JP4453577B2 - Waste geological disposal facility - Google Patents

Description

  The present invention relates to geological disposal of waste, and more particularly, to geological disposal of radioactive waste generated from nuclear power generation, which relates to the shape of a disposal facility for burying waste in a stable geological formation in the deep underground. .

  Among the radioactive waste generated from nuclear power generation, high-level radioactive waste is liquid waste separated in the reprocessing process of spent nuclear fuel, and not only has a high level of radioactivity but also continues to have radioactivity for a long period of time. It contains many long-lived radionuclides. Therefore, such high-level radioactive waste is dissolved in a stainless steel canister together with glass raw materials, stabilized as a glass solidified body, stored for several decades for cooling, and then the canister in which the glass solidified body is stored. To be disposed of in a sealed container made of thick steel plate called overpack, and disposed of in a stable formation deeper than 300m underground (determined by law). Yes.

  In this geological disposal of radioactive waste, as shown in FIG. 7, a measure to ensure safety is provided by a multi-barrier system of an artificial barrier B such as bentonite cushioning material around the waste A and a natural barrier C of the rock. Adopted. The role of the artificial barrier B is to reduce the release rate of the nuclide from the waste A to the natural barrier C, and the role of the natural barrier C is to delay the nuclide migration to the biosphere.

  As shown in FIG. 8, since the nuclide is released from the artificial barrier B to the natural barrier C via the buffer material by diffusion caused by the concentration gradient of the nuclide, the concentration gradient is used to reduce the nuclide release rate. It is necessary to prevent this from occurring. For example, to avoid diluting the concentration of released nuclides, (1) selection of a place where the flow of groundwater in the bedrock is slow, or (2) groundwater contaminated by one waste reaches the vicinity of another waste The design of the facility shape that can be considered.

  Moreover, since the nuclide in the natural barrier C moves with the flow of groundwater determined by the hydrodynamic gradient (driving force of groundwater flow) and the permeability of the rock mass, in order to delay the nuclide migration, It is necessary to select a small rock bed where water permeability is low. For example, (1) a place where the flow of groundwater in the bedrock is slow, or (3) a place far from the biosphere.

  Fig. 9 shows the transition image of nuclide buffer material due to diffusion. If the flow of groundwater in the bedrock is slow and the groundwater is contaminated, the concentration gradient of nuclide in the buffer material becomes small and the nuclide release occurs. The rate is reduced. On the other hand, if the flow of groundwater in the bedrock is fast and the groundwater is not polluted, the concentration gradient of nuclides in the buffer material increases and the nuclide release rate increases.

  In the prior art, the “location (location)” of the radioactive waste facility that satisfies the above (1) and (3) was considered so that the function of the multi-barrier system could be demonstrated. The “shape” of the facility satisfying 2) was not particularly considered, and a regular panel shape as shown in FIG. 10 was considered.

  In FIG. 10, a geological disposal facility 50 for high-level radioactive waste is composed of a ground facility 51 and an underground facility 52. The underground facility 52 is composed of an access tunnel 53 such as a vertical shaft or a tilt shaft connecting the ground and the underground, a disposal tunnel 54 formed by excavation horizontally in parallel in the deep underground, and a main tunnel 55 connected to these disposal tunnels. ing. The disposal tunnel 54 is partitioned and divided into independent horizontal disposal panels, and flexible panel layouts such as distributed layout and multilayer layout are possible according to the geological environmental conditions of the disposal site, and construction and operation are also possible.・ Major closure work can be carried out independently and in parallel.

  In addition, various methods are considered for placing waste in the disposal tunnel 54. For example, a disposal hole laying method as shown in FIG. 11 (a), as shown in FIG. 11 (b), and the like. There is a disposal tunnel horizontal installation method. In FIG. 11 (a), a disposal hole 56 is vertically drilled from the bottom of the disposal tunnel 54 formed in the rock C as a natural barrier, and a predetermined interval is provided in the tunnel axis direction. In this disposal hole 56, a buffer material (such as bentonite) B that reduces the influence of groundwater and rock pressure is laid as an artificial barrier, and the waste material A that is trapped in the buffer material B is buried. ing. The disposal tunnel 54 is backfilled. In FIG. 11B, the buffer material B is spread in the disposal tunnel 54, and the waste A lying in the buffer material B is buried in the tunnel axis direction at a predetermined interval.

Moreover, there are Patent Documents 1 to 6 as prior art documents related to the present invention. The invention of Patent Document 1 relates to a method for filling with water stoppage around a housing case such as radioactive waste. The invention of Patent Document 2 relates to safety evaluation of groundwater movement in geological disposal of radioactive waste. The invention of Patent Document 3 relates to a decision support system for site selection and specification selection of a radioactive waste geological disposal site. The invention of Patent Document 4 relates to an apparatus for monitoring specific harmful substances leaking from a waste disposal facility. The invention of Patent Document 5 relates to a system for evaluating the amount of leakage of nuclide leaked from a radioactive nuclide disposal site. The invention of Patent Document 6 sets the position of a vertical shaft in consideration of the flow of groundwater in a high-level radioactive waste storage facility.
Japanese Patent Laid-Open No. 2003-185796 JP 2003-139894 A JP 2003-43191 A JP 2002-328065 A JP 2002-277484 A JP 2002-196098 A

  The currently considered geological disposal facility configuration of radioactive waste includes the above-mentioned viewpoint (2) (designing the facility shape so that groundwater contaminated by one waste body reaches the periphery of another waste body). From the viewpoint, no study has been made to reduce the release rate of nuclides from the artificial barrier.

  The present invention was made to solve the above problems, and in geological disposal facilities such as radioactive waste, waste geological disposal that can reduce the release of nuclides and the like from waste in consideration of the flow of groundwater To provide facilities.

  The invention according to claim 1 of the present invention is a waste geological disposal facility for burying waste in an underground ground of a waste geological disposal site, wherein the waste is disposed along a migration path of groundwater And a waste geological disposal facility characterized in that it is disposed more downstream than upstream. The present invention is particularly effectively applied to geological disposal of high-level radioactive waste. It can also be applied to geological disposal of other waste.

  In the case of geological disposal of high-level radioactive waste, the present invention is based on the above-mentioned viewpoint (2), that is, the viewpoint of the design of the facility shape so that the groundwater contaminated with one waste reaches the periphery of another waste. Therefore, in order to take measures to reduce the nuclide release rate from the artificial barrier (buffer material) around the waste body, in the target area, the groundwater containing the nuclide released from the waste body placed upstream is The facility form that flows through the waste disposed on the downstream side is constructed.

  As shown in FIG. 5, the nuclide released from the waste A flows downstream by advection / dispersion. Here, the flow along the flow of groundwater in the main flow direction as seen on the large scale is referred to as “advection”, and the process in which the water flow is complicated and flows in various directions on a small scale is referred to as “dispersion”. It expresses. Because dispersion is added to the advection, the nuclides spread radially. Therefore, the present invention is basically based on arranging the wastes in this order on the downstream side. As the nuclide concentration is highest in the line along the groundwater transfer path, the ideal waste body layout image is shown in Figure 6 where all waste bodies A are placed along the groundwater transfer path. To do.

  However, since the method shown in FIG. 6 is unrealistic considering the size of the site to be a disposal site, in the present invention, based on the size of the site, as shown in FIGS. This is a facility configuration in which a lot of waste bodies are arranged on the downstream side where nuclides emitted from the waste bodies are distributed by advection and dispersion. The form of the facility only needs to be a form in which the waste body is disposed more downstream than the upstream side, and various forms are conceivable.

  The invention according to claim 2 of the present invention is the waste disposal facility according to claim 1, wherein the disposal block formed by juxtaposing a plurality of disposal tunnels in which waste is buried is disposed upstream of the groundwater transfer path. Is a waste geological disposal facility characterized in that the downstream side is formed in a wide planar shape or three-dimensional shape.

  This is an example in the case of embodying the facility form of the present invention. For example, as shown in FIG. 2 (b), the shape of a flat disposal block (disposal panel) itself having a plurality of disposal tunnels is discarded. The planar shape is such that the body is arranged more downstream than the upstream side, for example, the planar shape as shown in FIG. The planar disposal block may be arranged on a horizontal plane (which may be inclined with respect to the horizontal) or may be arranged on a vertical plane (which may be inclined with respect to the vertical). Alternatively, for example, as shown in FIG. 4A, a three-dimensional disposal block in which disposal tunnels are arranged in three dimensions using upper and lower spaces, and the shape of the three-dimensional disposal block is disposed upstream of the waste body. A three-dimensional shape that is arranged more downstream than that, for example, a three-dimensional shape as shown in FIG.

  The invention according to claim 3 of the present invention is the waste disposal facility according to claim 1, wherein the disposal block formed by juxtaposing a plurality of disposal tunnels in which waste is buried is disposed upstream from the groundwater transfer path. Is a waste geological disposal facility characterized by a large number of planar arrangements or three-dimensional arrangements on the downstream side.

  This is another example in the case of embodying the facility form of the present invention. For example, as shown in FIG. 2 (c), a flat disposal block (panel) having a plurality of disposal tunnels is disposed by a waste body. A plurality of planes are arranged so as to be arranged more on the downstream side than on the upstream side so that the overall shape becomes a planar shape as shown in FIG. Alternatively, for example, as shown in FIG. 4 (b), a plurality of planar disposal blocks (panels) having a plurality of disposal mine shafts are arranged in a three-dimensional manner so that the waste bodies are arranged more downstream than upstream. For example, the overall shape is a three-dimensional shape as shown in FIG. In this case, the planar disposal blocks may be arranged on a horizontal plane or a vertical plane. In addition, the planar disposal block is not limited to a regular rectangular disposal panel, and a disposal panel having a shape as shown in FIG. 1 can also be used.

  In the case of the geological disposal of high-level radioactive waste, a disposal tunnel anchoring method (see FIG. 11 (a)), a disposal tunnel horizontal placement method (see FIG. 11 (b)), or the like is used. The disposal holes and disposal tunnels are filled with artificial barriers such as bentonite cushioning materials.

  In the present invention configured as described above, in the case of geological disposal of high-level radioactive waste, the groundwater containing nuclides released from the waste disposed upstream of the groundwater passes through the vicinity of the waste disposed downstream. Therefore, due to the presence of contaminated groundwater, the concentration gradient of nuclides in the buffer material around the waste body is reduced, and the release rate of nuclides from the waste body disposed on the downstream side is reduced (see FIG. 9). Furthermore, by disposing many waste bodies on the downstream side, contaminated groundwater passes through more waste bodies, so that the nuclide release rate as a whole is reduced. In the case of other wastes, the release rate of harmful substances is similarly reduced.

Since this invention consists of the above structures, the following effects are acquired especially in the geological disposal of a high level radioactive waste. The same effect can be obtained with other wastes.
(1) By arranging waste bodies along the groundwater transfer path, the nuclide release rate of the waste bodies arranged downstream can be reduced, and by placing many waste bodies downstream, the overall The nuclide release rate can be reduced.
(2) Since the release rate of nuclides from the artificial barrier can be reduced, the safety of performance evaluation results is enhanced.
(3) Since it becomes possible to reduce the nuclide release rate from the population barrier, geological disposal becomes possible even in geological environments where geological disposal cannot be established so far.
(4) Since geological disposal is possible even at shallow depths where geological disposal cannot be established so far, it will lead to shortened construction period and cost.
(5) By showing that further efforts are being made to reduce the exposure dose, it will be easier for local residents to understand.
(6) Since it is possible to reduce the nuclide release rate from the artificial barrier, even if the uncertainty included in the understanding of geological environment characteristics is large, it is possible to have a margin for safety .
(7) Since the safety allowance for uncertainties increases, it becomes possible to reduce the amount of investigation for reducing uncertainties, leading to shortened construction period and cost.

  Hereinafter, the present invention will be described based on the illustrated embodiment. This embodiment is an example applied to the geological disposal of high-level radioactive waste. FIG. 1 shows various examples of planar types of geological disposal facilities according to the present invention. FIG. 2 shows an example of the embodiment of the facility form of FIG. FIG. 3 shows various examples of the three-dimensional type of the geological disposal facility according to the present invention. FIG. 4 shows an example of the embodiment of the facility form of FIG.

  As shown in the plan view (or elevation) of FIG. 1, the radioactive waste geological disposal facility 1 of the present invention is constructed in a natural barrier C of a stable rock in the deep underground. The form of this geological disposal facility 1 is arranged along the groundwater transfer path so that the groundwater containing nuclides released from the waste disposed on the upstream side flows through the waste disposed on the downstream side, and The configuration is such that a large amount of waste is arranged on the downstream side where the nuclides from the upstream side are distributed by advection and dispersion. As a specific form, the shape of the flat disposal section composed of a large number of waste bodies is formed so as to form a triangle, a trapezoid, a home base type, etc., and arranged so as to spread from the upstream side toward the downstream side. . The geological disposal facility 1 having such a configuration is arranged on a horizontal plane or a plane inclined with respect to the horizontal, but can also be arranged on a vertical plane or a plane inclined with respect to the vertical.

  In FIG. 2 (a), the waste body A surrounded by an artificial barrier B such as bentonite cushioning material is disposed at a predetermined interval along the groundwater transfer path and is orthogonal to the groundwater transfer path. The number of waste bodies is arranged so as to increase sequentially toward the downstream side, and one flat disposal section is formed. As a specific method for forming such a flat disposal section, there is a method using a panel shape as shown in FIG. 2B, and a method using a plurality of panels as shown in FIG. 2C. .

  In FIG.2 (b), the planar shape of the disposal panel 2 itself as a planar disposal block is made into the shape as shown, for example in FIG. The disposal panel 2 includes a plurality of disposal tunnels 3 that are parallel to the orthogonal direction of the groundwater transfer path, and a main tunnel 4 that connects the ends of the disposal tunnels 3.

  In FIG.2 (c), the disposal panel 2 is arrange | positioned at predetermined intervals along the transition route of groundwater, and the number of horizontal panels orthogonal to a groundwater transition route increases sequentially toward a downstream side. The plurality of disposal panels 2 as a whole have a planar shape as shown in FIG. 1, for example. Although the disposal panel 2 is a normal quadrilateral panel composed of the disposal mine 3 and the main mine shaft 4, the disposal panel 2 having a shape as shown in FIG. 1 can also be used.

  As a conventional method for placing the waste A, a disposal hole dredging method, a disposal tunnel horizontal placement method, and the like are used as in the past. In the disposal hole dredging method, disposal holes 5 are formed by excavating downward from the bottom of the disposal tunnel 3, and a large number of them are formed at predetermined intervals in the tunnel axis direction. A buffer material (such as bentonite) B that reduces the influence of groundwater and rock pressure is laid down, and the waste material A that is trapped in the buffer material B is buried. The disposal mine 3 is backfilled. In the disposal tunnel sideways system, the buffer material B is spread in the disposal tunnel 3, and the waste A lying in the buffer material B is buried at a predetermined interval in the tunnel axis direction. In the case where the disposal panel 2 is arranged vertically, there are a method in which the disposal mine shafts 3 are arranged in multiple stages in the vertical direction, a disposal shaft anchoring method, and the like.

  Next, FIGS. 3 and 4 show not only a plane but also an upper and lower space. In this case as well, the three-dimensional radioactive waste geological disposal facility 1 is constructed in the natural barrier C of the stable rock in the deep underground, as in the flat type. Similarly to FIG. 1, the geological disposal facility 1 is configured along the groundwater transfer path so that the groundwater containing nuclides released from the waste disposed on the upstream side flows through the waste disposed on the downstream side. In addition, a lot of waste bodies are arranged on the downstream side where nuclides emitted from the upstream side are distributed by advection and dispersion. As a specific form, as shown in FIG. 3, the shape of a three-dimensional disposal section composed of a large number of waste bodies is a cone, a truncated cone, etc., and is arranged so as to spread from the upstream side toward the downstream side. .

  Also in the case of this three-dimensional type, as a specific method for forming the three-dimensional disposal section as described above, a method using a three-dimensional disposal block as shown in FIG. 4 (a), shown in FIG. 4 (b). There is a method by arranging a plurality of panels.

  In FIG. 4A, the waste body A surrounded by the artificial barrier B such as bentonite cushioning material is disposed at a predetermined interval along the groundwater transfer path, and the horizontal direction orthogonal to the groundwater transfer path The number of waste bodies is arranged so as to increase sequentially toward the downstream side, and further arranged in a plurality of stages at predetermined intervals in the vertical direction to form one three-dimensional disposal block 10. ing. Specifically, for example, by disposing a plurality of disposal panels 2 as shown in FIG. 2B, a three-dimensional disposal block 10 having a shape as shown in FIG. 3 can be formed.

  In FIG.4 (b), the disposal panel 2 is arrange | positioned at predetermined intervals along the groundwater transfer path | route, and the number of the vertical or horizontal panels orthogonal to a groundwater transfer path | route is sequentially toward downstream. It arrange | positions so that it may increase, and it is made for the some disposal panel 2 to become a solid shape as shown, for example in FIG. 3 as a whole. Also in this case, the disposal panel 2 is a normal quadrilateral panel composed of the disposal tunnel 3 and the main tunnel 4, but the disposal panel 2 having a shape as shown in FIG. 1 can also be used.

  In the geological disposal facility configured as described above, after applying a groundwater flow analysis result that is performed as part of the geological environment evaluation of the site, an outline layout plan is made, and then the above-mentioned facility form is determined by the conventional design method be able to. In addition, construction is sufficiently possible by utilizing conventional shaft / tilt / tunnel excavation technology and backfill technology.

  In addition, although the above demonstrated the case where it applied to the geological disposal site of radioactive waste, it is applicable also to the geological disposal of other waste.

It is a top view which shows the various examples of the planar type of the form of the geological disposal facility which concerns on this invention. FIG. 2 shows an example of the embodiment of the facility form in FIG. 1, (a) is a perspective view showing an image of the facility form, (b) is a plan view of an example embodied in a panel shape, and (c) is a plurality. It is a perspective view of the example materialized with this panel. It is a perspective view which shows the various examples of the three-dimensional type of the geological disposal facility which concerns on this invention. FIGS. 3A and 3B show examples of implementation of the facility form of FIG. 3, in which FIG. 3A is a perspective view showing an image of the facility form, and FIG. It is a perspective view which shows the image of advection and dispersion | distribution of a nuclide. It is a perspective view which shows the ideal arrangement image of the waste body in the geological disposal facility concerning this invention. 1 is a vertical cross-sectional view showing a multi-barrier system for high-level radioactive waste. FIG. 8 is a vertical sectional view showing the nuclide migration principle in FIG. 7. It is the vertical sectional view and graph which show the buffer material transfer of the nuclide by diffusion. It is a partial cross section perspective view which shows the geological disposal facility and panel of a conventional general high level radioactive waste. It is a fragmentary sectional perspective view which shows the example of the placement method of the waste body in the geological disposal of a high level radioactive waste.

Explanation of symbols

A ... Waste B ... Artificial barrier (bentonite cushioning material)
C ... Natural barrier (bedrock)
1 ... Waste geological disposal facility 2 ... Flat disposal block (disposal panel)
3 ... Disposal tunnel 4 ... Main tunnel 5 ... Disposal hole 10 ... Three-dimensional disposal block

Claims (3)

  It is a waste geological disposal facility for burying waste in the underground ground of a waste geological disposal site, where the waste is disposed along the groundwater transfer path and downstream from the upstream side. Waste geological disposal facility characterized by a large number of locations.   The waste disposal facility according to claim 1, wherein a disposal block formed by juxtaposing a plurality of disposal tunnels in which waste is buried is formed in a planar shape or a three-dimensional shape having a wider downstream side than an upstream side of a groundwater transfer path. Waste geological disposal facility characterized by being. 2. The waste disposal facility according to claim 1, wherein a plurality of disposal blocks formed by juxtaposing a plurality of disposal tunnels in which waste is buried are arranged in a plane or three-dimensionally downstream from the upstream side of the groundwater transfer path. A waste geological disposal facility characterized by

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