JP2006289244A - Reclamation facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reclamation facility being easy to construct and capable of retaining a barrier function over a long period from the beginning and having gas permeability. <P>SOLUTION: The facility is constructed in the foundation 13 involving ground water and positioned at or under the level 12 of ground water and is for reclaiming waste 16 into its inside. The facility consists of (1) a reclaiming section 15 in which an air-permeable layer 17 permeable to air is formed around the waste 16 and an only slightly water-permeable water-shielding layer 18 is formed around the air-permeable layer 17 and (2) a smokestack-like gas passage 21 consisting of the water-shielding layer 18 including an air-permeable layer 17 communicating with the air-permeable layer 17 covering the waste 16 and extending from the reclaiming section 15 toward the surface 11 of the ground. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a buried disposal facility that is easy to construct and can maintain a barrier function for a long time from the beginning, and can release internal gas on the lower pressure side.

  The biggest theme in recent years has been the establishment of waste disposal facilities to landfill industrial and municipal waste as a result of social industry development, and hundreds of high and low levels of radioactive waste in nuclear power generation. It is how to deal with waste disposal over more than a year without causing any obstacle to social life.

  In a disposal facility for reclaiming industrial waste and general waste, in order to prevent industrial waste from affecting the human living environment, the leaked sewage from it penetrates underground and causes environmental pollution. It is obliged to treat them so that they are buried under the ground. An example thereof is shown in FIGS.

  FIG. 10 shows an example of a waste storage facility. In such a facility, a waste storage casing 101 is planned as a casing for storing these wastes, and a clay-based filling that hardly allows passage of groundwater between the waste storage casing 101 and the surrounding ground 102 is planned. It is considered to install the material 103.

  This clay-based filler 103 is used to greatly delay the entry of groundwater into the interior of the waste storage housing 101 or to prevent leakage of toxic substances in the waste by the groundwater. At the same time that the entire circumference of 101 is surrounded by a sufficient thickness, a clay-based filler is also laid on the bottom of the waste storage casing 101.

  In addition, regarding low-level radioactive waste in the nuclear power field, in order to prevent these low-level radioactive waste from affecting the human living environment, for example, as shown in FIG. A facility is planned in which an object 104 is stored in a radioactive waste storage housing 105 and embedded in an underground cavity 106.

  Even in such a facility, it is considered to install a clay-based filler 103 that hardly transmits groundwater between the radioactive waste storage housing 105 for storing the stored radioactive waste and the surrounding ground 102. .

  This clay-based filler 103 also greatly delays intrusion into the groundwater radioactive waste housing 105, or elutes into the groundwater into which toxic substances and radionuclides in the radioactive waste 104 have entered. In order to prevent leakage outside the facility, the radioactive waste storage casing 105 is installed in a form that surrounds the entire circumference of the radioactive waste storage casing 105 with a sufficient thickness as shown in the figure. A clay-based filler 103 is also laid on the bottom.

  Further, in order to safely isolate the high-level radioactive waste from the human living environment, a waste package 109 for storing the high-level radioactive waste in a solid metal container as shown in FIG. A high-level radioactive waste disposal facility is also planned to be buried in the buried hole 108 in the underground tunnel 110 drilled to a depth of several hundred meters below. It is considered to install a clay-based filler 103 in the gap of the tunnel 110.

  Also in the case of this clay-based filler 103, it is possible to suppress contact with the groundwater waste package 109, to leak out of the facility by elution from the waste package 109 into the groundwater into which the radionuclide has entered. In order to suppress this, as shown in the figure, the waste package 109 is installed in a form that surrounds the entire circumference with a sufficient thickness, and at the same time, a clay-based filler is also laid on the bottom of the waste package 109.

  Therefore, in the industrial waste or radioactive waste disposal facilities described above, it is important that the facilities have the required barrier function for a long period of thousands or thousands of years. The clay-based fillers installed around the enclosure for storing goods and the waste package are required to be able to maintain barrier functions such as water shielding performance and radionuclide delay performance over a long period of time.

For this reason, as the clay-based filler 103 filled around the waste storage casing 101, the radioactive waste storage casing 105, or the waste package 109, an aggregate such as sand or gravel is added to bentonite powder or bentonite. It is considered to use a filler in which the mixture is compacted to a density of about 1.3 to 2.5 Mg / m ³ .

  Since this bentonite-based filler has a remarkably small hydraulic conductivity, the amount of groundwater coming into contact with the waste can be suppressed, and leakage of radionuclides due to the diffusion phenomenon can also be suppressed. Further, even if it is assumed that the waste container expands in volume due to long-term corrosion, the bentonite-based filler is considered to exhibit a dynamic buffering effect (Patent Document 1).

FIG. 9 shows a conceptual diagram of such a waste burying disposal facility.
As shown in FIG. 9, in the waste burial disposal facility, an oblique mine shaft 14A is formed in the ground 13 below the groundwater level 12 from the ground portion 11, and the first burying portion 15- is formed at the bottom of the oblique mine shaft 14A. 1 and the 2nd embedding part 15-2 are embed | buried via the connecting mine shaft 14B.
A waste 16 is disposed in the support 19 of the first burying portion 15-1 and the second burying portion 15-2. The waste 16 is composed of a gas permeable layer 17 made of a gas permeable material and clay. The periphery is covered with a water-impervious layer 18 of a hydrophobic material. In addition, the inside of the oblique mine shaft 14A and the connecting mine shaft 14B and the space between the water shielding layer 18 and the supporting work 19 are filled with a filler 20 respectively.

JP 2003-279589 A

  By the way, although the waste burying and disposal facility aims to improve water shielding for its purpose, it has a strong water shielding function and is not air permeable, so it cannot release the gas generated inside the waste. The problem occurs.

  That is, it is assumed that gas is generated inside the waste due to anaerobic corrosion of the waste due to long-term embedding and hydrogen gas is generated due to radioactive decomposition. Although the water-permeable material allows gas to pass through in an unsaturated state, once it is saturated with groundwater, it does not permeate the gas until a gas pressure exceeding the swelling pressure of the material acts. As a result, high-pressure gas accumulates inside the facility, which may eventually destroy the barrier structure of the water shielding layer of the facility.

  In view of the above circumstances, it is an object of the present invention to provide a buried disposal facility that is easy to construct and can maintain a barrier function for a long time from the beginning, and can release internal gas on a lower pressure side. And

  1st invention which achieves said subject is provided in the ground where groundwater exists, and is a facility which embeds and disposes waste inside, and forms a permeable air permeable layer around the waste And a buried portion formed by forming a non-permeable impermeable layer around the permeable layer, and an impermeable layer having an permeable layer communicating with the permeable layer covering the waste inside, And a chimney-like gas passage extending from the buried portion toward the portion.

  A second invention is an embedded disposal facility according to the first invention, wherein a lid for transmitting an overload is provided at a top portion of the chimney-like gas passage.

  A third invention is the buried disposal facility according to the first or second invention, wherein the facility is covered with a permeable support.

  A fourth invention is an embedded disposal facility according to the third invention, wherein a filler is filled between the support and the water-impervious layer covering the waste.

  A fifth invention is the buried disposal facility according to any one of the first to fourth inventions, wherein there are a plurality of the buried disposal facilities, each having a chimney-like gas passage.

  A sixth invention is the communication path according to any one of the first to fourth inventions, wherein there are a plurality of the embedding disposal facilities and a water shielding layer in which a gas permeable layer communicating with the gas permeable layer covering the waste is disposed. The buried disposal facility is characterized in that at least one chimney-like gas passage is provided in any buried disposal facility.

  According to the buried disposal facility according to the present invention, an air-permeable air-permeable layer is formed around the waste, and a non-water-permeable impermeable layer is formed around the air-permeable layer. A chimney-shaped gas passage consisting of a water-impervious layer with an air-permeable layer that communicates with the air-permeable layer covering the waste extends toward the ground, so that the gas generated by waste reaches the vicinity of the ground. The gas can be quickly discharged through the extended gas passage.

  Exemplary embodiments of a buried disposal facility according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

FIG. 1 is a schematic view of a buried disposal facility according to Embodiment 1 of the present invention.
As shown in FIG. 1, an embedding disposal facility 10 according to the present embodiment is a facility that is provided in a ground 13 having a groundwater level of 12 or less in the presence of groundwater and in which waste 16 is embedded and disposed of. A gas-permeable air-permeable layer 17 is formed around the object 16, and a buried portion 15 in which a water-impervious water-impervious layer 18 is formed around the gas-permeable layer 17, and the waste 16 is covered. It comprises a water-impervious layer 18 having a gas-permeable layer 17 communicating with the gas layer 17 and a chimney-like gas passage 21 extending from the buried portion 15 toward the ground portion 11. In the present embodiment, the inside of the support 19 that forms the buried portion 15 is filled with a filler 20.

  Here, the gas permeable material constituting the gas permeable layer 17 may be a gas permeable material such as mortar or sand, and does not need to be a single material. Moreover, what is necessary is just to make the hardly water-permeable material which comprises the said water-impervious layer 18 into a bentonite etc., for example. The filler 20 may be a gas permeable material such as mortar or concrete. The material constituting the support 19 may be poor mortar or sand.

  Since the chimney-shaped gas passage 21 having a water-impervious structure having the air-permeable layer 17 is extended to the vicinity of the ground, the buried portion 15 buried deep in the depth of the underground is also at that point. The gas 22 from the inside of the embedded portion 15 can be smoothly permeated on the lower pressure side without being affected by the pressure from the outside.

  The shape of the chimney-shaped gas passage 21 is not particularly limited, and the cross-sectional shape may be any shape such as a circular diameter, a rectangle, a polygon, and the like.

  The working principle of the water permeability phenomenon and air permeability phenomenon of this buried disposal facility is shown in FIG. 2 and FIGS. 3-1 to 3-3. FIG. 2 shows the buried portion 15 of the buried disposal facility in which the chimney-like gas passage 21 is not formed, which is the same as the buried disposal facility of FIG. An enlarged view of the portion A in FIG. 2 is shown in FIGS. FIGS. 3-1 to 3-3 microscopically show the behavior of the fluid (water or gas) that passes through the water shielding material.

  First, in the case of FIG. 3A, the gas pressure inside the facility is equal to or lower than the water pressure of the groundwater outside the facility of the water shielding layer (internal gas pressure: small). The case where it cannot permeate | transmit the water shielding layer 18 and go out of a facility is shown.

Next, in the case of Fig. 3-2, the gas pressure inside the facility is higher than the water pressure of the groundwater outside the facility of the water shielding layer. If the gas inside is not high, the gas will go out to the outside of the facility. Shows if you can't go. In particular, when a swellable bentonite or the like is employed as the water-impervious layer 18, it is considered that the gas does not permeate unless the gas pressure exceeds the water absorption swelling pressure of clay in addition to the external groundwater pressure. For example, assuming that the depth of the buried portion where waste is buried is 100 m, the pressure corresponding to the groundwater pressure is 1 MPa, and the swelling pressure of bentonite corresponding to the dry density of 1600 kg / m ³ is about 1 to 2 MPa. If the total gas pressure does not exceed 2 to 3 MPa, the gas will not be smoothly permeated outside the facility. FIG. 3-2 shows a case where the gas 22 partially permeates through the impermeable layer 18.

Finally, in the case of FIG. 3-3, the case where the groundwater pressure outside the facility is small is shown, and the gas 22 inside the facility can ventilate the water shielding layer 18 and go out to the outside of the facility. ing.
For example, if the depth of the buried part is 20 m, the pressure corresponding to the groundwater pressure is 0.2 MPa, and the swelling pressure of bentonite corresponding to the dry density of 1600 kg / m ³ is about 1-2 MPa. Is the sum of them, and if it exceeds 1.2 to 2.2 MPa, gas can be smoothly permeated to the outside of the facility. Thus, when the depth is shallow, gas escapes even if the internal gas pressure is smaller than in the case of FIG. 3-2.

  Therefore, when embedding waste in a deep place, in order to allow the internal gas pressure to pass through at a low pressure, the chimney-like gas passageway from the facility where the waste is buried in the deep place to the vicinity of the ground By extending it, the groundwater pressure is reduced, and as a result, the gas can be smoothly released from the inside. As a result, even when gas is generated from waste that has been buried for a long period of time, the internal gas pressure can be reduced by positioning the top portion 21a of the gas passage 21 at a position shallower than the depth of the buried portion. Gas is vented at a pressure relatively lower than the gas pressure when the depth is deep, and early gas release is promoted.

In this embodiment, for example, when the waste is buried in a place having a depth of 100 m, the top portion 21a of the chimney-like gas passage is set to a depth of about 20 to 50 m from the ground portion 11, but the position of the top portion 21a is discarded. It can be appropriately changed depending on the volume of the object or the amount of gas generated.
For example, if the depth such as 300 m is made extremely deep, the gas stays inside the facility as described above, so that the chimney-like gas passage is no longer necessary. Therefore, the gas passage may be installed according to the depth, and the length of the gas passage may be set.

Moreover, in Example 1, although the case where there was one burying disposal facility was illustrated, this invention is not reduced to this, Two or more burying disposal facilities may be sufficient. An example is shown in FIG. In the embodiment shown in FIG. 4, the buried portions 15-1 and 15-2 of a plurality of buried disposal facilities are communicated with each other via a connecting mine shaft 14B, and each buried portion 15-1 and 15-2 has a chimney shape. Gas passages 21-1 and 21-2 are provided.
The gas permeable layer 17 may have any diameter as long as the gas 22 can be permeable, and is not particularly limited. However, the water shielding layer 18 has the same thickness as that covering the periphery of the waste 16 in the embedded portion 15. It is desirable from the viewpoint of the water shielding effect.

  According to the present embodiment, when a plurality of buried portions 15 are buried at a deep location in the waste, a chimney-like gas passage 21 that opens gas to each buried portion 15 is extended to the ground portion side. Therefore, the gas can be smoothly released from the inside.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 5 is a schematic view of a buried disposal facility according to the second embodiment. As shown in FIG. 5, in the present embodiment, the first buried portion 15-1 and the second buried portion 15-2 which are a plurality of buried disposal facilities are communicated with each other via a communication tunnel 14 </ b> B, An air permeable layer 17 covering the waste 16 is also connected in the connecting mine shaft 14B, and a chimney-like gas passage 21 is extended from the side surface of the second embedded portion 15-2 toward the ground portion.

  In this way, a plurality of buried disposal facilities are communicated with each other through the communication passage 14B, and the air permeable layer 17 having the water shielding layer 18 disposed around the passage 14B is also connected. Finally, the chimney-like gas passage 21 is connected. Since the gas permeable layer 17 is connected, all the generated gas is released from the top portion 21a of the gas passage 21 extending toward the ground portion 11 through the gas permeable layer 17.

  Next, another embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram of a buried disposal facility according to the second embodiment. FIG. 7 is an enlarged view of the B part. As shown in FIG. 6, in the above-described second embodiment, the lid body 31 for transmitting the overload is provided on the top portion 21 a of the chimney-like gas passage 21.

  The lid body 31 is a rigid lid plate having a planar area larger than the cross-sectional area of the top portion 21 a of the gas passage 21. As a material having high rigidity, for example, a thick plate obtained by cutting a rock into a disk shape can be exemplified, but the material is not limited thereto.

  Further, since the lid 31 is rigid, as shown in FIG. 7, when the internal gas pressure acts upward on the water shielding layer 18, the water shielding layer is prevented from being destroyed by the gas pressure, The upward force can be suppressed by the upper pressure of the ground 13 existing on the plate. Therefore, the water-impervious layer at the top of the upper end is not subject to deformation and destruction due to gas pressure, and the gas is released to the outside of the facility by slowly passing through the water-impervious layer 18. In addition, since the lid body 31 has a larger diameter, it is preferable because it receives a large amount of pressure on the ground.

Next, the flow of groundwater and the release of internal gas around the facility in which the internally generated gas is released in an embedding disposal facility in which waste is buried underground will be described with reference to FIG. FIG. 8 is a schematic diagram showing the flow of groundwater around the facility and the state of release of the internal gas. As shown in FIG. 4, the gas passages 21-1, 21-2 is provided.
As shown in FIG. 8, the gas generated from the waste 16 in the buried portions 15-1 and 15-2 is initially accumulated inside the clay-based water shielding layer 18, but is connected to the waste 16. It quickly shifts to the vent layer 17 and moves to a shallow portion that is the top portion 21 a of the chimney-like gas passage 21. Since the top portion 21a of the gas passage 21 is at a position shallower than the facility in which the waste 16 is buried, the gas passage 21 starts to penetrate the impermeable layer 18 with a relatively low gas pressure. Since a water shielding layer 18 is provided outside the air permeable layer 17, as shown in FIG. 8, the intrusion of ground water 12 into the facility and the leakage of harmful substances from the waste 16 to the outside of the facility are suppressed. can do. With such a function, the underground waste disposal facility can suppress the invasion of groundwater into the waste, prevent the leakage of harmful substances from the waste, and can smoothly release the gas generated inside the facility.

  As described above, according to the buried disposal facility according to the present invention, since the chimney-like gas passage extends from the buried facility toward the ground, the gas generated by the waste extends to the vicinity of the ground. It can be discharged quickly through the gas passage, and is suitable for use in facilities where waste is buried underground for a long period of time.

1 is a schematic configuration diagram of a buried disposal facility according to Embodiment 1. FIG. It is the schematic of the conventional burial facility. It is an action principle diagram of the water permeability phenomenon and air permeability phenomenon of a buried disposal facility. It is an action principle diagram of the water permeability phenomenon and air permeability phenomenon of a buried disposal facility. It is an action principle diagram of the water permeability phenomenon and air permeability phenomenon of a buried disposal facility. It is a schematic block diagram of the other buried disposal facility concerning Example 1. FIG. It is a schematic block diagram of the burying disposal facility concerning Example 2. FIG. It is a schematic block diagram of the buried disposal facility concerning Example 3. FIG. It is the B section enlarged view of FIG. It is a schematic diagram which shows the state of the flow of groundwater around a facility, and the release of internal gas. It is a schematic block diagram of the buried disposal facility concerning a prior art. It is a figure which shows the disposal facility of industrial waste. It is a figure which shows the disposal facility of a high and low level radioactive waste. It is a figure which shows the disposal facility of other high and low level radioactive waste.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Burial disposal facility 11 Above-ground part 12 Groundwater level 13 Ground 14A Diagonal tunnel 14B Connection tunnel 15, 15-1, 15-2 Embedded part 16 Waste 17 Air permeable layer 18 Impermeable layer 19 Supporting work 20 Filling material 21 Chimney-like Gas passage 21a Top

Claims (6)

It is a facility that is installed in the ground where groundwater exists, and buryes waste inside.
Forming an air-permeable air-permeable layer around the waste, and a buried portion formed by forming a water-impervious water-impervious layer around the air-permeable layer;
A chimney-like gas passage formed of a water-impervious layer having a gas-permeable layer communicating with the gas-permeable layer covering the waste inside and extending from the buried portion toward the ground portion, A buried disposal facility. In claim 1,
A buried disposal facility, wherein a lid for transmitting an overload is provided at the top of the chimney-shaped gas passage. In claim 1 or 2,
A buried disposal facility, wherein the facility is covered with a permeable support. In claim 3,
A buried disposal facility, wherein a filling material is filled between a water-impervious layer of a support that covers the waste. In any one of Claims 1 thru | or 4,
A buried disposal facility comprising a plurality of the buried disposal facilities, each having a chimney-like gas passage. In any one of Claims 1 thru | or 4,
There are a plurality of the buried disposal facilities, and a communication path including a water-impervious layer with an air permeable layer communicating with the air permeable layer covering the waste is formed therein, and at least one chimney-like gas passage is formed in any buried disposal facility. A buried disposal facility characterized by

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