JP3188379B2 - Integrated fast neutron reactor with removable internal structural elements - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated fast neutron reactor having a main vessel of a nuclear reactor from which internal structural elements can be removed.

[0002]

2. Description of the Related Art An integrated fast neutron reactor is provided with a main vessel of a nuclear reactor for containing a coolant of the nuclear reactor. Generally, the coolant of the nuclear reactor is a liquid metal such as sodium, The core of the reactor, a coolant circulation pump, and an intermediate heat exchanger that transfers the heat of the reactor coolant to the secondary coolant are submerged therein.

[0003] A pump submerged in the coolant inside the container, that is, a primary pump circulates the liquid metal constituting the coolant, passes through the reactor core, and contacts the fuel assembly to heat it. The heated liquid metal then enters the intermediate heat exchanger where it contacts and cools the secondary coolant. The secondary coolant is also typically a liquid metal. The cooled liquid metal exits the intermediate heat exchanger and is recovered by a primary pump.

[0004] The main vessel of the reactor is, inter alia, a part of the core cooling liquid metal used for compartmentalization of the volume of the main vessel of the reactor, for supporting the core and for cooling the inner surface of the main vessel of the reactor. It contains the internal structure that is responsible for the guidance. The internal structure of the main vessel of the reactor comprises, inter alia, an inner vessel, which inside the reactor has a first area, namely the heated liquid metal exiting the reactor core. And a second area, a cold tank for receiving cooled coolant exiting the intermediate heat exchanger.

[0005] The intermediate heat exchanger and pump are tall components having a generally cylindrical shape, both submerged longitudinally within the reactor vessel. The upper part of the reactor vessel is closed with a slab and has an opening through which the upper components of the pump and the heat exchanger pass.

An intermediate heat exchanger penetrates the inner vessel and has an opening in communication with the hot tank into which the heated liquid metal enters, and an opening through which the cooled liquid metal exits in communication with the cold tank. It has. The suction side of the primary pump is connected to the cold tank.

[0007] A fast neutron reactor generally comprises an assembly of a primary pump and an intermediate heat exchanger, which is arranged in an annular area whose symmetry axis is the longitudinal symmetry axis of the main vessel. Penetrates the lateral closure slab at the top of the reactor main vessel.

[0008] The core of a nuclear reactor is supported by a part of an internal structure called a girder, and the internal structure itself is attached to an internal structural element called a floor plate. In addition, the floor plate is supported by a part of the inner surface of the main vessel of the nuclear reactor and the bottom of the vessel. Part of the internal structure,
Separate the annular space on the inner surface of the container, and around the container,
It forms a circulation space for the liquid metal for cooling the container.

Regarding the internal structure of the main vessel of the nuclear reactor, a recovery device can be further provided at the top of the reactor core to protect the bottom of the vessel and collect waste materials generated from the reactor core. In a nuclear reactor according to the prior art, the internal structure is arranged inside the main vessel to constitute a reactor block, and generally constitutes a solid unit which is welded and assembled.

A method for realizing such an internal structure of a fast neutron reactor is described in, inter alia, French Patent FR-A-
2,506,062, FR-A-2,680,597,
FR-A-2,558,635, FR-A-2,54
1,496.

In particular, some of the large components of these fast neutron reactors which constitute the passage of the instrumentation of the core and the conduit of the liquid metal at the top of the vessel, such as primary pumps, intermediate heat exchangers, cores The plug-cover and the like are detachable parts, and can be taken out of the container by using a dedicated facility.

However, the internal component elements in the main vessel may pass through the opening of the main vessel closure slab, either because they are welded when assembling the reactor block at the site or because of their large dimensions. Cannot be removed and cannot be removed. In fact, since the slab is generally constructed so that it cannot be lifted and opened from the main container, the elements inside the container can only be removed through the opening in the slab.

According to the conventional method, the slab can be a hybrid structure in which metal parts are embedded in concrete to be constructed when constructing a reactor building.
Metal elements embedded in the concrete are left intact for welding the upper part of the reactor vessel. The main container is
It can also be suspended on a flange incorporated into the structure of the reactor building, in which case the slab is attached to a part of the reactor building.

[0014]

In the case of nuclear reactors according to existing techniques, the internal components cannot be disassembled or replaced, since the interior of the vessel is not accessible. Similarly, internal structural elements cannot be removed or installed from the reactor slab.
When it is necessary to take out the internal structure, that is, when the life of the reactor is over and dismantling is performed, the sodium inside the reactor vessel is completely discharged, and the reactor is placed in an inert gas atmosphere. The internal structure must be cut.

Accordingly, it is impossible to disassemble the internal structure and repair or replace it, for example.
Also, the entire internal structure cannot be lifted from the inside of the container to access the bottom of the container or to inspect or repair the bottom of the main container.

Further, as the internal structure must be welded to the interior of the main vessel, the assembly and fixing of the internal structure will take up a significant portion of the construction time of the reactor structure. Finally, due to the internal structure,
The size and weight of the internal equipment are also very important factors.

[0017]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to propose an integrated fast neutron reactor having the following configuration.

The components of the integrated fast neutron reactor of the present invention comprise a main vessel containing a reactor core submerged in a cooling liquid metal, and at least one circulating coolant within the vessel. A core comprising a primary circulation pump, at least one intermediate heat exchanger submerged in a cooling liquid metal, and a large metal element disposed inside the main vessel and mounted inside the main vessel; An internal structure comprising at least one inner container defining an area for receiving the heated liquid metal exiting from the intermediate heat exchanger, and an area for receiving the cooled liquid metal exiting from the intermediate heat exchanger, and for cooling in contact with the inner wall of the main container. A plate constituting a conduit for the liquid metal flow,
And core support elements. The internal structure of the nuclear reactor is realized so that it can be removed or lifted from the inside of the main vessel. This makes construction work easier and faster.

In accordance with this object, each internal structural element is maintained in a corresponding mechanism of at least one component of the assembly consisting of the main container and the internal structural element for easy support fixation inside the main container. And a support mechanism.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, a method of realizing a fast neutron reactor according to the present invention will be described below with reference to the accompanying drawings. The embodiments described below are merely examples, and the present invention is not limited thereto.

FIG. 1 is a front longitudinal sectional view of a vessel and an internal structure of a fast neutron reactor according to the present invention. FIG. 2 is a longitudinal sectional view of a part of the internal structure near the lower end of the main container and the pump. FIG. 3 is a longitudinal sectional view of a part of the internal structure near the lower ends of the main vessel and the intermediate heat exchanger. 4 and 5 are longitudinal cross-sectional views of two parts of the internal structure, showing the cooling sodium conduit of the main vessel. FIG. 6 shows arrows 5-5 in FIG.
FIG. FIG. 7 is a diagram according to arrow 6 in FIG. FIG. 8 is a vertical sectional view of a part of the internal structure of the nuclear reactor supporting the core. FIG. 9 is an enlarged view showing details of FIG. FIG. 10 is a diagram according to arrow 9 in FIG. FIG.
FIG. 3 is a half sectional view of a part of an internal structure constituting a pipe of a liquid metal for cooling of a main container. FIG. 12 shows arrow 1 in FIG.
It is sectional drawing by 1-11. FIG. 13 is a top view of a closed slab of a reactor vessel. FIG. 14 is a partial cross-sectional view of the periphery of a closed slab of a reactor vessel. FIG.
FIG. 3 is a top view of a part of a closed slab of a nuclear reactor. FIG.
FIG. 16 is a partial vertical sectional view taken along arrow 15-15 in FIG. FIG. 17 is a cross-sectional view of the main vessel and the internal structure of the reactor,
The order of decomposition of internal structural elements is shown.

FIG. 1 shows a main vessel 1 of a nuclear reactor containing a cooling liquid metal up to the level of 3 and mounted inside a reactor building structure 2. The reactor core, internal assembly, primary pump and intermediate heat exchanger are submerged.

The main container 1 is surrounded by a safety container 1 ',
The space around the main container 1 is filled with gas. The main vessel 1 is closed off by a rather thick horizontal slab 4 which is connected to the reactor structure 2 above the upper end of the vessel 1.
Attached to.

The slab 4 is provided with an opening,
The upper components of the primary pump 5 and the intermediate heat exchanger 6 pass through. As can be seen from FIGS. 13 and 15, the reactor has three primary pumps 5.
These primary pumps 5 are arranged at an angle of 120 ° to each other about the axis of the main container, and six intermediate heat exchangers 6 are arranged between the primary pumps 5. .

The assembly of the primary pump 5 and the intermediate heat exchanger 6 passes through the reactor slab 4 in an annular area centered on the vertical axis of the main vessel. The inner space of the container 1 between the upper level 3 filled with liquid metal made of liquid sodium and the lower surface of the closed slab 4 is filled with an inert gas made of argon.

An orifice is provided at the center of the slab 4, and a rotary plug 8 having a fuel charging machine 9 for a nuclear reactor is mounted therein. An assembly 10 called a plug-cover of the reactor core is arranged above the reactor core 11 of the reactor, and includes instruments for performing measurements in the reactor core. At the outlet of the reactor core 11, a bypass mechanism for liquid sodium circulating in the vessel is provided.

The core 11 is composed of a fuel assembly, and its lower part, that is, its leg, is attached to a mechanically welded structure 12 called a girder to constitute a part of the internal structure of the reactor vessel 1. are doing. The girder 12 is supported by a machine-welded structure 13 called a floor plate,
The sole plate itself is attached to the top of the support plate 14 at the bottom of the main container 1. The support plate 14 has on its inner surface an internal structural element 15 called a recovery device. The recovery device is attached to a lower portion of the bottom plate, and is capable of recovering waste material from the reactor core in the event of a fuel assembly accident or treatment.

An internal structural element 16, called the inner container,
A cylindrical body attached to the upper part of the bottom plate and mounted coaxially with respect to the vessel 7 about the core 11, an annular flat step 16a, and an upper outer cylindrical body having a diameter slightly smaller than the inner diameter of the main vessel 1; 16b.

The inner cylinder 16c of the inner container 16 is fixed along the inner periphery of the flat step 16a, and the upper outer cylinder 16b
Are fixed along the outer circumference of the flat step 16a. The flat step 16a is provided with a plurality of openings, each of which has a cylindrical body 17 penetrating the primary pump 5.
In addition, a cylindrical body 18 penetrating through the intermediate heat exchanger 6 is fixed.

The upper part of the cylinder 17 passing through the primary pump 5 is located above the upper level 3 of the liquid sodium in the container 1. However, the cylindrical body 18 penetrating the intermediate heat exchanger 6
Is located inside the liquid sodium,
An inert acid separating mechanism 18a cooperating with the corresponding mechanism of the intermediate heat exchanger 6 is provided to ensure the hermeticity of the intermediate heat exchanger 6 in the inner container.

As described above, the inner container fills the inner volume of the main container with the first space 19 called the hot tank above the core.
a and a second space 19b called a cold tank below the core. The liquid sodium is circulated in the vessel by the primary pump 5, passes through the core vertically from bottom to top (arrow 20), contacts the core assembly 11, is heated, and is heated by the hot tank 19a at the upper part of the core. Get in. The liquid level of the liquid sodium in the hot tank 19a of the main container 1 is a dynamic liquid level and comes near the upper level indicated by reference numeral 3.

Each intermediate heat exchanger 6 has a hot tank 19a
And a lower opening 6b connected to the cold tank 19b. The heated sodium exiting the reactor core has an upper opening 6a in each intermediate heat exchanger.
, Circulates through the intermediate heat exchanger, cools by contact with the secondary sodium, reaches a lower temperature than when entering the upper opening, and exits from the opening 6b to the cold tank 19b. The secondary sodium heated in contact with the primary sodium is utilized to generate steam in a steam generator located outside the vessel of the reactor.

Since the suction portion disposed at the lower end side of the primary pump 5 is located in the cold tank 19b, it sucks the cooled sodium flowing out from the lower opening 6b of the intermediate heat exchanger, and The cooled sodium is fed into the core through the girder 12. The liquid level of the liquid sodium 21 in the cold tank is arranged above the liquid level 3 in the hot tank.

A part of the cooled sodium is
Leaks from the inside and flows into an annular space formed by the inner surface of the main vessel 1 and the guide cylinder 22 made of a cooling liquid metal that forms a part of the internal structure of the nuclear reactor. The upper portion of the guide cylinder 22 constitutes a drain port for sending sodium for cooling back from the inner surface of the main container 1 to the area of the cold tank located outside the cylinder 16b of the inner container.

According to a general feature of the invention, each internal structural element 12,13,15,16,22 of the reactor may be a corresponding mechanism of another element of the internal structure or the inner vessel 1
And a maintenance and support mechanism attached to a portion of the inner surface of the vehicle. The internal structural elements can therefore be secured without welding or mechanical fastening methods such as screws and bolts.
It is securely fixed inside the main container by its own weight and the maintenance and support mechanism.

Usually, the primary pump 5 and the intermediate heat exchanger 6 are mounted inside the container via the opening of the slab 4 so that the primary pump 5 and the intermediate heat exchanger 6 can be lifted out of the main container 1 and taken out. The slab 4 is realized so that it can be lifted and separated from the structure of the nuclear reactor as described later, so that the elements of the internal structure of the main vessel 1 can be sequentially taken out as described later.

A girder 12 on which a reactor core 11 is mounted is supported on the upper surface of a floor plate 13. The collection device 15 is attached to the support portion inside the support plate 14, and is further attached to the bottom of the main container 1 via this. The inner container 16 includes a bottom plate 13 around the girder 12 and the core 11 through a lower portion of the inner cylindrical body 16c.
Attached to the top of

The lower portion of the sodium guide tube 22 for cooling is attached to the support portion of the floor plate on the inner surface of the main container 1. The side wall of the main container 1 has a cylindrical shape, the bottom is a very flat deep dish-shaped end plate, and the center of the bottom has a spherical shape with an extremely large curvature. The peripheral portion is joined to the side wall of the main container and the central portion of the spherical container bottom, and the longitudinal cross-sectional shape has an arcuate ring shape. In general, the ratio of the height to the diameter of the main vessel 1 is significantly higher than the proportion of the main vessel of a nuclear reactor according to existing techniques.

FIG. 2 shows the lower part of the container 1, in which the lower part of the primary pump 5 is arranged below the inner container 16 inside the cold tank 19b. The floor plate 13 is realized as a mechanical welding structure and includes upper and lower plates in the horizontal direction, outer side walls welded to the upper and lower plates, and reinforcing and fixing bars of the upper and lower plates. The sole plate has three aggregates 23 fixed to the outer side wall, each corresponding to the position of the opening in the side wall.

Each assembly 23 has a casing 24 in which the lower part of the primary pump 5 is incorporated, and a girder 12 and a sodium guiding pipe 25 supported by the girder 12 to the core 11. The casing 24 and the pipe 25 are welded to a connecting material welded in an opening provided in the wall of the floor board.

The pipe 25 has one end connected to the connecting material,
The other end is welded to another tether connected to the upper plate of the bottom plate 13 to form a hermetic connection element to the girder 12. The steel plate 25 a is fixed around the convex outer surface of the sodium supply pipe 25. This steel plate 2
5a serves to support the pipe when the pipe is broken.

A conical plate 26 is coaxially arranged on the bottom plate 13 below the side wall of the bottom plate 13 and surrounds the periphery of the bottom plate. The conical plate 26 is provided at its end with a support crown 27 through which the soleplate 13 is supported by a machined annular support heel 28 on top of the shim in the container 1. It has become. The guide cylinder 22 for cooling sodium
Via a support crown 27 of the container.

An opening is provided in the conical plate 26 of the floor plate 13 and the casing 24 of the primary pump 5 is provided therein.
A short plate for passing through is fixed. Slab 1
The lower plate 3 is arranged somewhat above the support plate 14 connected to the bottom of the container 1 when the soleplate rests on the support surface 28 of the main container 1 via the support crown 27.
The plate 14 is adapted to maintain and fix the soleplate when the support mechanism of the soleplate is broken by an accident.

The device 15 for collecting waste material from the reactor core includes a deflector and a waste material spreading mechanism, and is attached to the machined support surface 14 a above the shim inside the plate 14. It should be noted that the soleplate 13 and the collecting device 15 can be freely attached to the respective support mechanisms 28 and 14a without being welded to the container or the support plate 14 or mechanically connected.

FIG. 3 shows the lower part of the main vessel 1 of the nuclear reactor, in which the plate and the sealing penetrations 18, 18a are shown.
The intermediate heat exchanger 6 which passes through the inner container 16 is arranged at the position of. The upper opening 6a and the lower opening 6b of the intermediate heat exchanger are arranged on both sides of the flat step 16a of the inner container 16. Have been. The flat step 16a corresponds to the inner cylinder 1 of the inner container.
6c and the outer cylinder 16b are connected, but this step may be a step of another shape, for example, a step of a conical shape.

In general, preferentially flat stages can be used for medium and small capacity reactors, and conical shaped stages can be used for large capacity reactors. Protective screen 6
c is fixed to the support mechanism 26 of the floor plate 13 facing the outlet opening 6b of the intermediate heat exchanger 6. The cooling liquid recovery pipe 30 is attached to the upper part of the support plate 26 at a position inclined with respect to the horizontal direction.

As shown in FIGS. 4 and 5, the liquid sodium pipe 30 is inserted between the pump of the reactor and the intermediate heat exchanger in a direction parallel to the support plate 26 of the floor plate. ing. Then, one end thereof is welded to a pipe welded to the side wall of the base plate 13, and the other end is frictionally attached to the opening of the support crown 27 of the forged and machined crown-shaped base plate. Have been.

The support member 28 of the main container 1 at the position of the liquid sodium pipe 30 is forged and machined,
As shown in FIGS. 4 and 6, the recess 32 is partially formed. Thereby, the end of the pipe 30 is connected to the container 1
Is connected to an annular space 33 formed by the inner surface of the plate and the outer surface of the sodium guide tube 22 for cooling. With such a structure, the leak of the cooled sodium circulates through the lower part of the core 11 and is guided by the pipe 30 and enters the annular space 33, in which the sodium flows from bottom to top. To cool the plate of the main container.

The pipe 30, the support crown 27, the main container part 28, and the surface which is supported or is in frictional contact with the ring 22a of the guide cylinder for the cooling liquid metal is used to reduce friction and suppress wear. Aluminized or coated with an aluminized plate.
Aluminum treatment of the friction surface is preferred over alloy coatings such as stellite containing cobalt. As is well known, bringing cobalt into a reactor vessel must be avoided as much as possible.

As shown in FIG. 7, the mutually supporting parts 27, 28 are each embossed at an angle of 120 ° about the central axis of the container.
ent). These tenon grooves will be opposed to each other when the floor plate is installed in the container.

After the sole plate is installed in the container, the key 34 is inserted into each cavity defined by two facing mortise grooves. In this way, the soleplate is prevented from rotating with respect to the inner surface of the container. The cylinder 22 is also fixed so as not to rotate with respect to the wall of the main container 1.

As shown in FIGS. 8 and 9, the girder 12 is attached to the upper plate of the floor plate 13 via the lower part of the side wall constituting the support base of the girder. Furthermore, the center pivot 12a (FIG. 1)
3 is attached to a member fixed to the upper plate. The key is fixed so that the girder 12 does not rotate with respect to the floor plate 13.

Each of the three sodium supply pipes of the core is connected to a primary pump 5, and the other side of the pump 5 is connected to a pipe port 35 attached to an opening of the girder 12 provided with a forging ring. Connected to the forgings that make up. Each ring passing through the lower wall of the girder 12 is provided with a ring-shaped waterproof part 37, and a pipe port 3 is provided inside thereof.
5 is attached.

The joint 38 made of a metal ring is inserted between the upper shoulder of the annular waterproof component 37 and the ring passing through the opening of the girder 12. The joint 38 is compressed by the pressure of the liquid metal between the waterproof part 37 and the girder. The joint 39 having a snap ring shape is inserted between the outer surface of the pipe port 35 and the inner surface of the waterproof component 37 having a cylindrical shape. The application of the liquid pressure to the joint 39 presses the joint against the outer surface of the pipe port 35 to ensure a waterproof connection between the pump pipe and the girder.

In this way, when heat is transferred to the inside of the vessel of the nuclear reactor, the piping port 35 can move in the lateral direction with respect to the girder 12. Similarly, the pipe port 35 can also move inside the waterproof component 37 in the vertical direction.

The sodium is guided so as not to leak and passes between the pump piping and the inner space of the girder, as illustrated by arrow 40. Liquid sodium is applied to the upper plate opening 41 of the girder 12.
And enters the reactor core 11 above the girder 12.

The inner cylinder 16c of the inner container 16 is connected to a ring 36 whose lower part is forged and machined. Since this ring has a shoulder, when the inner container 16 is mounted in the main container 1, the ring is shaped so as to cover the upper part of the side wall of the floor plate 13. When the upper part of the side wall of the floor plate 13 is incorporated into the part 36 of the inner container, the inner container is
And the soleplate itself is perfectly positioned in the center of the container via the forged support ring 27. Similarly, when the upper part of the floor plate 13 is incorporated into the component 36, the inner container can be fixed so as not to swing with respect to the floor plate 13 in the main container.

In FIG. 10, the forged support part 36 is provided with a tenon groove 36a, which, when the inner container is mounted in the main container, faces the corresponding tenon groove formed on the upper part of the side wall of the floor plate 13. . To reinforce the fixation of the inner container in the main container, a key 42 is inserted into each cavity defined by the facing mortise of the support part 36 and the soleplate 13. In this way, rotation of the inner container with respect to the sole plate is prohibited, and the sole plate itself is also prevented from rotating with respect to the main container via the key 34 shown in FIGS.

All surfaces of the girder 12, the soleplate and the support component 36 are adapted to support each other. In this case, since the surfaces are made of stainless steel, when the internal structural elements support each other, they are brought into contact via aluminized parts so that the stainless steels do not come into direct contact with each other.

As can be seen from FIG. 11, the upper portion of the sodium induction tube 22 for cooling is connected to the
It is connected to the two cylinders 43 and 44 and constitutes an outlet for liquid sodium flowing from the pipe 30 in the annular space 33 between the main container 1 and the cylinder 22. The liquid sodium passes through the upper part of the upper end of the cylinder 43,
It is an inlet that flows into the outlet between 3,44.

The liquid metal dumping port 45 shown in FIGS. 11 and 12 can send the liquid metal back to the cold tank where the liquid sodium level 21 is significantly lower than the liquid sodium level 3 in the hot tank. The cooling liquid sodium thus circulates in contact with the inner wall of the main vessel, cools the main vessel and returns to the cold tank without vibrating the reactor structure.

FIG. 13 shows the closed slab 4 of the reactor vessel.
Is shown, and the closing slab is provided with an opening so that the primary pump 5 and the intermediate heat exchanger 6 can pass therethrough. The slab 4 further has an opening in the center, in which a large rotating plug 8 of the nuclear reactor is mounted so that the slab 4 rotates on the slab 4 about the vertical axis 7 of the vessel. Has become.

A small rotary plug 46 is attached to the large rotary plug 8 so as to be rotatable about a vertical axis different from the central axis of the container 7. The small rotary plug is provided with a fuel charging machine 9 of a nuclear reactor. Fixed. By combining the rotation of the large rotary plug 8 and the small rotary plug 46, the fuel exchanger can be mounted in a line in the vertical direction of any of the fuel assemblies in the reactor core 11 of the nuclear reactor. The large rotary plug 8 also has a core plug-cover 10 in the center.

FIG. 14 shows a part of the outer periphery of the slab 4 of the nuclear reactor, and the outer periphery is provided with a mechanism for supporting and fixing the slab to the fixing structure 2 of the nuclear reactor. The upper part of the cylindrical body of the main container 1 is connected to an annular flange 47. The other flange 48 is also annular in shape and is fixed to the upper part of the reactor structure 2 around the cavity forming the vessel pit in which the main vessel 1 is located. The flange 48 is fixed to the structure of the nuclear reactor and has an annular concave portion, so that the flange 47 connected to the upper part of the cylindrical body of the main vessel 1 can be attached.

The slab 4 consists of a very thick steel plate, the outer side of which is
7 is machined so as to be able to store the supporting and fixing mechanism. The slab 4 is provided with a shoulder 4 a forming an annular surface downward, and a support mechanism 49 is fixed on the annular surface, and is fixed to the upper surface of the flange 47 of the main container 1. It is shaped to face the corresponding support mechanism 49 '.

The support mechanisms 49, 49 'have curved support surfaces that are aligned according to a common vertical direction 51.
A support mechanism 52 is inserted between the pair of support mechanisms 49, 49 'of the slab, and is mounted so as to slide inside the support surfaces of the mechanisms 49, 49' and rotate.

In this way, the peripheral portion of the slab moves so that, for example, radial expansion can be absorbed. Similarly, the rotation support mechanism can absorb the deformation due to the deflection of the slab. The sliding and rotating support mechanism 52 is arranged at the periphery of the slab.

Between the two continuous support mechanisms 52, a slab 4 jump-out prevention fixture 53 is inserted. Each protrusion prevention mechanism 53 includes a tie beam 54, and the tie beam is attached to a through hole in a peripheral portion of the slab 4 and a through hole of a flange 47 of a container located on an extension in the axial direction.

The tie beam is disposed in the through hole of the flange 47 of the vessel, passes through the hole of the flange 48, and is fixed to the nut 55 embedded in the reactor structure 2.
Screwed. A waterproof closure cover 56 is attached to the upper portion of the head 54a of the tie beam 54 so that the space around the tie beam 54 can be closed while maintaining the tightness after the tie beam is fixed.

The flange 47 is fixed by welding 57 inside the recess of the flange 48. A waterproof plate 50 is welded to the inner peripheral portion of the upper portion of the flange 47 by welding 62.
Has been fixed. This plate can be connected by welding 61 on the opposite side of the welding 62 to a part of the outer periphery of the slab 4.

By closing the internal space of the main container 1 while maintaining the hermeticity in this way, an inert gas such as argon can be sealed above the liquid level of liquid sodium. The welding 61 is a non-homogeneous welding, and is performed between the time when the slab 4 is mounted on the support mechanism 52 and the time when the projection preventing tie beam 54 is mounted and fixed when the slab is mounted. The welding 61 can be performed because a free space is provided in the upper peripheral portion between the outer peripheral portion of the slab 4 and the fixed structure 2 of the nuclear reactor.

After the performance of the seal welding 51, the free space in the periphery between the slab 4 and the fixed structure 2 is made in the periphery of the slab 4 by a removable closure and filling plug 58 fixed to the fixed structure 2. Filled one by one along. The seal joint 59 is provided between the outer peripheral surface of the slab 4 and the plug 58.
Between the slab and the plug 58 can be maintained.

By providing and fixing the illustrated slab, the entire slab can be disassembled and lifted. Thus, the entire interior cross section of the container can be accessed, for example, to disassemble and withdraw internal structural elements.

All the supporting surfaces of the internal structural elements that support each other or are supported on the inner surface of the container are located in an area called a “cold area”. Within that area, the temperature of the liquid sodium is about 4 during the functioning of the reactor.
Since the temperature is 00 ° C., for example, the temperature is significantly lower than the temperature of sodium in the hot tank on the outlet side of the core.

FIGS. 15 and 16 show a large rotary plug 8 of the nuclear reactor, the plug being mounted so as to rotate at the center of the slab 4, and the periphery of the slab being connected to the primary pump 5 and The intermediate heat exchanger 6 has passed. In two areas located radially opposite each other on the edge of the rotary plug, the slab 4 has two cavities,
Into the cavity, decomposable projections 60a and 60b made of steel and having almost the same thickness as the slab 4 can be inserted.

The large rotary plug 8 can be disassembled and lifted off the plug-cover 10 at the center of the core, and then disassembled and separated from the slab. After disassembling the large rotating plug and lifting it up, disassembling the protrusions 60a and 60b will give
An opening of sufficient size can be provided in the radial direction to allow the girder 12 to pass through at an angle in the vertical direction, and the girder 12 can be taken out of the main container using a lifting device.

FIG. 15 is a longitudinal sectional view of the girder 12.
2 'is shown, which girder is located inside the opening of the large rotary plug 8, which extends radially due to the two mounting cavities for the disassembled projections 60a, 60b. After the reactor has been shut down and cooled, all assemblies can be removed from the reactor core and stocked in a temporary depot using the reactor's fuel charger.

After that, the large-sized rotary plug and the decomposable projections 60a and 60b can be disassembled and stored in a temporary storage place. This allows access to the inside of the container so that the girder can be pulled out after moving it to the vertical position. These operations are performed after the sodium has been completely drained from the vessel, preferably in an inert gas atmosphere.

The girder can be disassembled and pulled out by freely mounting the girder on the base plate, and mounting the three central plates 37 attached to three pipe openings of the central pivot 12a attached to the mounting part and the piping 35 of the base plate. And no disassembly of welded or mechanical joints is required. To disassemble the internal structural element assembly, it is necessary to disassemble and lift the reactor slab.However, the maintenance and support elements are attached to the fixed structure slab of the reactor. can do.

FIG. 17 shows the internal structural elements during the drawing operation in the raised position inside the container. FIG. 17 does not correspond to the actual disassembly stage of the internal components, but shows the sequence of disassembly of these internal components to be carried out after lifting the slab of the reactor.

First, as described above, the girder 12 can be lifted and pulled out. This withdrawal can be performed without lifting the slab, by opening the plug or by opening the container after lifting the slab.

Similarly, since there is no supporting element other than the internal structure, the sodium guiding cylinder 22 for cooling the container or the inner container 16 can be disassembled by a simple lifting operation. These two elements 16,22
Are independently attached to the floor plate 13, so it does not matter which of them is disassembled first.

After disassembly of the elements 12, 16, 22 the main container 1
The sole plate 13 attached to only the inner part 28 can be disassembled. Finally, the collecting device 15 attached to the support plate 24 connected to the bottom of the main container 1 can be disassembled.

Withdrawal of any internal structural elements can be performed without disassembling welded or mechanical joints. In fact, each internal structural element is attached to another internal structural element by a maintenance and support mechanism, or to a portion of the inner surface of the reactor vessel. The support by the inner surface of the container can be reliably performed by a support mechanism such as the portion 28 protruding from the inside of the main container or the support plate 14 connected to the container bottom.

The support mechanism of the internal structural element is usually constituted by an annular flange or an end of a cylindrical body, and is realized by forging or machining. The contact and centering surfaces of the support mechanism are machined on a high precision lathe to accurately maintain and center the internal structural elements.

Due to the high working accuracy of the support surface, the assembly and disassembly of the internal structural elements can be easily carried out under favorable conditions. An aluminized plate is arranged between the contact surfaces of the support mechanism of the internal structural element so that stainless steel does not come into contact in the container.

High precision machining of some of the components that make up the internal structural elements using a forged product simplifies the manufacture of the internal structure and greatly increases the accuracy of the flange geometry and dimensions. Therefore, work such as welding of the plate and the flange can be a completely automatic work. Also,
A high-precision annular space can be provided between the internal structural elements.

The machining can be carried out at the factory or at the reactor site using a vertical lathe with high capacity. Before welding, to improve the connection between the forged and machined flange and the plate, cold rolling of the steel plate of the plate, at least near the joint, improves the toroidal shape of both faces. it can. The development of the cylinder is then measured to accurately calculate the machining radius of the joint of the forged flange. Then, since the connection is perfect, an automatic welding method such as TIG in a narrow place can be used.

The internal structural elements according to the invention are, for example, T
The arrangement is such that a plurality of branched connecting parts having a mold cross section need not be welded. Similarly, there is no necessity of thickening the metal at the binding site. Also,
Welding can be made much easier than before, except at difficult joints.

Although the diameter of the support mechanism for the internal structural element according to the present invention is large, the size of the support surface is large.
On the other hand, the contact pressure remains low and the capacity is 50
In the case of a 0 MWe fast neutron reactor, this contact pressure remains below 3 MPa. Also, an aluminized plate is inserted between the forged support parts of the internal structural element to avoid any contact that could cause seizure, for example, between stainless steels.

The concept of the internal structure according to the present invention further
It is possible to optimize the substructure of the large components of the nuclear reactor, that is, the primary pump and the intermediate heat exchanger. As mentioned above, a container having a relatively flat bottom in the shape of a deep dish-shaped end plate can also be used. With such a shape, the length of the component can be maximized if the component is disposed over the entire height of the container up to the vicinity of the flat bottom. In this way, the diameter of the components and the entire reactor block can be reduced, and the height of the vessel can be kept virtually the same as the height of the vessel according to existing techniques.

The use of each of the partially precision machined internal components allows the density of the internal structure to be very high, and thus the diameter of the main container and the size used for the production of the container and the internal structure. Material can be reduced in weight. Similarly, the size of the enclosure slab and the size of the reactor building can be reduced.

Lifting of the internal structural elements to separate them from each other is possible not only when pulling out the element from the container, but also when accessing another element located below the lifting element or the bottom of the container. . Machining around the support surface not only allows the internal structural elements to be perfectly connected to each other, but also achieves a seal against leakage from the reactor without the use of joints or other sealing elements Become like

The present invention is not limited to the implementation method described above. For example, the use of internal structural elements that differ in shape from those described above and that have different support mechanisms may be envisaged. The present invention is generally applicable to any integrated fast neutron reactor, regardless of the number of primary pumps or intermediate heat exchangers used in the main vessel of the reactor.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view of a vessel and an internal structure of a fast neutron reactor according to the present invention.

FIG. 2 is a longitudinal sectional view of a part of an internal structure near a lower end of a main container and a pump.

FIG. 3 is a longitudinal sectional view of a part of an internal structure near a lower end of a main vessel and an intermediate heat exchanger.

FIG. 4 is a longitudinal sectional view of a part of the internal structure, showing a cooling sodium channel of the main container.

FIG. 5 is a longitudinal sectional view of another portion of the internal structure similar to that of FIG. 4, showing a channel for sodium for cooling of the main container.

FIG. 6 is a sectional view taken along arrow 5-5 in FIG. 4;

FIG. 7 is a view according to arrow 6 in FIG. 4;

FIG. 8 is a longitudinal sectional view of a part of an internal structure of a nuclear reactor supporting a reactor core.

FIG. 9 is an enlarged view showing details of FIG. 8;

FIG. 10 is a view according to arrow 9 in FIG. 9;

FIG. 11 is a longitudinal sectional half view of a part of an internal structure constituting a conduit of a cooling liquid metal of a main container.

FIG. 12 is a sectional view taken along arrow 11-11 in FIG.

FIG. 13 is a top view of a closed slab of a reactor vessel.

FIG. 14 is a partial cross-sectional view of the periphery of a closed slab of a reactor vessel.

FIG. 15 is a top view of a portion of the reactor closure slab.

FIG. 16 is a partial longitudinal sectional view taken along arrow 15-15 in FIG.

FIG. 17 is a sectional view of the main vessel and the internal structure of the nuclear reactor, showing the disassembly order of the internal structural elements.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main container 4 Closed slab 5 Primary pump 6 Intermediate heat exchanger 6b Outlet opening 6c Protection plate 11 Core 12 Girder (supporting element) 12a Central pivot 13 Floor plate (supporting element) 14 Support plate 15 Waste material recovery device 16 Inner container 16a Stage 16b Outer cylinder 16c Inner cylinder 19a / 19b Area 22 Cylindrical body 22a, 27, 36 Maintaining / supporting mechanism, circular flange 24 Casing 25 Induction pipe 26 Support plate 27 Support mechanism 28 Support surface 30 Pipe 33 Circulation space 34, 42 Key 35 Piping port 36 Annular flange 37 Seal ring 38 Supporting / waterproof joint 39 Joint 52 Supporting mechanism 54 Tie beam 60a, 60b Projection for closing

────────────────────────────────────────────────── ─── Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G21C 1/02 G21C 5/00 JICST file (JOIS)

Claims (21)

(57) [Claims] 1. A main vessel (1) containing a reactor core (11) submerged in a cooling liquid metal, and at least one unit for circulating the cooling liquid metal in the main vessel (1).
Primary pump (5) and at least one intermediate heat exchanger submerged in the cooling liquid metal (6), an internal structural element attached to the main container (1) within the main container (1) A large metal element assembled therein, and further comprising, in the main vessel (1), an area (19a) for receiving the heated liquid metal exiting the core and a cooled exit from the intermediate heat exchanger (6). An inner container (16) forming an area (19b) for receiving liquid metal, a cylinder (22) for piping of cooling liquid metal in contact with the inner wall of the main container (1), and a support element for the core (11) (12, 13), wherein each of the internal structural elements (12, 13, 16, 22) is fixed to the main container (1) by simple support without using mechanical fixing means. (1) and internal structural elements (12, 13, At least one component of the retention and support mechanism for the corresponding mechanisms (22a, integrated fast neutron reactors, characterized in that it comprises a 27, 36) of the assembly constituted by 6 and 22). 2. Each of the internal structural elements (12, 13, 15, 1)
6. The nuclear reactor according to claim 1, wherein the support mechanism of (6, 22) has at least one contact surface machined with high precision. 3. The structural element (12, 13, 15, 16, 2)
3. The nuclear reactor according to claim 2, wherein the machined contact surface of the support mechanism of (2) is turned. 4. An internal structural element (12, 13, 15, 1)
The nuclear reactor according to any one of claims 1 to 3, wherein at least one of the support mechanisms (6, 22) is a forged and machined circular flange (22a, 36). 5. The core support element (12, 13) comprises a soleplate connected to a conical support plate (26), said conical support plate comprising a circular flange (27).
And wherein the circular flange (27) has a support surface disposed on an annular surface of a portion (28) formed by forging and machining of the side wall of the main container (1). The nuclear reactor according to any one of claims 1 to 4, wherein 6. The core support element (12, 13) comprises a lower part of the fuel assembly, i.e., a girder (12) for mounting the legs, the girder being horizontal to the floor plate (13). The girder (12) includes a base supported on the upper plate, at least one central pivot (12a) associated with a mounting part fixed to the upper plate of the sole plate (13), and a girder (12).
6. Reactor according to claim 5, characterized in that it comprises at least one key for preventing rotation about the floor (13) about 2a). 7. At least one liquid sodium guide pipe (25) disposed in a girder (12) below a reactor core (11) is fixed to a bottom plate (13) and connected to one end thereof. A mouth (35), and a girder (12) at the location of the liquid metal passage opening;
A sealing ring (37) which is incorporated in the opening of the girder (12) with a gap in the radial direction and has an inner hole for attaching a piping port (35) of the floor plate (13); (37) includes a support and waterproof joint (38) disposed on the girder (12) and a radially deformable joint (39) for ensuring the sealing around the pipe port (35). The nuclear reactor according to claim 6, comprising: 8. A bottom plate (13) is provided with a cooling liquid metal pipe (30) on the inner wall of the main container (1), and one end of the pipe (30) is fixed to a lower portion of the bottom plate. The other end of (30) is connected to a floor plate (2) on a support mechanism (28) protruding inside the inner container (1) so as to communicate with a cooling sodium circulation space (33) on the inner wall of the main container (1).
The reactor according to any one of claims 5 to 7, wherein the reactor is inserted into a through-opening of the support mechanism (27). 9. A cylindrical inner cylinder (16) in which the inner container (16) is coaxially arranged with each other by a step (16a).
c) and a cylindrical outer cylinder (16b), wherein the support mechanism for the inner container (16) comprises an annular flange (36) with a support surface arranged on the periphery of the soleplate (13). The reactor according to any one of claims 5 to 8, wherein: 10. The step (16a) of the inner container (16) comprises:
10. The nuclear reactor according to claim 9, comprising a flat annular plate. 11. Reactor according to claim 9, characterized in that the step (16a) of the inner vessel (16) consists of a cone-shaped plate. 12. A conical support plate (2) is provided at its lower part with a sodium pipe cylinder (22) for cooling the container.
The support mechanism (2) for the sole plate (13) fixed to the end of (6)
The reactor according to any one of claims 5 to 11, further comprising a support mechanism (22a) having a flat annular support surface supported on the corresponding annular plane of (7). . 13. Core waste, wherein the internal structural elements are further mounted without restraint on a support plate (14) coaxially fixed to the main vessel (1) at the bottom of the main vessel (1). Reactor according to any of the preceding claims, comprising a recovery device (15). 14. The pump casing (24) is provided with a liquid metal guide pipe (2) opposite the connection of the pipe (35).
A nuclear reactor according to claim 7, characterized in that it is fixed to the end of (5) and to which the lower end of the primary pump (5) is attached. 15. An opening for an intermediate heat exchanger (6) is provided in a conical support plate (26) of a bottom plate (13), and a protective plate (6c) is provided for an intermediate heat exchange. Tableware (6)
13. A conical support plate (26), which is fixed to a conical support plate (26) at the position of the opening for the intermediate heat exchanger opposite the outlet opening (6b). The reactor described in Crab. 16. At least two of the elements in the main container (1) and the internal structural elements (12, 13, 15, 16, 22) that support each other are provided with mortise grooves facing each other at the support position. The reactor according to any one of claims 1 to 15, wherein rotation of the two elements is prohibited by inserting a key (34, 42) into the opposing tenon groove. 17. The support mechanism for the internal structural elements and the elements of the main container (1) is provided with an aluminized plate between the respective contact surfaces for separating the contact surfaces of the support mechanism. 2. The method according to claim 1, wherein:
A nuclear reactor according to any one of the preceding claims. 18. The method according to claim 1, wherein the main container has a cylindrical shape as a whole, and a bottom plate having a flat bottom. Nuclear reactor as described. 19. Reactor according to claim 18, wherein the pump (5) and the heat exchanger are arranged along substantially the entire axial height of the vessel (1). 20. The main container comprises a closure slab (4) consisting of a very thick steel flat plate, said plate being disassembled to open the upper end of the container (1). Claims 1 to 5 characterized in that it comprises a sliding and rotating support mechanism (52) and a tie beam (54) screwed to the reactor fixing structure (2). Item 20. The nuclear reactor according to any one of Items 19 to 18. 21. A circular plug (8) is rotatably and removably mounted in the opening of the slab, which is extended diametrically by two grooves, in the closing slab (4), said two grooves being provided. Some of the dismantling closure projections (60
21. A nuclear reactor according to claim 20, wherein each of a, 60b) is fixed.