JPH0862371A - Upper end plate type reactor vessel - Google Patents

Abstract

PURPOSE: To provide a reactor vessel which is suitable to the core upper mechanism drawing method for making the reactor vessel compact, easily adaptable to various modes of reactor vessel, and improved in manufacturing property, economic property and structural health. CONSTITUTION: This reactor vessel is formed by combination of a reactor vessel body 10 for fast reactor, and an upper end plate type superstructure 20 situated so as to cover its upper part to form a cover gas boundary and supported independently of the reactor vessel body 10. The upper end plate superstructure is formed out of an upper end plate 32 having an arch structure having an opening in the center and a flange part 40 on the inner circumference of the opening, and a heat shielding body 34 of laminated structure provided under it. A drawing type core upper mechanism 26 is supported by the flange part of the upper end plate. Upper outflow and inflow pipings 22, 24 are curved substantially at a right angle after passing the upper opening of the reactor vessel body, and extended through the upper end plate, and a bellows 56 is provided in the through part to absorb the piping thermal expansion displacement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor vessel comprising a combination of a reactor vessel body and an upper mirror lid type upper structure which are separated from each other. More specifically, the upper mirror lid type upper structure is an arch type structure. And an upper mirror lid having an opening in the center and a flange portion on the inner circumference of the opening, and a heat shield provided below the upper mirror lid to support the pull-out type core upper mechanism on the flange portion of the upper mirror lid. The present invention relates to a mirror lid type reactor vessel. This reactor vessel can be applied to, for example, a liquid sodium cooled fast reactor.

[0002]

2. Description of the Related Art A current reactor vessel has a structure in which a shield plug is installed on an upper portion of a bottomed cylindrical reactor vessel body. The shield plug is composed of a combination of a fixed plug and a rotary plug, and an upper core mechanism penetrates the rotary plug. There is a cover gas space filled with a cover gas (usually argon gas) between the coolant liquid level and the shield plug in the furnace container body.

The shield plug here serves both as a radiation shield and a heat insulator and as a cover gas boundary. Therefore, in addition to forming a radiation shielding layer filled with heavy concrete, a gas flow path is provided in the lower part so that cooling with nitrogen gas or the like is possible. Since such a shielding plug has a total weight of several hundreds of tons to over 1,000 tons in some cases, it has a multiple welding box structure (multi-box structure) in order to enhance rigidity. That is, a large number of vertical reinforcing members are radially and circumferentially provided between a plurality of horizontal flat plates, and a large number of box-shaped structures (cell structure) are formed by the flat plates and the reinforcing members.
Is making.

Therefore, the number of welding steps and the amount of material are very large. Also, in order to keep the upper surface of the shielding plug at a low temperature, heat is shielded and cooled in the box structure, but in the case of the upper inflow and outflow piping system, the ambient temperature rises in the box structure cell through which the high temperature main piping passes, and Temperature unevenness easily occurs between mold structure cells. For this reason, in the case of the shielding plug and the upper inflow and outflow piping, use a forced cooling facility such as nitrogen gas and make sure that the box-shaped cell near the pipe penetration does not significantly differ from the box-shaped cells in other parts. It is necessary to perform uniform and precise cooling to achieve a uniform temperature.

An upper end plate type fast reactor has been proposed as a technique capable of solving the problem of such a box-shaped shielding plug (Japanese Patent Laid-Open No. 6-27280). This is to cover the upper part of the reactor vessel with an upper mirror plate to form a cover gas boundary, provide an upper structure including a heat insulating structure in the cover gas space inside the reactor container, and arrange a radiation shield above the upper mirror plate. Then, the core upper mechanism is installed by penetrating the radiation shield, the upper end plate and the upper structure.

[0006]

The upper end plate type fast reactor proposed here has a structure in which the periphery of the upper end plate is flange-connected to the reactor vessel or is welded directly to the reactor vessel. It is difficult to adapt to various styles. In addition, when attaching the pull-out type upper core mechanism, it will be supported by the radiation shield located above the reactor vessel,
Since the supporting part requires high dimensional accuracy with high horizontal flatness, the manufacturability is low, and it is insufficient for downsizing the entire reactor vessel. Further, the arrangement of the inflow and outflow pipes for the coolant is not specified in particular, and there is room for improvement and improvement so as to be compatible with various types of reactor vessels.

An object of the present invention is to adapt to an upper core mechanism withdrawing method for compacting a reactor vessel, to facilitate adapting to various modes of the reactor vessel, manufacturability, economical efficiency,
Another object of the present invention is to provide a top-cover-type reactor vessel which can improve the structural soundness and can be easily designed.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a furnace container body for a fast reactor and a cover gas boundary formed so as to cover the upper portion thereof are formed and are separately supported from the furnace container body. An upper-view-cover-type nuclear reactor vessel is formed by combining the upper-view-cover-type upper structure described above. Here, the upper structure of the upper mirror lid is
The upper mirror cover has an arch-shaped structure and has an opening at the center and a flange portion on the inner periphery of the opening, and a heat shield provided below the upper mirror cover. The pull-out type upper core mechanism is supported by the flange portion of the upper mirror lid.

The flange portion of the upper mirror lid is provided, for example, on the inner peripheral side of the lower end of the cylindrical portion that extends downward from the central opening of the upper mirror lid. The radiation shield is a floor concrete located above the upper mirror lid and having an opening of substantially the same diameter as the upper mirror lid, and an outer peripheral side fixed type and an inner peripheral side provided so as to reach the upper surface of the floor concrete from above the flange portion. This is done with a movable double shield. The upper inflow / outflow pipe is provided at a substantially right angle after passing through the upper opening of the furnace vessel main body and penetrating the upper mirror lid, and a bellows is provided at the penetrating portion to absorb the thermal expansion displacement of the pipe.

[0010]

The type in which the reactor vessel main body and the upper mirror lid type upper structure are separately installed is suitable for various types of reactor vessels. The arch-shaped upper mirror lid has a high loading capacity and receives the weight of the pull-out type upper core structure. In addition, the upper mirror lid type upper structure achieves uniform temperature with a simple design by the lower heat shield and the outer cooling on the upper side. Inflow and outflow piping).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing an embodiment of a top-cover-type reactor vessel according to the present invention. This reactor vessel is a reactor vessel body 10 for a liquid sodium cooled fast reactor, and a cover gas boundary is formed so as to cover the upper portion of the reactor vessel body 10 and is separately supported from the reactor vessel body 10. In combination with the upper mirror lid type upper structure 30.

As clearly shown in FIG. 2, the reactor vessel body 10 is a bottomed cylindrical vessel having an open top, and a flange portion 14 at a pedestal (supporting pedestal) 12 on the reactor building side. Supported. Specifically, the pedestal 1
A steel plate (sole plate) having horizontal flatness is installed on the upper surface of the furnace 2, and the furnace vessel body 10 is installed so that the lower surface of the flange portion 14 is in contact therewith. The outside of the furnace container body 10 is covered with a guard vessel 16. The guard vessel 16 is supported by the reactor building at the upper flange portion.

A core 2 is provided at the center of the inside of the furnace container body 10.
No. 0 is installed, the heat generated in the core 20 is removed by the coolant sodium flowing in from the cold leg pipe 22, and the coolant sodium having a high temperature is hot leg pipe 2
It flows out from 4. These sodium inflow and outflow pipes do not penetrate the side surface of the furnace vessel body 10 but are drawn out through the upper opening to the outside. An upper core mechanism 26 is located above the core 20, and the upper core mechanism 26 is of a pull-out type. The space above the liquid surface of sodium in the furnace container body 10 is a cover gas (usually argon gas) space 28.

The upper mirror lid type upper structure 30 for covering the upper portion of the furnace container body 10 is composed of an upper mirror lid 32 and a heat shield 34 provided below the upper mirror lid 32. The upper mirror lid 32 is shown in FIG.
As clearly shown in FIG. 2, a cylindrical portion 38 is provided with an opening 36 in the center with an arcuate structure as a whole, and a cylindrical portion 38 hangs downward from the opening 36, and a flange provided on the inner peripheral side of the lower end of the cylindrical portion 38. It has a section 40. Further, as shown in FIG. 3, the heat shield 34 has a structure in which a large number of stainless steel plates 42 are stacked at regular intervals via spacers 44 and held by columns 46. The heat insulating laminated structure is provided to prevent the heat from being diffused to the outside through 32. Usually, since the gas is cooled from above the upper mirror lid 32, the cover gas space 28 has a lower temperature in the upper portion and a higher temperature in the lower portion, so that the cover gas may spontaneously convect. The laminated heat shield 34 shown in FIG. 3 also functions to block such natural convection.

As described above, the upper mirror lid type upper structure 30 is
It is installed so as to cover the upper part of the furnace container body 10. The details are shown in FIG. The installation portion 48 formed on the outer periphery of the upper mirror lid 32 is installed on the pedestal 12 on the reactor building side (actually, on a steel plate having horizontal flatness as described above). As is apparent from the drawing, the upper mirror lid 32 is completely separated from the furnace vessel body 10 and is on the same pedestal 12, but the upper mirror lid installation portion 48 is located on the flange portion 14 of the furnace vessel body. The relationship is such that it is located on the outer peripheral side.
A U seal 50 is provided between the two to form a cover gas boundary.

In the present invention, the pull-out type core upper mechanism 26
Is mounted on the flange portion 40 provided in the central opening of the upper mirror lid 32, and is supported by the arch-shaped upper mirror lid 32. A double O-ring 52 is used to seal that portion.

The upper sodium inflow and outflow pipes (hot leg pipe 22 and cold leg pipe 24) are connected to the furnace container body 10.
It is provided so as to rise straight up from above through the upper opening so as to be bent at a substantially right angle inside the heat shield 34, and penetrates the upper mirror lid 32. Therefore, a bellows 56 is provided in the penetrating portion 54 to form a cover gas boundary, and the bellows 56 absorb the thermal expansion displacement of the pipe.

In this embodiment, the shielding function is the upper mirror lid 32.
Floor concrete 60 provided on the upper part of the, and double additional shields 62 arranged around the central opening of the upper mirror lid 32,
64 does. The additional shield 62 on the outer peripheral side is a fixed shield and has a lead can structure. The additional shield 64 on the inner peripheral side is
It has a movable structure that can be removed when refueling, and is made of steel. These double additional shields 62 and 64 mainly shield gamma rays of sodium-24, and
It has the function of lowering the dose equivalent rate on the upper surface of the to a predetermined value.

The ring girder 66 supports the floor concrete 60 made of a steel frame having concrete inside and transmits the load to the building side, and is a ring-shaped steel structural material. Ring girder 66
The concrete filled in the inside also functions as a radiation shield. The snubber 68 is a vibration isolator that fixedly supports the pipe against earthquake vibration.

[0020]

The present invention having the above-mentioned structure has the following effects. Since the weight of the upper core mechanism is received by the arch-shaped upper mirror lid, which has a shape with high loading capacity, the amount of material can be reduced compared with the conventional box-shaped shield plug, and the man-hours for welding can also be reduced, thus improving manufacturability. improves. Furthermore, the entire reactor can be made compact. Since the upper mirror lid type upper structure of the present invention is configured to be installed separately from the reactor vessel body, it is easy to adapt to various types of reactor vessels. In addition, the inside of the upper lid type upper structure can obtain a uniform temperature with a simple design by cooling the inner heat shield and the outside of the upper lid, so a system in which high temperature piping is incorporated locally (upper inflow and outflow piping) Also fits. Compared with the conventional box-shaped shield plug, temperature uniformity is easily achieved, so thermal deformation is small and the structural soundness margin is improved. In addition, compared to the assumption of main pipe damage inside the furnace upper box, it is easier to take measures and safety is improved. Although the dimensional accuracy of horizontal flatness is required for the part on which the pull-out type core upper part mechanism is mounted and supported, the support system of the present invention limits the part supported by the upper mirror lid, and is therefore highly manufacturable.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a top-cover-type reactor vessel according to the present invention.

FIG. 2 is an explanatory view of a furnace container main body and an upper mirror lid.

FIG. 3 is a structural explanatory view of a heat shield.

FIG. 4 is an explanatory view showing an installed state of the upper mirror lid type upper structure.

[Explanation of symbols]

 10 Reactor Vessel Main Body 20 Core 22 Cold Leg Piping 24 Hot Leg Piping 26 Extraction Type Core Upper Mechanism 30 Upper Mirror Lid Upper Structure 32 Upper Mirror Lid 34 Heat Shield 36 Open 38 Cylinder 40 Flange 54 Penetration 56 Bellows 60 Floor Concrete 62 , 64 additional shielding

Claims (3)

[Claims] 1. A reactor vessel main body for a fast reactor, and an upper mirror lid-type upper portion that is positioned so as to cover the upper portion of the furnace vessel body and forms a cover gas boundary and is separately supported from the furnace vessel body. The upper structure of the upper mirror lid is an arch-shaped structure and has an opening in the center and a flange portion on the inner peripheral side of the opening, and a heat provided below the upper cover. An upper reactor lid type reactor vessel comprising a shield and a pull-out reactor upper core mechanism supported on the flange portion of the upper reactor lid. 2. A cylindrical portion is provided so as to extend downward from a central opening of the upper mirror lid, and a flange portion of the upper mirror lid is provided on an inner peripheral side of a lower end of the cylindrical portion, and the upper mirror is provided above the upper mirror lid. A floor concrete having an opening having substantially the same diameter as the lid is located, and a double type additional shield is provided on the outer peripheral side and on the inner peripheral side so as to reach the floor concrete upper surface from above the flange portion. Item 1. The upper mirror lid type reactor vessel according to Item 1. 3. An upper inflow / outflow pipe is provided at a substantially right angle after passing through an upper opening of a furnace vessel main body and penetrating an upper mirror lid, and a bellows is provided at the penetrating portion to absorb thermal expansion displacement of the pipe. The upper mirror lid type reactor vessel according to claim 1.