JP6801427B2 - Radioactive waste storage device - Google Patents

Description

The present invention relates to a radioactive waste storage device.

At nuclear power plants, etc., radioactive waste is generated by the operation and dismantling of facilities. Such radioactive waste is classified into high-level radioactive waste including spent fuel and the like, and low-level radioactive waste other than high-level radioactive waste. Of these, low-level radioactive waste is mixed with glass, for example, and cooled as a vitrified waste in a low-level radioactive waste storage facility for a certain period of time.

In such a low-level radioactive waste storage facility, the vitrified waste is cooled by contacting it with cooling air. For example, in Patent Document 1, an air heater for heating the cooling air is provided in the exhaust shaft of the cooling air, the draft force is improved by heating the cooling air, and the cooling air is stored in the radioactive waste storage facility. Forming a flow.

Jikkenhei 6-22999

However, in the radioactive waste storage facility of Patent Document 1, an air heater is provided in the main flow path of the cooling air of the exhaust shaft, and the air heater obstructs the flow of the cooling air. Since the heat generated by the vitrified waste of low-level radioactive waste is small, the draft force generated in the cooling air is small, and the flow rate of the cooling air passing through the exhaust shaft is also small. Therefore, the air heater obstructs the flow of cooling air on the exhaust shaft, which may reduce the cooling efficiency of the vitrified body of low-level radioactive waste.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to secure a draft force of cooling air without obstructing the flow of cooling air in the exhaust shaft.

According to the present invention, as a first means for solving the above-mentioned problems, the air taken in from the introduction opening is ventilated around the low-level radioactive solid waste and exhausted from the discharge opening to exhaust the low-level radioactive solid waste. A radioactive waste storage facility that cools and stores the waste, and the flow path from the air that cooled the low-level radioactive solid waste to the discharge from the discharge opening includes a ventilation flow path and at least one bypass. A configuration is adopted in which a flow path is provided and a heating element is provided in the bypass flow path.

As a second means, in the first means, a plurality of the bypass flow paths are provided so as to surround the ventilation flow paths, and a heating element is provided in a part or all of the plurality of bypass flow paths. Adopt the configuration.

As a third means, in the first or second means, the bypass flow path extends in the vertical direction, and the heating element is provided in the lower part of the bypass flow path. To do.

As the fourth means, in the third means, the bypass flow path is provided with a maintenance opening in the area where the heating element is provided.

As a fifth means, in any of the first to fourth means, the configuration that the heating element is an electric heater is adopted.

According to the present invention, in the chimney region, the heating element flow path in which the heating element is installed and the main flow path through which the cooling air flows are separated. This heating element can heat the surrounding cooling air and improve the draft force of the cooling air in the chimney region. Further, even in a situation where the heating element does not generate heat, the heating element does not easily obstruct the flow of the cooling air in the exhaust shaft. Therefore, the radioactive waste storage facility of the present invention does not obstruct the flow of cooling air in the exhaust shaft while improving the draft force of cooling air.

It is sectional drawing which shows the schematic structure of the radioactive waste storage facility in one Embodiment of this invention. FIG. 1 is a sectional view taken along the line AA of FIG. It is an enlarged schematic view of the storage pipe provided in the radioactive waste storage facility of one Embodiment of this invention. It is a partial cross-sectional view which shows typically the solidified body stored in the radioactive waste storage facility in one Embodiment of this invention.

FIG. 1 is a cross-sectional view showing a schematic configuration of the radioactive waste storage facility 1 of the present embodiment. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is an enlarged schematic view of a storage pipe 6 included in the radioactive waste storage facility 1 of the present embodiment. As shown in any one or more of FIGS. 1 to 3, the radioactive waste storage facility 1 of the present embodiment includes a building 2, a lower plenum forming plate 3, an upper plenum forming plate 4, and a plurality of ventilation pipes 5. A plurality of storage pipes 6, a plug 7, a storage pipe lid 8, a heat insulating material 9, a heat generating portion 10, and a floor traveling crane 11 are provided.

The radioactive waste storage facility 1 of the present embodiment is a facility for storing the solidified body for a long period of time while cooling it. As will be described later with reference to the drawings, in the present embodiment, the solidified body X is a solid waste (solidified glass or the like) containing radioactive waste (low-level radioactive waste) and this solid waste. Includes a canister that houses the.

The building 2 is a concrete structure having a storage area R1. The building 2 is constructed so that the lower part is buried in the ground, and has a floor portion 2a installed at substantially the same height as the surrounding ground. In the building 2, the space below the floor 2a is the storage area R1 described above, and the space above the floor 2a is the transport room R2. The storage area R1 is a space for storing the solidified material. Further, the transport chamber R2 is a space in which the floor traveling crane 11 is arranged and the solidified body is carried in from the solidified body receiving building (not shown) adjacent to the building 2.

Further, the building 2 has a building bottom 2b and a storage area side wall 2c. As shown in FIG. 1, the storage area R1 is formed by being surrounded by the floor portion 2a, the building bottom portion 2b, and the storage area side wall 2c. Further, the building 2 has an introduction opening 2d opened at the upper part of the side wall of the building 2, a chimney portion 2e connected to the storage area side wall 2c and protruding upward, and an upper part from the chimney bottom portion 2f of the chimney portion 2e. A partition wall 2g erected toward the wall, a vent 2h formed in the partition wall 2g, a maintenance opening 2i formed in the lower region of the chimney portion 2e, and a discharge opening formed in the tip portion of the chimney portion 2e. It has 2j.

The chimney portion 2e is a tubular portion formed so as to project from the storage area side wall 2c (left-right direction in FIG. 1) of the storage area R1 and project upward from the floor surface. Further, in the chimney portion 2e, the internal region on the upper side is the outlet shaft R4. In the present embodiment, the height of the chimney bottom portion 2f corresponds to the ground surface.

Further, as shown in FIG. 2, the chimney portion 2e is provided with two partition walls 2g parallel to each other in the internal region along the vertical direction (vertical direction in FIG. 1) from the chimney bottom portion 2f. As a result, the lower region of the chimney portion 2e is divided into three spaces: a main flow path Ra (ventilation flow path), a first bypass flow path Rb on both sides thereof, and a second bypass flow path Rc. Further, each of the two partition walls 2g is formed with a vent 2h communicating with the region on the chimney bottom 2f side. As a result, in the chimney portion 2e, the flow of the cooling air Y passing through the main flow path Ra between the two partition walls 2g and toward the outlet shaft R4, and the respective partition walls 2g from the main flow path Ra through the vent 2h. A flow of cooling air Y that passes through the first bypass flow path Rb or the second bypass flow path Rc formed between the chimney portion 2e and the inner wall surface and toward the outlet shaft R4 is formed. The first bypass flow path Rb and the second bypass flow path Rc extend from the chimney bottom portion 2f in the vertical direction to a predetermined height.

Further, a maintenance opening 2i that communicates the first bypass flow path Rb with the outside is formed on the side wall surface of the chimney portion 2e near the chimney bottom portion 2f. Further, a maintenance opening 2i that communicates the second bypass flow path Rc with the outside is also formed on the side wall surface facing the side wall surface on which the maintenance opening 2i is formed across the main flow path Ra. There is. The maintenance opening 2i is provided on the side of the first heating element 10a and the second heating element 10b (the region where the first heating element 10a and the second heating element 10b are provided) of the heating unit 10, and the first heating element is generated. It is an opening for carrying in or out the body 10a and the second heating element 10b. Further, these maintenance openings 2i are normally closed by a removable door. Further, the discharge opening 2j is an opening for discharging the cooling air Y discharged from the storage area R1 to the outside of the building 2.

As shown in FIG. 1, the lower plenum forming plate 3 is a plate member arranged in the storage area R1 and is fixed to the storage area side wall 2c so that the front and back surfaces face in the vertical direction. The lower plenum forming plate 3 is arranged with a certain gap from the bottom of the building 2b, and forms the lower plenum R5 between the lower plenum forming plate 3 and the bottom of the building 2b. The lower plenum R5 is a space provided in the lowermost layer of the storage area R1 and is connected to the inlet shaft R3. Such a lower plenum R5 is a space to which the cooling air Y is supplied from the inlet shaft R3, and the supplied cooling air Y is distributed to the respective ventilation pipes 5.

The upper plenum forming plate 4 is a plate member arranged above the lower plenum forming plate 3 in the storage area R1, and is fixed to the storage area side wall 2c so that the front and back surfaces face in the vertical direction. The upper plenum forming plate 4 is arranged with a certain gap from the floor portion 2a, and forms the upper plenum R6 between the upper plenum forming plate 4 and the floor portion 2a. The upper plenum R6 is a space provided in the uppermost layer of the storage area R1 and is connected to the outlet shaft R4 via the main flow path Ra of the chimney portion 2e. Such an upper plenum R6 is a space in which the cooling air Y is discharged from the plurality of ventilation pipes 5, and the cooling air Y discharged from the plurality of ventilation pipes 5 is collectively guided to the outlet shaft R4.

As shown in FIGS. 1 and 3, the ventilation pipe 5 is a straight pipe member communicating from the lower plenum R5 to the upper plenum R6, and is arranged so that the pipe shaft faces in the vertical direction. The ventilation pipe 5 penetrates the lower plenum forming plate 3 and the upper plenum forming plate 4 so that the lower end opening is arranged in the lower plenum R5 and the upper end opening is arranged in the upper plenum R6. It is supported by the upper plenum forming plate 4. Such ventilation pipes 5 are provided in the same number as the number of storage pipes 6.
In the present embodiment, 20 storage pipes 6 are arranged in the lateral direction (left-right direction in FIG. 1) and 4 in the depth direction, and a total of 80 storage pipes are installed. For this reason, 20 ventilation pipes 5 are similarly arranged in the lateral direction and 4 in the depth direction, for a total of 80 ventilation pipes. These ventilation pipes 5 guide the cooling air Y supplied to the lower plenum R5 to the upper plenum R6.
That is, the cooling air Y flows from the lower plenum R5 to the upper plenum R6 through the inside of the ventilation pipe 5.

The storage pipe 6 is a straight pipe member whose upper end portion penetrates the floor portion 2a of the building 2 and is suspended and supported by the floor portion 2a so as to be inserted into the ventilation pipe 5. The storage pipe 6 has a bottomed shape in which the upper end is opened and the lower end is closed, and the lower end position has a length that is substantially the same as the lower end position of the ventilation pipe 5. Further, the storage pipe 6 has a smaller diameter than the ventilation pipe 5 so that a space is formed between the storage pipe 6 and the inner wall surface of the ventilation pipe 5. In such a storage pipe 6, the solidified body is stored in a laminated state inside.

As described above, 20 storage pipes 6 are arranged in the horizontal direction and 4 in the depth direction, and a total of 80 storage pipes are installed. The storage pipe 6 stores a solidified body containing low-level radioactive waste. In the following description, the solidified body containing low-level radioactive waste is referred to as low-level radioactive solid waste.

The plug 7 is fitted to the upper end portion of the storage pipe 6 and seals the area in which the solidified body of the storage pipe 6 is housed. The storage pipe lid 8 is arranged further above the plug 7 and is attached to the storage pipe 6 so as to close the open end of the storage pipe 6. The heat insulating material 9 is provided on the inner wall around the heat generating portion 10 to prevent heat transfer from the heat generating portion 10 to the wall surface.

As shown in FIGS. 1 and 2, the heating element 10 is a first heating element 10a on the chimney bottom 2f and arranged in the first bypass flow path Rb, and a second bypass on the chimney bottom 2f. It is composed of a second heating element 10b arranged in the flow path Rc. These first heating element 10a and second heating element 10b are electric heaters that heat the cooling air Y around the chimney portion 2e. These heat generating portions 10 improve the draft force of air by heating the air inside the chimney portion 2e, and form an air flow toward the outlet shaft R4.

As shown in FIG. 1, the floor traveling crane 11 is arranged in the transport chamber R2 by being installed on the floor portion 2a of the building 2. The floor traveling crane 11 is capable of traveling vertically and horizontally along the floor portion 2a, and is further configured to be able to move the solidified body X up and down. Such a floor traveling crane 11 receives the solidified body X from a solidified body receiving building (not shown), transports the received solidified body X to the upper part of the storage pipe 6, and then stores the solidified body X in the storage pipe 6. ..

FIG. 4 is a partial cross-sectional view schematically showing the solidified body X stored in the radioactive waste storage facility 1 in the present embodiment. As shown in FIG. 4, the solidified body X has a canister X1 which is a metal container and a solid waste X2 housed inside the canister X1. The canister X1 has a hollow substantially cylindrical shape, and a grip portion X11 is formed on the upper portion. The grip portion X11 is, for example, a portion gripped by the floor traveling crane 11. A recess X12 that can accommodate the grip portion X11 is formed at the bottom of the canister X1. In such a recess X12, when the solidified body X is laminated, the grip portion X11 of the solidified body X arranged below is accommodated. The solid waste X2 contains a radioactive substance, and if it is a high-level radioactive vitrified waste, it contains a high-level radioactive waste, and if it is a low-level radioactive solid waste, it contains a low-level radioactive waste. I'm out.

In the radioactive waste storage facility 1 of the present embodiment having such a configuration, the solidified body X is stored for a long period of time in a state where low-level radioactive solid waste is laminated and arranged in the storage pipe 6. At this time, the air in the storage area R1 warmed by the amount of heat of the heat generating portion 10 becomes lighter, so that the air is discharged to the outside from the discharge opening 2j through the outlet shaft R4. At this time, in the chimney portion 2e, the air passes through the main flow path Ra and flows toward the outlet shaft R4, and flows from the main flow path Ra into the first bypass flow path Rb or the second bypass flow path Rc and exits. It is branched into a flow toward the shaft R4.

Further, as the warmed air is exhausted from the discharge opening 2j, the cooling air Y flows into the inlet shaft R3 from the introduction opening 2d. The cooling air Y that has flowed into the inlet shaft R3 in this way flows from the lower plenum R5 into each ventilation pipe 5, rises through the ventilation pipe 5, and is guided to the upper plenum R6. As the cooling air Y flows from the lower side to the upper side inside the ventilation pipe 5 in this way, the solidified body X stored in the storage pipe 6 is cooled by heat exchange. The cooling air Y that has flowed from the ventilation pipe 5 into the upper plenum R6 is discharged to the outside of the building 2 through the discharge opening 2j through the outlet shaft R4.

Further, for example, when a worker carries out replacement or maintenance of the first heating element 10a, the worker operates the second heating element 10b to secure the draft force of the cooling air Y for maintenance. The first heating element 10a is taken out from the opening 2i. Similarly, when the operator replaces or maintains the second heating element 10b, the first heating element 10a is operated to secure the draft force of the cooling air Y, and the maintenance opening 2i to the second heating element generate heat. Take out body 10b.

According to the radioactive waste storage facility 1 according to the present embodiment, the first heating element 10a and the second heating element 10b are provided in the first bypass flow path Rb and the second bypass flow path Rc, respectively. The draft force of the cooling air Y is improved to form a flow of the cooling air Y toward the outlet shaft R4. As a result, the radioactive waste storage facility 1 according to the present embodiment can secure the draft force of the cooling air Y, and the cooling air Y passes through the main flow path Ra, so that the flow of the cooling air Y is generated as a heat generating portion. It is less likely to be inhibited by 10.

Further, according to the radioactive waste storage facility 1 according to the present embodiment, the first heating element 10a and the second heating element 10b are arranged below the chimney bottom portion 2f, that is, the chimney portion 2e. As a result, the cooling air Y near the inlet (outlet of the storage area R1) of the chimney portion 2e can be heated to improve the draft force, and the cooling air Y can be efficiently flowed into the chimney portion 2e. .. Further, by generating a draft force in the cooling air Y at the chimney bottom 2f, it is possible to form a flow of the cooling air Y from the chimney bottom 2f toward the discharge opening 2j in the chimney 2e. Therefore, the draft force of the cooling air Y can be improved, and the flow of the cooling air Y to the chimney portion 2e can be made smooth. Further, since the first heating element 10a and the second heating element 10b are arranged at the chimney bottom portion 2f, there is no possibility of falling, and the installation and fixing to the chimney portion 2e are easy.

Further, the radioactive waste storage facility 1 according to the present embodiment includes a first heating element 10a and a second heating element 10b as heating elements. Since the heating unit 10 is composed of a plurality of heating elements, it is possible to stop the operation of one of the heating elements and perform replacement or maintenance even while the low-level radioactive solid waste is being cooled.

Further, according to the radioactive waste storage facility 1 according to the present embodiment, the first heating element 10a and the second heating element 10b are electric heaters. Unlike hot water heating elements, electric heaters do not have moving parts like pumps and have a low failure rate. Therefore, the maintenance frequency of the first heating element 10a and the second heating element 10b can be reduced.

Further, according to the radioactive waste storage facility 1 according to the present embodiment, the maintenance opening 2i is provided, and the first heating element 10a and the second heating element 10b can be maintained and replaced from the maintenance opening 2i. is there. Since the radioactive waste storage facility 1 stores only low-level radioactive waste, the cooling air Y does not activate, and one of the first heating element 10a and the second heating element 10b is in operation. , The maintenance opening 2i can be opened. As a result, maintenance of the first heating element 10a and the second heating element 10b is easy.

Further, the chimney portion 2e is formed so as to project laterally from the side wall 2c of the storage area. Therefore, the radiation emitted from the solidified body X is shielded by the side wall 2c of the storage area and does not directly reach the region where the first heating element 10a and the second heating element 10b are arranged. Therefore, maintenance of the first heating element 10a and the second heating element 10b can be performed from the maintenance opening 2i.

Although preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. The various shapes and combinations of the constituent members shown in the above-described embodiment are examples, and can be variously changed based on design requirements and the like without departing from the spirit of the present invention.

(1) In the above embodiment, the heating unit 10 is composed of two heating elements, but the present invention is not limited to this. The heating unit 10 may be composed of three or more heating elements of the same type. In this case, a bypass flow path in the chimney portion 2e is also formed for each heating element. By providing three or more heating elements, two or more heating elements can be operated at all times including during maintenance, and the draft force of the cooling air Y can be further improved.
Further, the heating unit 10 may be composed of one heating element. Further, the radioactive waste storage facility 1 may be provided with a plurality of bypass channels and may adopt a configuration having one heating element.

(2) In the above embodiment, the first heating element 10a and the second heating element 10b are electric heaters, but the present invention is not limited thereto. The first heating element 10a and the second heating element 10b may be hot water type heating elements or the like.

(3) In the above embodiment, the first bypass flow path Rb and the second bypass flow path Rc extend in the vertical direction from the chimney bottom portion 2f, but the present invention is not limited thereto. For example, the first bypass flow path Rb and the second bypass flow path Rc may be configured to extend in a direction inclined from the vertical direction.

1 Radioactive waste storage facility 2 Building 2a Floor 2b Building bottom 2c Storage area side wall 2d Introductory opening 2e Chimney 2f Chimney bottom 2g Partition 2h Ventilation 2i Maintenance opening 2j Discharge opening 3 Lower plenum forming plate 4 Upper plenum forming plate 5 Ventilation pipe 6 Storage pipe 7 Plug 8 Storage pipe lid 9 Insulation material 10 Heat generating part 10a 1st heating element 10b 2nd heating element 11 Floor traveling crane R1 Storage area R2 Conveyance room R3 Inlet shaft R4 Outlet shaft R5 Lower plenum R6 Upper plenum Ra Main flow path Rb 1st bypass flow path Rc 2nd bypass flow path X Solidified body Y Cooling air

Claims (5)

A radioactive waste storage facility that cools and stores the low-level radioactive solid waste by ventilating the air taken in from the introduction opening around the low-level radioactive solid waste and exhausting it from the discharge opening.
The flow path from the low-level radioactive solid waste to the discharge opening is provided with a ventilation flow path and at least one bypass flow path.
A radioactive waste storage facility characterized in that a heating element is provided in the bypass flow path. The first aspect of the present invention is characterized in that a plurality of the bypass flow paths are provided so as to surround the ventilation flow path, and the heating element is provided in a part or all of the bypass flow paths. The listed radioactive waste storage facility. The bypass flow path extends in the vertical direction and extends in the vertical direction.
The radioactive waste storage facility according to claim 1 or 2, wherein the heating element is provided below the bypass flow path. The radioactive waste storage facility according to claim 3, wherein the bypass flow path is provided with a maintenance opening in a region where the heating element is provided. The radioactive waste storage facility according to any one of claims 1 to 4, wherein the heating element is an electric heater.

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