JPS6033086A - 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 of the Invention] The present invention relates to fast breeder reactors, and particularly to improvements in vibration damping structures.

[Technical background of the invention]

A conventional example will be explained with reference to FIG. FIG. 1 is a sectional view showing a schematic configuration of a tank-type fast breeder reactor. Code 1 in the diagram
indicates a reactor vessel, and this reactor vessel 1 is supported by a reactor building 13 via a ring gutter 12. An opening 18 is formed in the upper part of the reactor vessel 1, and a roof slab 2 is provided so as to close this opening IA. A coolant 3 made of liquid sodium or the like is housed within the reactor vessel 1 .

In addition, there are multiple fuel assemblies (not shown) inside the reactor vessel 1.
A reactor core 4 consisting of control rods 48 and the like is accommodated.

This reactor core 4 is supported from the bottom wall of the reactor vessel 1 by a core support mechanism 5. A corner wall 6 is provided between the reactor core 4 and the reactor vessel 1, dividing the interior of the multi-nuclear reactor vessel 1 into two vertically, with an upper plenum 7 serving as an upper plenum 7 and a lower plenum 8 serving as the lower part. Further, an intermediate heat exchanger 9 and a circulation pump 10 are provided between the reactor core 4 and the reactor vessel 1, passing through the roof slab 2 and the partition wall 6. A core upper mechanism 11 is provided above the core 4 and extends through the roof slab 2. A control rod drive mechanism (not shown) is provided in the upper part of the core (section 11), and this control rod drive mechanism controls the insertion and withdrawal of the aforementioned control rods 4A into the core 4. It is the composition.

According to the above configuration, the coolant 3 rises from the bottom to the top of the core 4, increasing its temperature.

The heated coolant 3 then flows into the upper plenum 7,
It flows into the intermediate heat exchanger 9 and is cooled by exchanging heat with a secondary coolant (not shown). The cooled coolant 3 flows out from the intermediate heat exchanger 9 into the lower plenum 8, is pressurized by the circulation pump 10, and is sent below the core 4 again. This cycle is then repeated.

[Problems with background technology]

According to the above configuration, for example, in the case of a 1000 MWe class plant, the diameter of the reactor vessel 1 is 22 m or more, and the diameter D' of the roof slab 2 is also 22 m or more. When an earthquake occurs, for example, a vertical earthquake, the roof slab 2 vibrates in the upward and downward directions because the diameter of the roof slab 2 is large as described above. This upward and downward vibration of the roof slab 2 may cause relative displacement between the control rod 4A supported by the roof slab 2 and the reactor core 4 supported from the reactor vessel 1. . Generally, the limit value of relative displacement to ensure the safety of a nuclear reactor is about 15 m. Therefore, in order to suppress this relative displacement amount to 15 degrees or less, conventional methods have been taken to improve the rigidity of the roof slab 2.9 For example, the thickness of the roof slab 2 in the axial direction has been set to about 5 m. On the other hand, a core support structure 5 that similarly supports the core 4 in order to suppress the amount of displacement on the core 4 side
The rigidity was increased. However, such a configuration increases the quantities of the roof slab 2 and the core support structure 5, which is not preferable in terms of reducing costs, shortening the construction period, and simplifying the structure.

[Purpose of the invention]

The purpose of the present invention is to suppress the relative displacement between the roof slab and the reactor core side in the event of a vertical earthquake, without increasing the quantities of the roof slab and core support structure, thereby improving not only the soundness of the reactor but also the entire f-rant. The objective of the present invention is to provide a fast breeder reactor that can improve safety.

[Summary of the invention]

The fast breeder reactor according to the present invention includes: a reactor vessel having an opening at the top and containing a coolant; a roof slab provided to close the opening; and a reactor core housed in the reactor vessel. A load transmission arm rotatably attached to the upper surface of the reactor vessel via a pedestal, a housing that rotatably accommodates the tip of the load transmission arm and is fixed to the reactor building; This structure includes a highly viscous substance.

In other words, when an earthquake occurs, especially when a vertical earthquake occurs, the roof slab tends to vibrate upward and downward.

As the roof slab vibrates, the load transfer arm also tries to move in the axial direction, but the housing song is filled with a highly viscous substance, and this highly viscous substance resists small deformations of the load transfer arm. also generates a large drag force. This is a configuration that attempts to suppress vertical displacement of the roof slab.

Therefore, the vertical displacement of the roof slab in the event of an earthquake, especially in the vertical direction, can be suppressed, and the displacement of the control rods can thereby be suppressed, and the relative displacement between them and the reactor core can be reduced. The overall safety of Toyotashi Brand can be significantly improved. In addition, there is no need to consider the rigidity of roof slabs, etc., as in the past.
It is possible to reduce the amount of materials, shorten the construction period, and reduce costs.

[Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIGS. 2 to 5.

FIG. 2 is a sectional view showing the outline and structure of a tank-type fast breeder reactor. Reference numeral 101 in the figure indicates a reactor vessel, and this reactor vessel 101 is supported by a reactor building 113 via a ring gutter 112. An opening 1-011 is formed in the upper part of the reactor vessel 10.
A roof slug 102 is provided to block people. Inside the reactor vessel 101, liquid 1. A coolant 103 made of sodium or the like is accommodated.

Further, the reactor vessel 101 accommodates a reactor core 104 consisting of a plurality of fuel assemblies (not shown), control rods 104, and the like. This core 104 is supported from the bottom wall of the reactor vessel 101 by a core support mechanism 105 . A partition wall 106 is provided between the reactor core 104 and the reactor vessel 101, and divides the inside of the reactor vessel 101 into upper and lower halves, with the upper part serving as an upper solenum 107 and the lower part serving as a lower plenum 108. Furthermore, there is a space between the reactor core 104 and the reactor vessel 101 that penetrates the roof slag 102 and the partition wall 106.
An intermediate heat exchanger 109 and a circulation pump 110 are housed therein. A core upper mechanism 111 is provided above the core 104, passing through the roof line j'102. This core upper mechanism 111 is provided with a control rod drive mechanism (not shown), etc., and this control rod section #I mechanism controls the insertion and withdrawal of the control rod 104A described above into the core 104. It is the composition.

According to the above configuration, the coolant 103 rises from the bottom to the top of the reactor core 104, and its temperature increases at this time. The heated coolant 103 flows into the upper lunum 107. It flows into the intermediate heat exchanger 109 and is cooled by exchanging heat with a secondary coolant (not shown). The cooled coolant 103 flows out from the intermediate heat exchanger 109 into the lower brenum 10B, is pressurized by the circulation ponder 110, and is sent below the core 104 again. This cycle is then repeated.

A plurality of pedestals 114 are provided concentrically and at equal intervals on the upper surface of the roof slab 102.

Each of the pedestals 114 is rotatably provided with a load transmission arm 115. 9. This load transmission arm 11
The side opposite to the pedestal 114 of No. 5 is rotatably housed in a housing 116 fixed to the reactor building 113. The housing 116 is filled with a highly viscous substance 112. The tip of the load transmission arm 115 inside the housing 116 is formed to have a large diameter as shown in FIG. This is a highly viscous substance 11. This is to increase the contact area with the surface. That is, when an earthquake occurs, particularly a vertical earthquake, the Lou7 slap 102 begins to vibrate upward and downward.

As the roof line 2102 vibrates, the load transmission arm 115 also begins to rapidly vibrate upward and downward. At this time, even with a small deformation of the load transmission arm 115, the highly viscous substance 118 generates an extremely large drag force as shown in the characteristic diagram of FIG. The configuration is such that the upward and downward displacements of the load transmission arm 115 and the roof slab 102 are controlled by this drag force.

According to the above configuration, even in the event of an earthquake, especially a vertical earthquake, it is possible to control the upward and downward displacement of the roof slab 102, thereby controlling the upward and downward displacement of the control rod 104A, which is displaced integrally with the roof slab 1o2. Downward displacement can be suppressed. Therefore, a part of the control rod 104 will not be pulled out from the reactor core 104, and the stability of the reactor core output and the safety of the entire plant can be greatly improved. And as before, the roof slab 102
Since there is no need to consider rigidity, etc., it is possible to reduce the amount of materials, and furthermore, it is possible to shorten the construction period and reduce costs. In addition, the high viscosity material 117 can also absorb thermal expansion of the roof slab 102.

That is, when the roof line f102 is slowly displaced due to thermal expansion, a drag force as shown in FIG. 5 is generated. Therefore, thermal expansion can be absorbed without being restricted more than necessary.

〔Effect of the invention〕.

The fast breeder reactor according to the present invention includes a reactor vessel having an opening at the top and containing a coolant, a louver 7 and 2 provided to close the opening, and a reactor vessel housed in the reactor vessel. A reactor core, a load transfer arm rotatably attached to the upper surface of the reactor vessel via a pedestal, a housing that rotatably accommodates the tip of the load transfer arm and is fixed to the reactor building, and the housing. This structure includes a highly viscous substance filled inside.

In other words, when an earthquake occurs, especially when a vertical earthquake occurs, the roof slab tends to vibrate upward and downward.

As the roof slab vibrates, the load transmission arm also tries to move in the axial direction, but the housing is filled with a highly viscous substance, and this highly viscous substance can resist small deformations of the load transmission arm. Generates large drag force. This is a configuration that attempts to suppress the upward and downward displacement of the roof slab.

Therefore, in the event of an earthquake, especially in the vertical direction, the vertical displacement of the roof slab can be suppressed, and the displacement of the control rods can thereby be suppressed, significantly improving the safety of not only the reactor but also the entire Sibrand. can be done. In addition, there is no need to consider the rigidity of roof slabs, etc. as in the past, and the effects are outstanding, such as reducing the amount of material, shortening the construction period, and reducing costs.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a conventional tank-type fast breeder reactor.
Figures 2 to 5 are diagrams showing one embodiment of the present invention.
The figure shows a longitudinal cross-sectional view of a tank-type fast breeder reactor, Figure 3 is a partial cross-sectional view of Figure 2, and Figures 4 and 5 show the relationship between the drag force generated in a highly viscous substance and the stroke of the load transfer arm. FIG. 101... Reactor vessel, 101 people... Opening of reactor vessel, 102... Roof slab, 103... Coolant, 104... Reactor core, 114... Pedestal, 115...
Load transmission 7-1-%116...housing, 117.
・Highly viscous substance.

Claims (2)

[Claims] (1) A reactor vessel having an opening at the top and containing a coolant, a roof slab provided to close the opening, a reactor core housed in the reactor vessel, and the reactor vessel. A load transfer arm rotatably attached to the upper surface via a pedestal, a housing that rotatably accommodates the tip of the load transfer arm and is fixed to the reactor building, and a high viscosity filled inside the housing. A fast breeder reactor characterized by comprising: (2) The load transmitting arm has a distal end located within the housing having a large diameter to increase the contact area with the highly viscous substance.
Fast breeder reactor described in section.