JPS62177494A - Method of storing spent fuel and spent-fuel storage rack - 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 [Technical Field of the Invention] The present invention relates to a spent fuel storage method and a spent fuel storage rack 1 used in the storage method.

[Technical background of the invention and its problems]

Generally, in a nuclear power plant, approximately one-third of the fuel loaded in the reactor core is removed once a year. The removed spent fuel is stored in a spent fuel storage pool until it is reprocessed, and is cooled by pool water.

FIG. 3 shows a longitudinal sectional view of a conventional spent fuel storage pool. A plurality of spent fuel storage racks 2 are installed in the spent fuel storage pool 1, and a large number of spent fuels 3 are stored in the spent fuel storage racks 2. As shown in FIG. 4, the spent fuel storage rack 2 is composed of a rack body 5 that individually stores a large number of spent fuels, and a base 7 provided at the bottom of the rack body 5. The rack body 5 is
It is formed to be able to hold the spent fuel 3 vertically for a long period of time. The base 7 also fixes the spent fuel storage rack 2 to the floor surface of the spent fuel storage boule 1.

When storing the spent fuel 3, as shown in Figure 3,
First, the spent fuel storage rack 2 is installed in the spent fuel storage boule 1.
Install the book by fixing it to the floor. Next, the spent fuel 3 is suspended using a crane or the like, and the spent fuel 3 is horizontally moved above the spent fuel storage rack 2 . Then, at a predetermined position of a predetermined spent fuel storage rack 2, the spent fuel 3 is inserted into the spent fuel storage rack 2 from vertically above and stored therein.

Therefore, the space inside the spent fuel storage boul 1 from the floor surface of the spent fuel storage boul 1 to the water surface 9 is a space for storing racks (corresponding to the rack height C) and a space for horizontally transferring the spent fuel 3. Space required for fuel transfer (corresponding to transfer fuel height D) and release r from spent fuel 3 to be transferred.
JJ! ! Transfer fuel shielding space required to shield (
The area is divided into sections corresponding to the transfer fuel shielding water depth E.

Therefore, the pool water depth F is the sum of the rack height C1, the transfer fuel height D, and the transfer fuel shielding water depth E. for example,
In conventional boiling water nuclear power plants, the rack height C
is about 4.57 FL, the transferred fuel height D is about 4.5 m, the transferred fuel shielding water depth E is about 285 m, and the pool water depth F is about 11.5 m.

By the way, the storage m of the spent fuel 3 depends on the floor area of the spent fuel storage boul 1 because the spent fuel storage rack 2 is set up one stage on the floor surface of the spent fuel storage boul 1. . On the other hand, the space inside spent fuel storage boul 1 is for fuel transfer.

Although the space (corresponding to the transferred fuel height D) is necessary when inserting the spent fuel 3, it becomes a wasted space when storing the fuel. Therefore, there is a waste space within the spent fuel storage boule 1 that does not contribute to the storage of the spent fuel 3.

Therefore, a spent fuel storage method has been proposed in which the conventional spent fuel storage racks 2 in which the spent fuel 3 is vertically stored are stacked in two stages to save wasted space (
Specification of Japanese Patent Application No. 51-79889, Japanese Patent Publication No. 58-217
Publication No. 19). However, in this case, since the amount of spent fuel 3 to be stored increases, the storage fuel shielding space necessary to shield radiation during storage is the transferred fuel shielding space (corresponding to the transferred fuel shielding water depth E). Become bigger. For example, the transferred fuel shielding depth E is approximately 2.5
However, the depth of the water for shielding the stored fuel in the space for shielding the stored fuel is required to be approximately 3.5 m.

Therefore, in this case, the pool water depth F is twice the rack height C (2 x approximately 4.5 m) and the stored fuel shielding depth (approximately 3.5 m).
m) (approximately 12.5 m). As a result, the conventional spent fuel storage boule 1 lacks a pool depth gauge (approximately 1.0 TrL), necessitating a change in the design of the spent fuel storage boule.

[Purpose of the invention]

This invention was made in consideration of the above facts, and provides a spent fuel storage method and a spent fuel storage method that can efficiently store spent fuel without wasting it (without changing the design of the spent fuel storage boule). The purpose is to provide fuel storage racks.

[Summary of the invention]

The spent fuel storage method according to the present invention involves inserting and storing spent fuel from vertically above into a spent fuel storage rack temporarily installed in a spent fuel storage pool, and then storing the spent fuel in a spent fuel storage rack that is temporarily installed in a spent fuel storage pool. The direction of the spent fuel storage rack is changed so that it is in a horizontal state, and the spent fuel storage racks whose direction has been changed are stacked in multiple stages and placed in the spent fuel storage pool. The spent fuel storage rack consists of a rack body that individually stores a large number of spent fuels, a side plate fixed to the rack body on the tip side of the stored spent fuel, and a side plate fixed to the rack body on the opposite side of the side plate. The rack has a removably attached lid plate, and is configured so that the spent fuel is held horizontally within the rack body for a long period of time. Both of these inventions allow spent fuel to be stored in the fuel transfer space, which was previously a waste space, in the spent fuel storage pool, thereby increasing the spent fuel storage capacity.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

Figure 1 is a poly sectional view of a spent fuel storage pool in which an embodiment of the spent fuel storage method according to the present invention is implemented;
The figure is a front view showing an embodiment of a spent fuel storage rack according to the present invention. The spent fuel storage rack 13 installed in the spent fuel storage pool 11 is mainly composed of a rack body 15, a side plate 17, and a cover plate 19, as shown in FIG.

The rack body 15 is formed by assembling a large number of rectangular tubes or plates in a lattice shape, and is configured such that one spent fuel 21 is stored in one rectangular tube or in one lattice. Further, the thickness of the rectangular tube or grid plate is set so as to have enough strength to hold the spent fuel 21 horizontally for a long period of time. Further, supports 11JI23 are fixed to the four corners of the lower surface of the main body rack 15 in FIG. 2, and bottle holes 25 are bored in the support legs. This bottle hole 25 is provided so that a planted bottle 27 installed in the bed of the spent fuel storage pool 11 shown in FIG. 1 can be inserted therein. Furthermore, on the top surface of the rack body 15 in FIG.
Support pins 29 are fixed to the four corners. The support bottle 29 is disposed coaxially with the bottle hole 25 and has approximately the same diameter. Moreover, the rack body 15 provided with the support bin 29
Hanging ears 31 for horizontal support are fixed to the upper surface of the housing, and are used for suspension by a crane.

A cover plate 19 and side plates 17 for closing the opening of the rack body 15 are disposed on the left and right sides of the rack body 15 as shown in FIG. The side plate 17 is fixed to the rack body 15 so as to close the opening of the rack body 15 corresponding to the leading end side of the spent fuel 21 .

Further, the cover plate 19 is removably attached to the opposite side of the side plate 17 in the rack body 15. A hanging ear 33 for vertical support is fixed to this cover plate 19, and is used for suspending the spent fuel storage rack 13 by a crane.

On the other hand, the rack height A of the spent fuel storage rack 13 having such a configuration is determined by the width W of each square tube or one grid and the number of square tubes or grids arranged in the rack height. Ru. This rack height A is determined taking into consideration the strength of the support leg 23, the implanted bottle 27, and the support bottle 29, and is, for example, about 4 m in this embodiment.

Next, a spent fuel storage method using such a spent fuel storage rack 13 will be explained.

First, with the cover plate 19 attached to the rack body 15,
Spent fuel storage rack 13 using hanging ears 33 for vertical support
The spent fuel storage pool 11 (first
Temporarily install it on the floor as shown in the figure.

In this temporary installation, the side plate 17 is attached to the spent fuel storage pool 11.
The cover plate 19 is located vertically above. Next, the cover plate 19 is removed, and the spent fuel 21 is removed from the spent fuel storage pool 11 using a crane, as shown in FIG.
At a predetermined position, the spent fuel 21 is pushed vertically into the spent fuel storage rack 13 and stored therein.

When the spent fuel storage rack 13 is full of spent fuel 21, the cover plate 19 is attached to the rack body 15. Then, the spent fuel storage rack 13 is suspended by a crane using the hanging ears 31 for horizontal support, and the direction of the spent fuel storage rack 13 is changed. This direction change causes the spent fuel 21 stored in the spent fuel storage rack 13 to be in a horizontal state. In this state, the spent fuel storage rack 13 containing the spent fuel is moved within the spent fuel storage pool 11 by a crane and suspended at a predetermined position. At this time, the implanted bottle 27 is inserted into the bottle hole 25 of the support leg 23 in the spent fuel storage rack 13, and the spent fuel storage rack 13 is permanently installed.

Next, in the same manner as described above, an empty spent fuel storage rack is temporarily installed on the floor of the spent fuel storage pool 11 with the side plate 17 facing downward and the cover plate 19 facing upward. The spent fuel 21 is inserted and stored from vertically above. Thereafter, in the same manner as described above, the direction of the spent fuel storage rack 13 is changed so that the stored spent fuel 21 is in a horizontal state. In this state, this spent fuel storage rack 13 is moved to above the fully installed spent fuel storage rack 13 using a crane and suspended. Then, the support bin 29 of the spent fuel storage rack 13 that has been permanently installed on the floor of the pool 11 is inserted into the bin hole 25 of the support leg 23, and the spent fuel storage rack 13 is permanently installed. In this way, the spent fuel storage racks 13 containing the spent fuel 21 in a horizontal state are stacked in two stages in the spent fuel storage pool 11. Thereafter, two spent fuel storage racks 13 are stacked on the anvil surface of the spent fuel storage pool 11 in the same manner.

According to the above embodiment, the space for transferred fuel (corresponding to the transferred fuel height D in FIG. 3) that was necessary when inserting the spent fuel 21 into the spent fuel storage rack 13 is also filled with spent fuel. Since the storage rack 13 is arranged and the spent fuel is stored, the fuel storage capacity of the spent fuel storage boul 11 can be increased, and the spent fuel can be efficiently stored in the spent fuel storage boul 11 without waste. Can be stored.

In addition, the rack height Δ is not determined as −(1!) by the length of the spent fuel 21 in the longitudinal direction as in the conventional case, but is determined by the rack height of the rectangular tube or lattice of the rack body 15 in the six directions. The number of arrays can be adjusted depending on the number of arrays. Therefore, the space for shielding the stored fuel required to shield the radiation emitted from the spent fuel 21 stored in the spent fuel storage boule 11 (the space for shielding the stored fuel m at the water depth B) ) can be secured by adjusting the rack height A without changing the design of the spent fuel storage boule 11. For example, if the stored fuel shielding water depth B is required to be approximately 3.5 m, If the rack height A is about 4 m, the total of these will be about 11.5 m. This is the same value as the pool water depth E of the spent fuel storage boule 11, and This means that no design changes are required.

In the above embodiment, the spent fuel storage racks 13 are stacked in two stages in the spent fuel storage boule 11. Rack height A of storage rack 13
In the case where the spent fuel storage racks 13 are set to be small, the spent fuel storage racks 13 may be stacked in multiple stages.

〔Effect of the invention〕

As described above, according to the spent fuel storage method of the present invention, after the spent fuel is inserted into the spent fuel storage rack from vertically above, the spent fuel is placed in a horizontal position. By changing the direction of the fuel storage racks and stacking them in multiple tiers, spent fuel can be stored in the fuel transfer space, which used to be a waste of space in the spent fuel storage pool, increasing fuel storage capacity. This has the effect that spent fuel can be efficiently stored without waste without changing the design of the spent fuel storage pool.

Further, according to the spent fuel storage rack according to the present invention, a side plate and a lid plate are attached to the rack body that individually accommodates a large number of spent fuels, and the spent fuel is maintained in a horizontal state within the rack body for a long period of time. By stacking these spent fuel storage racks in multiple stages within the spent fuel storage pool, spent fuel can be efficiently stored without waste without changing the design of the spent fuel storage pool. Qin effect can be stored.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a spent fuel storage pool in which an embodiment of the spent fuel storage method according to the present invention is implemented, and Fig. 2 shows an embodiment of the spent fuel storage rack according to the present invention. FIG. 3 is a longitudinal sectional view of a spent fuel storage pool without showing a conventional spent fuel storage method, and FIG. 4 is a front view of a conventional spent fuel storage rack. DESCRIPTION OF SYMBOLS 11... Spent fuel storage pool, 13... Spent fuel storage rack, 15... Rack body, 21... Spent fuel, 31... Hanging ears for horizontal support, 33... Hanging ears for vertical support, A...rack height, B...stored fuel shielding water depth, F...pool water depth. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. Spent fuel is inserted and stored from vertically above into a spent fuel storage rack temporarily installed in a spent fuel storage pool, and then the stored spent fuel is placed in a horizontal state. A spent fuel storage method characterized by changing the direction of the spent fuel storage rack so that the direction is changed, and stacking the spent fuel storage racks with the changed direction in multiple stages and finally installing them in the spent fuel storage pool. . 2. A rack body that individually stores a large number of spent fuel;
A side plate is fixed to the rack body on the front end side of the stored spent fuel, and a lid plate is removably attached to the rack body on the opposite side of the side plate, and the spent fuel is stored in the rack. A spent fuel storage rack characterized in that it is configured to be held horizontally within a main body for a long period of time.