JPS6021491A - Storage facility for used fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel storage facility for a nuclear reactor that stores nuclear fuel assemblies used in a nuclear power plant.

[Background of the invention]

Spent fuel removed from the reactor core at a nuclear power plant is kept in the reactor building (for about six months to a year) until it is transported to a fuel reprocessing plant for reprocessing. It is stored underwater in a spent fuel pool (hereinafter referred to as the pool).

A spent fuel storage rank (hereinafter referred to as a rack) is installed within the pool, and the spent fuel is stored vertically in the rack.

In recent years, there has been concern about the lack of spent fuel reprocessing capacity, and there is a desire for long-term storage of spent fuel in pools inside reactor buildings. In order to increase the storage capacity of spent fuel,
The size of the pool is limited due to the size of the reactor building and its internal layout, so an efficient fuel storage method is required. For this reason, so-called high-density racks made of stainless steel or other neutron-absorbing materials are used to reduce the spacing between the stored fuels.

However, even with this method, there is a limit to increasing storage capacity, and new storage methods are desired.

Figure 1 shows the breakdown of conventional pool water depth for boiling water reactors. The pool water depth is approximately 11.5 m, and its configuration is: storage fuel height a, clearance between the stored fuel and transferred fuel b, transfer fuel height C1, transfer fuel shielding water depth d, each approximately 4 m.
．． 6m, 0.2m, 4.5m.

It is 2.2m. As is clear from this configuration, the shielding water depth for the stored fuel is 5.9 m, which is ample compared to the 2.2 m shielding water depth for the transferred fuel. In order to effectively utilize the space inside the pool, it is possible to stack two racks for storing fuel inside the pool to reduce the depth of the water that shields the stored fuel. Ensuring stability was a problem.

[Purpose of the invention]

An object of the present invention is to provide a multi-tiered spent fuel storage rack with improved earthquake resistance.

[Summary of the invention]

In order to achieve the above object, the spent fuel storage device of the present invention has a base that binds and integrates a large number of spent fuel storage racks installed in the lower tier to each other and the spent fuel storage racks of the lower tier and the upper tier. It is characterized by being provided in between.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to FIGS. 2 to 12.

FIG. 2 is an example of a typical spent fuel storage rack. e
, f, and g are the length, width, and height of the rack. The vertical and horizontal dimensions e-f of the rack are limited by the rack capacity and installation workability, and the height g is determined by the height of the spent fuel. Therefore, let us consider the restoring moment relative to the overturning moment.

Assuming that all the racks are fully filled with spent fuel and have a uniform density, the ratio of the restoring moment to the overturning moment due to the shape is proportional to (base) ÷ (height), and this ratio is β). The higher the value, the less likely it will fall. The ratio βl of the restoring moment to the overturning moment in Fig. 2 is expressed as /”1=α・−.In conventional general spent fuel racks, the rack is bolted to the bottom of the pool to withstand horizontal forces such as those caused during an earthquake. Safety is ensured by doing this.Also, if another rack is simply placed on top of the rack, the ratio of the restoring moment, β2, will be as follows when the height is 2g.In the event of an earthquake, etc. The stability against horizontal forces makes it one of the conventional storage formats.

FIG. 3 is an example of a two-tiered storage using the base 4 in claim No. (υ, (2), 0).

f and g are the width and height of the rack, h is the distance between the upper and lower racks, and i is the clearance between the racks. A base 4 is installed between the upper and lower racks for the purpose of fixing and connecting them. When the ratio β3 of the overturning moment and the restoring moment is calculated, the base ar1-21. height 2g
It becomes ten. Even if t == 11 == Q, you can get 9.1.5 times the stability when using one rack, and 3 times as much stability when simply stacking two racks.

FIG. 4 is a three-dimensional diagram showing the structure of the base 4 in detail at part A in FIG. 5.6 is a space divided into ribs that forms the frame of the rack of this base 4. This space 5.
There are four or more 6's on both the top and bottom. The space 5 on the upper surface of the base 4 is occupied by the bottom of the two racks 3 in FIG. 2, and the space 6 on the lower surface occupies the upper part of the rack 3 in FIG. This is provided to prevent the upper part of the fuel rods 2 stored in the base 4 from interfering with the plate 8 of the base 4. Further, if the height of the lower rack is made higher than the height of the fuel rods 2, the step 7 becomes unnecessary.

There are two possible methods for fixing the rack 3 and the base 4: bolt type and insertion type.

FIG. 5 is a detailed view of part A showing an example of fixing using the bolts in FIG. The bolt mounting parts provided on the lower rack 3 and the bolt mounting parts provided on the base 4 fixed to the upper rack are fixed by welding for remote mounting, and the upper and lower bolt mounting positions are designed to improve workability. It is conceivable to take this into account and shift it.

FIG. 6 is a detailed view of part A in FIG. 3 using the square pipe and foot (hereinafter referred to as the insertion part) according to claim (4), and shows a fixing method in the case of the insertion type, and The structure of the insertion port 11 provided on the rack 3 and the insertion portion 12 provided on the base 4 is shown. This figure utilizes four spent fuel storage areas in a rack 3 installed at the top. Thereby, it is also possible to eliminate the lip as a rack frame on the base 4. It can also be used as a method of fixing the lower rack and the base 4, and the bolt part shown in FIG. 5 can be inserted into a structure. This insertion type facilitates replacement of the rack 3 or base 4 in consideration of workability.

In this way, by fixing the base 4 and the rack 3 using the bolt type or insertion type, the upper rack is also stabilized, and there is no need to worry about it falling over or moving horizontally.

FIG. 7 is an example of claims (1) and (4) of the present invention, in which feet J, L and M are provided on the base 13 (
2 is a three-dimensional view of a rack 3 and a table 13 (hereinafter referred to as a table 13).

Rack 3 N, 0. Spent fuel is not stored in the spent fuel storage parts P and Q, and the spent fuel is stored in the legs J and L of the table 13.
Used to insert M. This table 13 has legs J, L, M corresponding to N, 0. By inserting it into the P and Q outlets, the four racks can be integrated. This outlet N, 0. It is also possible to provide P and Q in advance on the outside of the rack. As a result, the four racks are integrated, increasing stability and making it possible to perform double rows. Furthermore, if there are two racks, a table with two legs may be used, and even if there are a large number of racks, the table 13 may be used continuously. FIG. 8 shows how these racks are connected. In this example, there are six tables 13, ten tables 14 each having two legs, and 12 racks integrated.

FIG. 9 shows the base 4 and the insert-type table 13.
This is an example of parallel usage. The square pipe 15 has a structure that is higher than the fuel for the purpose of supporting the weight of the upper rack, and the legs of the daples 13 and 14 are inserted into it. In this figure, there is a slight change in the role of the base 4 compared to Figure 4.5.6. In FIG. 4, it was necessary to fix the base 4 and the rack with bolts or a plug-in type, but this is not necessary in FIG. 9, and the base 4 only serves to prevent horizontal movement of the upper rack. table 13
．． 14 connects the racks and at the same time serves as a frame for the base 4 in the lower stage.

FIG. 10 is a front view of the body tax fraud claim public service charger head 54-1. One end of this support 16 is fixed to the pool wall. The contact portion 17 at the other end is attached to the base 4 to resist sudden horizontal movement of the rack (such as during an earthquake). FIG. 11 shows an example of the internal structure of this support.

The support 16 has a cylindrical shape and has a fixed part 18. spring 19
．． Valve with hole 20. A contact portion 17 with the rack is provided. Sustained and unchanging forces transmitted to the contact portion 17 are counteracted by the spring, while sudden forces are counteracted by the perforated valve 20.
However, it repulses because it makes it difficult for the water inside the cylinder to come out. or,
The valve 20 does not resist tension due to the spring's repulsive force.

FIG. 12 shows base 4. An example of a storage facility using tables 13, 14 and supports 16 is shown. The base 4 is provided with a rib/insertion part 12 as a rack frame, and is supported by a square pipe 15 and a support 16 while fixing the upper and lower racks. Tables 13, 14 - make the integration of the upper rack more solid.

The part 21 is the same as the part in the upper part of the base 4 that houses the rack on the upper rack. Conventionally, the rack is fixed to the floor with bolts, but in this case, bolts are not required.

In addition, when the base 4 is divided and used, the support 16 can also be provided on the base in advance and used between the bases.

〔Effect of the invention〕

According to the present invention, by stacking spent fuel racks in two stages,
The danger of overturning and horizontal movement can be eliminated by 11F, highly stable two-level storage is possible, and inexpensive fuel storage equipment can be provided.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a pool showing details of the pool water depth of a boiling water reactor. FIG. 2 is a three-dimensional diagram showing the shape of a general rack. FIG. 3 is a state diagram of two-tiered storage using the base of the present invention. FIG. 4 is a three-dimensional diagram showing the structure of the base in detail at part A in FIG. 3. FIG. 5 is a detailed view of part A showing a fixing method using the bolts shown in FIG. 3. FIG. 6 is a three-dimensional view of the base with the insertion part of the present invention. FIG. 7 is a three-dimensional view of the connecting table and rack according to the present invention. FIG. 8 is a plan view in which the connection table of the present invention is installed. FIG. 9 is a state diagram using the base and table according to the present invention. FIG. 10 is a detailed view of section B in FIG. 12. FIG. 11 is a sectional view taken along the line CC in FIG. 10. FIG. 12 is a state diagram of constructing a two-tiered rack using the base table support according to the present invention. 1... Spent fuel storage pool, 2... Spent fuel assembly, 3... Spent fuel storage rack, 4... Base, 5... Space within upper frame, 6... Lower part Space within the frame, 7... Lip attached to the frame of the base, 8... Plate part of the base, 9... Pol+-110... How many parts for the bolt, 11... Insertion port, 12. ...Insertion part, 13...Connecting wheel 7'le, 14...Connecting table, 15...Square pipe, 16...Support, 17
...Contact part, 18...Fixed No. 1 (2) Mei 2 Figure No. 30 Calendar 4 ■ Jealousy 5 Meko 6 Kasumi Atsushi 80 Tsuji 9 Kuchi No. 10 Kasumizu ¥ 11 Kuchi

Claims (1)

[Scope of Claims] 1. In a spent fuel storage facility in which a plurality of spent fuel storage racks for holding spent fuel taken out from inside a nuclear reactor in an upright alignment are arranged on a plane and stacked in multiple stages. A spent fuel storage facility characterized in that a base is provided between the lower and upper spent fuel storage racks to bind and integrate a plurality of spent fuel storage racks installed in the lower tier. 2. The spent fuel storage facility according to claim 1, wherein the base is a frame that covers a plurality of spent fuel storage racks installed at a lower stage. 3. The spent fuel storage equipment according to claim 1, wherein the base has legs that are inserted into respective square pipes of adjacent spent fuel storage racks. 4. The spent fuel storage facility according to claim 1, 2, or 3, characterized in that a support is provided between the base and the wall surface of the fuel pool.