JP2000275395A - Method for storing spent fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency in the storage of spent fuels whose heat release is low by using a single cask, housing a single canister in the cask and stacking baskets stowing the spent fuels in layers in the canister. SOLUTION: A single long one is used for either of a concrete cask 1 and a canister 2, and two pairs of short baskets 3 where spent fuels 4 are inserted and supported respectively are provided. In a main body 2a of the canister 2, the baskets 3 are stacked in two layers and the basket 3 in the lower layer is housed in the canister 2 and is supported on the bottom face of it. Moreover, a support plate 20 welded to the entire inner perimeter of the main body 2a of the canister 2 is formed in the upper part of the basket 3 in the lower layer so as to sit at about the midpoint position in a vertical direction in the main body 2a of the canister 2. The basket 3 in the upper layer is housed in the canister 2 and is supported on the support plate 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method 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.

FIGS. 9 and 10 show an example of conventional spent fuel storage means for storing spent fuel. FIG. 9 is a partially cutaway perspective view of the spent fuel storage means, and FIG. It is a longitudinal section of a fuel storage means.

In FIGS. 9 and 10, reference numeral 1 denotes a concrete cask, 2 denotes a steel canister stored in a single layer in the concrete cask 1, 3 denotes a grid-like partition in plan view, and Stored in a single stack,
An outer cylindrical basket 4 is a large number of spent fuels inserted and supported in each lattice portion of the basket 3.

The concrete cask 1 has a cask main body 1a formed in a cylindrical shape, and a through hole 6 communicating with a canister housing portion 5 inside the cask main body 1a is formed in a shaft center portion of a bottom surface 1b of the cask main body 1a. ing.

On the bottom surface 1b of the cask body 1a, there are formed a plurality of convex mounting tables 7 which extend in the radial direction in plan view and on which the canister 2 is mounted and supported. A ventilation groove 8 is formed between the mounting tables 7 adjacent in the circumferential direction.

On the lower surface of the bottom surface 1b of the concrete cask 1, the concrete cask 1
A plurality of ventilation grooves 9 that allow the through holes 6 to communicate with the outside
Is provided so as to extend in the radial direction, and air 11 introduced from the outside into the ventilation groove 9 of the concrete cask 1, which is supported on the floor surface 10 and whose lower surface is closed, passes through the ventilation groove 9. The canister 2 having the hole 6 and the cylindrical canister body 2a can flow into the canister housing portion 5 of the cask body 1a through the ventilation groove 8 whose upper part is closed by the bottom surface 2b.

An annular lid support 12 is fixed in the canister housing 5 at the upper end of the cask main body 1a, and a stepped disk-shaped lid 14 is bolted on the lid support 12 by bolts 13. It can be concluded. Thus, the upper end of the lid support 12 is slightly lower than the upper end of the cask body 1a, and when the lid 14 is installed on the lid support 12 so that the small-diameter portion is fitted into the lid support 12, The upper surface of the large diameter portion of the lid 14 fitted inside the cask body 1a is flush with the upper end of the cask body 1a. The head of the bolt 13 is housed in a hole provided in the lid 14 so as not to protrude from the upper surface of the lid 14.

In the vicinity of the upper end of the cask main body 1a, a plurality of ventilation holes 15 extending in the radial direction at predetermined intervals in the circumferential direction of the cask main body 1a are provided below the lid support base 12. The air 11 rising through a gap between the outer periphery of the canister 2 housed in the canister housing portion 5 of the cask main body 1a and the inner periphery of the cask main body 1a flows through the air hole 15 into the concrete cask. 1 is discharged to the outside. The ventilation hole 15 penetrates the cask body 1a in the radial direction, and
Is radially outwardly bent downward at a radially intermediate portion, in order to prevent radiation from leaking from inside the cask main body 1a to the outside.

The canister 2 in which the basket 3 in which the spent fuel 4 is inserted and supported is stored and stored in the concrete cask 1 is located near the upper end of the canister body 2a.
An annular seat 16 is fixed to the inner periphery of the canister body 2a.
The shield 16 is provided on the upper surface of the seat 16.
And a primary lid 18 on the shielding plug 17, and a secondary lid 19 on the primary lid 18, respectively.
a. The primary lid 18 and the secondary lid 19 are welded to the entire inner periphery of the canister body 2a, and the upper surface of the secondary lid 19 is substantially the same height as the upper end of the canister body 2a. Thus, the lower surface of the lid 14 is located on the upper surface of the secondary lid 19.

The canister 2 in which the basket 3 into which the spent fuel 4 is inserted and supported is stored in a sealed state is stored in a concrete cask 1 and stored in a storage facility.

Air 11 introduced from outside into the ventilation groove 9
Flows into the canister housing 5 of the concrete cask 1 from the through hole 6 through the ventilation groove 8, rises inside the canister housing 5 along the outer periphery of the canister body 2 a, and disintegrates the decay heat generated from the spent fuel 4. It is robbed and discharged to the outside through the vent hole 15.

[0013] In the conventional spent fuel storage means,
The canister 2 is stacked in the concrete cask 1 in one stage, and the basket 3 is stacked in the canister 2 in one stage. Therefore, the spent fuel 4 is stacked in one stage with respect to the concrete cask 1 and the canister 2. The reason why the spent fuel 4 is stacked in one stage is that when the spent fuel 4 has a large decay heat, the spent fuel 4 is stacked in a plurality of stages such as a two-stage stack and the spent fuel 4 is used within a predetermined period. This is because the fuel 4 cannot be cooled to a predetermined temperature.

[0014]

When the spent fuel 4 is cooled down to a predetermined temperature in a single-stack state and the decay heat becomes low, the spent fuel is kept in a single-stack state thereafter. And the storage efficiency of spent fuel is poor. Therefore,
When the spent fuel cools and generates low heat, it is necessary to improve the storage efficiency of the spent fuel.

The present invention has been made in view of the above circumstances, and has as its object to improve the storage efficiency of spent fuel having low heat generation.

[0016]

According to the present invention, a canister containing a basket containing spent fuel is stored in a cask, and air is introduced into the cask from below the cask to generate the spent fuel. In a method for storing spent fuel while cooling the decay heat of low heat generated from the outer peripheral side of the canister, the method includes storing the spent fuel in a single cask and storing one canister in the cask. A plurality of baskets containing spent fuel are stacked in the canister.

In the method for storing spent fuel, among the baskets stacked in a plurality of stages in the canister, the uppermost basket can be suspended and supported by the canister.

Further, according to the present invention, in the method for storing spent fuel, the single cask and a plurality of canisters housed in the cask are stacked, and the spent fuel is stored in each canister. This is to store each basket.

Further, the present invention provides the method for storing spent fuel, wherein the casks are stacked in a plurality of stages, and the canisters accommodating the baskets containing the spent fuel are each stacked in one stage in each of the casks. Is what you do.

According to the method for storing spent fuel of the present invention, the storage efficiency of spent fuel having a low calorific value is improved.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that, in FIGS. 1 to 8, components having the same functions and effects as those shown in FIGS. 9 and 10 are denoted by the same reference numerals even if their shapes and structures are slightly different.

FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a partially cutaway perspective view of a spent fuel storage means, and FIG. 2 is a perspective view of the spent fuel storage means shown in FIG. It is a longitudinal cross-sectional view.

In the embodiment of the present invention, each of the concrete cask 1 and the canister 2 has a long one, and the basket 3 into which the spent fuel 4 is inserted and supported is a short one. A set is provided.

Thus, the canister body 2 of the canister 2
a, baskets 3 are stacked in two stages, and the lower basket 3 is stored in the canister 2 and
Is supported by the bottom surface 2b. Also, the lower basket 3
A support plate 20 welded to the entire inner circumference of the canister body 2a is provided at an upper portion of the canister body 2a at a substantially middle portion in the vertical direction of the canister body 2a.
It is stored in the canister 2 and is supported by the support plate 20.

Such a spent fuel storage means is shown in FIGS.
This is applied to the storage of the spent fuel 4 in which the decay heat becomes low as a result of storage as shown in FIG.

The air 1 for further cooling the spent fuel 4
The flow of 1 is the same as the case shown in FIGS.

In this embodiment, the spent fuel 4 whose decay heat has become low is stacked in two stages and stored in one canister 2, and the canister 2 is stored in the concrete cask 1. Therefore, the storage density of the spent fuel 4 and thus the storage efficiency are improved.

Further, since the concrete cask 1 and the canister 2 are long, the draft is improved and the cooling effect can be expected to be improved. Furthermore, since the canister 2 has one stage, the primary lid 18 and the secondary lid 19 need only be welded once, and therefore, the sealing management of the spent fuel 4 is easy.

FIGS. 3 and 4 show a second embodiment of the present invention. FIG. 3 is a longitudinal sectional view of the spent fuel storage means, and FIG. 4 is an enlarged view of a portion IV in FIG.

In this embodiment, the concrete cask 1 and the canister 2 each have one long one, and the basket 3 into which the spent fuel 4 is inserted and supported is two short ones. , FIG. 1 and FIG.

The present embodiment is different from the first embodiment in that the canister body 2 of the canister 2 is different from the first embodiment.
a A stepped portion 2c is formed on the inner periphery of the upper end so that the locking portion 3a of the upper basket 3 can be locked, and a part of the weight of the upper basket 3 and the spent fuel 4 is suspended by the stepped portion 2c. The difference is that the supporting plate 20 can support the upper basket 3 and the remaining weight of the spent fuel 4.

By doing so, the same operation and effect as those of the above-described embodiment can be obtained, and the strength of the support plate 20 can be reduced as compared with the case of FIGS. Specifically, the thickness of the support plate 20 shown in FIG. 3 can be made smaller than the thickness of the support plate 20 shown in FIGS.

FIGS. 5 and 6 show a third embodiment of the present invention. FIG. 5 is a partially cutaway perspective view of the spent fuel storage means.
FIG. 6 is a vertical sectional view of the spent fuel storage means shown in FIG.

In the present embodiment, the concrete cask 1 is one long one, the canister 2 is two short ones, and the spent fuel 4 is inserted and supported in each canister 2, respectively. The stored basket 3 can be stored.

The lower canister 2 is mounted on a mounting table 7 provided on the bottom surface 1b of the concrete cask 1.
Supported. A support plate 21 fitted into the cask main body 1a and attached to the inner periphery of the cask main body 1a is disposed above the lower canister 2, and the upper canister 2 is placed and supported on the support plate 21. Have been. The support plate 21 has air 11 rising in the canister housing 5.
So that air can flow upward from below.
1a is drilled.

In the present embodiment, the canister 2
Has two stages, so that the welding of the primary lid 18 and the secondary lid 19 must be performed twice each. Therefore, the sealing management is more disadvantageous than in the first and second embodiments. Except for the above, the same operation and effect as those of the first and second embodiments can be obtained.

FIGS. 7 and 8 show a fourth embodiment of the present invention. FIG. 7 is a partially cutaway perspective view of the spent fuel storage means.
FIG. 8 is a longitudinal sectional view of the spent fuel storage means shown in FIG.

In the present embodiment, each of the concrete casks 1 and the canisters 2 is of a short length, each of which is two, and the basket 3 in which the spent fuel 4 is inserted and supported is stored in each canister 2. Like that.

A support plate 22 having substantially the same diameter as the outer periphery of the cask body 1a is provided on the upper surface of the lower concrete cask 1.
The concrete casks 1 at the upper stage are placed on the support plate 22.

In this embodiment, the draft is not improved, so that the cooling effect is disadvantageous as compared with the first to third embodiments. In addition, since the canister 2 has two stages, the primary lid 18, The welding of the secondary lid 19 must be performed twice, which is more disadvantageous than the first to third embodiments in terms of welding management, but each of the above-described embodiments in terms of improving storage efficiency. The same effect as the example can be obtained.

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 scope of the present invention.

[0042]

According to the method for storing spent fuel of the present invention, an excellent effect of improving the storage efficiency of spent fuel can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view of an example of a spent fuel storage means applied to a first example of a spent fuel storage method according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the spent fuel storage means shown in FIG.

FIG. 3 is a longitudinal sectional view of an example of a spent fuel storage means applied to a second example of the embodiment of the spent fuel storage method of the present invention.

FIG. 4 is an enlarged view of a part IV in FIG. 3;

FIG. 5 is a partially broken perspective view of an example of spent fuel storage means applied to a third embodiment of the spent fuel storage method according to the present invention.

FIG. 6 is a longitudinal sectional view of the spent fuel storage means shown in FIG.

FIG. 7 is a partially broken perspective view of an example of a spent fuel storage means applied to a fourth example of the embodiment of the spent fuel storage method of the present invention.

8 is a vertical sectional view of the spent fuel storage means shown in FIG.

FIG. 9 is a partially broken perspective view of a conventional spent fuel storage means.

FIG. 10 is a longitudinal sectional view of the spent fuel storage means shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete cask (cask) 2 Canister 3 Basket 4 Spent fuel 11 Air

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G21F 5/002 G21F 5/00 W 5/005

Claims (4)

[Claims] 1. A canister storing a basket containing spent fuel in a cask, and introducing low-heat decay heat generated from the spent fuel by introducing air into the cask from below the cask. In the method for storing spent fuel, the spent fuel is stored while being cooled from the outer peripheral side of the basket, and the basket in which the spent fuel is stored is formed by using one cask and storing one canister in the cask. A method for storing spent fuel, comprising stacking a plurality of stages in the canister. 2. The method according to claim 1, wherein the uppermost basket among the baskets stacked in the canister is suspended and supported by the canister. 3. A canister storing a basket containing spent fuel in a cask, and introducing low-heat decay heat generated from the spent fuel by introducing air from a lower portion of the cask into the cask. In the method for storing spent fuel while cooling from the outer peripheral side of the spent fuel, the single cask and a plurality of canisters housed in the cask are stacked, and the spent fuel is stored in each canister. A method for storing spent fuel, characterized by storing baskets each containing a fuel. 4. A canister in which a basket containing spent fuel is stored in a cask, and low-heat decay heat generated from the spent fuel is introduced by introducing air into the cask from below the cask. In the method for storing spent fuel while cooling from the outer peripheral side of the spent fuel, the casks are stacked in a plurality of stages, and a canister containing a basket containing the spent fuel is placed in each of the casks. A method for storing spent fuel, characterized in that the fuel is stored in a single stack.