JP3147686B2 - Annular tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annular tank in which a liquid such as a radioactive fluid is stored in an annular storage tank body.

[0002]

2. Description of the Related Art Generally, an annular tank having an annular storage tank body is used for storing a high-level radioactive solution generated in a spent nuclear fuel reprocessing plant or the like. In such an annular tank, the radioactive fluid filled in the container is arranged in an annular shape, so that criticality safety can be ensured. For example, the annular tank disclosed in Japanese Patent Application Laid-Open No. 4-172299 has a plurality of circular projecting edges formed in a circular shape in plan view on a ring-shaped upper lid of the annular tank. One end of a nozzle part (reducer) with a smaller diameter than the edge is welded. By welding an external pipe to the other end of the nozzle part, high-level radioactive fluid is passed through the external pipe to the inside. It is supposed to be introduced. In such an annular tank, since the external piping is welded to the upper lid of the annular tank via the nozzle component, there is an advantage that machining of the upper lid is simplified.

[0003]

In the above-described annular tank, stainless steel excellent in strength and corrosion resistance is generally used as a material of each member. When the temperature is high, the external pipe needs to be made of a material having higher corrosion resistance such as zirconium. However, in the above annular tank, since the upper lid and the nozzle part or the nozzle part and the external pipe are welded and joined, the parts must be made of the same material. For this reason, there is a problem that only a certain external pipe cannot be made of a different material from the others.

The present invention has been made in order to solve the problems of the above-described conventional annular tank, and an object of the present invention is to provide an annular tank which can use an external pipe made of a material different from the others. .

[0005]

In the annular tank according to the present invention, the upper end opening of the annular storage tank main body is concealed by a ring-shaped upper lid, and the opening edge of the external pipe is welded and fixed to the upper lid. A plurality of through-holes having a nozzle portion therearound, and one through-hole having a protruding edge in the periphery is provided. The dissimilar joint composed of the same material as that of the protruding edge is welded and fixed, and a joining nozzle made of the same material as the upper end is fixed to the upper end of the dissimilar joint. The joint pipe stand has a small-diameter pipe portion having a lower end portion and an upper end portion disposed on the inner peripheral side and the outer periphery of the dissimilar material joint, and extends radially outward from an outer peripheral portion of the small-diameter pipe portion. And a large-diameter pipe welded to the upper end opening edge of the small-diameter pipe. The end, the opening edge portion is characterized in that a sufficient length located below the dissimilar material joint.

[0006]

In the annular tank having the above construction, the fitting nozzle is fixed to the projecting edge of the upper lid via the dissimilar joint, so that the material of the upper end of the dissimilar joint and the joining nozzle are supplied to the external piping. By making the material equivalent, it becomes possible to fix those parts by welding. Further, since the opening edge of the small diameter pipe portion of the joining pipe portion is located below the dissimilar material joint, the liquid flowing through the small diameter pipe portion does not contact the dissimilar material joint. Therefore, it is not necessary to consider the corrosion of the dissimilar joint due to the liquid, and the annular tank can be used safely.

[0007]

【Example】

(1) Configuration of Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side sectional view showing a storage tank main body 1 of an annular tank according to an embodiment, and FIG. 2 is a plan view. In FIG. 1, reference numeral 2 denotes a base plate. The base plate 2 has a ring shape, and protrudes in a flange shape from the inner and outer peripheries of the storage tank main body 1 so that a base (not shown) is formed by bolts or the like.
Is to be fixed to. A lower ring 3 is fixed to an upper surface of the base plate 2. Lower ring 3
Is formed with a concave portion 3a extending over the entire circumference. The bottom surface of the concave portion 3a is inclined so as to have a downward slope from the left side to the right side in FIG.
In addition, a drain port (not shown) is disposed at the lowest position on the bottom surface of the concave portion 3a. In the drawing, reference numeral 60 denotes a first lower flat plate, 61 denotes a second lower flat plate, and the first lower flat plate 60 is attached to the base plate 2 by bolts,
The lower flat plate 61 is attached to a base (not shown) by bolts together with the base plate 2.

The upper edge of the lower ring 3 has an inner wall 4
The liquid storage section outer wall 5 is fixed, and the high-level radioactive fluid is stored in the liquid storage section 6 formed by the lower ring 3, the liquid storage section inner wall 4, and the liquid storage section outer wall 5. The upper end opening of the liquid storage unit 6 is concealed by an upper ring (upper lid) 7 fixed to the upper edges of the inner wall and the outer walls 4 and 5 of the storage unit.

On the lower surface of the upper ring 7, there are formed two protruding edges 7a, 7b extending over the entire circumference thereof, and these protruding edges 7a, 7b are formed on the upper edge of the inner wall 4 and the outer wall 5 of the liquid storage section. It is fixed to the part by welding. Also, the upper ring 7
Are formed with holes (through holes) 10 penetrating in the vertical direction in the circumferential direction. Around the hole 10, a cylindrical upper nozzle (stub portion) 12 and a lower nozzle 13 are formed. An outer pipe 15 for low temperature is fixed to the upper nozzle 12 by butt welding, and an inner pipe 16 is fixed to the lower nozzle 13 by butt welding. FIG. 4 shows an example in which the internal piping 16 is provided. However, there is no internal piping 16 in some places, and therefore, there is also a place where there is no lower nozzle 13 for fixing this.

In the upper ring 7, one hole (through hole) 20 having an inner diameter larger than the hole 10 is formed.
A convex edge 22 having a cylindrical shape is formed in the upper end opening of the zero. A dissimilar material joint 25 is fixed to the protruding edge portion 22 by butt welding. The dissimilar material joint 25 is formed by joining materials made of two types of materials by diffusion bonding, explosive bonding, hot rolling bonding, or the like, and processing the cylindrical material. In this embodiment, the dissimilar material joint 25 includes a lower end 25a made of stainless steel and an upper end 25b made of zirconium. It should be noted that a different material can be interposed between the two types of materials. For example,
Tantalum can be interposed between stainless steel and zirconium.

The lower end 25a of the dissimilar material joint 25 is made of stainless steel because the upper ring 7 is also made of stainless steel, so that both can be welded and fixed.
The reason why the upper end portion 25b is made of zirconium is to enable welding and fixing to the reducer (joining nozzle) 30. As shown in FIG. 3, the reducer 30 includes a cylindrical small-diameter tube portion 31 and a large-diameter tube portion 32 extending axially in a skirt shape from an outer peripheral portion of the small-diameter tube portion 31. The reducer 30 is made of zirconium, and the large-diameter pipe portion 32 is fixed to the upper end portion 25b of the dissimilar material joint 25 by butt welding.

A high-temperature external pipe (not shown) made of zirconium is connected to the upper end of the small-diameter pipe section 31 of the reducer 30. A radioactive solution having a higher temperature than that of the above-described low-temperature external pipe 15 is allowed to flow through the high-temperature external pipe. Radioactive solutions with high temperatures are highly corrosive, and therefore, zirconium, which has better corrosion resistance than stainless steel, is used as a material for high-temperature external piping. Further, the lower end of the small diameter pipe portion 31 is connected to the dissimilar material joint 25.
It extends to below. Thereby, the small diameter pipe section 3
The radioactive solution flowing through 1 is injected into the liquid storage unit 6 without contacting the dissimilar material joint 25.

Next, a ring-shaped first upper flat plate 40 and a second upper flat plate 41 are attached to the inner and outer peripheral sides of the upper surface of the upper plate 7 by bolts or the like. The inner peripheral edge of the lower surface of the first upper flat plate 40 and the first lower flat plate 60
, A stainless steel plate 52 forming an outer shell inside the liquid storage tank main body 1 is fixed by welding. A neutron moderator 50 is attached to the outer peripheral surface of the stainless steel plate 52. As a material of the neutron moderator 50, for example,
Any material containing sufficient hydrogen and carbon, such as resins such as high-density polyethylene and silicone resin, concrete and carbon blocks, can be used.

A neutron absorber 43 is attached to the outer peripheral surface of the neutron moderator 50. As a material of the neutron absorber 43, cadmium, boron, gadolinium, samarium, europium, or the like may be used alone, or a compound of such a substance, or a composite of such a substance or a compound and another substance may be used. Can be. further,
The neutron-absorbing substance as described above can be mixed with, for example, plastic to form a plate-like composite.

Next, a stainless steel plate 58 constituting an outer shell of the liquid storage tank body 1 is fixed to the outer peripheral edge of the lower surface of the second upper flat plate 41 and the second lower flat plate 61 by welding. . A neutron moderator 56 is attached to the inner peripheral surface of the stainless steel plate 58, and a neutron absorber 54 is attached to the inner peripheral surface of the neutron moderator 56. The neutron moderator 56 and the neutron absorber 54 are made of the same material as the neutron moderator 50 and the neutron absorber 43.

(2) Operation and Effect of the Embodiment In the annular tank having the above-described configuration, the radioactive solution flowing through the low-temperature external pipe 15 passes through the hole 10 of the upper plate 7 and the internal pipe 16 and is stored in the storage tank. Injected into 6. The radioactive solution flowing through the high-temperature external piping is reduced by the reducer 3.
The liquid is injected into the liquid storage tank 6 through the small-diameter pipe portion 31 of the “0”. At this time, since the small diameter pipe portion 31 extends to the lower side of the dissimilar material joint 25, the radioactive solution is injected into the liquid storage unit 6 without contacting the dissimilar material joint 25. The radioactive solution flowing through the high-temperature external pipe is high in temperature and highly corrosive on the upstream side, but is cooled and weakened when injected into the circular storage tank 6. Therefore, there is no problem such as corrosion of the liquid storage tank 6.

In the annular bath having the above structure, since the dissimilar joint 25 is interposed between the protruding edge portion 22 of the upper plate 7 and the reducer 30, the upper end of the dissimilar joint 25 and the material of the reducer 30 are heated to a high temperature. By using the same zirconium as the material of the external piping, the parts can be welded and fixed. In addition, since the radioactive liquid flowing through the small-diameter tube portion 31 does not come into contact with the dissimilar joint 25, there is no need to consider corrosion of the dissimilar joint 25 due to the radioactive liquid, and the annular tank can be used safely. .

(3) Modifications The present invention is not limited to the above embodiment, and various modifications are possible. For example, as a method for forming the dissimilar material joint 25, in addition to the above-described joining method, it is also possible to use friction welding or the like in which two kinds of materials are brought into contact with each other and relatively rotated to frictionally heat. The forming method is arbitrary. Further, in the above embodiment, the material of the dissimilar material joint 25 is stainless steel and zirconium, but a combination of other materials such as stainless steel and titanium, or stainless steel and a titanium alloy (for example, titanium 5 tantalum) may be appropriately selected. it can.

[0019]

As described above, according to the present invention, even when the material of a certain external pipe is different from the material of another external pipe, the external pipe can be fixedly welded to the nozzle. In addition, the effect of preventing corrosion of the dissimilar material joint can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an annular tank according to an embodiment.

FIG. 2 is a plan view showing an annular tank according to the embodiment.

FIG. 3 is a side view showing a part of an annular tank to which an external pipe for high temperature is connected.

FIG. 4 is a side view showing a part of an annular tank to which a low-temperature external pipe is connected.

[Description of Signs] 1 ... Reservoir main body, 7 ... Top plate (top lid), 10 ... Hole (through hole), 12 ... Top nozzle (stub portion), 20 ... Hole (through hole), 22 ... Protruded edge Part, 25: dissimilar material joint, 25a: lower end, 25b: upper end, 30: reducer (joint nozzle), 31: small diameter pipe, 32: large diameter pipe.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21F 9/22 G21C 19/40

Claims (1)

(57) [Claims] 1. A through hole having a ring-shaped upper lid for covering an upper end opening of an annular storage tank main body, and having a nozzle portion around the periphery for welding and fixing an opening edge of an external pipe to the upper lid. Are provided, and one through-hole having a protruding edge is provided on the periphery, and the upper and lower ends are formed of different materials, and the lower end is formed of a material equivalent to the same protruding edge. The dissimilar material joint is welded and fixed, and an upper end of the dissimilar material joint is fixed to a joining nozzle made of the same material as the upper end, and the joining nozzle is connected to its lower end and upper end. A small-diameter pipe portion which is disposed on the inner peripheral side and the outer side of the dissimilar joint, and a large-diameter pipe which extends radially outward from an outer peripheral portion of the small-diameter pipe portion and is welded to an upper end opening edge of the dissimilar joint. And a lower end of the small-diameter pipe portion, the opening edge of which is formed of the dissimilar material. An annular tank characterized by having a length sufficient to be positioned below a hand.