JP6195048B2 - Box-type structure for storing radioactive waste - Google Patents

Description

  The present invention relates to a box-type container and a box-type structure for storing radioactive waste and a method for manufacturing the same. More specifically, the present invention relates to a box-type container and a box-type structure. The present invention relates to a box-type container for storing radioactive waste, a box-type structure, and a method for manufacturing the same.

  Due to the accident at the nuclear power plant, an intermediate storage facility for temporary storage of soil contaminated with radioactive materials and incineration ash is required. Metal containers for storing radioactive waste are expensive. On the other hand, in normal concrete, if the thickness is not sufficiently increased, the shielding effect is not obtained, so that the container becomes large, and there is a possibility that cracking or the like may occur in long-term storage.

  In Patent Document 1, a mixture of steelmaking dust, steel slag and sulfur is mixed, mixed and heated, then cooled and solidified to form sulfur concrete, and the surface thereof is covered with a metal plate such as zinc, aluminum, or chromium. Containers have been proposed. Sulfur concrete is excellent in radiation shielding effect, but it is desired to improve the strength of sulfur concrete so that the surface does not have to be covered with a metal plate.

Japanese Examined Patent Publication No. 2-49680

  The objective of this invention is providing the box-type container and box-type structure which store the radioactive waste excellent in intensity | strength and radiation shielding capability.

  The box-type container for storing radioactive waste according to the present invention has a container body and a lid having a thickness of 10 to 20 cm, 30% by weight of sulfur, 30% by weight of blast furnace slag, and 30% by weight of coal incineration ash. %, And a compound comprising 10% by weight of a solidifying agent of dicyclopentadiene or barium sulfate containing tungsten or lead metal powder, and made of sulfur concrete formed by heating and kneading.

  The box structure for containing radioactive waste according to the present invention has a thickness of 10 to 20 cm at the front, rear, left and right walls, ceiling and bottom, 30% by weight of sulfur, 30% by weight of blast furnace slag, A rectangular panel made of sulfur concrete formed by heating and kneading a blend of 30% by weight of incinerated ash and 10% by weight of a solidifying agent of dicyclopentadiene or barium sulfate containing tungsten or lead metal powder; It is characterized by comprising a column holding a panel, a steel material comprising a frame and a crosspiece.

  The method for manufacturing a box-type container or a box-type structure for storing radioactive waste according to the present invention is such that a rectangular panel constituting the box-type container or box-type structure for storing radioactive waste has 30% by weight of sulfur and a blast furnace. Powder having an average particle size of 2 mm or less of a composition comprising 30% by weight of slag, 30% by weight of coal incineration ash, and 10% by weight of solidifying agent of dicyclopentadiene or barium sulfate containing metal powder of tungsten or lead And a step of kneading the compound by heating at 115 ° C. to 150 ° C. and a step of pouring into a mold of an iron frame and solidifying.

  According to the box-type container and the box-type structure according to the present invention and the method for producing the box-type container and the box-type structure according to the present invention, (1) 30% by weight of sulfur, 30% by weight of blast furnace slag, and 30% of incineration ash Since sulfur concrete formed by heating and kneading a composition comprising 10% by weight and 10% by weight of a solidifying agent is used, a container or structure excellent in strength and radiation shielding ability can be obtained. (2) In particular, the solidifying agent dicyclopentadiene is melted to be polymerized and bonded in a network, so that the strength can be improved. (3) Further, when barium sulfate is used as the solidifying agent, it acts as an aggregate, so that the strength can be improved. (4) Since tungsten and lead shield radiation, the radiation shielding effect of sulfur concrete can be further improved. Since this sulfur concrete has strength, it is not necessary to cover the outside with a metal plate as in the prior art.

It is a perspective view of the box-shaped container by this invention. It is explanatory drawing when the box-shaped container of FIG. 1 is installed in the underground storage hole. It is a front view of the box-type structure by this invention. It is a right view of the box-shaped structure of FIG. It is a top view of the box-shaped structure of FIG. It is explanatory drawing when the box-shaped structure of FIG. 3 is installed in the underground storage hole. It is a figure which shows the connection part of the rectangular panel used for the wall of the box-shaped structure of FIG. 3, (a) is a figure which shows the case where a rectangular panel is connected in a step part, (b) is a figure where a rectangular panel is H. It is a figure which shows the case where it connects with steel. It is a figure which shows the ratio of the compound which comprises sulfur concrete. It is a flowchart which shows the manufacturing method of a box-type container or a box-type structure.

  Hereinafter, a box-shaped container and a box-shaped structure according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a box-type container 1 according to the present invention. The box-type container 1 is a container made of sulfur concrete, and includes a container main body 1a and a lid 1b, and stores radioactive waste. The container body 1a is provided with legs at the bottom, and can be easily transported by a forklift. The upper surface of the lid 1b is flat, and the box-shaped containers 1 can be stacked. The thickness was 10 cm, the width was 2.2 m, the depth was 2, 2 m, and the height was 2.5 m. The width and height were calculated from the dimensions that can be loaded on the truck. The thickness needs to be 10 cm according to experiments, and if it is thicker than this, the amount of radiation that leaks out can be reduced, but the thickness of the container is preferably 20 cm or less.

  FIG. 2 is an explanatory diagram when the box-shaped container 1 is installed in the underground storage hole 10. The depth of the underground storage hole 10 is 10 m as an example. At this depth, the box-type container 1 can be stacked in 10 stages. The period during which the radioactive waste is stored in the intermediate storage is, for example, 30 years. Then, it is finally disposed of.

  FIG. 3 is a front view of the box-type structure 2 according to the present invention. The box-shaped structure 2 has a height of 2.7 m and a width of 5.4 m. In the width direction, H steel pillars 2b are erected every 1.8 m. Steel bars 2c are stretched between the pillars 2b. A brace 2e is provided at a necessary place. A rectangular panel 2a made of sulfur concrete is supported by pillars 2b and crosspieces 2c to form a front wall. The rectangular panel 2a on the front side has a width of 1.8 m and a length of 0.9 m. Thicknesses of 10 and 15 cm were produced.

  FIG. 4 is a right side view of the box-type structure 2. The depth (side length) is not limited to this dimension, but is 9 m. In the depth direction, H steel pillars 2b are erected every 1.8 m, and steel bars 2c are stretched between the pillars 2b. A brace 2e is provided at a necessary place. A rectangular panel 2a made of sulfur concrete is held by a pillar 2b and a crosspiece 2c to form a side wall. The rectangular panel 2a on the side surface has a width of 1.8 m and a length of 0.9 m. Thus, the box-shaped structure 2 has a (5.4 m, 9 m, 2.7 m) box shape (horizontal, depth, height) and can accommodate a long radioactive waste such as a bar.

  FIG. 5 is a plan view of the box-type structure 2. The ceiling wall serving as a lid has a width of 5, 4 m and a depth of 9 m, and is bordered by a steel frame 2d. Steel bars 2c each having two vertically and four horizontally are hung inside the frame 2d. The rectangular panel 2a made of sulfur concrete is a square having a width of 1.8 m and a length of 1.8 m. Although not shown, the bottom surface of the box-type structure 2 can be similarly configured.

FIG. 6 shows a case where the box-type structure 2 is installed in the underground storage hole 10. When the underground storage hole 10 is deep, the box-type structures 2 can be stacked. Regardless of this, the box-type structure 2 may be constructed according to the dimensions of the underground storage hole 10.
FIG. 7 is a diagram illustrating a connection portion of the rectangular panel 2a, and FIG. 7A illustrates a case where the rectangular panel 2a is connected at a stepped portion. (B) shows the case where the rectangular panel 2a is inserted and connected to the column 2b of H steel. The gap between the rectangular panel 2a and the column 2b or the crosspiece 2c is preferably sealed with separately prepared sulfur concrete.

  FIG. 8 is a diagram showing the proportion of the compound constituting the sulfur concrete of the present invention. Sulfur concrete consists of 30% by weight of sulfur, 30% by weight of blast furnace slag, 30% by weight of coal incineration ash, and 10% by weight of solidifying agent of dicyclopentadiene or barium sulfate containing tungsten or lead metal powder. The blend is mixed, heated and melted, put into a mold and cooled and solidified. It is about 5 times stronger than Portland cement concrete. Therefore, there are no reinforcing materials such as reinforcing bars inside. The temperature when heating and melting is 115 to 150 degrees. Above 150 degrees, it becomes rubber and cannot be restored. Therefore, kneading is performed while maintaining a temperature of 115 to 150 degrees. In addition, it hardens at 115 degrees or less, and the time which solidifies by natural cooling is about 5 hours.

  This sulfur concrete is hydrophobic and does not penetrate seawater, and it is strong and chemically stable against chemicals such as acids. The service life can be 2000 years. When calculated from the experiment, when the thickness of the box-shaped container 1 was 10 cm, the transmittance was 0.2% and the shielding rate was 99.8%. For example, when waste having a radiation dose of 2.3 μSv / h is stored, the amount leaking out of the box-type container 1 is 0.046 μSv / h. In the case of radioactively contaminated soil, since it is about 1.1 μSv / h, the amount leaked to the outside is 0.0022 μSv / h, which sufficiently satisfies the safety standard of 0.1 μSv / h. μSv / h is a unit of exposure energy per unit time and is called a microsievert. The lethal dose is 2000 mSv / h.

  Blast furnace slag is discharged from a blast furnace that produces pig iron from coke and iron ore. Main components are silicon dioxide (SiO2) 33.6%, calcium oxide (CaO) 42%, aluminum oxide (Al2O3) 1.9%, magnesium oxide (MgO) 7.3%, etc. . Coal incineration ash includes clinker ash that has fallen to the bottom of the boiler and fly ash in which particles in the combustion gas are collected by an electric dust collector. Main components are 60 to 63% silicon dioxide (SiO2), 17 to 20% aluminum oxide (Al2O3), 3 to 8% calcium oxide (CaO), 4 to 13% ferric oxide (Fe2O3), etc. It has become.

  FIG. 9 is a flowchart showing a method for manufacturing a box-type container or a box-type structure. S1 is a stage in which a compound comprising sulfur, blast furnace slag, coal incineration ash, and a solidifying agent of dicyclopentadiene or barium sulfate containing tungsten or lead metal powder is made into a powder having an average particle size of 2 mm or less. . S2 is a stage in which this compound is kneaded while being heated to 115 to 150. S3 indicates the stage in which the compound is poured into a steel frame mold and, after natural cooling for several hours, solidifies and is removed from the mold. The mold includes a mold for forming a box-type container or a mold for forming a rectangular panel of a box-type structure. The iron frame mold can be stamped on the molded product by the marks dug into the mold.

  The rectangular panel 2a used in the box-type structure 2 shown in the present embodiment can also be used as a shielding plate that shields the entire building contaminated with radiation. It can also be made into a corridor that passes through dangerous places in the form of a tunnel.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a box-type container and a box-type structure for storing radioactive waste having high strength, a small amount of radiation leakage, and high shielding ability, and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 1 Box-type container 1a Container body 1b Lid 1c Leg 2 Box-type structure 2a Rectangular panel 2b Pillar 2c Crosspiece 2d Frame 2e Bracing 10 Underground storage hole

Claims (1)

  The front, back, left and right walls, ceiling and bottom have a thickness of 10 to 20 cm, 30% by weight of sulfur, 30% by weight of blast furnace slag, 30% by weight of coal incineration ash, and tungsten or lead metal powder. A rectangular panel made of sulfur concrete formed by heating and kneading a composition comprising 10% by weight of a dicyclopentadiene or barium sulfate solidifying agent, and a steel material made of pillars, frames and bars that hold the rectangular panel A box-shaped structure for containing radioactive waste, characterized in that it is constructed.

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