JPS5948685A - Fast breeder - 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 fast breeder reactor having a vertical displacement suppression mechanism for suppressing vertical displacement of a reactor core.

[Technical background of the invention]

A conventional example will be explained with reference to FIG. FIG. 1 is a vertical cross-section showing the schematic structure of a tank-type fast breeder reactor. In the figure, 1 indicates a reactor vessel that accommodates a coolant 2. This reactor vessel 1
A roof slab 3 is provided so as to close the upper opening IA. A reactor core 4 including a plurality of fuel assemblies (not shown), control rods (not shown), etc. is installed in the reactor vessel 1. This core 4 is accommodated and supported by a core support mechanism 5. And the lever core support mechanism 5
is suspended from the roof slab 3 by a suspension body 6. A core upper mechanism joint shell 7 that houses core upper mechanisms such as a control rod drive mechanism (not shown) is provided above the reactor core 4 and penetrates through the roof slab 3. In other words, since the reactor core 4, the support mechanism 5, and the core upper mechanism are all supported by the roof slab 3, when a vertical seismic motion occurs, the relative vertical displacement of the two can be reduced, and the control rod position can be reduced. This is a configuration that can prevent accidents that would occur if the core output fluctuated due to a shift in the power output. The interior of the reactor vessel 1 is divided into two vertically by a partition wall 8 provided between the reactor vessel 1 and the suspension shell 6, with an upper plenum 9 above and a lower plenum 10 below.
is formed. A steady rest member 11 is provided between the reactor vessel 1 and the core support mechanism 5 below the partition wall 8, and is configured to prevent the core 4 and the core support mechanism 5 from steadying in the horizontal direction. Further, an intermediate heat exchanger I2 and a circulation bonder 13 are provided between the reactor vessel 1 and the suspension shell 6, passing through the roof slab 3.

According to the tank-type fast breeder reactor configured as described above, the coolant 2 flows through the reactor core 4 from below to above, and its temperature is increased. The coolant 2 flowing upward from the core 4 then flows out of the suspension shell 6 through the opening 6A of the suspension shell 6, flows into the intermediate heat exchanger 12, and exchanges heat with the secondary coolant (not shown). exchange and flow into the lower plenum 10. Then, it is pressurized by the circulation pump 13 and sent to the lower part of the reactor core 4 again.

[Problems with background technology]

In general, the reactor vessel 1 is used at low pressure and high temperature, so it has a large diameter and thin structure, and the roof slab 3 has a large diameter and a complicated structure.

For example, when trying to suppress vertical displacement of the reactor core 4 and core support mechanism 5 due to vertical seismic motion, methods such as improving the tonality of the reactor vessel 1 and roof slab 3 have been considered, but the amount of material increases. Therefore, it is desired to suppress the vertical displacement of the core 4 and the core support mechanism 5 without causing an increase in the amount of material.

[Purpose of the invention]

An object of the present invention is to provide a fast breeder reactor capable of suppressing the vertical displacement of the reactor core in response to vertical seismic motion without increasing the amount of material, thereby improving safety and reliability. There is a particular thing.

[Summary of the invention]

The fast breeder reactor according to the present invention includes: a reactor vessel containing a coolant and having an opening at the top; a roof slab provided to close the opening; and a core provided within the reactor vessel. A core support mechanism for supporting and accommodating the core, a suspension shell for suspending the core support mechanism housing the core from the roof slab, and a plenum formed between the reactor vessel and the core support mechanism, - The configuration includes a vertical displacement suppression mechanism that suppresses vertical movement of the core and core support mechanism by compressing the coolant in the plenum when vertical displacement occurs in the core support mechanism.

In other words, a plenum is formed between the reactor vessel and the core support mechanism, and when vertical movement occurs in the reactor core and core support mechanism, the coolant in the plenum is compressed to suppress the vertical movement of the core and core support mechanism. It is configured to do this.

Therefore, vertical movement of the core and core support mechanism due to vertical seismic motion can be suppressed without increasing the amount of material, and safety and reliability can be significantly improved. As a result, the requirements for the tonality of the reactor vessel, roof slab, etc. can be reduced, and the amount of materials can also be reduced.

[Embodiments of the invention]

FIG. In the figure, 101 indicates a reactor vessel that accommodates a coolant 102. A roof slab 103 is provided to close the upper opening 101k of the reactor vessel 101. Inside the reactor vessel 101, a reactor core 104 is installed which includes a plurality of fuel assemblies (not shown), control rods (not shown), and the like. This core 10
4 is accommodated and supported by the core support mechanism 105.

The core support mechanism 105 is suspended from the roof slab 103 by a suspension shell 106. Above the core 104, a core upper mechanism joint shell 107 that accommodates a core upper mechanism such as a control rod drive mechanism (not shown) is provided so as to penetrate through the roof slab 103. That is, since the core 104, the core support mechanism 105, and the core upper mechanism are all supported by the roof slag 103, when a vertical seismic motion occurs, the relative vertical displacement of the two can be reduced, and the control rod position can be reduced. This configuration can prevent accidents in which the reactor core output fluctuates due to deviation of the reactor. Furthermore, the interior of the reactor vessel 101 is divided into two vertically by a partition wall 108 provided between the reactor vessel 101 and the suspension shell 106, with an upper plenum 109 at the top and a lower plenum 110 at the bottom. It is formed. A steady rest member 111 is provided between the reactor vessel 101 below the partition wall 108 and the core support mechanism 105.
This configuration provides a steady rest in the horizontal direction. Additionally, an intermediate heat exchanger 11 is provided between the reactor vessel 101 and the suspended nine shell 106.
2 and a circulation bonder 113 are provided to penetrate the roof slab 103.

The bottom wall 101B of the reactor vessel 101 and the core support mechanism 10
5, a cylindrical body 114 is provided upright from the bottom wall 101B. A gap 114A is formed between the inner periphery of this cylindrical shell 114 and the outer periphery of the core support mechanism 105, and the inner side of the cylindrical shell 114 serves as a core lower plenum 115. When the core support mechanism 105 moves up and down, pressure fluctuations occur within the core lower plenum 115 due to this up and down movement. This pressure acts on the lower end surface of the core support mechanism 105 to suppress vertical movement of the core 104 and the core support mechanism 105.

According to the tank type fast breeder reactor with the above configuration, the coolant 10
2 flows through the core 104 from below to above, raising the temperature at that time. The coolant 102 flowing above the core 104 then flows out of the suspension shell 106 through the opening 106A of the suspension shell 106, flows into the intermediate heat exchanger 112, and exchanges heat with the secondary coolant (not shown). and flows into the lower plenum 110.

Then, it is pressurized by the circulation bomb f113 and sent to the lower part of the reactor core 104 again.

Next, a case where a vertical seismic motion occurs will be explained. In this case, vertical movement occurs in the core 104 and the core support mechanism 105. By this vertical movement, 9 cylindrical bodies 11
Pressure fluctuations occur in the coolant 102 in the lower core plenum 115 inside the core. The pressure due to this pressure fluctuation acts on the lower end surface of the core 9-support mechanism 105. Therefore, core 10
4 and the vertical movement of the core support mechanism IOS can be suppressed. That is, the lower core plenum 115 is the core 104.
It also functions as a buffer mechanism that buffers the vertical movement of the core support mechanism 105. Therefore, vertical movement of the reactor core 104 and the core support mechanism 105 when vertical seismic motion occurs can be suppressed, and safety can be greatly improved. Thereby roof slab 103 reactor vessel 1
It is also possible to reduce the amount of material required for the rigidity of 01.

Next, another embodiment will be described with reference to FIG.

From the bottom wall 101B of the reactor vessel 101 to the outer cylindrical shell 116
is set upright, and the outer ring 11 is placed inside the upper part of this cylindrical body 116.
7 is provided. An inner cylindrical shell 118 is provided on the lower end surface of the core support mechanism 105, and an inner ring 119 is provided on the outer side of the lower part.
This is provided. The inner ring 119 is located below the outer ring 117 with a space therebetween. That is, a core lower plenum 120 is formed between the bottom wall 101B of the reactor vessel 101 and the core support 10-supporting mechanism 105, and a small hollow hole 21 is formed between the outer ring 117 and the inner ring 119.

For example, if a vertical seismic motion occurs and the reactor core 104 and the core support mechanism 105 move up and down, the core 104
When the core support mechanism 105 vibrates downward, the core lower plenum 120 suppresses the vibration, and when the core support mechanism 105 vibrates upward, the small solenoid holes 21 suppress the vibration.

According to the fast breeder reactor having the above configuration, for example, when an earthquake occurs in the vertical direction, the core 104 and the core support mechanism 10
5, vertical movement occurs. When the core 104 and the core support mechanism 105 vibrate downward, the coolant 102 in the core lower plenum 120 is compressed, and as a result, pressure acts on the lower end surface of the core support mechanism 105.

This suppresses downward vibration of the core 104 and the core support mechanism 105. Furthermore, when the core 104 and the core support mechanism 105 vibrate upward, the coolant 102 in the small plenum 121 is compressed, and the core 105 is also compressed.
4 and the upward vibration of the core support mechanism 105.

That is, the core lower plenum 120 and the small plenum No. 2
1, it is possible to suppress the downward and upward vibrations of the core 104 and the core support mechanism 105, respectively, and the vertical movement of the core 104 and the core support mechanism 105 can be suppressed more effectively. Therefore, as in the embodiment described above, not only safety can be improved, but also the requirements for rigidity of the roof slab 103, the reactor vessel 101, etc. can be reduced, and the amount of materials can also be reduced. Components that are the same as those in the above embodiments are designated by the same numbers.

[Effects of the Invention] The fast breeder reactor according to the present invention has a reactor vessel containing a coolant and having an opening at the top, a roof slab provided to close the opening, and a roof slab provided in the reactor vessel. A plenum is formed between a reactor core, a core support mechanism that supports and accommodates the core, a suspension shell that suspends the core support mechanism that accommodates the core from the roof slab, and the reactor vessel and the core support mechanism. The structure includes a vertical displacement suppression mechanism that suppresses vertical movement of the core and core support mechanism by compressing fluid in the plenum when vertical displacement occurs in the core and core support mechanism.

In other words, a plenum is formed between the reactor vessel and the core support mechanism, and when vertical displacement occurs in the reactor core and core support mechanism, the coolant in the plenum is compressed. This is a configuration that suppresses motion.

Therefore, vertical movement of the core and core support mechanism due to vertical seismic motion can be suppressed without increasing the amount of material, and safety and reliability can be greatly improved. As a result, the requirements for the rigidity of the reactor vessel, roof slab, etc. can be reduced, and the amount of material can also be reduced.

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[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a conventional tank-type fast breeder reactor.
FIG. 2 is a longitudinal sectional view of a tank-type fast breeder reactor showing one embodiment of the present invention, and FIG. 3 is a longitudinal sectional view of a tank-type fast breeder reactor showing another embodiment of the invention. 101... Reactor vessel, 102... Coolant, 103
...Roof slab, 104...Reactor core, 105...
Core support mechanism, 106... Hanging shell, 114... Cylindrical shell, 115.120... Core lower plenum, 116.
...Outer cylindrical body, 117...Outer ring, 118...
・Inner cylindrical body, 119...Inner ring, 12...
Small plenum. Applicant's agent Patent attorney Takehiko Suzue 14-

Claims (3)

[Claims] (1) A reactor vessel containing coolant and having an opening at the top, a roof slab provided to close the opening, a reactor core installed in the reactor vessel, and supporting and accommodating this core. a core support mechanism that suspends the core support mechanism that accommodates the core from the roof slab, a plenum that forms a plenum between the reactor vessel and the core support mechanism, and a suspension shell that suspends the core support mechanism that accommodates the core from the roof slab; A fast breeder reactor comprising a vertical displacement suppression mechanism that suppresses vertical movement of a reactor core and a core support mechanism by compressing coolant in a plenum when dynamic displacement occurs. (2) The vertical displacement suppression mechanism is characterized in that a cylindrical body is raised from the bottom wall of the reactor pressure vessel with a gap between the outer periphery of the core support mechanism and a core lower plenum is formed inside. A fast breeder reactor according to claim 1. (3) The vertical displacement suppression mechanism includes an outer cylindrical shell having an outer ring erected from the bottom wall of the reactor vessel at the upper inner side, and an inner cylindrical shell having an inner ring from the lower end of the core support mechanism to the outer periphery of the lower part; Claim 1, characterized in that the reactor core is constructed by forming a lower core plenum between the core support mechanism and the bottom wall of the reactor vessel, and a small plenum between the outer ring and the inner ring. Fast breeder reactor.