JP6887362B2 - Waste storage container and waste monitoring system - Google Patents

Description

The present invention relates to a waste storage container and a waste monitoring system.

Patent Document 1 discloses a buried waste storage container and a method for detecting an abnormality thereof. This buried waste storage container has a steel container for storing radioactive waste in a sealed state and a concrete container for covering the container. A rare earth element layer is provided on the inner surface of the steel container.

Japanese Unexamined Patent Publication No. 2--13899

In recent years, it has been desired to continue to monitor the storage condition of buried waste for a long period of several decades to several hundred years. For example, in the buried waste storage container of Patent Document 1 and its abnormality detection method, whether or not the rare earth element component is dissolved in water is detected by sampling water from a drain line provided in the concrete container. To do. By this detection operation, the deterioration of the barrier function in the steel container is detected.

However, if the earth element layer constituting the buried waste storage container flows out of the container, the shielding property of the buried waste storage container may be lower than that of the buried waste storage container at the time of burial. Occurs.

Therefore, an object of the present invention is to provide a waste storage container and a waste monitoring system capable of suppressing deterioration of the function of the container while enabling monitoring over a long period of time.

The waste storage container according to one embodiment of the present invention seals a container containing a radioactive substance, covers a container portion formed of an iron-based material, and covers the outer surface of the container portion, and is formed of a bentonite-based material containing montmorillonite. The barrier portion includes a first portion containing a rare earth element as an interlayer cation of montmorillonite, and a second portion containing sodium or calcium as an interlayer cation of montmorillonite.

In this waste storage container, the barrier portion is formed of a bentonite-based material containing montmorillonite. The barrier portion has a first portion containing a rare earth element as an interlayer cation and a second portion containing sodium or calcium as an interlayer cation. Now, when the divalent cation is provided to the barrier portion, in the first portion, the interlayer cation is replaced with the provided divalent cation from the rare earth element, and the rare earth element flows out. In the soil where the waste storage container is buried, the abundance ratio of rare earth elements is low, and there are few factors that change the abundance ratio. Then, if an increase in the abundance ratio of rare earth elements in the soil in which the waste storage container is buried is confirmed, it means that the rare earth elements have flowed out from the waste storage container, and further, the waste storage container. It can be shown that some change has occurred in the state of. Further, even when the interlayer cations are replaced, the function of the barrier portion is not affected, so that the deterioration of the function of the container can be suppressed.

In the above form, the rare earth element may be europium, and the interlayer cation contained in the second portion may be sodium. The rare earth element is europium, and the interlayer cation contained in the second portion may be sodium. According to this configuration, the first portion containing a rare earth element as an interlayer cation can be easily formed.

In the above embodiment, the container portion has a cylindrical shape with both ends closed, the barrier portion has a cylindrical shape with both ends closed to define the space in which the container portion is arranged, and the first portion has a cylindrical shape. It may be formed so as to sandwich the container portion along the diameter direction of the container portion. According to this configuration, changes in the surroundings where the waste storage container is buried can be reliably captured.

In the above form, the first portion may have a disk shape having a through hole through which the container portion is inserted. According to this configuration, changes in the surroundings where the waste storage container is buried can be more reliably captured.

In the above embodiment, the first portion may have a contact surface in contact with the outer surface of the container portion. According to this configuration, the first portion containing the rare earth element comes into contact with the container portion. Then, when water seeps into the barrier portion and reaches the container portion formed of the iron-based material, iron ions as divalent cations are generated. This iron ion is replaced with a rare earth element which is an interlayer cation in the first portion in the first portion in contact with the container portion. The replaced rare earth element flows out of the waste storage container. Therefore, according to this configuration, it is possible to quickly indicate that the water has reached the container portion.

In the above embodiment, the second portion has a disk shape having a through hole through which the container portion is inserted, and the first portion has a disk shape having a through hole in which the second portion is arranged. You may. According to this configuration, the first portion containing the rare earth element forms the outer peripheral surface of the waste storage container. Then, when the divalent cation is provided from the portion in contact with the outer peripheral surface of the waste storage container, the divalent cation is promptly replaced with the rare earth element which is the interlayer cation of the first portion in the first portion. The replaced rare earth element flows out of the waste storage container. Therefore, according to this configuration, it is possible to promptly indicate that a change such that a divalent cation is generated around the waste storage container has occurred.

The waste monitoring system according to another embodiment of the present invention is provided in the above-mentioned waste storage container, a disposal area where the waste storage container is buried underground, and a waste storage near the disposal area. A detection unit for detecting rare earth elements discharged into the soil from the first portion of the barrier unit in the container is provided. According to this system, since the above-mentioned waste storage container is provided, it is possible to suppress deterioration of the function of the container while enabling monitoring over a period of time.

According to the present invention, there is provided a waste storage container and a waste monitoring system capable of suppressing deterioration of container performance while enabling monitoring over a long period of time.

FIG. 1 is a schematic view showing a geological disposal facility in which the waste storage container according to the first embodiment is disposed of. FIG. 2 is a diagram showing a cross-sectional structure of the tunnel shown in FIG. FIG. 3 is a plan view of the arrangement of the waste storage container in the disposal area shown in FIG. FIG. 4 is an exploded view showing the waste treatment container according to the first embodiment. Part (a) of FIG. 5 is a graph showing the swelling pressure of europiumized montmorillonite, part (b) of FIG. 5 is a graph showing the swelling rate of europiumized montmorillonite, and part (c) of FIG. , It is a graph which shows the hydraulic conductivity of europiumized montmorillonite. FIG. 6 is a diagram for explaining the state of the reaction in the waste treatment container. FIG. 7 is a diagram for explaining the state of the reaction in the waste treatment container. FIG. 8 is a graph showing the abundance ratio of rare earth elements. FIG. 9 is an exploded view showing the waste treatment container according to the second embodiment. FIG. 10 is a diagram for explaining the state of the reaction in the waste treatment container. FIG. 11 is an exploded view showing the waste treatment container according to the modified example.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

<First Embodiment>
The first embodiment exemplifies a mode in which a waste storage container containing a high-level radioactive waste (HLW) (radioactive substance) is buried in a geological disposal facility.

<Geological disposal facility>
As shown in FIG. 1, the geological disposal facility 100 (waste monitoring system) disposes of the waste storage container 1 in a stable geological formation. The geological disposal facility 100 includes a waste storage container 1, a building F provided on the ground G, a buried concrete structure 110, a tunnel 120, and a water sampling facility 130 (detection unit). Building F is the entrance to the geological disposal facility 100. The building F is connected to a tunnel 120 leading to the concrete structure 110. The concrete structure 110 accommodates the waste storage container 1. The concrete structure 110 has a tunnel 111 for accommodating the waste storage container 1.

In such a geological disposal facility 100, a management period of about several decades to several hundreds of years is set. Then, during this management period, it is monitored that the performance of the geological disposal facility 100 is transitioning as designed. The performance of the geological disposal facility 100 is, for example, the ability to keep radionuclides trapped. Therefore, it is possible to confirm the performance of the geological disposal facility 100 by checking the presence or absence of leakage of the radionuclides confined by the waste storage container 1 to the periphery. Therefore, an intake hole 131 of the water sampling facility 130 is provided in the vicinity of the concrete structure 110. The water sampling facility 130 is for collecting groundwater flowing through the area where the concrete structure 110 is provided. Check whether the collected groundwater contains radionuclides.

As shown in FIG. 2, the tunnel 111 is provided in the bedrock forming a stable formation. For example, a treatment layer 112 formed of concrete or bentonite may be formed on the inner surface of the tunnel 111. The waste storage container 1 is embedded in a vertical hole H1 provided on the floor surface of the tunnel 111. Further, the waste storage container 1 may be embedded in a horizontal hole H2 provided on the wall surface of the tunnel 111. Further, the waste storage container 1 may be placed on the floor surface of the tunnel 111. Then, after arranging the waste storage container 1, the tunnel 111 is filled with concrete or the like and backfilled. Therefore, workers and the like will not enter the tunnel 111 in which the waste storage container 1 is arranged and backfilled.

As shown in FIG. 3, the tunnel 111 has an installation tunnel 113 in which the waste storage containers 1U, 1D, and 200 are embedded, and a connecting tunnel 114 connecting the installation tunnels 113 to each other. The installation tunnel 113 is provided in the disposal area area S1 (disposal area portion). The waste storage container 1 arranged in the installation tunnel 113 is arranged two-dimensionally when viewed in a plan view. Here, it is assumed that groundwater flows in the installation tunnel 113 in the direction indicated by the arrow A1. In this environment, the intake hole 131 of the water sampling facility 130 is installed on the downstream side in the direction of groundwater flow (arrow A1) with respect to the installation tunnel 113. According to this position, the groundwater that has passed through the disposal area area S1 in which the waste storage container 1 is arranged can be preferably captured. Further, all of the waste storage containers arranged in the installation tunnel 113 may be the waste storage container 1 according to the present embodiment, or some of them may be the waste storage container 1. ..

For example, the waste storage container 1U may be arranged only on the upstream side, and another waste storage container 200 may be arranged at other locations. According to this arrangement, the waste storage container 1U arranged on the upstream side is quickly affected by the groundwater. Therefore, the change of the waste storage container 1U in the geological disposal facility 100 can be detected quickly. The other waste storage container 200 is a container that does not have the Eu block B1 described later and has the artificial barrier 3 composed of the Na block B2.

On the other hand, the waste storage container 1D may be arranged only on the downstream side, and the waste storage container 200 may be arranged at other places. According to this arrangement, the waste storage container 1D arranged on the downstream side is affected by the groundwater at the latest. Then, if the waste storage container 1D is affected by the groundwater, it can be expected that the waste storage container 200 arranged on the upstream side thereof is also affected by the groundwater. Therefore, it can be detected that the entire waste storage containers 1D and 200 in the geological disposal facility 100 are affected by groundwater.

<Waste storage container>
As shown in FIG. 4, the waste storage container 1 has a cylindrical shape. The waste storage container 1 has a canister 2 (container portion) and an artificial barrier 3 (barrier portion). The canister 2 is a metal container for sealing radioactive waste. The canister 2 encloses the vitrified body 300 (contained object) in which radioactive waste and glass are mixed. The vitrified body 300 is filled in a stainless steel cask. The vitrified body 300 fixes the radionuclide uniformly and safely, and has stability against heat and radiation. Furthermore, the vitrified body 300 suppresses the elution of radionuclides into groundwater due to its high chemical durability.

The canister 2 is made of, for example, carbon steel (FeC). The canister 2 is a so-called overpack, and prevents contact between the groundwater and the vitrified body 300 during a period of high heat generation and high radioactivity of the vitrified body 300. Further, the canister 2 maintains the reducing property in the vicinity of the vitrified body 300 by the reaction with the groundwater. In addition, the canister 2 adsorbs to the corrosion products of radionuclides. The canister 2 has a cylindrical shape whose upper end and lower end are closed, and has an upper end surface 2a, a lower end surface 2b, and an outer peripheral surface 2c. The upper end surface 2a, the lower end surface 2b, and the outer peripheral surface 2c form an outer surface of the canister 2.

The artificial barrier 3 is formed of a material containing clay as a main component, and specifically, a bentonite-based material containing montmorillonite. Montmorillonite has high swelling properties and significantly low permeability. Therefore, the artificial barrier 3 prevents groundwater that can be provided from the bedrock from reaching the canister 2. The artificial barrier 3 has low water permeability and suppresses contact between the canister 2 and groundwater. In addition, the artificial barrier 3 has a low mass transfer rate and delays the transfer of radionuclides. Furthermore, the artificial barrier 3 exhibits chemical buffering properties and has low solubility in void water. Then, the artificial barrier 3 acts as a filter against the movement of colloids, microorganisms, and organic substances.

The artificial barrier 3 covers the entire outer surface of the canister 2. That is, the artificial barrier 3 covers the upper end surface 2a, the lower end surface 2b, and the outer peripheral surface 2c of the canister 2. The artificial barrier 3 has a cylindrical shape with the upper and lower ends closed. The artificial barrier 3 has a cylindrical main body 4 and a pair of lids 6 arranged at both ends of the main body 4. The main body 4 has a hole 4a penetrating in the axial direction. The hole 4a has an inner diameter substantially the same as the outer diameter of the canister 2.

The main body 4 and the lid 6 each have a europium-containing block (hereinafter referred to as “Eu block B1”) and a sodium-containing block (hereinafter referred to as “Na block B2”). That is, the artificial barrier 3 is composed of a tubular Eu barrier 7 (first portion) composed of Eu block B1 and a tubular Na barrier 8 (second portion) composed of Na block B2. It is composed. That is, in the tubular main body 4, the Eu block B1 and the Na block B2 are provided in the order of concentric circles from the inside. The Eu barrier 7 has a cylindrical shape with both ends closed, and has an inner peripheral surface 7a and an outer peripheral surface 7b. The outer peripheral surface 2c of the canister 2 comes into contact with the inner peripheral surface 7a. The Na barrier 8 has a cylindrical shape with both ends closed, and has an inner peripheral surface 8a and an outer peripheral surface 8b. The outer peripheral surface 7b of the Eu barrier 7 comes into contact with the inner peripheral surface 8a. Further, the outer peripheral surface 8b of the Na barrier 8 constitutes the outer peripheral surface of the artificial barrier 3.

Eu block B1 and Na block B2 have different interlayer cations contained in the bentonite-based materials. The Eu block B1 contains europium (Eu) as an interlayer cation. The Na block B2 contains sodium (Na) as an interlayer cation.

When Eu block B1 and Na block B2 are stacked, gaps between Eu block B1 and Na block B2, between Eu block B1 and Na block B2 and canister 2, and between Eu block B1 and Na block B2 and the bedrock surface. Even if there is, the swelling property of montmorillonite constituting Eu block B1 and Na block B2 fills the gap by containing water, and low water permeability can be exhibited. Therefore, the artificial barrier 3 can be easily constructed.

Bentonite generally contains sodium or calcium as interlayer cations. Therefore, when forming Eu block B1, it is necessary to prepare bentonite in which the interlayer cation is replaced with europium. For example, first dissolve europium in water. For this reason, as the rare earth element contained in Eu block B1, an element easily soluble in water may be used. The aqueous solution is mixed with bentonite containing sodium ions or calcium ions. This mixing replaces the interlayer cations with europium. Subsequently, the water is replaced with ethanol. The ethanol excreted contains sodium or calcium. While confirming the concentration of these ions contained in ethanol, the progress of substitution with europium is confirmed. Then, by performing the solidification treatment, a material containing europium as an interlayer cation can be obtained.

The bentonite-based material (montmorillonite Eu) containing europium as an interlayer cation obtained by the above step has sufficient properties as a material constituting the artificial barrier 3. For example, the part (a) in FIG. 5 is a graph showing the change over time in the swelling pressure of montmorillonite Eu. Eulated montmorillonite reached a swelling pressure of 5000 kPa in a few days. Then, the swelling pressure of about 5000 kPa was maintained for a measurement period of about 130 days. In addition, part (b) of FIG. 5 is a graph showing the time course of the swelling rate of Eu montmorillonite. Eulated montmorillonite reached a swelling rate of 45% in a few days. Then, during the measurement period of about 110 days, the swelling rate of about 45% or more and 50% or less was maintained. Further, the part (c) in FIG. 5 is a graph showing the change over time in the hydraulic conductivity (m / s) of montmorillonite Eu. Eu montmorillonite continued to maintain a hydraulic conductivity of ^{approximately 1 × 10 -14} to 1 × 10 ^-13 over a measurement period of approximately 100 days.

Next, the phenomenon that occurs when groundwater seeps into the waste storage container 1 will be described in detail. 6 and 7 show an enlarged cross section of the waste storage container 1 and schematically show the state of atoms at each part constituting the waste storage container 1. As shown in part (a) of FIG. 6, since the canister 2 is made of carbon steel, it contains an iron atom (Fe). The Eu barrier 7 contains europium (Eu ²⁺ ). Na barrier 8 contains sodium (Na ⁺ ).

Now, as shown in part (b) of FIG. 6, it is assumed that water W has permeated into a part of the artificial barrier 3 from the bedrock Gs. Then, the permeated water W passes through the Na barrier 8 and the Eu barrier 7 and reaches the outer peripheral surface 2c of the canister 2. When water W comes into contact with the canister 2, a chemical reaction occurs between water and iron. As a result, iron becomes iron ions (Fe ²⁺ ), which are divalent cations, and moves to water W (that is, Eu barrier 7).

The iron (Fe ²⁺ ) transferred to the Eu barrier 7 is replaced with ^{the europium (Eu 2+} ) that was present as an interlayer cation in the Eu barrier 7. The replaced europium (Eu ²⁺ ) moves from the Eu barrier 7 to the Na barrier 8 with the movement of water W, and finally flows out from the artificial barrier 3 to the bedrock Gs.

^{Further, when iron (Fe 2+} ) is further supplied after the substitution in the Eu barrier 7 ^{, the interlayer cation exchange (Na +} →) is also carried out in the Na barrier 8 as shown in the part (a) of FIG. Fe ²⁺ ) may occur. Then, as shown in part (b) of FIG. 7, in the region where water W finally soaks in the artificial barrier 3, the interlayer cation changes to bentonite which is ^{iron (Fe 2+).}

Hereinafter, the operation of the geological disposal facility 100 using the above-mentioned waste storage container 1 will be described.

First, the waste storage container 1 is created. Specifically, Eu was prepared by artificially exchanging the interlayer cations of bentonite, which is the base material of the bentonite-based artificial barrier 3 of a high-level radiation warfare waste disposal facility, with europium (Eu), which is a rare metal. Prepare mold bentonite. Then, the Eu-type bentonite is provided in the bentonite-based artificial barrier 3 in a state of being compacted to a predetermined drying density.

In this state, when the geological disposal facility 100 is submerged and the Eu-type bentonite portion is saturated, cations (for example, iron ions) contained in europium and the pore water undergo cation exchange depending on the composition of the pore water. Then, europium is released into the interstitial water. Europium in the interstitial water passes through the bentonite-based artificial barrier 3 and is finally moved by the groundwater. Water sampling boring is performed at the geological disposal facility 100 to confirm that no radionuclides have been eluted. At this time, the presence or absence of increase or decrease of europium is confirmed using the collected groundwater. By this confirmation, the infiltration state in the geological disposal facility 100 can be grasped.

Here, when this method is carried out, the abundance ratio of rare metals (rare earth elements) contained in the groundwater is grasped in advance by using the Masuda-Coryell plot as shown in FIG. Eu becomes divalent in a reducing environment and behaves differently from other rare earth elements. Therefore, it may deviate from the curve shown in the Masuda-Coryell plot.

If the change in Eu anomaly in the Masuda-Coryell plot obtained in advance can be confirmed, it can be seen that groundwater infiltrates the installation position of Eu-type bentonite in the geological disposal facility 100 and cation exchange occurs. Therefore, the state in the geological disposal facility 100 can be known.

In the waste storage container 1, the artificial barrier 3 is formed of a bentonite-based material containing montmorillonite. The artificial barrier 3 has an Eu barrier 7 containing europium as an interlayer cation and a Na barrier 8 containing sodium as an interlayer cation. Now, when iron that has become a divalent cation is provided to the artificial barrier 3, in the Eu barrier 7, the interlayer cation is replaced with the iron provided by europium, and europium flows out. In the soil where the waste storage container 1 is buried, the abundance ratio of europium is low, and there are few factors that change the abundance ratio. Then, when an increase in the abundance ratio of europium in the soil in which the waste storage container 1 is buried is confirmed, it means that europium has flowed out from the waste storage container 1, and further, the waste storage container 1 is used. It can be shown that some change has occurred in the state of 1. Further, even when the interlayer cations are replaced, the function of the artificial barrier 3 is not affected, so that the functional deterioration of the waste storage container 1 can be suppressed.

Here, it is known that the distribution of rare earth elements is determined during the formation process of the earth. Therefore, it can be considered that the distribution of rare earth elements is almost constant in the surrounding environment of the geological disposal facility 100 within the management period. On the other hand, when short-term disturbances occur due to human activities, the rare earth distribution changes. In particular, monitoring using the Eu anomaly that characterizes the rare earth distribution has remarkable changes and can be easily grasped. The Eu-type bentonite has the same properties as bentonite at another location (for example, the outer peripheral portion of the barrier) (see portions (a), (b) and (c) in FIG. 5). Therefore, even if it is installed in a high-level radioactive waste disposal facility, the effect on the shielding performance is extremely small. And since it does not require a power source and can continue to exist for a long period of time, it is suitable as a monitoring method for hundreds of years.

Further, it is not necessary to provide the waste storage container 1 with parts such as a sensor and a cable attached to the sensor. Therefore, there is no possibility of impairing the performance of the waste storage container 1 and the geological disposal facility 100.

The rare earth element that is an interlayer cation contained in the EU barrier 7 is europium. The interlayer cation contained in the Na barrier 8 is sodium. According to this configuration, the Eu barrier 7 containing europium as an interlayer cation can be easily formed.

The canister 2 has a cylindrical shape with both ends closed. The artificial barrier 3 has a cylindrical shape with both ends closed to define the space in which the canister 2 is arranged. The Eu barrier 7 is formed so as to sandwich the canister 2 along the diameter direction of the canister 2. According to this configuration, changes in the surroundings in which the waste storage container 1 is buried can be reliably captured.

The Eu barrier 7 has a disk shape having a hole 7h through which the canister 2 is inserted. According to this configuration, changes in the surroundings in which the waste storage container 1 is buried can be more reliably captured.

In the above embodiment, the Eu barrier 7 has an inner peripheral surface 7a in contact with the outer peripheral surface 2c of the canister 2. According to this configuration, the Eu barrier 7 containing europium comes into contact with the canister 2. Then, when water seeps into the artificial barrier 3 and reaches the canister 2 formed of the iron-based material, iron ions as divalent cations are generated. This iron ion replaces europium, which is an interlayer cation of the Eu barrier 7, in the Eu barrier 7 in contact with the canister 2. The replaced europium flows out of the waste storage container 1. Therefore, according to this configuration, it can be quickly indicated that the water has reached the canister 2.

The geological disposal facility 100 is provided in the vicinity of the above-mentioned waste storage container 1, the disposal area area S1 in which the waste storage container 1 is buried underground, and the disposal area area S1, and is artificially provided in the waste storage container 1. It is provided with a water sampling facility 130 for detecting europium discharged into the soil from the Eu barrier 7 of the barrier 3. According to the geological disposal facility 100, since the above-mentioned waste storage container 1 is provided, it is possible to suppress the functional deterioration of the waste storage container 1 while enabling monitoring over a period of time.

<Second Embodiment>
The waste storage container according to the second embodiment will be described. The waste storage container according to the second embodiment has an artificial barrier configuration different from that of the waste storage container 1 according to the first embodiment.

As shown in FIG. 9, the waste storage container 1A has a canister 2 and an artificial barrier 3A. The artificial barrier 3A has an Eu barrier 7A composed of Eu block B1 and a Na barrier 8A composed of Na block B2. Here, in the first embodiment, the Eu barrier 7 is arranged inside the Na barrier 8 and the Na barrier 8 is arranged outside the Eu barrier 7. On the other hand, in the second embodiment, the Eu barrier 7A is arranged outside the Na barrier 8A and the Na barrier 8A is arranged inside the Eu barrier 7A. According to this configuration, the Eu barrier 7A contacts the mortar layer 115.

Next, the phenomenon that occurs when groundwater seeps into the waste storage container 1A will be described in detail. FIG. 10 shows an enlarged cross section of the waste storage container 1A, and schematically shows the state of atoms at each part constituting the waste storage container 1A. In the second embodiment, a change in the mortar layer 115 surrounding the waste storage container 1A is detected. Specifically, it is assumed that groundwater has penetrated into the mortar layer 115 from the bedrock Gs. Then, the calsim (Ca) contained in the mortar dissolves. When this calcium-containing water soaks into the EU barrier 7A, the calcium is replaced with europium. The replaced europium reaches the bedrock Gs through water and is moved by the flow of groundwater.

In the above form, the Na barrier 8A exhibits a cylindrical shape having a hole 8h through which the canister 2 is inserted. The Eu barrier 7A has a cylindrical shape with a hole 7h in which the Na barrier 8 is placed. According to this configuration, the Eu barrier 7A containing europium forms the outer peripheral surface of the waste storage container 1A. Then, when calcium that has become a divalent cation is provided from the mortar layer 115 that is in contact with the outer peripheral surface of the waste storage container 1A, it is promptly replaced with europium, which is an interlayer cation of the Eu barrier 7A, in the Eu barrier 7A. To do. The replaced europium flows out of the waste storage container 1A. Therefore, according to this configuration, it is promptly shown that a change (that is, infiltration of groundwater into the mortar layer 115) has occurred around the waste storage container 1A so as to generate calcium as a divalent cation. Can be done.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

In the above embodiment, the artificial barrier 3 has an Eu barrier 7 and a Na barrier 8. For example, as shown in FIG. 11, the artificial barrier 3B of the waste storage container 1B has a one-layer structure formed by the Na barrier 8B, and the Eu block B1A may be fitted in a part of the one-layer structure.

In the above embodiment, the rare earth element contained in Eu block B1 may be an element different from europium. For example, as the rare earth element contained in Eu block B1, an element that becomes divalent in a reducing environment (an environment in which oxygen is diluted) may be used. For example, scandium (Sc), yttrium (Y), lantern (La), cerium (Ce), placeodim (Pr), neodym (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), terbium (Tb). ), Dysprosium (Dy), Holmium (Ho), Turium (Tm), Ytterbium (Yb), Lutetium (Lu).

Further, in the above embodiment, a bentonite-based material containing sodium as an interlayer cation has been exemplified. For example, as the bentonite-based material, a bentonite-based material containing calcium as an interlayer cation may be used.

Further, the portion containing a rare earth element as a bentonite-based material containing an interlayer cation is not limited to the arrangement of the above-described embodiment. For example, the Eu barrier may have a donut-shaped (annular) configuration having an inner peripheral surface in contact with the canister 2 and an outer peripheral surface in contact with the mortar layer 115. Further, it can be formed on a desired portion of the artificial barrier 3. In other words, the method of constructing the artificial barrier 3 is not limited to the method of stacking Eu block B1 and Na block B2 as described above. It may be formed by methods such as in-situ compaction, pellet filling, and spraying.

Further, the waste contained in the waste storage container 1 is not limited to high-level radioactive waste. For example, the contained waste may be low-level radioactive waste (LLW) or radioactive waste containing transuranium elements (TRU). Therefore, the geological disposal facility 100 may be a facility that disposes of low-level radioactive waste or a facility that disposes of radioactive waste containing a transuranium element.

1,1A, 1U, 1D ... Waste storage container, 2 ... Canister (container part), 2a ... Upper end surface, 2b ... Lower end surface, 2c ... Outer surface surface, 3 ... Artificial barrier (barrier part), 4 ... Main body part, 4a ... hole, 6 ... lid, 7,7A ... Eu barrier (first part), 7a ... inner peripheral surface, 7b ... outer peripheral surface, 8,8A, 8B ... Na barrier (second part), 8a ... Inner peripheral surface, 8b ... Outer surface, 100 ... Geological disposal facility, 110 ... Concrete structure, 111 ... Tunnel, 112 ... Treatment layer, 113 ... Installation tunnel, 114 ... Connecting tunnel, 115 ... Mortar layer, 120 ... Tunnel, 130 ... Water sampling facility, 131 ... Intake hole, 300 ... Vitrified body (container), B1, B1A ... Eu block, B2 ... Na block, G ... Ground, F ... Building, Gs ... Bedrock, S1 ... Disposal area area , W ... water.

Claims (7)

A container part formed of an iron-based material by sealing the contained material containing radioactive substances,
A barrier portion that covers the outer surface of the container portion and is formed of a bentonite-based material containing montmorillonite is provided.
The barrier part is
The first portion containing a rare earth element as an interlayer cation of the montmorillonite, and
A waste storage container having a second portion containing sodium or calcium as an interlayer cation of the montmorillonite. The rare earth element is europium,
The waste storage container according to claim 1, wherein the interlayer cation contained in the second portion is sodium. The container portion has a cylindrical shape with both ends closed.
The barrier portion has a cylindrical shape with both ends closed, which defines a space in which the container portion is arranged.
The waste storage container according to claim 1 or 2, wherein the first portion is formed so as to sandwich the container portion along the diameter direction of the container portion. The waste storage container according to claim 3, wherein the first portion has a disk shape having a through hole through which the container portion is inserted. The waste storage container according to claim 4, wherein the first portion has a contact surface in contact with the outer surface of the container portion. The second portion has a disk shape having a through hole through which the container portion is inserted.
The first portion exhibits a disk shape having a through hole in which the second portion is arranged.
The waste storage container according to claim 3. The waste storage container according to any one of claims 1 to 6 and
In the basement, the disposal area where the waste storage container is buried and
A waste monitoring system provided in the vicinity of the disposal area portion, comprising a detection unit for detecting rare earth elements discharged into the soil from the first portion of the barrier portion in the waste storage container.

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