-down shaft are separated from each other. 21 and move the fuel assembly 2 lifted by the gripper 34 to a predetermined position in the reactor vessel 1, that is, the in-reactor relay rack 51 shown in FIG. VJwisu. Although the handling of the fuel assembly 2 has been explained above, the core components handled by the fuel conversion device 13 include the core fuel assembly 52, the blanket fuel assembly 53, and other fuel assemblies as shown in FIG. , neutron shield 54, control rod assembly 55, neutron source assembly 56, etc. Furthermore, the handled area within the reactor vessel extends over a wide area including the in-reactor relay rack 51 and the in-reactor rack 57.

[Problems with the background technology] In the reactor configured as described above, the rotary plug is rotated during fuel exchange, and the reactor vessel is closed! ! ! In order to perform extensive refueling while avoiding vessel interference, it was necessary to provide a very large reactor vessel.

These relationships will be explained using FIG. 9.

The eccentricity of the center of the rotating plug 8 with respect to the reactor center is el
, the eccentricity of the center of the old down shaft 21 of the fuel exchange device 13 with respect to the center of the rotating plug 8 is 02, the rotation radius of the gripper guide tube 24 of the fuel exchange device 13 about the old down shaft 21 is 03, and the upper part of the core is If the radius of the mechanism 12 is rl, the earliest point that the fuel exchange device needs to access, which is usually the in-reactor relay rack 51, the radius that envelops this is rz, and the radius of the reactor vessel is r3, then the following relationship is obtained. needs to hold true.

・Condition e for accessing the in-furnace relay rack 51
2 + ei>8+X rz/core upper mechanism 1
Condition 01>r to be able to access the lower part of reactor vessel 2, e3-8 2 - Condition for the upper core mechanism 12 to not interfere with the reactor vessel 1 r3>3r+ The radius of the reactor vessel 4 is the same as that of the upper core mechanism 12. A radius of at least three times is required, and as shown in Fig. 5, if the inner cylinder 1a is installed inside the reactor vessel 1, the inner cylinder 1a must satisfy the above conditions, and the reactor vessel 1 is It needs to be made even bigger.

[Object of the Invention] The present invention was made based on the above circumstances, and an object of the present invention is to provide a compact fast breeder reactor that is not affected by the first year of rotation of the rotating plug.

[Summary of the Invention 1 The present invention provides a fast breeder reactor cooled with liquid metal, particularly sodium, which is equipped with a shielding plug that closes an opening at the upper end of the reactor vessel, and in which a control rod drive mechanism is held in the upper part of the reactor core. In a fast breeder reactor equipped with a rotating plug equipped with a mechanism and a fuel exchange device for fuel exchange, a notch is provided in a part of the upper core mechanism, and a gripper of a pantograph type fuel exchange device moves within this notch. It is characterized by being incorporated into a possible structure.

[Embodiments of the Invention] Examples of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows the structure of the upper part of the nuclear reactor of this embodiment. At the top of the core consisting of fuel assemblies 2, etc., there is a core upper machine W.
S12 is installed, and the control rod layer #lJ mechanism 11 is installed in it.
is stored. The upper core mechanism 12 is installed on the rotating plug 8, and a fuel exchange device 13 is also installed adjacent to the upper core mechanism 12 via the rotating plug. A cross section of the upper core mechanism 12 is shown in FIG. There is a notch in a part of it 6.
o is provided so that the gripper of the fuel exchange device 13 can be moved by a pantograph.

FIG. 3 is a layout diagram of the upper surface of the fixing plug 7.

A rotary plug 8 is disposed at the end of the fixed plug 7, and an in-furnace relay device 88 is installed above an in-furnace relay rack (not shown) which is the earliest point to be accessed by the fuel conversion device 13. The fuel exchange device 13 is located at the center of the reactor and the center of the in-reactor relay rack, and is provided with a bold down rotation device RA61 that rotates a hold down shaft.

FIG. 4 shows the fuel exchange device 13, and reference numeral 21 in the figure is a hollow hold-down shaft attached to the shielding plug 6. As shown in FIG.

Inside the bold down shaft 21, there is a pantograph opening/closing shaft 44.
The gripper vertical movement drive shaft 45 is inserted through the pantograph opening/closing shaft 44.
The gripper guide tube 24 is connected to the gripper guide tube 24 via the gripper members 37a, 37b, and 37c. The gripper vertical drive shaft 45 is connected to a gripper guide rod 47 in the gripper guide tube 24 via a connecting member 25 having a stroke adjustment mechanism 46 .

Furthermore, an elongated gripper 34 is inserted into the gripper guide tube 24, and this gripper has a gripper claw 35 at its lower end. The fuel assembly 2 is provided with a handling head 36 on its upper part.

Moreover, on the upper part of the hold-down shaft 21, there is a van tag flap opening/closing shaft blocking device 48 and a gripper vertical movement drive device! 4
9 is provided. A hold-down rotating device H61 is attached to the upper surface of the shielding plug 6, and a door valve 27 is mounted on the hold-down rotating device 61.
is provided.

Next, the operation of the embodiment will be explained.

When performing fuel exchange according to the present invention, the upper part of each fuel assembly is accessed by adjusting the hold-down shaft and the gripper shaft by the rotating operation of the rotary plug and the opening/closing operation of the pantograph of the fuel exchange device. The fuel assembly is gripped by opening and closing operations of the gripper and stored in the gripper guide tube. In this state, all the gripper guide tubes are housed in the hold-down shaft, rotated 1800 times by the hold-down rotating device, and then the fuel assembly is moved up to the relay rack position in the reactor by opening the pantograph.

Through the above operations, fuel assemblies at all positions (including all core components explained in FIG. 7) can be freely handled.

In such a nuclear reactor, since the core upper mechanism rotates around the center of the reactor, there is no risk of interference with the reactor due to rotational movement. Therefore, the radius of the reactor vessel may be the minimum size that accommodates the in-reactor relay rack, and the reactor can be made more compact.

Next, other embodiments of the present invention will be described.

In order to realize the present invention, it is necessary not to install a control rod drive mechanism or the like in the notch 60 shown in FIG. To this end, basically, in addition to adopting a core that does not require control rods in this area as in this embodiment, the control rods located in the notches 60 are driven from the bottom of the core to connect with the upper core mechanism. It is also possible to adopt a method that does not require any combination of .

In addition, during normal exit operation, all devices in the hold-down shaft of the fuel exchange device are removed, and instead, a device for illuminating the outlet of the fuel assembly is inserted into the hold-down shaft, and this is opened and closed. It is also possible to instrument the core exit in exactly the same way as other parts.

[Effects of Launch] As described above, the present invention enables a very compact nuclear reactor by providing a notch in a part of the upper core mechanism and moving a pantograph type fuel exchanger inside the notch.

For example, a conventional nuclear reactor having a diameter of about 7111 mm is reduced to less than 5 m according to the present invention. In addition, the present invention
Approximately 19% when applied to a tank-type fast breeder reactor of 1,000,000 class.
A nuclear reactor with a diameter of m can be reduced to about 16 Il, and the cost reduction associated with this has an extremely large impact.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the upper part of a nuclear reactor structure showing essential parts of an embodiment of the nuclear reactor according to the present invention, FIG. 2 is a cross-sectional view taken along arrow A-A in FIG. Figure 3 is a top layout H diagram of the shielding plug in Figure 1, Figure 4 is a vertical sectional view showing a pantograph type fuel exchange device, Figure 5 is a sectional view showing the internal structure of a conventional nuclear reactor, and Figure 6 is a conventional Figure 7 is a top view of the shielding plug arrangement, and Figure 7 is a cross-sectional view showing the fixed arm type fuel exchange device.
FIG. 8 is a sectional view of the interior of a conventional nuclear reactor structure, and FIG. 9 is a top view for explaining factors determining the dimensions of a conventional nuclear reactor vessel. 1......Reactor vessel 1a...
...Inner cylinder 2...Fuel assembly 3...
・・・・・・Core support mechanism 4・・・・・・・・・・・・
Liquid sodium 5... Inert gas 6... Shielding plug 7a...
・・・Circular hole

Claims (1)

[Claims] (1) It is equipped with a shielding plug that closes the upper end opening of the reactor vessel, and a rotary plug mounted on the core upper mechanism holding the control rod drive mechanism and the fuel exchange device for fuel exchange is arranged in this shielding plug. A liquid metal cooled fast breeder reactor, characterized in that a notch is provided in a part of the upper core mechanism, and a pantograph type fuel exchange device is built into a movable structure within the notch.