JPH0342636B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to fast breeder reactors.

[Technical background of the invention]

A conventional example will be explained with reference to FIG. FIG. 1 is a schematic diagram of a tank-type fast breeder reactor. Reference numeral 1 in the figure indicates a reactor vessel. A coolant 2 is housed within the reactor vessel 1 . The above reactor vessel 1
The roof slab 3 is installed so as to close the upper opening 1A of the roof slab 3.
is provided. Inside the reactor vessel 1 are a plurality of fuel assemblies (not shown) and control rods (not shown).
A reactor core 4 is installed.
This core 4 is accommodated and supported by a core support mechanism 5. The core support mechanism 5 containing the reactor core 4 is suspended from the roof slab 3 by a suspension shell 7. This suspension barrel 7 has an opening 7A formed therein. A core upper mechanism 8 is provided above the reactor core 4, passing through the roof slab 3 and being supported by the roof slab 3. That is, since both the core support mechanism 5 housing the reactor core 4 and the core upper mechanism 8 are supported by the roof slab 3, even if a vertical seismic motion occurs, for example, the core support mechanism 5 housing the core 4 and the core upper mechanism 8 are supported by the roof slab 3. The relative displacement with the upper core mechanism 8 is extremely small. Therefore, this configuration can prevent a situation where the core output fluctuates due to the control rods being misaligned. Further, a horizontal vibration damping member 9 is provided between the core support mechanism 5 and the reactor vessel 1 to suppress horizontal vibration of the core 4 and the core support mechanism 5 when an earthquake occurs. A partition wall 11 is provided between the suspension shell 7 and a partition wall 10 provided on the inner peripheral side of the reactor vessel 1 above the horizontal damping member 9 . The partition wall 11 allows the inside of the reactor vessel 1 to be moved vertically in two directions.
The upper part is divided into an upper plenum 12 and the lower part is a lower plenum 13. Between the suspension shell 7 and the reactor vessel 1, an inlet 14A and an outlet 14 are provided.
Intermediate heat exchanger 14 and circulation pump 1 with B
5 is provided passing through the roof slab 3 and the partition wall 11 and being supported by the roof slab 3. A sealing mechanism 16 is provided between the intermediate heat exchanger 14 and the partition wall 11, and seals the upper plenum 12 side and the lower plenum 13 side. The sealing mechanism 16 is a thin plate 1 provided on the partition wall 11 and the lower outer periphery of the intermediate heat exchanger 14, respectively.
7 and 18 and a bellows 19 provided between the thin plates 17 and 18.

According to the fast breeder reactor having the above configuration, the coolant 2 flows through the reactor core 4 from below to above, and its temperature is increased. The coolant 2 that has flowed into the suspension shell 7 from the core 4
flows out of the suspension shell 7 through the opening 7A of the suspension shell 7, and flows into the intermediate heat exchanger 14 via the inlet 14A. Then, heat is exchanged with the secondary coolant in the intermediate heat exchanger 14, and from the outlet 14B to the lower plenum 13.
leaks inside. Then, it is pressurized by the circulation pump 15 and sent to the lower part of the reactor core 4 again. This cycle is then repeated.

[Problems with background technology]

According to the above configuration, the partition wall 11 is provided in a completely connected state with the partition wall 10 and the suspension shell 7, and forms both a thermal boundary and a pressure boundary between the upper and lower sides of the reactor vessel 1. For example, when a vertical or horizontal seismic motion occurs, the reactor core 4 and the core support mechanism 5 vibrate in the vertical or horizontal direction. At that time, there is a possibility that high stress may be generated at the joints between the partition wall 11, the partition wall 10, and the hanging body 7. Furthermore, there is a severe temperature difference in the coolant near the joint between the hanging body 7 and the partition wall 11, and stress may be generated in the partition wall 11 due to thermal deformation.

[Purpose of the invention]

The object of the present invention is to prevent excessive stress from being generated in the bulkhead even when the suspension shell is displaced in the horizontal and vertical directions, and to reduce thermal deformation of the bulkhead due to the temperature of the coolant. An object of the present invention is to provide a fast breeder reactor that can ensure the integrity of partition walls.

[Summary of the invention]

The fast breeder reactor according to the present invention includes a reactor vessel, a roof slab installed on the top of the reactor vessel and closing the upper opening of the vessel, and an interior of the reactor vessel from the roof slab. A hanging shell suspended vertically from the ceiling, a core support mechanism provided at the lower end of the hanging barrel and housing the core inside, and an annular labyrinth seal mechanism provided on the outer periphery of the core support mechanism through a small gap. , a stop seat that supports the labyrinth seal mechanism in a vertically movable manner, and a horizontal control provided from the inner wall surface of the reactor vessel toward the center of the vessel to suppress horizontal swing of the core support mechanism. A labyrinth is formed between the vibration member, a support surface that is provided at the tip of the horizontal vibration damping member and supports the lower end of the labyrinth seal mechanism, and an outer peripheral surface of the core support mechanism that is provided on the inner peripheral surface of the labyrinth seal mechanism. The present invention includes an annular groove forming a seal, and a partition wall supported by the horizontal damping member via a support member and forming a thermal boundary of the coolant above the horizontal damping member.

That is, in the present invention, an annular labyrinth seal mechanism is provided on the outer periphery of the core support mechanism with a small gap between the annular labyrinth seal mechanism and the annular labyrinth seal mechanism that forms the labyrinth seal between the inner circumferential surface of the labyrinth seal mechanism and the outer circumferential surface of the core support mechanism. By forming the grooves, the pressure boundary of the coolant is formed below the bulkhead, so that the bulkhead can be provided without being joined to the suspension shell or the reactor vessel. Therefore, even if the suspension shell is displaced in the horizontal and vertical directions due to an earthquake or the like, excessive stress will not be generated in the partition wall, and stress failure of the partition wall can be prevented. In addition, since the partition wall only forms the thermal boundary of the coolant, thermal stress will not occur even if the coolant temperature is severe, and thermal deformation of the partition wall can be reduced. can.

[Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a schematic diagram of a tank-type fast breeder reactor. In the figure, 101 indicates a reactor vessel. A coolant 102 is contained within this reactor vessel 101 . The roof slab 103 is configured to close the upper opening 101A of the reactor vessel 101.
is provided. A reactor core 104 including a plurality of fuel assemblies (not shown), control rods (not shown), etc. is installed within the reactor vessel 101 . This core 104 is accommodated and supported by a core support mechanism 105. The core support mechanism 105 containing the reactor core 104 is suspended from the roof slab 103 by a suspension shell 107. This suspension barrel 107 has an opening 107A formed therein. A core upper mechanism 108 is provided above the core 104, passing through the roof slab 103 and being supported by the roof slab 103. That is, since both the core support mechanism 105 housing the reactor core 104 and the core upper mechanism 108 are supported by the roof slab 103, even if a vertical seismic motion occurs, for example, the core support mechanism 105 housing the core 104 and the core upper mechanism 108 are supported by the roof slab 103. Upper core mechanism 108
The relative displacement between is extremely small. Therefore, this configuration can prevent a situation where the core output fluctuates due to the control rods being misaligned. In addition, the core support mechanism 105 and the reactor vessel 1
01, there is a reactor core 104 and a core support mechanism 1.
A horizontal vibration damping member 109 is provided to prevent vibration in the horizontal direction when the 05 earthquake occurs. A partition wall 111 is connected to a support member 130 provided on the upper surface of the horizontal damping member 109 between a partition wall 110 provided on the inner peripheral side of the reactor vessel 101 above the horizontal damping member 109 and the suspension shell 107. supported and provided. This partition wall 111 is installed in a free state with gaps 124 and 125 between it and the hanging body 107 and the partition wall 110. And this partition wall 111
divides the inside of the reactor vessel 101 into upper and lower halves, with the upper part being an upper plenum 112 and the lower part being a lower plenum 113, forming a thermal boundary. An inlet 11 is provided between the hanging shell 107 and the reactor vessel 101.
An intermediate heat exchanger 114 having an outlet 4A and an outlet 114B and a circulation pump 115 are connected to the roof slab 1.
03 and the partition wall 111, and is supported by the roof slab 103. The intermediate heat exchanger 114 is installed in a free state with a gap 126 from the partition wall 111. A labyrinth seal mechanism 116 is provided between the horizontal damping member 109 and the core support mechanism 105 to form a pressure boundary.

As shown in FIG. 3, the labyrinth seal mechanism 116 has an annular shape and is divided into a plurality of parts in the circumferential direction, and has a structure in which a portion of each adjacent divided labyrinth 117 is overlapped. Further, a gap 118 is formed in the circumferential direction at the overlapping portion, so that each divided labyrinth 117 can move within a predetermined range in the circumferential direction. Divided labyrinth 117
Fig. 4 shows a vertical cross section of. Divided labyrinth 117
A hole 119 having a stepped structure is formed in the radial direction, and the horizontal damping member 10 is inserted into the hole 119.
A retaining seat 120 having a smaller diameter than the hole 119 is fitted from the 9 side. The radial position of the divided labyrinth 117 is regulated by screwing the bolt 121 into the core support mechanism 105 via the stop seat 120. A gap 122 is formed between the divided labyrinth 117 and the core support mechanism 105, and the hole 11 of the divided labyrinth 117
A plurality of annular grooves 123 are formed above and below 9 in the vertical direction. The gap 122 can be adjusted as appropriate by changing the thickness of the flange portion 120A of the stopper seat 120 in the radial direction from the core. And split labyrinth 11
7 is simply mounted on the horizontal vibration damping member 109 by its own weight, so even if a horizontal or vertical earthquake occurs, the core support mechanism 10
The configuration is such that relative displacement between the 5 side and the horizontal damping member 109 side is not restricted. Although some coolant leaks through the gap 122 during reactor operation, the gap 122 should be made sufficiently small (several
(within 2 mm), this configuration can suppress the amount of leakage to an extent that does not affect the performance and efficiency of the plant. The relationship between the amount of leakage and the gap 122 is now shown in FIG. Figure 5 shows the gap 122 on the horizontal axis.
(mm) and the vertical axis shows the leakage amount (Kg/S) and the leakage amount/core flow rate (%), and shows the relationship between them. In the figure, the allowable leakage amount line is indicated by a dashed line. That is, the overall allowable leakage amount is about 5%. However, considering that leaks occur in locations other than the labyrinth seal mechanism 116 in this embodiment, approximately
It is necessary to suppress the gap to about 1.5%, and therefore, it can be said that the appropriate gap 122 in this embodiment is about 5 to 7.5 (mm). Note that the labyrinth seal mechanism 116 is connected to the horizontal vibration damping member 10 as shown in FIG.
The lower end is supported by a support surface 131 provided at the tip of the holder 9 .

According to the above configuration, the coolant 102 is supplied to the core 10
4 is passed from the bottom to the top, and the temperature is raised at that time. The coolant 102 that has flowed into the suspension shell 107 from the core 104 flows out of the suspension shell 107 through the opening 107A of the suspension shell 107, and flows into the intermediate heat exchanger 114 via the inlet 114A. Then, it exchanges heat with the secondary coolant in the intermediate heat exchanger 114, and flows out into the lower plenum 113 from the outlet 114B. Then, it is pressurized by the circulation pump 115 and sent to the lower part of the reactor core 104 again. At this time, a small amount of coolant leaks from the labyrinth seal mechanism 116, but as mentioned above, by making the gap 122 small (5 to 7.5 mm), the leak amount/core flow rate can be suppressed to about 1.5%. Plant performance and efficiency are not affected. Furthermore, the core support mechanism 105 has a large diameter, for example, 10 m, and therefore it is difficult to keep the gap 122 within several mm with normal machining accuracy.
16 is divided into multiple parts in the circumferential direction, it is only necessary to adjust the gap for each divided labyrinth 117, and the gap 122 can be easily suppressed to within a few mm. Furthermore, the overall eccentricity can be reduced during manufacturing. This can be done easily since there is no need to take this into account.

Further, according to the above configuration, the inner circumferential surface of the labyrinth seal mechanism 116 and the core support mechanism 105
Since the pressure boundary of the coolant is formed below the partition wall 111 by the labyrinth seal formed between the outer circumferential surface of . Therefore, even if the suspension shell 107 is displaced in the horizontal and vertical directions due to an earthquake or the like, excessive stress will not be generated on the bulkhead 111.
No. 11 stress fracture can be prevented. Also,
Since the partition wall 111 only forms a thermal boundary of the coolant, thermal stress does not occur even if the coolant temperature is severe, and the partition wall 111
The thermal deformation of can be reduced.

In addition, the labyrinth seal mechanism 116
Since the lower end is supported by a support surface 131 provided at the tip of the horizontal vibration damping member 109, which is supported movably in the vertical direction by the horizontal vibration damping member 109, there is a The function of the labyrinth seal can be maintained even if relative displacement occurs in the vertical and horizontal directions. When horizontal vibration occurs in the core support mechanism 105, the labyrinth seal mechanism 116 is mounted with its own weight on the horizontal vibration damping member 109 with gaps 122, 128 in the radial direction from the core support mechanism 105. Therefore, the vibration of the core support mechanism 105 is suppressed by the horizontal vibration damping member 109 on its outer periphery, and at the same time, the horizontal displacement can be absorbed. In particular, the labyrinth seal mechanism 116 according to this embodiment is divided into a plurality of parts in the circumferential direction, and the plurality of divided labyrinths 117 partially overlap each other and are configured to be movable vertically and horizontally. Thermal expansion in the circumferential direction can be effectively absorbed.

〔Effect of the invention〕

The fast breeder reactor according to the present invention includes a reactor vessel, a roof slab installed on the top of the reactor vessel to close the upper opening of the vessel, and a hanging shell suspended from the roof slab into the reactor vessel. , a core support mechanism that is installed at the lower end of this hanging barrel and houses the core inside, an annular labyrinth seal mechanism that is installed on the outer periphery of this core support mechanism through a small gap, and a labyrinth seal mechanism that connects the labyrinth seal mechanism in the vertical direction a stop seat movably supporting the reactor vessel, a horizontal vibration damping member provided from the inner wall surface of the reactor vessel toward the center of the vessel and suppressing horizontal vibration of the reactor core support mechanism; an annular groove forming a labyrinth seal between a support surface provided at the tip of the member and supporting the lower end of the labyrinth seal mechanism and an outer circumferential surface of the core support mechanism provided on the inner circumferential surface of the labyrinth seal mechanism; A partition wall is supported by the horizontal vibration damping member via a support member and forms a thermal boundary of the coolant above the horizontal vibration damping member.

Therefore, the pressure boundary of the coolant is formed below the bulkhead by the labyrinth seal formed between the inner peripheral surface of the labyrinth seal mechanism and the outer peripheral surface of the core support mechanism. It can be installed without being joined to the reactor vessel. Therefore, even if the suspension shell is displaced in the horizontal and vertical directions due to an earthquake or the like, excessive stress will not be generated in the partition wall, and stress failure of the partition wall can be prevented. In addition, since the partition wall only forms a thermal boundary of the coolant, thermal stress will not occur even in areas where the temperature distribution of the coolant is severe, and thermal deformation of the partition wall can be prevented. I can do it. moreover,
The labyrinth seal mechanism is supported movably in the vertical direction by a stopper, and its lower end is supported by a support surface provided at the tip of the horizontal vibration damping member, so there is no space between the core support mechanism and the horizontal vibration damping member. The function of the labyrinth seal can be maintained even if relative displacement occurs in the vertical and horizontal directions.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a tank-type fast breeder reactor showing a conventional example, FIGS. 2 to 4 are views showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a tank-type fast breeder reactor. 3 is a cross-sectional view taken from FIG. 2, and FIG. 4 is a partially enlarged view of FIG. 2. FIG. 5 is a diagram showing the relationship between the gap in the labyrinth seal mechanism and the amount of leakage. 101... Reactor vessel, 101A... Upper opening of reactor vessel, 102... Coolant, 103... Roof slab, 104... Core, 105... Core support mechanism, 10
7... Hanging shell, 109... Horizontal vibration damping member, 111... Partition wall, 114... Intermediate heat exchanger, 116... Labyrinth seal mechanism, 117... Division labyrinth.

Claims (1)

[Scope of Claims] 1. A reactor vessel, a roof slab installed on the top of the reactor vessel and closing the upper opening of the vessel, and a suspension shell suspended from the roof slab into the reactor vessel; A core support mechanism that is installed at the lower end of this hanging barrel and houses the core inside, an annular labyrinth seal mechanism that is installed on the outer periphery of this core support mechanism through a minute gap, and a labyrinth seal mechanism that connects this labyrinth seal mechanism vertically. a stop seat movably supported; a horizontal vibration damping member provided from the inner wall surface of the reactor vessel toward the center of the reactor vessel to suppress horizontal vibration of the reactor core support mechanism; and the horizontal vibration damping member. an annular groove that forms a labyrinth seal between a support surface that is provided at the tip of the labyrinth seal mechanism and supports the lower end of the labyrinth seal mechanism, and an outer circumferential surface of the core support mechanism that is provided on the inner circumferential surface of the labyrinth seal mechanism; A fast breeder reactor comprising: a partition wall supported by a horizontal damping member via a support member and forming a thermal boundary of a coolant above the horizontal damping member. 2. Claim 1, wherein the labyrinth seal mechanism is divided in the circumferential direction.
Fast breeder reactor described in section.