JPH10253799A - Method for sealing hermetically sealing container of radio active waste encasement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce on-site welding work in encasing radioactive wastes in a sealed container and prevent an interstice from appearing between a container made of a strong material and a container made of an anticorrosive material due to the thermal deformation caused by welding. SOLUTION: A container 1a made of a strong material is constituted by encasing an encasement 2 for radioactive wastes in a main body 4 of the container 1a which is placed so that an opening can face upward and welding 12 a lid 15 made of a string material onto the opening of the main body 4 of the container 1a, which is lifted and then is placed on a floor plate 21 made of an anticorrosive material. Subsequently, a main body 20 of a container 1b made of an anticorrosive material fitted with the main body 4 of the container 1a made of a strong material beforehand is lifted by a lift equipped with a holding-down device so that an opening can face downward and is press-fitted and thermally inserted into the outside of the main body 4 of the container 1a made of a storing material by the holding-down device while heating the main body 20 of the container 1b made of an anticorrosive material. Afterward, a container 1b made of an anticorrosive material is constituted by welding 43 the lower end of the main body 20 of the container 1b onto the floor plate 21 made of an anticorrosive material and the encasement 2 for radioactive wastes is encased in a sealed container 1 comprising the container 1a made of a strong material and the container 1b made of an anticorrosive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed radioactive waste disposal container (overpack) for geologically disposing of radioactive waste used in a nuclear power plant or the like in a stable state. The present invention relates to a method for enclosing a radioactive waste container in a sealed container which can be manufactured by the method described above.

[0002]

2. Description of the Related Art High-, medium-, and low-activity materials (waste, spent fuel, etc.) generated in nuclear reactors and other nuclear reactors are classified by level (high, medium, low).
They are stored in special sealed containers suitable for them, and stored and stored.

[0003] In order to isolate the radioactive waste from the living sphere by storing and disposing the radioactive waste in a deep underground layer, the radioactive waste is first vitrified to form a storage container called a vitrified body. The storage container is subjected to an overpacking process for further sealing it with a sealed container called an overpack made of metal or the like, and then the sealed container is carried into a geological disposal site, and these are disposed in a disposal hole provided in the geological disposal site. And a geological disposal in which a buffer material such as bentonite is filled around the sealed container loaded in the disposal hole.

[0004] Here, since the production of the sealed container must be performed by remote control in view of handling waste, there is a condition that the production must be simple, reliable, and efficient.

[0005] However, the production of the above-mentioned sealed container has been repeated only in trials and studies in the experimental stage, and there is no equipment at the practical stage at present.

FIG. 17 shows an example of a sealed container experimentally manufactured. The sealed container 1 is called a canister in which radioactive waste is vitrified and housed in the container as a vitrified body. The radioactive waste container 2 has a cylindrical shape as a whole for storing in a sealed state.

The sealed container 1 has an opening 3 on the upper side and a strength material container body 4 having a cylindrical storage space s for housing the radioactive waste container 2 therein, and the strength material container body 4.
A strength material container 1a comprising a disc-shaped strength material lid 6 dropped into the opening 3 through the hanging portion 5 and sealed by welding, and further provided on the outer periphery of the opening 3 with the opening 3 A corrosion-resistant container main body 8 provided with an outer peripheral lid 7a having a larger opening 7 formed thereon so as to closely cover the outer periphery of the strength material container main body 4, and a corrosion-resistant material center integrally attached to the strength material lid 6; A corrosion-resistant container 1b comprising a lid 9 and a corrosion-resistant ring lid 10 which is fitted in a ring-shaped groove between the opening 7 and the corrosion-resistant central lid 9 and sealed by welding.
The strength material container body 4 and the corrosion-resistant material container body 8 are assembled integrally in a factory or the like, and the strength material cover 6 to which the corrosion-resistant material center cover 9 is attached and the corrosion-resistant material ring cover 10 are also provided. These are manufactured in a factory or the like, and are carried into a radioactive waste treatment facility to enclose the radioactive waste container 2.

In order to enclose the radioactive waste container 2 in the sealed container 1 in the radioactive waste treatment facility, first, the radioactive waste container 2 is inserted into the strength material container main body 4 as shown in FIGS. After being suspended and accommodated in the accommodation space s, the strength material lid 6 is lifted by the lid suspension device 11 (FIG. 17) and fitted on the opening 3 to be placed on the radioactive waste container 2. Subsequently, the strength material container body 4 and the strength material lid 6 are welded 1
2, sealing with the strength material container 1a is performed.

Next, as shown in FIG. 19, the corrosion-resistant material ring cover 10 is dropped into a ring-shaped groove between the opening 7 of the corrosion-resistant material container main body 8 and the corrosion-resistant material central cover 9 as shown in FIG. Between the outer periphery of the ring lid 10 and the opening 7 of the outer peripheral lid 7a, and between the inner periphery of the corrosion-resistant ring lid 10 and the corrosion-resistant central lid 9,
Sealing with the corrosion-resistant material container 1b is performed by performing one round welding 13 and 14 in the circumferential direction, respectively.

Thus, the outer periphery of the strength material container 1a in which the radioactive waste container 2 is housed in a hermetically sealed state is provided with the corrosion-resistant material container 1b.
Thus, a sealed container 1 is formed.

The sealed container 1 assembled as described above is
After the outer periphery is surrounded by a buffer material container made of a buffer material (not shown), geological disposal is performed in a disposal hole of the geological formation.

[0012]

However, the radioactive waste container 2 is sealed in the sealed container 1 by the above-described method.
When the outer periphery of the strength material container 1a is sealed with the corrosion-resistant material container 1b, the outer peripheral cover 7a and the corrosion-resistant material central cover 9
And the corrosion-resistant ring cover 10 are welded twice in the circumferential direction 13,
In particular, the corrosion-resistant ring cover 10 of the corrosion-resistant material container 1b, which needs to be assembled at 14, and is thinner and lighter than the strength material container 1a, rises due to thermal deformation during the two weldings 13 and 14, There is a problem that a gap is formed between the strength material container 1a and the adhesion property is deteriorated, and the heat transfer between the strength material container 1a and the corrosion-resistant material container 1b is deteriorated due to the gap. There was a problem that the cooling effect was reduced.

As shown in FIG. 17, when assembling the corrosion-resistant container body 8 integrally with the outer periphery of the strength material container body 4 in the factory, the outer peripheral lid 7a is welded to the end of the corrosion-resistant container body 8 by welding 7b. In addition, as described above, the outer peripheral cover 7 is provided on the flat upper surface of the strength material container 1a.
It is necessary to weld the anti-corrosion material ring lid 10 between the a and the anti-corrosion material central lid 9, but since the anti-corrosion material container 1 b is thinner than the strength material container 1 a, 7
At the time of performing b, 13, and 14, there is a problem that the dissimilar metal material of the strength material container 1a is mixed, thereby significantly reducing the strength of the welds 7b, 13, and 14 parts. There has been a problem that various measures have to be taken to prevent the problem of mixing different metals.

In view of the above situation, the present invention reduces on-site welding work when accommodating a radioactive waste container in a sealed container, and reduces the distance between the strength material container and the corrosion-resistant material container by thermal deformation due to welding. It is an object of the present invention to provide a method for enclosing a radioactive waste container in a hermetically sealed container, which can be put to practical use without gaps.

[0015]

According to a first aspect of the present invention, there is provided a strength material container body in which a radioactive waste container is suspended and accommodated in a strength material container body having an opening facing upward. A strength material container is constructed by hanging and welding a strength material lid to the opening of the container, and the strength material container is lifted and placed on a horizontally placed anticorrosion material bottom plate, one end of which is open and the other end of which is anticorrosion material. A corrosion-resistant container main body provided with a flange and previously rubbed with the strength material container main body is lifted by a lifting device provided with a pushing device such that an opening faces downward, and the corrosion-resistant container main body is heated by a preheating device. A press-fitting device press-fits the outside of the strength material container body and shrink-fits the same, and then welds the lower end of the corrosion-resistant material body and the bottom plate of the corrosion-resistant material to form a corrosion-resistant material container. And made of corrosion-resistant container Sealed container method for encapsulating radioactive waste container, characterized in that encapsulating the radioactive waste container by the container are those of the.

According to a second aspect of the present invention, there is provided the corrosion-resistant bottom plate,
2. The method for sealing a radioactive waste container in a sealed container according to claim 1, wherein a step-shaped groove having a height adjustment margin with which the lower end of the corrosion-resistant material container main body can be fitted is formed. It is related.

According to the first aspect of the present invention, it is possible to improve the heat transfer by forming a sealed container in which the strength material container and the corrosion-resistant material container are in close contact with each other, and to set the strength material lid to the strength material container body. Since the welding and the welding of the corrosion-resistant bottom plate to the buffer material container main body are only performed locally, the radioactive waste container can be easily and reliably sealed in a sealed container by remote control.

Further, since the corrosion-resistant material container main body is rubbed in advance with the strength material container main body, shrink fitting can be performed reliably and good adhesion can be achieved.

According to the second aspect of the present invention, since the welding is performed at a position farther than the height adjustment allowance from the strength material container main body by the stepped groove, the dissimilar metal of the strength material container main body is formed at the welded portion. Is prevented from being mixed, and a good welded portion can be formed.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a strength material container of a sealed container used in the present invention. The strength material container 1a has a cylindrical shape having an opening 3 on the upper side and containing a radioactive waste container 2 therein. It is composed of a strength material container main body 4 having an accommodation space s, and a disk-shaped strength material lid 15 for closing the opening 3 of the strength material container main body 4, and is manufactured at a factory or the like.

The strength material cover 15 does not include the hanging portion 5 as shown in FIG. 17, and is a clamp method in which the strength material cover 15 is gripped from the outer periphery, a method in which the upper surface of the strength material cover 15 is vacuum-adsorbed, or a strength method. The strength material lid 15 can be suspended from the opening 3 by a lid suspending device 16 made of a method of attracting an electromagnet to the upper surface of the material lid 15.

FIG. 2 shows an example of a corrosion-resistant material container used in the present invention. The corrosion-resistant material container 1b has a corrosion-resistant material flange 17 fixed at one end in advance by welding 18 and an opening 19 at the other end. A corrosion-resistant material container body 20 having a cylindrical shape, and a corrosion-resistant material bottom plate 21 having a stepped groove 44 that fits into the lower end 20 ′ of the corrosion-resistant material container body 20 and closes the opening 19.
Manufactured in factories. An inspection screw hole 17a is formed at the center of the corrosion-resistant material flange 17.

The corrosion-resistant material container body 20 is fitted to the outside of the strength material container body 4 in a factory or the like and rubbed in advance, and the rubbed materials are sent to a radioactive waste treatment facility as a pair. So that
The corrosion-resistant material container body 20 is lifted up by a rotatable suspension stopper 23 attached to a suspension device 22 having a pushing device 37 so as to fit the outer periphery of the strength material container body 4.

Next, a procedure for enclosing the radioactive waste container in a sealed container in the radioactive waste treatment facility will be described with reference to FIGS.

First, as shown in FIG. 3, the strength material container main body 4 is supported by the support arm 24 so that the bottom of the strength material container body 4 is supported by the support arm 24 so that the opening 3 faces upward. It is suspended by 25 and placed on a container support 27 having a groove 26 into which the support arm 24 can enter.

Subsequently, as shown in FIG. 4, the radioactive waste container 2 is suspended by the container suspending device 28 and stored in the storage space s of the strength material container body 4.

Next, as shown in FIG. 5, the strength material lid 15 is hung from the lid hanging device 16 and is hung over the opening 3 of the strength material container main body 4.

Then, as shown in FIG. 6, the outer periphery of the strength material container main body 4 is preheated by a preheating device 29 to control the temperature while controlling the welding device 30 (normal TIG welding or MIG).
The opening 3 of the strength material container main body 4 and the strength material lid 15 are welded 12 by IG welding, thereby sealing the radioactive waste container 2 with the strength material container 1a.

Subsequently, as shown in FIG. 7, an inspection device 32 provided with a seal box 31 surrounding the upper outer periphery of the strength material container body 4 and the strength material container body 4 and the strength material lid 15 are provided.
Inspection of the welded joint portion by ultrasonic inspection and surface inspection by a television monitor or the like are performed. If there is a problem in the welding 12, repair welding is performed and the above inspection is performed again.

Next, as shown in FIG. 8, the corrosion-resistant bottom plate 21 shown in FIG.
And the strength material container 1a is suspended by the strength material container main body suspending device 25 shown in FIG.
The preheating device 33 is placed on the upper side, and is further disposed outside the upper part of the strength material container 1a.

Further, the corrosion-resistant material flange 17 of the corrosion-resistant material container body 20 shown in FIG.
3, the corrosion-resistant container body 20 is pressed into the outside of the strength material container body 4 by a pushing device 37 provided in the suspending device 22 while being heated by the preheating device 33, thereby shrink-fitting. Do.

As shown in FIG. 9, the pushing device 37 includes a pneumatic or hydraulic cylinder 36 provided at, for example, four places in the circumferential direction in the suspension main body 35 of the suspension device 22 suspended by the suspension wire 34. A spring 38 connected to a piston 36a of each cylinder 36, a hammer 39 connected to a lower end of the spring 38,
A working fluid pipe 41 that supplies and discharges a working fluid to and from the cylinder 36 via a valve 40 to expand and contract the piston 36 a. The corrosion-resistant material container body 20 heated by the preheating device 33 is Hammer 39 by action
Are made to collide against the corrosion-resistant material flange 17 and are pressed into the outer periphery of the strength material container body 4 by the impact force.

The corrosion-resistant container body 20 shrink-fitted into the strength material container body 4 is in a state shown in FIG. 10, and the lower end 20 'of the corrosion-resistant material container body 20 and the corrosion-resistant bottom plate 21 are welded by a welding device 42. Welding 43.

At this time, as shown in FIG. 11, the corrosion-resistant material bottom plate 21 is formed with a step-shaped groove 44 into which the lower end 20 'of the corrosion-resistant material container body 20 can be fitted. 44
A height adjustment margin 45 is provided so that when the corrosion-resistant material container body 20 comes into close contact with the outside of the strength material container body 4 by the shrink fitting, the height dimension can be adjusted.

Therefore, the stepped groove 44 is further away from the strength material container body 4 than the height adjustment allowance 45, so that the dissimilar metal of the strength material container body 4 is prevented from entering the weld 43. Thus, a good weld 43 can be formed.

Further, the welding 43 is performed on the corrosion-resistant material bottom plate 21 in a state where the strength material container body 4 containing the radioactive waste container 2 and the corrosion-resistant material container body 20 are weighted. The bottom plate 21 does not undergo thermal deformation or the like, and the corrosion-resistant bottom plate 21 can be securely adhered to the bottom surface of the strength material container body 4. Therefore, heat transfer between the strength material container 1a and the corrosion-resistant material container 1b can be improved.

Subsequently, as shown in FIGS. 12 and 13, a leakage inspection device 46 is screwed and connected to the inspection screw hole 17a of the corrosion-resistant material flange 17 to perform a leakage inspection of the corrosion-resistant material container 1b. Subsequently, the leakage inspection device 46 is removed, the inspection screw hole 17a is closed and welded by the welding device 42, and a weld inspection of the closed and welded portion is performed.

Thus, the sealed container 1 in which the radioactive waste container 2 is sealed can be constructed.

Further, as shown in FIG. 14, the hermetically sealed container 1 is lifted by a hermetically sealed container suspending device 47 and suspended in a buffer material container main body 48 installed in a disposal hole 52 formed in the stratum. And then, as shown in FIG.
The cushioning material cover 50 is suspended by the cushioning material cover suspending device 49 so as to close the upper opening 51 of the cushioning material container body 48, and the sealed container surrounded by the cushioning material container body 48 and the cushioning material cover 50 as described above. 1 is geologically disposed as shown in FIG.

As described above, the sealed container 1 in which the strength material container 1a and the corrosion-resistant material container 1b are in close contact with each other can be formed, and the strength material lid 15 is welded to the strength material container main body 4 by the welding 12
In addition, only by performing welding 43 of the corrosion-resistant bottom plate 21 to the corrosion-resistant material container body 20 on site, welding can be performed easily and without mixing different kinds of metals, and therefore, radioactive disposal can be easily and reliably performed by remote control. Object container 2 in sealed container 1
Can be enclosed in

It should be noted that the present invention is not limited only to the above-described embodiment, and is not limited to the shape of the illustrated sealed container and other various changes without departing from the gist of the present invention. Can of course be added.

[0043]

According to the first aspect of the present invention, it is possible to improve the heat transfer by forming a sealed container in which the strength material container and the corrosion-resistant material container are in close contact with each other, and to the strength material container body. Since the welding of the strength material lid and the welding of the corrosion-resistant bottom plate to the buffer material container main body are only performed on site, the effect of being able to easily and securely enclose the radioactive waste container in a sealed container by remote control is achieved. is there.

Further, since the corrosion-resistant material container main body is rubbed in advance with the strength material container main body, there is an effect that shrink fitting can be performed reliably and good adhesion can be achieved.

According to the second aspect of the present invention, the welding is performed at a position farther than the height adjustment allowance from the strength material container main body by the stepped groove, so that the strength material container main body is welded to the welded portion. There is an effect that a foreign metal is prevented from being mixed and a good welded portion can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a strength material container constituting a sealed container according to an example of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a corrosion-resistant material container constituting a sealed container according to an example of an embodiment of the present invention.

FIG. 3 is a side view showing a state where a strength material container main body is placed on a container support base.

FIG. 4 is a cut-away side view showing a state where a radioactive waste container is accommodated in a strength material container main body.

FIG. 5 is a cut-away side view showing a state in which the opening of the strength material container main body is closed by a strength material cover.

FIG. 6 is a cut-away side view showing a state in which a strength material lid is welded to an opening of a strength material container main body to form a strength material container.

FIG. 7 is a cut-away side view showing a state where a leakage inspection of a strength material container is performed.

FIG. 8 is a cut-away side view showing a state in which the corrosion-resistant material container body is shrink-fitted to the outside of the strength material container body placed on the corrosion-resistant material bottom plate.

FIG. 9 is a partially cut-away side view showing an example of a pushing device provided in the hanging device.

FIG. 10 is a cut-away side view showing a state in which the corrosion-resistant material bottom plate is welded to the lower end of the shrink-fitted corrosion-resistant material container body to form the corrosion-resistant material container.

FIG. 11 is a sectional view showing details of an XI part in FIG. 10;

FIG. 12 is a side view showing a state in which the leakage inspection and the inspection screw hole of the corrosion-resistant material container are closed and welded.

FIG. 13 is a cut-away side view showing details of the inspection device of FIG. 12;

FIG. 14 is a cut-away side view showing a state in which the sealed container is accommodated in the buffer material container main body.

FIG. 15 is a cut-away side view showing a state in which the cushioning material container main body is closed by an annular material lid.

FIG. 16 is a cut-away side view showing a state where the sealed container is surrounded by the cushioning material container body and the cushioning material lid and subjected to geological disposal.

FIG. 17 is a cut-away side view showing an example of a sealed container experimentally considered in recent years.

18 is a cut-away side view showing a state in which a strength material container is formed by welding a strength material lid to the strength material container main body of FIG. 17;

FIG. 19 is a cut-away side view showing a state in which the probe ring cover is welded to the corrosion-resistant container main body to form a corrosion-resistant container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing container 1a Strength material container 1b Corrosion-resistant material container 2 Radioactive waste container 3 Opening 4 Strength material container main body 12 Welding 15 Strength material lid 17 Corrosion-resistant material flange 19 Opening 20 Corrosion-resistant material container main body 20 'Lower end 21 Corrosion-resistant bottom plate 22 Suspension Device 37 Pushing device 43 Welding 44 Stepped groove 45 Height adjustment allowance

Claims (2)

[Claims] 1. A radioactive waste container is suspended and stored in a strength material container body having an opening facing upward, and a strength material lid is suspended from the opening of the strength material container body and welded. The strength material container is constructed by lifting and placing the strength material container on a horizontally placed anticorrosion material bottom plate, provided with an anticorrosion material flange at one end and rubbed in advance with the strength material container body. Lifting the corrosion-resistant container body by a lifting device equipped with a pushing device so that the opening faces downward,
While the corrosion-resistant material container body is heated by a preheating device, it is press-fitted to the outside of the strength material container body by a pushing device and shrink-fitted. A method for sealing a radioactive waste container, comprising forming a food container and enclosing the radioactive waste container with a sealed container comprising the strength material container and the corrosion-resistant material container. 2. The radioactive waste according to claim 1, wherein a stepped groove having a height adjustment allowance for fitting a lower end of the corrosion-resistant container body is formed on the corrosion-resistant bottom plate. A method for enclosing a container in a sealed container.