JP4040854B2 - Radioactive waste disposal container, disposal facility and disposal method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radioactive waste disposal container, a disposal facility, and a disposal method for burying radioactive waste in the ground.
[0002]
[Prior art]
When radioactive waste discharged from a nuclear power plant is buried in the ground, it is generally buried in a disposal facility with the radioactive waste stored in a disposal container. When radioactive waste is stored in a disposal container, a gap is created between the disposal container, the radioactive waste, and the radioactive waste, but the gap is filled with cement and the gap is filled before closing the disposal container. It is being buried.
[0003]
As radioactive waste buried in the ground is exposed to soil and groundwater for a long time, the disposal container deteriorates and the radioactive material in the radioactive waste is released out of the disposal container. Therefore, in the conventional radioactive waste disposal container, disposal facility, and disposal method, even if radioactive material is released from the disposal container, the cement filled in the disposal container or the cement, clay, or disposal constituting the disposal facility It is designed to reduce the amount and speed of radioactive materials that are absorbed by the bedrock and soil surrounding the facility and reach the ground surface.
[0004]
[Problem to be Solved by the Invention]
However, there are inorganic and organic radioactive materials. Of the radioactive materials, organic radioactive materials have a problem that their ability to adsorb on cement etc. is poor compared to inorganic radioactive materials. This is a cause of hindering the reduction of the amount and speed of the radioactive material that reaches it.
[0005]
Therefore, in the present invention, the amount of radioactive material that reaches the earth's surface by adding an oxidizing agent or photocatalyst, which is a material that mineralizes organic radioactive materials, to the filler for the disposal container or the constituent material of the disposal facility. , Provide a radioactive waste disposal container, disposal facility and disposal method capable of reducing the speed.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the first invention stores a plurality of radioactive wastes, fills the gaps generated in the state of storing the radioactive wastes, and fills the gaps before closing the lid. The disposal container is configured to add a photocatalyst or an oxidizing agent to the filler.
[0007]
According to the above configuration, even if the groundwater flows into the disposal container due to deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, and the organic radioactive material diffuses in the groundwater, the disposal The amount and rate of radioactive materials that reach the surface of the earth by being oxidatively decomposed by contact with the photocatalyst or oxidant in the filler filled in the container, and decomposed into inorganic substances such as CO ₂ and H ₂ O. Can be reduced.
[0008]
The second invention is a radioactive waste disposal method for burying a disposal container containing a plurality of radioactive wastes in an underground disposal facility, wherein the disposal container according to the first invention is used. .
According to the above configuration, even when the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive substance is dissolved in the groundwater, and the organic radioactive substance diffuses in the groundwater, The amount and rate of radioactive materials that reach the surface of the earth by being oxidatively decomposed by contact with the photocatalyst or oxidant in the filler filled in the disposal container, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O Can be reduced.
[0009]
The third invention is a disposal facility disposed underground disposal container containing a plurality of radioactive waste into the ground, is characterized by the addition of photocatalyst or oxide to the structure material forming the disposal facility .
According to the above configuration, the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, the organic radioactive material diffuses in the groundwater, and the groundwater enters the disposal facility. Even if it flows in, radioactive materials that reach the earth's surface by being decomposed by contact with the photocatalyst or oxidizing agent in the components of the disposal facility, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O This can reduce the amount and speed.
[0010]
A fourth invention is a radioactive waste disposal method in which a disposal container containing a plurality of radioactive wastes is buried in an underground disposal facility, wherein the disposal facility according to the third invention is used. .
According to the above configuration, the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, the organic radioactive material diffuses in the groundwater, and the groundwater enters the disposal facility. Even if it flows in, radioactive materials that reach the earth's surface by being decomposed by contact with the photocatalyst or oxidizing agent in the components of the disposal facility, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O This can reduce the amount and speed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
As shown in FIG. 2 , the radioactive waste disposal method according to the embodiment of the present invention is performed in an underground disposal facility 1 in which radioactive waste discharged from a nuclear power plant or the like is buried in a geological formation. The disposal facility 1 forms a hole 7 (lateral hole or longitudinal hole) in rigid ground comprising a rock or the like for disposal and carrying a disposal container 2 housing a radioactive waste will be described later in the bore 7.
[0012]
First , an example of the disposal container 2 will be described. The configuration of the disposal container 2 of the present invention is not necessarily limited to be the you described below, can be applied a variety of configurations. Disposal container 2 and a container present body and the lid. Container to the body houses a filler and radioactive waste. The disposal container 2 is made of metal, concrete, or the like. Moreover, you may form the shape of the disposal container 2 in various shapes other than a square container shape.
[0013]
Container the body, the interior so as to be able to house the radioactive waste Mono及 beauty filler is in the cavity. The lid is placed on the upper surface of the container the body, can be opened when storing radioactive wastes, the upper surface of the container the body by removing the lid. Further, the inside of the container the body so as to be able to house the radioactive waste at regular intervals, guides to match the size of the radioactive waste is placed.
[0014]
The radioactive waste is composed of , for example, a cylindrical container type canister, and the canister contains a radioactive substance to be disposed of from a nuclear power plant or the like. Moreover, radioactive waste, in the case of scrap generated from nuclear power plants, is housed in a container the body intact without receiving the canister.
[0015]
Radioactive waste, with opened lid of disposal container 2 is housed in guide provided on the container the body thus to the container the body. When storing the radioactive waste in a container the body, between the container the body and radioactive wastes, or the gap between the radioactive waste Monodo mechanic occurs, this gap is filled with a filling material, the gap Fill with a lid and seal the radioactive waste.
[0016]
The filler is added to a photocatalyst or oxidant. The main component of the filler, cement, sand, and silica sand or the like is considered, may be used in the photocatalyst alone only or oxidizing agent and the filler. Further, the filler, around the radioactive waste is filled with a filler photocatalyst or disposal container 2 as to be covered with an oxidizing agent.
[0017]
As shown in FIG. 1 , the disposal facility 1 includes a hole 7, a disposal container 2, and a component 13. The component 13 includes a concrete layer 8, a bottom wall portion 9, a pit 10, a side wall portion 11, and an upper wall portion 12. The disposal facility 1 first reinforces the entire inside of the hole 7 formed in a solid ground made of rock or the like with a concrete layer 8. Thereafter, bentonite fluid or the like is spread on the bottom surface of the hole 7 to form the bottom wall portion 9, and then a pit 10 is formed on the bottom wall portion 9 by placing concrete, and the disposal container 2 is placed in the pit 10. Carry in. And after filling the bentonite type fluid etc. between the pit 10 and the side wall of the hole 7 and forming the side wall part 11, the upper wall part 12 is similarly formed with a bentonite type fluid. Thereafter, the disposal facility 1 is completed by filling the upper side of the hole 7 above the pit 10 with mixed soil containing bentonite-based fluid or the like.
[0018]
A photocatalyst or an oxidizing agent is added to the component 13 of the disposal facility 1. As the main component of the constituent material 13, cement, sand, silica sand, and the like are conceivable, but only the photocatalyst or the oxidizing agent may be used as the constituent material 13. Moreover, the constituent material 13 is arrange | positioned so that the circumference | surroundings of the disposal container 2 to embed may be covered with a photocatalyst or an oxidizing agent. That is, it is optimal to add a photocatalyst or an oxidizing agent to the pit 10 in the constituent material 13 of the disposal facility 1. In addition, it is preferable to add a photocatalyst or an oxidizing agent to the bottom wall part 9, the side wall part 11, and the upper wall part 12 simultaneously. Furthermore, it is preferable to add a photocatalyst or an oxidizing agent to the concrete layer 8 as well.
[0019]
Photocatalyst, in order to improve the probability of contact with the radioactive material organic, and granulated, filling Zaima other disposal container 2 is added a number in the constituting material 13 of the disposal facility 1. Examples of the photocatalyst material include commercially available anatase type or rutile type titanium oxide powders for photocatalysts. Both anatase-type titanium oxide and rutile-type titanium oxide have photocatalytic activity and can be used in the present invention, but appropriate use is necessary depending on the radioactive waste system. In general, anatase-type titanium oxide has higher photocatalytic activity, but rutile-type titanium oxide is a stable phase and has a feature that it is not easily decomposed by radiation damage. Therefore, in the embodiment of the present invention, since it is made inorganic by reacting little by little in the long term, in the case of a system with severe radiation damage, the photocatalytic activity is low, and the long-term stability is excellent even if the reaction is slow. The rutile type is more effective.
[0020]
Also, oxidizing agents, like photocatalyst to improve the probability of contact with the radioactive material organic, filling Zaima other disposal container 2 in the granulated is added a number in the constituting material 13 of the disposal facility 1. Examples of the oxidizing agent material include Fe ₂ O ₃ and MnO ₂ . Either one of the addition of the photocatalyst or the oxidant to the filler of the disposal container 2 and the addition of the photocatalyst or the oxidant to the constituent material 13 of the disposal facility 1 may be employed. Both may be adopted.
[0021]
Then, in the above configuration will be described schematically effects of adding a photocatalyst to filler disposal container 2.
[0022]
As you long term store disposal container 2 in underground disposal facility 1, while exposed to soil and ground water for a long period of time, it progresses corrosion or alteration of the disposal container 2, the container is broken For example, the disposal container 2 deteriorates. When ground water from the damaged portion of the degraded disposal container 2 flows into the disposal container 2, radioactive substances for radioactive waste containing a radioactive substance organic dissolves into groundwater. Then, radioactive materials organic diffuses the groundwater and reaches the surface of the photocatalyst contained in the filler is disposed in the vicinity of the radioactive waste. Radiation is supplied to the photocatalyst from organic radioactive materials, other radioactive materials present in the disposal container 2, or other radioactive materials present in the disposal facility 1 to exert a catalytic effect, and the catalyst surface The organic radioactive material in contact with oxidative decomposition is decomposed into inorganic substances such as CO ₂ and H ₂ O.
[0023]
Moreover, in said structure, the rough effect | action at the time of adding a photocatalyst to the component 13 of the disposal facility 1 is demonstrated.
[0024]
If the disposal container 2 is stored in the disposal facility 1 for a long period of time, the disposal container 2 deteriorates in the same manner as described above. Groundwater from the damaged portion of the degraded disposal container 2 to flow into the disposal container 2, radioactive substances for radioactive waste containing a radioactive substance organic dissolves into groundwater. Then, the organic radioactive substance diffuses in the groundwater, the groundwater flows into the disposal facility 1, and reaches the surface of the photocatalyst contained in the constituent material 13 of the disposal facility. Radiation is supplied to the photocatalyst from organic radioactive materials, other radioactive materials present in the disposal container 2, or other radioactive materials present in the disposal facility 1 to exert a catalytic effect, and the catalyst surface The organic radioactive waste that comes into contact with oxidatively decomposes into inorganic substances such as CO ₂ and H ₂ O.
[0025]
Next, an outline effect | action at the time of adding an oxidizing agent to the component 13 of the disposal facility 1 in said structure is demonstrated.
[0026]
If the disposal container 2 is stored in the disposal facility 1 for a long period of time, the disposal container 2 deteriorates in the same manner as described above. Groundwater from the damaged portion of the degraded disposal container 2 to flow into the disposal container 2, radioactive substances for radioactive waste containing a radioactive substance organic dissolves into groundwater. Then, the organic radioactive material diffuses in the groundwater, the groundwater flows into the disposal facility 1, and reaches the surface of the oxidizing agent contained in the component 13 of the disposal facility. The oxidizing agent oxidizes and decomposes an organic radioactive substance in contact with the surface of the oxidizing agent, and decomposes it into inorganic substances such as CO ₂ (CO ₃ ²⁻ ) and H ₂ O.
[0027]
Further, in the above configuration will be described schematically effects of adding an oxidizing agent to the filler disposal container 2.
[0028]
If the disposal container 2 is stored in the disposal facility 1 for a long period of time, the disposal container 2 deteriorates in the same manner as described above. Groundwater from the damaged portion of the degraded disposal container 2 to flow into the disposal container 2, radioactive substances for radioactive waste containing a radioactive substance organic dissolves into groundwater. Then, radioactive materials organic diffuses the groundwater and reaches the surface of the oxidant contained in the filler is disposed in the vicinity of the radioactive waste. The oxidizing agent oxidizes and decomposes an organic radioactive substance in contact with the surface of the oxidizing agent, and decomposes it into inorganic substances such as CO ₂ (CO ₃ ²⁻ ) and H ₂ O.
[0029]
As described above, according to the method for disposing of radioactive waste according to the present embodiment, for example, in the case where methanol in which the configured carbon atom is radioactive C-14 is an organic radioactive substance, C-14 is converted into the form of CO ₂ and is adsorbed on Ca (OH) ₂ contained in the filling material of the disposal container 2 or the constituent material 13 of the disposal facility 1 so that it is not released into the ground as CaCO ₃ . Can do.
[0030]
Also, the probability is the case of adding a photocatalyst or oxidizing agent to filler disposal container 2, the filler in contact for surrounding the radioactive waste directly, radioactive substances dissolved but organic in groundwater photocatalyst or oxidizing agent Is expensive. That is, a high effect can be obtained with a small amount of photocatalyst or oxidizing agent.
[0031]
Furthermore, when filling Zire Rui disposal container 2 with the addition of photocatalyst constituting material 13 of the disposal facility 1, a photocatalyst, because while the radiation is present, which can continue to oxidation, are consumed time the reaction Compared with other oxidizing agents whose effectiveness decreases with the passage of time, it is particularly effective for organic radioactive materials including radioactive materials having a long half-life such as C-14. Even if the radiation quality of the radioactive material is not as permeable as α rays and β rays, and energy cannot be supplied to the photocatalyst from a distance, the organic radioactive material itself emits radiation, and the catalyst Since the radiation is emitted in contact, the catalytic effect is exhibited even if the radiation quality is α rays or β rays.
[0032]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. For example, in the above-described embodiment, commercially available anatase type and rutile type titanium oxide powders for photocatalysts are used as photocatalysts, but stainless steel or titanium to which a film of anatase type titanium oxide or rutile type titanium oxide is applied. A metal material such as may be used. Such a metal material can be made into a net-like or linear shape and added to the filler in the disposal container, or can be a part of the constituent material of the disposal facility.
[0033]
The photocatalytic film formation on the metal material is generally performed by applying an organic titanium compound such as titanium alkoxide and baking at around 500 ° C., and an anatase type titanium oxide film is formed. In this case, since the cost is relatively low, it is effective for a system in which radiation damage is not so severe.
[0034]
Further, a titanium oxide formed by a method of forming a film by arc discharge in an oxygen-containing atmosphere using a metal target containing titanium as a main component (arc ion brazing: AIP) is a rutile titanium oxide film having a columnar crystal. In particular, when the <110> direction of rutile type titanium oxide is strongly oriented so as to be perpendicular to the surface of the photocatalyst film, it is comparable to anatase type titanium oxide while being rutile type titanium oxide that is stable even under irradiation. This is effective in the case of a system in which radiation damage is severe.
[0035]
In the present invention, it is proposed to use a photocatalyst or an oxidant as a material added to the constituent material of the disposal facility or the filler of the disposal container, but mineralization of organic substances (such as lower alcohol) in the disposal facility is proposed. For this, the use of a photocatalyst is superior to the use of an oxidizing agent. For example, this relates to a mineralization (carbonation) reaction of methanol (CH ₃ OH + 4OH ⁻ + CO ₃ ²⁻ + 2H ₂ O + 2e ⁻ ), and an oxidizing agent such as MnO ₂ is generally used. By being reduced, methanol is mineralized. Therefore, there is a possibility that the environment of the disposal facility is changed by the reduction of the oxidizing agent, in particular, the redox potential is changed. In addition, the oxidizing agent is consumed by reacting with a reducing material present in nature other than the methanol mineralization reaction under low Eh conditions such as the environment of the disposal facility. That is, it is difficult to expect long-term retention performance of the oxidizing agent, and it is necessary to have a long-term oxidizing function for radioactive substances having a long half-life (for example, C-14 is 5730). On the other hand, since the photocatalyst is a catalyst using radiation, the catalyst performance can be expressed during the period in which the radionuclide to be decomposed exists, and the catalyst itself does not change chemically, so there is no influence on the environmental change of the disposal facility.
[0036]
【The invention's effect】
As described above, the first invention is configured to store a plurality of radioactive wastes, fill a gap generated in a state in which the radioactive waste is stored, and fill the gap and then cover the gap. The disposal container is configured to add a photocatalyst or an oxidizing agent to the filler.
[0037]
According to the above configuration, even if the groundwater flows into the disposal container due to deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, and the organic radioactive material diffuses in the groundwater, the disposal The amount and rate of radioactive materials that reach the surface of the earth by being oxidatively decomposed by contact with the photocatalyst or oxidant in the filler filled in the container, and decomposed into inorganic substances such as CO ₂ and H ₂ O. There is an effect that it can be reduced.
[0038]
A second invention is a radioactive waste disposal method in which a disposal container containing a plurality of radioactive wastes is buried in a disposal facility in the ground, and uses the disposal container of the first invention .
According to the above configuration, even when the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive substance is dissolved in the groundwater, and the organic radioactive substance diffuses in the groundwater, The amount and rate of radioactive materials that reach the surface of the earth by being oxidatively decomposed by contact with the photocatalyst or oxidant in the filler filled in the disposal container, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O There is an effect that can be reduced.
[0039]
The third invention is a plurality of radioactive waste disposal facility for receiving the disposal container disposed underground in the ground, and is configured to add the photocatalyst or oxide to the structure material forming the disposal facility.
According to the above configuration, the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, the organic radioactive material diffuses in the groundwater, and the groundwater enters the disposal facility. Even if it flows in, radioactive materials that reach the earth's surface by being decomposed by contact with the photocatalyst or oxidizing agent in the components of the disposal facility, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O This has the effect of reducing the amount and speed.
[0040]
The fourth invention is a method for disposing radioactive waste disposed underground disposal container containing a plurality of radioactive waste into the ground disposal facility, a configuration using a disposal facility of the third invention.
According to the above configuration, the groundwater flows into the disposal container due to the deterioration of the disposal container, the organic radioactive material dissolves in the groundwater, the organic radioactive material diffuses in the groundwater, and the groundwater enters the disposal facility. Even if it flows in, radioactive materials that reach the earth's surface by being decomposed by contact with the photocatalyst or oxidizing agent in the components of the disposal facility, and by being decomposed into inorganic substances such as CO ₂ and H ₂ O This has the effect of reducing the amount and speed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a hole in a disposal facility.
FIG. 2 is a schematic view showing the entire disposal facility.
[Explanation of symbols]
1 Disposal Facility 2 Disposal Container 13 Components

Claims (12)

A disposal container configured to store a plurality of radioactive wastes in a container body, fill a gap generated in a state in which the radioactive waste is stored, fill the gap, and then cover the gap. disposal container of radioactive waste, characterized in that the addition of photocatalytic catalytic effect is exhibited by α rays or β rays to the filler. The disposal container according to claim 1, wherein the photocatalyst is added in the form of granules. The radioactive waste disposal container according to claim 1, wherein rutile type titanium oxide is used as a material of the photocatalyst. The disposal container according to claim 3, wherein the rutile-type titanium oxide is coated with a metal material. The disposal container according to claim 4, wherein the <110> direction of the titanium oxide is oriented so as to be perpendicular to the surface of the photocatalyst film. A disposal method for radioactive waste in which a disposal container containing a plurality of radioactive wastes is buried in a disposal facility in the ground, wherein the disposal container according to any one of claims 1 to 5 is used. A disposal method of radioactive waste characterized by the above. The disposal container containing a plurality of radioactive waste, a disposal facility disposed underground in the ground surrounding the periphery thereof by constituting material, the catalytic effect by α rays or β rays to part or all of the constituent elements disposal facility for radioactive waste, characterized in that the addition of photocatalytic exerted. The disposal facility according to claim 7, wherein the photocatalyst is added in the form of granules. The radioactive waste disposal facility according to claim 7, wherein rutile type titanium oxide is used as a material of the photocatalyst. The disposal facility according to claim 9, wherein the rutile-type titanium oxide is coated with a metal material. The disposal facility according to claim 10, wherein the <110> direction of the titanium oxide is oriented so as to be perpendicular to the surface of the photocatalytic film. A disposal method for radioactive waste, wherein a disposal container containing a plurality of radioactive wastes is buried in an underground disposal facility, wherein the disposal facility according to any one of claims 7 to 11 is used. A disposal method of radioactive waste characterized by the above.

Images