JPH06235787A - Fast breeder reactor - Google Patents

Abstract

PURPOSE:To reduce thermal stress in the wall of a reactor vessel. CONSTITUTION:Upper opening of a reactor vessel (main vessel 1) is closed by an upper cover, i.e., a conical shell 24, having inner face touching the reactor cover gas 22 and outer face applied with an upper cover part thermal insulation member 27. A gas piping 26 is disposed on the inside of the thermal insulation member 27. In order to deal with such phenomenon as trip immediately after start, the conical shell 24 is heated by feeding high temperature gas into a gas piping 26 at the time of start. At the time of normal stoppage, low temperature gas is fed into the gas piping 26 thus lowering the temperature and preventing abrupt temperature variation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fast breeder reactor, and more particularly to a tank type fast breeder reactor capable of rationalizing heat resistance design of a reactor vessel.

[0002]

2. Description of the Related Art FIG. 5 shows a schematic structure of a conventional tank type fast breeder reactor. Inside a reactor vessel, that is, a main vessel 1 having a cylindrical shape with a bottom, a reactor core 2 for generating thermal energy by a nuclear reaction is provided. Further, inside the main container 1, a plurality of main circulation pumps 4 that circulate a liquid metal 3 (usually liquid sodium) as a primary coolant, a liquid metal (not shown) as a primary coolant to a secondary coolant (not shown) ( A primary cooling system facility including a plurality of intermediate heat exchangers 5 that transfers heat energy to normal sodium) is housed.

A core inlet plenum portion 6 is provided below the core 2, and the core 2 and the core inlet plenum portion 6 are supported by a core support 7 provided at the bottom of the main vessel 1. A core upper mechanism 8 is arranged above the core 2. A partition wall 9 is arranged inside the main container 1. The partition 9 divides the space inside the main container 1 into an upper hot pool 10 and a lower cold pool 11.

The plurality of main circulation pumps 4 and the plurality of intermediate heat exchangers 5 are arranged in the main container 1 at equal intervals in the circumferential direction. An internal pipe 12 is connected to the lower end of the main circulation pump 4, and the lower end of the internal pipe 12 extends from the cold pool 11 to the core inlet plenum 6.

Then, a thin-walled cylindrical body 13 is surrounded from the lower part of each main circulation pump 4 to the in-furnace piping 12, and the lower end of this cylindrical body 13 penetrates the partition wall 9 to cold pool 11
The inside of the cylindrical body 13 is communicated with the internal space of the cold pool 11 by being introduced into the inside.

On the outside of the main container 1, there is provided a bottomed cylindrical safety container 14 in case of a coolant leakage accident.
The fast breeder reactor configured as described above is supported by the cavity wall 16 of the reactor building via the support member 15 provided on the outer periphery of the upper portion.

The upper opening of the main container 1 is closed by a roof slab 17 forming an upper lid. A cooling layer 18 is formed on the roof slab 17, and a cooling gas is circulated through the cooling layer 18 to prevent the roof slab 17 from overheating. Liquid metal (usually liquid sodium) is contained in the hot pool 10 and the cold pool 11 as a primary coolant. The reactor cover gas 22 is provided between the liquid surface of the liquid metal 3 and the roof slab 17. Is filled.

Next, the operation of the conventional fast breeder reactor will be described. First, the liquid metal 3, which is the primary coolant, receives heat energy from a nuclear reaction while passing through the core 2 in the upward direction, becomes high in temperature, and flows into the hot pool 10. Then, it flows into the intermediate heat exchanger 5 from above and flows into the cold pool 11 while lowering the temperature by transferring heat energy to the liquid metal as the secondary coolant.

On the other hand, the liquid metal 3 in the cold pool 11 is pressurized by the main circulation pump 4 and returned to the core inlet plenum 6 through the in-core piping 12. The intermediate heat exchanger 5
The liquid metal as the secondary coolant heated in (4) is introduced to the outside of the main container 1 and heats the steam for driving the turbine.

[0010]

In the conventional tank-type fast breeder reactor constructed as described above, the roof slab is used.
17 is cooled to a low temperature, on the other hand, the vicinity of the liquid surface of the liquid metal 3 in the main container 1 is at a high temperature due to the liquid metal in the hot pool 10, and as a result, the axial temperature drop in this region of the main container 1 is large, Since the axial length is short, the temperature gradient becomes large.

Since this causes an increase in thermal stress, from the viewpoint of heat resistance, this portion of the main container 1 is cooled by the liquid metal of the cold pool 11, or a furnace wall heat protection structure is provided. There are issues that require some measures.

FIG. 6 shows the axial temperature gradient of the main vessel 1 when the furnace wall is cooled by the liquid metal of the cold pool 11. Even in this state, a steep temperature gradient of about 150 ° C./m is applied. ing. Therefore, there is a problem that the furnace wall must be protected against heat.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fast breeder reactor capable of reducing the thermal stress in the reactor wall of the reactor vessel.

[0014]

According to the present invention, a core, an upper core mechanism, a main circulation pump and an intermediate heat exchanger are housed inside, and the main circulation pump and the intermediate heat exchanger are supported by a conical shell on the upper side of the furnace. And a bottomed cylindrical main container whose interior is divided into a hot pool and a cold pool by a partition wall,
A high-speed container provided with a safety container arranged so as to cover the outside of the main container, and a main container supporting skirt that is placed on the base mat of the reactor building downward from the bottom plate of the main container. In the breeder reactor, a heat insulating material having excellent heat insulation performance is arranged outside the conical shell of the reactor vessel to increase the temperature of the conical shell.

Further, by arranging a gas pipe in the conical shell, the temperature of the upper lid can be controlled at the time of normal startup and normal shutdown of the plant without delaying the temperature from near the liquid surface of the hot pool in the reactor vessel. In the equipment support pedestal part of the conical shell part, a gentle axial temperature gradient is provided in the part away from the vicinity of the liquid surface of the hot pool in the reactor vessel to control the ambient temperature of the reactor cavity room where the reactor vessel is installed. The feature is that the temperature is raised close to the allowable temperature of reinforced concrete.

[0016]

According to the present invention, since the reactor vessel is supported by the lower portion, it is not necessary to contact the concrete on the upper portion, and it is not necessary to cool the reactor vessel cover portion.

Therefore, in the procedure for shifting the reactor from the low temperature state to the rated output operation state through the high temperature standby state, the temperature near the liquid surface of the hot pool in the reactor vessel rises, but the upper portion of the reactor vessel Also, the conical shell part of the above heats up without radiant heat transfer from the hot pool liquid surface via the reactor vessel cover gas part, convective heat transfer, and temperature delay from the hot pool liquid surface through the externally arranged pipe. Because the outside of these conical shells is insulated,
The temperature drop along the reactor vessel from the vicinity of the liquid level of the reactor vessel to the upper side becomes smaller.

Further, in a stop operation for shifting the reactor from a high temperature state to a low temperature state, heat is removed by an external pipe so that the upper lid portion of the reactor vessel can follow the temperature change near the liquid metal liquid surface. It will be possible. That is, even if the output of the reactor changes, a steep temperature gradient is not generated in the vicinity of the liquid surface of the reactor vessel, and the thermal stress can be relaxed.

[0019]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a fast breeder reactor according to the present invention. In FIG. 1, inside a reactor vessel, that is, a bottomed cylindrical main vessel 1, a reactor core 2 for generating thermal energy by a nuclear reaction is provided. Inside the main container 1, a plurality of main circulation pumps 4 for circulating a liquid metal 3 (usually liquid sodium) as a primary coolant, a liquid metal (not shown) as a primary coolant to a secondary coolant (normal liquid) A primary cooling system facility including a plurality of intermediate heat exchangers 5 for transmitting heat energy to sodium) is housed.

A core inlet plenum portion 6 is provided below the core 2, and the core 2 and the core inlet plenum portion 6 are supported by a core support 7 provided at the bottom of the main vessel 1. A core upper mechanism 8 is arranged above the core 2. A partition wall 9 is arranged inside the main container 1. The partition 9 divides the space inside the main container 1 into an upper hot pool 10 and a lower cold pool 11.

The plurality of main circulation pumps 4 and the plurality of intermediate heat exchangers 5 are all arranged in the main container 1 at equal intervals in the circumferential direction. A furnace pipe 12 is connected to the lower end of the main circulation pump 4, and the lower end of the furnace pipe 12 is connected to the cold pool 11
It extends from inside to the core inlet plenum 6. A safety container 14 having a bottomed cylindrical shape is provided outside the main container 1 in case of a coolant leakage accident.

In the fast breeder reactor configured as described above, the bottom plate 19 of the main vessel is curved so as to draw a downwardly convex arc in the main vessel support skirt 20 with respect to the vertical cross section passing through the central axis of the main vessel 1. It is formed into a shape. The main vessel support skirt 20 is erected and supported by a base mat 25 of the reactor building.

The upper opening of the main container 1 is closed by a conical shell 24 forming an upper lid. The inner surface of the conical shell 24 is shown in a partially enlarged view in FIG.
It is in contact with the outside, and the outer surface has a heat insulating material with excellent heat insulation performance.
27 is provided so that the temperature of the conical shell 24 does not suddenly change from the temperature near the liquid surface of the liquid metal 3.

Liquid metal (usually sodium) is contained in the hot pool 10 and the cold pool 11 as a primary coolant, and the liquid surface of the liquid metal 3 and the roof slab 17 are contained.
A cover gas is filled between and.

Reference numeral 17 in FIG. 1 denotes a roof slab, which has a rotary plug 23 having the core upper part mechanism 8 and the like attached to the central portion thereof. Further, 21 is a furnace vessel cover heat insulating material, which is a conical shell 24
Other than the above, the outer surface of the upper part of the reactor vessel 1 is covered.

FIG. 2 is an enlarged view of the structure of the reactor vessel upper lid portion in FIG. Conical shell 24 that serves as the upper lid of the main container 1
A gas pipe 26 is provided in the pipe, a high-temperature medium flows in the pipe at the time of start-up, and a heat removal gas flows at the time of stop.

An upper lid heat insulating material 27 is arranged outside the gas pipe 26, and an equipment pedestal heat insulating material 29 is arranged outside the equipment supporting pedestal portion 28. Also, the atmosphere 30 in the reactor cavity room where the main container 1 is installed is cavity concrete.
It shall be raised up to the allowable temperature limit of 31.

Next, the operation of this embodiment having such a configuration will be described. The liquid metal 3 as the primary coolant is sent to the intermediate heat exchanger 5 as in the conventional device, and the liquid metal as the secondary coolant heated in the intermediate heat exchanger 5 is the main container 1
Will be heated to the steam for driving the turbine.

When the reactor is shifted from the low temperature state to the rated output operation state through the high temperature standby state, the temperature rises near the liquid surface of the hot pool 10 in the reactor vessel, but the upper lid of the main vessel is closed. The temperature of the conical shell 24 part also rises due to radiation heat transfer and convection heat transfer from the liquid surface of the hot pool 10 through the reactor cover gas 22 part.

The outside of the conical shell 24 is heated by flowing a high temperature gas into the gas pipe 26, and is insulated by the upper lid heat insulating material 27. The temperature drop along 1 is not large.

Further, even in the stop operation of shifting from the high temperature state to the low temperature state contrary to the output increase of the nuclear reactor, the heat can be removed by flowing the low temperature gas into the gas pipe 26, so that the liquid metal 3 It is possible to cause the temperature of the conical shell 24 to follow the liquid surface temperature of the liquid metal 3 in accordance with the temperature change in the liquid surface vicinity portion.

FIG. 3 shows the transient change of the axial temperature gradient from the vicinity of the liquid surface of the liquid metal 3 of the hot pool 10 of the main container 1 at the time of starting the plant in the above embodiment, and FIG. Similar to Fig. 3, this is when the plant is stopped. In either case, the axial temperature gradient is approximately 80 ° C / m
It is recognized that the thermal stress is relaxed.

The embodiments of the present invention are summarized as follows. (1) Inside the core, the upper core mechanism, the main circulation pump and the intermediate heat exchanger, a cylindrical main container with a bottom, whose inside is divided into a hot pool and a cold pool, and the outside of this main container In a fast breeder reactor having a safety container arranged so as to cover the main container supporting skirt, which is placed on the base mat of the reactor building downward from the bottom plate of the main container. The upper opening is closed by a conical shell forming an upper lid, the inner surface of the conical shell is in contact with the reactor cover gas, and the outer surface is provided with a heat insulating material having excellent heat insulation performance.

(2) By arranging a gas pipe in the conical shell, it is possible to raise the temperature of the conical shell during normal startup of the plant without delaying the temperature from near the liquid surface of the hot pool in the main vessel. It is possible, and on the contrary, when the plant is normally shut down, the temperature of the upper lid can be lowered without a temperature delay from the vicinity of the liquid level of the hot pool in the main container.

(3) A gentle temperature gradient in the axial direction is provided at a portion of the equipment supporting pedestal portion of the upper lid of the main container, which is separated from the vicinity of the liquid surface of the hot pool in the main container. (4) The ambient temperature of the reactor cavity room in which the main vessel is installed is raised close to the allowable temperature of reinforced concrete.

[0036]

EFFECTS OF THE INVENTION According to the present invention, the temperature gradient in the vicinity of the liquid surface of the main vessel where the severest thermal stress is generated in the conventional reactor structure becomes gentle, and the thermal stress can be reduced in the conventional example. Therefore, the reactor wall cooling device and the reactor wall heat protection structure, which are required for this, are not required, and the cost of the reactor structure can be reduced. In addition, it is possible to reduce the diameter of the main vessel without the need for an extra device inside the main vessel in the reactor, which in turn reduces the size of the reactor building and contributes to a reduction in plant construction costs. Becomes

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a fast breeder reactor according to the present invention.

FIG. 2 is an enlarged vertical cross-sectional view showing the vicinity of a reactor vessel upper lid part of the fast breeder reactor in FIG.

FIG. 3 is a characteristic diagram showing an axial temperature distribution when the fast breeder reactor according to the present invention is started up.

FIG. 4 is a characteristic diagram showing an axial temperature distribution when the plant is stopped, as in FIG. 3.

FIG. 5 is a configuration diagram for explaining a configuration of a conventional fast breeder reactor.

FIG. 6 is a characteristic diagram showing a temperature distribution near a liquid surface of a conventional fast breeder reactor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main container, 2 ... Core, 3 ... Liquid metal, 4 ... Main circulation pump, 5 ... Intermediate heat exchanger, 6 ... Core inlet plenum part, 7 ...
Core support, 8 ... Upper core mechanism, 9 ... Partition, 10 ... Hot pool, 11 ... Cold pool, 12 ... Reactor piping, 13 ... Cylindrical body, 14 ... Safety container, 15 ... Main container support member, 16 ... Cavity・ Wall, 17 ... Roof slab, 18 ... Cooling layer, 19 ... Main vessel bottom plate, 20 ... Main vessel supporting skirt, 21 ... Main vessel cover insulation material, 22 ... Reactor cover gas, 23 ... Rotating plug, 24 ...
Conical shell, 25 ... Reactor building base mat, 26 ... Gas piping, 27 ... Upper lid heat insulating material, 28 ... Equipment pedestal part, 29 ...
Equipment pedestal insulation, 30 ... Reactor cavity room atmosphere, 31 ... Cavity concrete.

Claims (1)

[Claims] 1. A bottomed cylindrical main container having a core, an upper core mechanism, a main circulation pump, and an intermediate heat exchanger housed therein, and having a partition partitioned into a hot pool and a cold pool, and the main container. In a fast breeder reactor comprising a safety container arranged so as to cover the outside of the main container and a main container support skirt mounted on a base mat of the reactor building downward from the bottom plate of the main container. The upper opening of the container is closed by a conical shell forming an upper lid, the inner surface of the conical shell is in contact with the reactor cover gas, and the outer surface is provided with a heat insulating heat insulating material. Breeder reactor.