JPH0547898U - Gas permeability test equipment for buffer material for geological disposal - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The present invention relates to a gas permeation test device for a buffer material for geological disposal, which reduces measurement errors due to the capacity and size of the pressure container for testing and the buffer material. , Perform a test that accurately simulates gas permeability. A pressure-resistant container 11 in which a buffer material under test in a swollen state is loaded, a fluid inlet 12 and a fluid outlet 13, and a porous layer interposed between the fluid inlet 12 and fluid outlet 13 and the buffer material under test. And a gas permeation suppression concavo-convex portion 15 arranged so as to surround the porous layer on the fluid inlet side or the fluid outlet side.
And. The gas permeation suppression concavo-convex portion 15 concentrates gas permeation in the buffer layer, assuming that the flow path along the inner surface of the pressure-resistant container 11 is long and has high resistance.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a gas permeability test apparatus for a buffer material for geological disposal.

[0002]

[Prior Art]

 The high-level radioactive waste (waste liquid, etc.) generated in facilities related to nuclear power plants can be improved in handleability by, for example, vitrification treatment.

A solidification package (canister) containing glass solidified material in a container is placed in an artificially constructed radioactive waste storage facility to prevent radiation contamination, until radiation emission is significantly reduced. In addition to long-term storage and storage, there are plans to store and store in deep geological formations to isolate them from living areas.

In this plan for deep geological disposal, it is possible to suppress the migration and diffusion of radionuclides by utilizing the properties of natural rocks, but it is not possible to completely understand the state of rocks in deep geological formations. Based on this, it is considered practical to control the leakage of radionuclides by using artificial structures. In the plan, borosilicate glass should be used as the solidified body, a solidified package (canister) should be made by using a stainless steel alloy as the container, and metal and ceramics should be used as the overpack material. It is said to be influential.

FIG. 3 shows an example of the structure of a geological disposal plan for radioactive waste, in which a rock (host rock) 1 is excavated to open a disposal hole 2 and bentonite is formed at the bottom of the disposal hole 2. Place a suitable amount of cushioning material consisting of, on which the canister 4 is placed with the overpack 3 made of an appropriate metal material such as carbon steel sealed, and further fill the cushioning material around the overpack 3 uniformly. After forming the buffer layer 5, the cover 6 is covered with the cover 6 and the cover 6 is fixed to the bedrock 1 with anchor bolts 7. In the figure, reference numeral 8 is a tunnel.

With such a disposal structure, a groundwater permeable layer exists in a part of the bedrock 1, and when this groundwater permeable layer intersects or approaches the disposal hole 2, groundwater enters the disposal hole 2. When a phenomenon occurs, the uniformly filled water-filled portion of the buffer layer 5 swells and the internal pressure of the buffer layer 5 increases, so that water can be prevented from entering and the hermeticity can be ensured. Is.

On the other hand, when the overpack 3 is made of an iron-based metal, it is considered that Fe ₂ O ₃ and hydrogen gas are generated by a chemical reaction at the time of corrosion due to contact with water. In this case, it is important to understand the behavior (gas permeability) of the buffer layer 5 in advance.

FIG. 4 shows an example of a gas permeability test apparatus for a cushioning material. A fluid inlet 12 and a fluid outlet 13 are arranged in the pressure-resistant container 11, and a porous layer 14 such as a filter is interposed in the vicinity of the fluid inlet 12 and the fluid outlet 13 to form the pressure-resistant container 11 and the pair of porous layers 14. The above-mentioned buffer material 5 is loaded into the enclosed space, and water is injected to make the buffer material 5 swell, and then hydrogen gas in a pressurized state is sent from the fluid inlet 12 to the buffer layer 5 and the fluid outlet. The gas permeability of the buffer layer 5 is tested by discharging the hydrogen gas from the buffer layer 5.

[0009]

[Problems to be solved by the device]

 However, in the gas permeation test of the example of FIG. 4, even if hydrogen gas is spread outward by the porous layer 14 and evenly permeated through the entire area of the buffer layer 5, the hydrogen gas of the buffer layer 5 and the pressure-resistant container 11 is not changed. Since the resistance of the flow path passing through the boundary with the inner wall becomes small, the hydrogen gas permeation path tends to be in a state of being shifted to the outside as shown by the arrows in Fig. 4, and the volume and size are limited. Since the test is performed on the buffer layer 5 in a different range, the ratio of the gas insertion amount of the portion closer to the outside becomes large, and it becomes difficult to accurately verify the gas permeability of the buffer layer 5.

The present invention has been made in view of the above circumstances, and accurately simulates the gas permeability of the buffer layer even when the capacity and size of the pressure container for testing and the buffer material are limited. The purpose is to carry out the tests described above.

[0011]

[Means for Solving the Problems]

 In order to achieve such an object, in a device for testing the gas permeability characteristics of a cushioning material used during geological disposal, a pressure-resistant container loaded with a buffer material to be tested in a swollen state, and a pressure-resistant container arranged in the pressure-resistant container. The fluid inlet and the fluid outlet, the porous layer interposed between the fluid inlet and the fluid outlet and the buffer material under test, and the fluid inlet side or the fluid at the contact portion between the inner wall surface of the pressure-resistant container and the buffer material under test. The gas permeation test equipment for the buffer material for geological disposal is provided with a concavo-convex portion for suppressing gas permeation that is arranged so as to surround the porous layer on the outlet side.

[0012]

[Action]

 When the test gas is sent from the fluid inlet to the inside of the pressure vessel, the gas is diffused by the porous layer and permeates the inside of the swollen buffer layer, and the fluid flows along the inner surface of the pressure vessel to the fluid outlet. A flow passage is formed without passing through the layer.In this case, however, a gas permeation suppression uneven part surrounding the porous layer is placed near the fluid inlet / outlet. Since the flow path along the inner surface of the pressure vessel is long, the amount of gas passing therethrough is limited, and the flow of gas that passes through the buffer layer between the separated porous layers is averaged as a whole. It is similar to a large volume and size buffer layer.

[0013]

【Example】

 1 and 2 show an embodiment of a gas permeability test apparatus for a buffer material for geological disposal according to the present invention, in which reference numeral 5 is a buffer material to be tested (buffer material, buffer layer), and 11 is Pressure-resistant container, 11A is a container barrel, 11B is an inlet side lid, 11C is an outlet side lid, 11D is a flange part, 11E is a sealing material, 11F is a fastener such as a bolt, 12 is a fluid inlet, 13 is a fluid Outlet, 14A is an inlet side porous layer (porous layer), 14B is an outlet side porous layer (porous layer), 15 is an uneven portion for suppressing gas permeation, 20 is a pressurized test gas supply system, 21 is gas supply Piping, 22 is an open / close valve, and 23 is a pressure gauge.

As shown in FIG. 1, the pressure-resistant container 11 has a container body 11A formed in, for example, a right cylindrical shape, and a seal is provided between both flange portions 11D and the inlet side lid body 11B and the outlet side lid body 11C. With the material 11E interposed, it is integrated with the sealing structure by the fastener 11F.

The inlet-side porous layer 14A and the outlet-side porous layer 14B are interposed between the fluid inlet 12 and the fluid outlet 13 and the buffer material 5 to be tested, as in the example of FIG. However, in the example of FIG. 1, the diameter of the inlet side porous layer 14A is set to be small.

The gas permeation suppression concavo-convex portion 15 is provided with a plurality of annular walls 15a, 15b, 15c, etc. arranged so as to concentrically surround the inside of the fluid inlet 12, and these annular walls are arranged. 15a, 15b, 15c are integrally formed in a state of protruding with respect to the inner surface of the inlet side lid body 11B. Then, the protrusion height of the annular wall 15a close to the fluid inlet 12 is set to be maximum.

The pressurized test gas supply system 20 is, for example, a pressurized hydrogen gas supply device, is connected to the fluid inlet 12 via an on-off valve 22 by a gas supply pipe 21, and applies a test pressure up to the test pressure. The pressurized hydrogen gas is supplied, and the test pressure is successively detected by the pressure gauge 23.

When carrying out the gas permeability test of the buffer material 5 to be tested, as shown in FIG. 1, the outlet side lid body 11C is removed with the container body 11A standing upright and surrounded by the annular wall 15a. A desired amount of the buffer material 5 to be tested is sequentially loaded into the container barrel 11A in a state where the porous layer 14A is formed by loading a filter or the like in the recessed portion, and then the outlet-side lid 1 is attached to the container barrel 11A. 1C is attached to make the whole a sealed structure.

Next, water is injected from the fluid inlet 12 into the inside of the container body 11A so that the buffer material 5 to be tested absorbs water. The buffer material 5 to be tested is bentonite or the like as described above, and has a large swelling property due to taking in a large amount of water between the layers due to the property of montmorillonite which is its main component.

When the test gas (hydrogen gas) is sent from the pressurized test gas supply system 20 to the inside of the pressure resistant container 11 from the fluid inlet 12 with the buffer material 5 under test swollen, the inlet side porous layer 14A The gas diffuses from the area where the buffer layer 5 is formed to the swollen buffer layer 5, and in this case, the flow path that passes only through the buffer layer 5 and the fluid outlet along the inner surface of the pressure container 11 are formed. The flow path reaching 13 is considered. That is, the gas flow path that penetrates only the inside of the buffer layer 5 extends from the inlet side porous layer 14A to the entire area of the buffer layer 5, as indicated by the solid arrow in FIG. On the other hand, the gas flow path along the inner surface of the pressure-resistant container 11 has an inlet-side porous layer 14A, annular walls 15a, 15b, 15c, the inner surface of the container body 11A and an outlet-side lid as shown by the dashed arrow in FIG. 11C in order, the distance is longer and the resistance is larger than that in the example of FIG. 4, so that the amount of gas passing therethrough is suppressed. Therefore, in the buffer layer 5 in a slightly wider range than the inlet side porous layer 14A, the flow of gas passing through the buffer layer 5 is averaged such that the flow is almost parallel as a whole, and the volume and size of the buffer layer 5 are remarkably increased. It will be in a state similar to a larger one.

<Other Embodiments> The following techniques can be adopted in the gas permeability test apparatus for the buffer material for geological disposal according to the present invention. Disposing the gas permeation suppression uneven portion 15 on the fluid outlet 13 side. The gas permeation suppression concavo-convex portion 15 is provided at both the fluid inlet 12 and the fluid outlet 13. Make the number of the annular walls 15a, 15b, 15c arbitrary.

[0022]

[Effect of the device]

 As described above, according to the gas permeability test apparatus for the buffer material for geological disposal according to the present invention, the pressure resistant container in which the buffer material under test in the swollen state is loaded, the fluid inlet and the fluid outlet, and the fluid inlet. And a porous layer interposed between the fluid outlet and the cushioning material to be tested, and a gas permeation suppression uneven portion arranged on the fluid inlet side or the fluid outlet side so as to surround the porous layer. Therefore, the following effects are obtained. (1) Due to the gas permeation suppression irregularities, the flow path along the inner surface of the pressure vessel becomes long and has a large resistance. Therefore, during the gas permeability test caused by the capacity and size of the pressure vessel for test and the cushioning material. It is possible to reduce the measurement error of. (2) By allowing most of the test gas to permeate through the swollen buffer layer, the parallel volume of the gas flow path increases, and a test that accurately simulates gas permeability in the buffer layer is performed. You can

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a gas permeability test apparatus for a cushioning material for geological disposal according to the present invention.

2 is a front sectional view showing a gas permeation state by the gas permeation test device of FIG. 1. FIG.

FIG. 3 is a front sectional view showing a structural example of a geological disposal plan for radioactive waste.

FIG. 4 is a front sectional view showing a gas permeation state by a conventional gas permeation test device.

[Explanation of Codes] 5 Buffer material to be tested (buffer material, buffer layer) 11 Pressure-resistant container 11A Container body 11B Entrance side lid body 11C Exit side lid body 11D Flange portion 11E Seal material 11F Fastener 12 Fluid inlet 13 Fluid outlet 14 Porous Quality layer 14A inlet side porous layer 14B outlet side porous layer 15 gas permeation suppression uneven portion 15a annular wall 15b annular wall 15c annular wall 20 pressurized test gas supply system 21 gas supply pipe 22 on-off valve 23 pressure gauge

Claims (1)

[Scope of utility model registration request] 1. A device for testing the gas permeability of a cushioning material used for geological disposal, which is provided with a pressure resistant container loaded with a buffer material to be tested in a swollen state, and arranged in the pressure resistant container. The fluid inlet and the fluid outlet, the porous layer interposed between the fluid inlet and the fluid outlet and the buffer material under test, and the fluid inlet side or the fluid at the contact portion between the inner wall surface of the pressure resistant container and the buffer material under test. A gas permeation test device for a buffer material for geological disposal, comprising: a gas permeation suppression concavo-convex portion that is arranged so as to surround a porous layer on the outlet side.