JP2001174592A - Storage method and device for spent fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the storage cost and the quantity of metal waste after finishing the storage, to safely carry a canister by a new carrier cask after finishing the storage, and to dispense with the monitoring of the vessel during the storing period. SOLUTION: A basket 3 storing spent fuel 1 is stored in the canister 11 and sealed by welding a sealing cover, the canister 11 is stored in the carrier cask 12 having a neutron shielding body 5 in the outer circumference of the metal vessel 4 and sealed by an airtight cover 14, and a buffer material 10 is attached to the carrier cask 12 to be carried to a storage place in storage facilities. At the storage place, the canister 11 is taken out of the carrier cask 12 and stored in a concrete storage cask 16 installed in the storage place.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for storing spent fuel for storing spent fuel generated in a nuclear power plant or the like.

[0002]

2. Description of the Related Art In recent years, it has been studied to store spent fuel generated in a nuclear power plant in a storage facility until decay heat is removed.

FIG. 5 shows an example of a conventionally proposed metal storage cask for storing spent fuel in a dry state.

In FIG. 5, reference numeral 1 denotes a spent fuel, and reference numeral 2 denotes a shielding container (hereinafter referred to as a storage cask) for storing and storing the spent fuel 1.

The spent fuel 1 of the nuclear reactor is supported by inserting a plurality of the spent fuels 1 into each lattice portion of an outer peripheral cylindrical basket 3 partitioned in a lattice shape in plan view.

[0006] The storage cask 2 has a metal container 4 supported by the basket 3 and capable of storing the spent fuel 1, and a neutron shield 5 provided on the outer periphery of the metal container 4. The upper opening of the metal container 4 is sealed by tightening the inner lid 6 and the outer lid 7 with bolts 9 with the metal gasket 8 interposed therebetween.

[0007] Further, at the upper and lower ends of the metal container 4, FIG.
As shown in FIG. 1, a cushioning material 10 for buffering an impact due to a collision or the like during transportation is attached.

The metal container 4 of the storage cask 2 is for shielding radiation (γ-rays) and is generally made of steel or the like to have a thickness of about 300 mm. The neutron shield 5 is made of rubber, resin or the like. For shielding neutrons using the above organic material, and usually has a thickness of about 150 mm.

Conventionally, to store spent fuel 1 of a nuclear reactor in a storage facility, first, in a reactor building,
As shown in FIG. 6, the spent fuel 1 stored in the basket 3 is inserted into the metal container 4 of the storage cask 2 from which the outer lid 7 and the inner lid 6 have been removed. As shown, the inner cover 6 is fixed to the opening of the metal container 4 with the bolt 9 via the metal gasket 8, and the outer cover 7 is fixed by the bolt 9 via the metal gasket 8. Is sealed. Thereby, the storage cask 2 in which the spent fuel 1 is stored in an airtight manner is formed.

Next, as shown in FIG. 7, a cushioning material 10 for ensuring safety during transportation is attached to the upper and lower portions of the metal container 4 of the storage cask 2.

Storage cask 2 to which cushioning material 10 is attached
Is transported from the reactor building to the storage facility by the required transport means.

In the storage facility, the cushioning material 10 is removed from the storage cask 2 shown in FIG. 7 to be in the state shown in FIG. 5, and the storage cask 2 is stored in the storage place of the storage facility. ing.

[0013]

However, in the conventional storage of spent fuel, spent fuel 1 is stored in a storage cask 2 in a reactor building, and is sealed with an inner lid 6 and an outer lid 7. Since the storage cask 2 is transported to the storage facility and the storage facility stores the storage cask by directly installing it in the storage place, the storage cask 2 is used for both transportation and storage. In addition, there is a problem that a large number of expensive storage casks 2 are required and storage costs are increased.

That is, the metal container 4 of the storage cask 2
Since the thickness is about 0 mm, the material amount is large, and the material cost and processing cost are enormous. Further, there is a problem that the amount of metal waste generated after storage is increased.

Further, it is considered that the strength of the storage cask may become a problem during transportation after the storage is completed. Therefore, there is a problem that long-term soundness needs to be confirmed by a verification test or the like. Furthermore, since the metal container 4 is hermetically sealed by fastening the inner lid 6 and the outer lid 7 to the opening of the metal container 4 with bolts 9 with the metal gasket 8 interposed therebetween, the container can be monitored during the storage period. Had the problem of being necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is possible to reduce storage costs, reduce the amount of metal waste after storage, and safely transport canisters in a new transport cask after storage. It is an object of the present invention to provide a method and an apparatus for storing spent fuel, which can eliminate the need for monitoring a container during a storage period.

[0017]

According to the present invention, there is provided a transportation cask having a neutron shield on the outer periphery of a metal container, in which a basket containing spent fuel is accommodated in a canister and sealed by welding a sealing lid. The canister is housed inside, sealed with an airtight lid, a cushioning material is attached to the transport cask, transported to the storage location of the storage facility, the canister is taken out of the transport cask at the storage location, and the concrete storage installed in the storage location A method for storing spent fuel, wherein the canister is stored and stored in a cask.

Further, the present invention provides a canister comprising a metal canister body for accommodating a basket containing spent fuel, a hermetic lid for closing an opening of the canister body by welding, and an inner canister. A transport cask comprising: a metal container that can be accommodated in a metal container, a neutron shield provided on the outer periphery of the metal container, an openable / closable airtight lid provided at an opening of the metal container, and a cushioning material attached to the outside of the metal container. And a concrete storage cask that can be installed at the storage location and accommodate the canister taken out of the transport cask,
And a storage device for spent fuel, characterized by comprising:

According to the present invention, the canister containing the spent fuel is airtightly housed in a dedicated transport cask, transported from the reactor containment vessel to the storage facility, and the concrete provided in the storage place of the storage facility in advance. The canisters taken out of the transport casks are exchanged and stored in the storage casks, so that expensive transport casks can be used repeatedly, and concrete storage casks can be replaced with conventional metal storage casks. It can be implemented at a lower cost than a cask, so that storage costs can be significantly reduced.

Furthermore, since the storage is carried out by a storage cask made of concrete, the amount of metal waste after the storage can be reduced, and the canister is transported by the transport cask after the storage is completed. Since the canister can be safely transported and the canister is sealed by welding using the primary lid and the secondary lid, it is not necessary to monitor the container during the storage period as in the related art.

[0021]

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

FIG. 1 shows a canister 11 used in the present invention.
FIG. A plurality of spent fuels 1 are supported by being inserted into each lattice portion of an outer peripheral cylindrical basket 3 partitioned in a lattice shape in plan view, and the basket 3 containing the spent fuels 1 in this manner. Is housed in a canister body 11a made of, for example, a stainless steel metal container having a thickness of about 16 mm, a plug 11b is fitted into an upper opening of the canister body 11a, and a primary sealing lid 11c is further provided thereon. And secondary closed lid 11d
Are fixed by welding to form a canister 11 in which the spent fuel 1 is stored in an airtight manner.

FIG. 2 shows a transport cask 1 used in the present invention.
2 shows an example of a transport cask 12
Is a conventional metal storage cask 2 shown in FIGS.
It has a substantially similar configuration.

That is, the transport cask 12 has the metal container 4 capable of housing the canister 11 and the neutron shield 5 provided on the outer periphery of the metal container 4. The metal container 4 can be sealed or opened by squeezing the airtight lid 14 provided with the metal gasket 13 therebetween with bolts 15. At this time, as shown in FIG. 5, the opening of the metal container 4 may be sealed with a double lid including the inner lid 6 and the outer lid 7.

Further, at both upper and lower ends of the metal container 4, FIG.
As shown in FIG. 7, similarly to FIG. 7, a cushioning material 10 for buffering an impact due to a collision or the like during transportation is attached.

FIG. 3 shows an example of a concrete storage cask 16 used in the present invention. The storage cask 16 is set in advance at a storage location of a storage facility.

The storage cask 16 is provided with the canister 11
Is provided with a concrete container 18 formed into a container shape by using reinforced concrete so as to form a canister housing portion 17 in which canister can be housed. The upper opening of the concrete container 18 is fixed by bolts 19. The lid 20 can be closed by the above-mentioned structure. In FIG. 3, a plurality of annular concrete bodies are stacked and fixed with fixing bolts 18a to form a concrete container 18.
Although the case of forming is illustrated, a concrete container 18 having an integral structure may be used.

In the vicinity of the upper end of the concrete container 18,
A plurality of ventilation holes 21 extending in the radial direction at a position having a required interval in the circumferential direction and communicating with the outside are provided. The ventilation hole 21 is a radially intermediate portion of the concrete container 18,
It is bent down toward the outside in the radial direction,
This is to prevent radiation from leaking from inside the concrete container 18 to the outside.

In the center of the bottom of the concrete container 18, a through hole 22 opened at the lower part is formed. Further, on the inner bottom surface of the concrete container 18, there are formed a plurality of ridged mounting tables 23 which extend in the radial direction in plan view and on which the canister 11 is mounted and supported.
A ventilation groove 23 'communicating with the through hole 22 is formed between the two. Further, on the lower surface of the concrete container 18, there are provided a plurality of ventilation grooves 24 which extend in the radial direction at positions having a predetermined interval in the circumferential direction and communicate the through hole 22 and the outer peripheral surface of the concrete container 18. Have been.

The air introduced from the outside into the ventilation groove 24 of the concrete container 18 is introduced into the canister housing 17 through the through hole 22 and the ventilation groove 23 ′ between the mounting table 23, and is housed in the canister housing 17 and the inside thereof. When heated by the canister 11 when passing through a gap between the canister 11 and the canister 11, the ascended air is discharged to the outside of the concrete container 18 from the upper vent 21. The canister 11 is cooled by the natural circulation of the air.

Hereinafter, a method for storing the spent fuel 1 will be described.

When storing the spent fuel 1 of the nuclear reactor in the storage facility, first, as shown in FIG. 1, the spent fuel 1 stored in the basket 3 is placed in the canister body 11a in the reactor building. The canister body is closed, the opening of the canister body 11a is closed with a plug 11b, and a primary sealing lid 11c
And the secondary sealing lid 11d are fixed by welding. Thus, a canister 11 in which the spent fuel 1 is hermetically stored as shown in FIG.

Subsequently, in the reactor building, FIG.
As shown in (B), in the metal container 4 of the transport cask 12 in which the lid 20 of the metal container 4 is removed to open the opening,
The canister 11 is inserted, and then the airtight lid 14 is inserted into the opening of the metal container 4 with the metal gasket 13 therebetween.
The transport cask 12 is sealed by squeezing the transport cask 12.

Subsequently, as shown in FIG. 4C, the cushioning material 10 is attached to the upper and lower ends of the metal container 4 of the transport cask 12.

In this state, the transport cask 12 is transported from the reactor building to the storage facility by a required transport means.

In the storage facility, as shown in FIG.
After removing the upper cushioning material 10 and the airtight lid 14, the canister 11 is taken out of the transport cask 12 to the outside, and FIG.
As shown in (E), the container is housed in a concrete storage cask 16 previously installed in a storage location of a storage facility and having an open lid 20, and then the opening of the storage cask 16 is closed with the lid 20. As a result, the spent fuel 1 is stored in the storage location of the storage facility.

As shown in FIG. 3, the air introduced from the outside into the ventilation groove 24 of the concrete container 18 constituting the storage cask 16 is accommodated in the canister by the ventilation hole 23 ′ between the through hole 22 and the mounting table 23. Canister housing 17 and canister 1 housed therein
1 and rises by being heated by the canister 11 when passing through the gap between the container 1 and the container 1 and is discharged to the outside of the concrete container 18 through the upper vent 21. The canister 11 is cooled by the natural circulation of the air.

As described above, the canister 11 containing the spent fuel 1 is accommodated in the exclusive transport cask 12 and transported from the reactor containment vessel to the storage facility, and the concrete canister 11 is provided at the storage location of the storage facility. Storage cask 16
In addition, since the canister 11 taken out of the transport cask 12 is stored by being exchanged and stored, the expensive transport cask 12 can be used repeatedly, and the concrete storage cask 16 can be replaced with a conventional metal storage cask. 2 can be implemented at a lower cost, and the storage cost can be greatly reduced.

Further, a concrete storage cask 16
, The amount of metal waste after storage is reduced, and the canister 11 is transported by the new transport cask 12 even after storage is completed.
The canister 11 can be transported safely, and the canister 11 is further composed of a primary sealing lid 11c and a secondary sealing lid 11c.
Since d and d are sealed by welding, there is an advantage that monitoring of the container during the storage period as in the related art can be omitted.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

[0041]

According to the method and apparatus for storing spent fuel of the present invention, the canister containing spent fuel is airtightly stored in a dedicated transport cask and transported from the reactor containment vessel to the storage facility. Since the canisters taken out of the transport casks are stored and stored in the concrete storage casks provided in advance at the storage locations of the storage facilities, the expensive transport casks can be used repeatedly, and The storage cask made of metal can be implemented at a lower cost than a conventional metal storage cask, and thus has the effect of greatly reducing the storage cost.

Further, since the storage is carried out by the concrete storage cask, the amount of metal waste after the storage is completed can be reduced. Further, the canister is transported by the transport cask after the storage is completed. Transport can be performed safely, and the canister is sealed by welding using the primary lid and the secondary lid, eliminating the need for conventional monitoring of containers during storage. There is.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a canister used in the present invention.

FIG. 2 is a perspective view showing an example of a transport cask used in the present invention.

FIG. 3 is a perspective view showing an example of a concrete storage cask used in the present invention.

FIGS. 4 (A), (B), (C), (D), and (E) are explanatory views showing an example of a procedure of a method for storing spent fuel according to the present invention.

FIG. 5 is a cutaway front view of a conventional storage cask.

6 is a cut-away front view showing a state where the opening of the storage cask of FIG. 5 is opened.

FIG. 7 is a cutaway front view showing a state where a cushioning material is attached to the storage cask of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spent fuel 3 Basket 4 Metal container 5 Neutron shield 10 Buffer material 11 Canister 11a Canister body 11c Sealing lid 11d Sealing lid 12 Transport cask 14 Airtight lid 16 Concrete storage cask

Claims (2)

[Claims] 1. A basket containing spent fuel is accommodated in a canister and hermetically sealed by welding a sealing lid, and the canister is accommodated in a transport cask provided with a neutron shield on the outer periphery of a metal container. Seal with an airtight lid, attach a cushioning material to the transport cask, transport it to the storage location of the storage facility, take out the canister from the transport cask at the storage location, and store the canister in the concrete storage cask installed at the storage location. A method for storing spent fuel, characterized by storing the spent fuel. 2. A canister comprising a metal canister body for accommodating a basket containing spent fuel, a canister comprising a sealing lid for closing an opening of the canister body by welding, and the canister can be accommodated therein. A transport cask comprising a metal container, a neutron shield provided on the outer periphery of the metal container, an openable airtight lid provided at the opening of the metal container, and a cushioning material attached to the outside of the metal container; And a concrete storage cask capable of storing a canister taken out of a transport cask and installed in a transport cask.