JPH06273592A - Stratum simulation device - Google Patents

Abstract

PURPOSE:To provide a stratum simulation device capable of exactly testing with a simple structure the transportation state of radioactive species in soil by simulating an actual disposal environment state near the objective location for ground disposal. CONSTITUTION:A container vessel 1 having a sample water inlet opening 1d and a sample water draining opening 1e at the top and the bottom, respectively, a multihole plate 4 arranged on an upper filter 10 over a soil containing part 2 formed in the container vessel to press the upper filter downward, and a pressing plate 5 connected to the multihole plate 4 in the container vessel by a connection rod 13 are provided. Also, a bellows 6 placed between the pressing plate and the inner surface of the container vessel to support the pressing plate movablly up and down in sealed state, and a rupture disk 7 which is fixed in a hole 5a formed in the pressing plate and broken when a load over a specified value is added, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stratum simulation apparatus used for testing the migration status of radionuclides in soil near a geological disposal target site.

[0002]

2. Description of the Related Art A radioactive waste (a waste liquid or the like) generated in a facility associated with a nuclear reactor plant can be handled easily, for example, by vitrification treatment.

[0003]

Then, a solidified package (canister) in which a glass solidified product is contained in a container
In order to prevent radiation pollution, in addition to the plan to store and store in an artificially constructed radiation waste storage facility for a long time until the emission of radiation is significantly reduced, There is a plan to isolate it.

In this plan for deep geological disposal, the nature of natural rocks can be used to suppress the migration and diffusion of radionuclides, but in consideration of safety, leakage of radionuclides is artificial. Multiple suppression measures are considered by suppressing with various workpieces. In addition, in the current plan, it is said that it is effective to use borosilicate glass as a solidified body and use a stainless alloy as a storage container to form a solidified package (canister).

Further, in the solidified package in which radioactive waste is confined, rock is excavated to open a disposal hole, an appropriate amount of a cushioning material made of bentonite is laid on the bottom of the disposal hole, and carbon steel or the like is placed on the cushioning material. Place the canister with the overpack made of a metal material closed, and
After filling the cushioning material around the overpack to form the cushioning layer, the disposal is performed by covering it with a lid.

[0006] When such disposal is performed, when infiltration water is generated from the bedrock due to groundwater flowing in the deep formation, a part of the cushioning material swells and the internal pressure of the cushioning layer is increased, so that water is absorbed. It is possible to prevent the infiltration of the water and ensure the hermeticity.

On the other hand, in the case of bedrock in the deep underground and soil near the geological disposal target site, assuming the phenomenon of groundwater inundation, researches and studies on the migration status of radionuclides to these soils in advance. Preservation is necessary and is being implemented in the performance evaluation of geological disposal.

Conventionally, in order to test the migration status of radionuclides in soil near the geological disposal target site, a geological simulation device has been considered which pressurizes the soil to a predetermined pressure and injects sample water in this state. The above-mentioned stratum simulation device has a soil pressurizing system in addition to the sample supply system for pressurizing the soil, and has a drawback that the structure becomes complicated.

The present invention has been made in view of the above circumstances, and it is possible to test the transfer status of radionuclides in the soil in the vicinity of the geological disposal target site with an accurate and simple structure in a state simulated in an actual disposal environment. It is an object of the present invention to provide a formation simulation device capable of performing the above.

[0010]

In order to achieve such an object, in a formation simulation apparatus according to the present invention, a storage container having a sample water injection opening and a sample water discharge opening at the top and bottom, respectively, A soil storage part formed by covering the upper and lower sides with a filter in the storage container, a perforated plate arranged above the upper filter forming the soil storage part and pressing the upper filter downward, the storage container And a pressure plate connected to the perforated plate via a connecting rod, and vertically movable between the pressure plate and the inner peripheral surface of the storage container, and the inner periphery of the storage container. A bellows that supports the surface in an airtight state, a rupture disc that is assembled in a hole formed in the pressure plate and is broken when a predetermined load or more is applied, and the storage container that is connected to the sample water injection opening of It has a configuration and a sample water supply means for supplying the water sample under pressure to the section.

[0011]

According to the formation simulation apparatus having the above-described structure, first, the soil sample is filled in the soil container in the container, the upper sample is covered with the soil sample, and the perforated plate is further arranged thereon. A pressure plate connected to the perforated plate is supported by a bellows in a vertically movable and airtight state. From this state, the sample water supply means supplies the sample water in a pressurized state into the storage container through the sample water injection opening.

When the sample water is supplied under pressure to the storage container, the upper space inside the storage container, that is, the upper space partitioned by the pressure plate, is pressurized, whereby the pressure plate is pressed downward. To be done. The perforated plate, which is integrated with the pressure plate, is also pressed downward, which pressurizes the soil.

When the pressure in the storage container reaches a predetermined pressure, the rupture disc is broken, and the sample water existing on the upper side of the storage container passes through the broken rupture disc into the space below the pressure plate. Then, it penetrates the soil sample from the perforated plate through the filter. The radionuclide remains in the soil sample after the test where the sample water has been infiltrated, whereby the transfer status of the radionuclide can be equivalently understood.

[0014]

1 to 3 show an embodiment of a formation simulation apparatus according to the present invention. In these figures, reference numeral 1 is a storage container, 2 is a soil storage portion, 3 is a soil sample stored in the soil storage portion 4, 4 is a porous plate, 5 is a pressure plate, 6 is a bellows, and 7 is a pressure plate 5. The incorporated rupture disc, 8 is a sample water supply means.

In the storage container 1, an upper lid 1b and a lower lid 1c are provided on the upper and lower sides of a cylindrical body portion 1a, and a flange 30a,
30b is fastened with bolts and nuts 31.
An opening is formed in the center of the upper lid 1b and the lower lid 1c, and the sample water injection nozzle 1d and the sample water discharge nozzle 1 are formed in the opening.
e is attached.

At the bottom of the storage container 1, the soil storage portion 2 is formed by covering the top and bottom with filters 10 and 11, respectively. The lower filter 11 has a small diameter such that it can cover the base end of the sample water discharge nozzle 1e. These filters 10 and 11 allow the inflow and outflow of the sample water while blocking the outflow of the soil sample 3 when a predetermined pressure is applied to the soil sample 3, and specifically, nylon Made of cloth or non-woven fabric. The soil storage unit 2 stores soil such as soil in a deep geological formation, and the soil sample 3 collected from the vicinity of the geological disposal target site.

As shown in FIG. 2, the perforated plate 4 is provided with a large number of holes 4a penetrating vertically, and has a rigidity such that the soil sample 3 can be pressed downward through the upper filter 10. Be prepared. The lower end of the connecting bolt 13 is screwed into the center of the perforated plate 4 via a nut 14, and the pressing plate 5 is attached to the upper end of the connecting bolt 13 by a nut 15.
It is screwed through. The pressure plate 5 is integrally mounted above the perforated plate 4 via the connecting bolt 13 so as to be parallel to the perforated plate 4.

The pressure plate 5 is a portion which receives the hydrostatic pressure of the sample water when the sample water is supplied from the nozzle 1d for injecting the sample. Therefore, the pressurizing plate 5 has such a rigidity that it is not damaged even when the hydrostatic pressure of the sample water is applied. It is made of material. Reference numeral 16 denotes a collar portion formed on the inner circumference of the storage container 1, and the bellows 6 is interposed between the collar portion 16 and the pressure plate 5. The pressure plate 5 is vertically movable by the bellows 6 and is supported in an airtight state with respect to the inner peripheral surface of the storage container 1. Therefore, the upper and lower spaces 17 and 18 in the storage container partitioned by the pressure plate 5 are airtightly divided.

The pressurizing plate 5 is formed with a plurality of holes 5a penetrating vertically, and the rupture disc 7 is assembled therein. The rupture disc 7 is broken when a load of a predetermined amount or more is applied, specifically, when the pressure difference between the upper and lower spaces 17 and 18 partitioned by the pressure plate 5 becomes a predetermined amount or more, such as plastic or metal. Made by the material.

The sample water supply means 8 for supplying sample water under pressure to the inside of the storage container 1 through the sample water injection nozzle 1d comprises a sample water tank 19 and the sample water tank 1
9 for connecting 9 and the sample water injection nozzle 1d
And a pressurizing pump 21 interposed in the conduit 20. Reference numeral 22 is a sluice valve interposed in the pipe 20. A bypass passage 24 is formed in the pipe 20 to branch from the pipe passage 20 to the open tank 23, and a pressure relief valve 25 is provided in the bypass passage 24. The pressure relief valve 25 is on / off controlled by a sensor 26 that detects the pressure in the upper space 17 of the storage container 1. Incidentally, 27 is a tank for storing the sample water.

A nuclide migration test of soil using a stratum simulation apparatus having such a structure will be described. The sample water discharge nozzle 1e is previously used by the lower filter 11.
The soil sample 3 is filled in the soil storage part 2 in the storage container 1 with the base part of 1 being closed. Then, the soil filter 3 is covered with the upper filter 10 and the perforated plate 4 is arranged thereon. Next, the pressure plate 5 and the collar portion 1 on the inner peripheral surface of the storage container 1
A bellows 6 is arranged between the pressure plate 5 and the pressure plate 5, and the pressure plate 5 is supported so as to be movable up and down, and the upper and lower spaces 17 and 18 in the storage container sorted by the pressure plate 5 are airtightly divided. In this state, the outer periphery of the upper lid 1b is welded to the body portion 1a of the storage container 1.

The pressure pump 21 is driven to drive the sample water tank 1
The sample water stored in 9 is injected into the upper space 17 of the container 1 through the pipe 20 and the sample water injection nozzle 1d. By the injection of the sample water, the pressure in the upper space 17 gradually rises, and the pressing plate 5 and the porous plate 4 connected to the pressing plate 5 are pushed downward together with this, and as a result, the pressing force is applied to the soil sample 3. Is added. Then, by continuously injecting the sample water, the pressing force on the soil sample 3 gradually increases, and eventually the pressure becomes equivalent to the pressure received by the soil through which the groundwater at the geological disposal target site is inserted.

The upper space 17 in the storage container 1 reaches a predetermined pressure and is partitioned by the pressure plate 5 into upper and lower spaces 17, 18.
The rupture disk 7 is broken when the pressure difference between the two exceeds a predetermined value. Along with this, as shown by the arrow in FIG. 1, the sample water existing in the upper space 17 of the storage container 1 passes through the broken rupture disc 7 and the space 18 below the pressure plate 5.
To the inside of the soil sample 3 through the upper filter 10 from the hole 4a of the porous plate 4. Then, the excess sample water that has reached the bottom of the container is collected from the lower filter 11 through the sample water discharge nozzle 1e into the sample water tank 27 below. In the soil sample 3 after the test in which the sample water is infiltrated, the radionuclide remains along the infiltrating direction of the sample water.

In the actual geological disposal environment, since the area and volume of the soil part are large, the transfer directions of the radionuclide are considered to be parallel to each other. Therefore, the concentration distribution of the sample nuclide of the soil sample 3 in the test range of FIG. Even in sandy soil, it is equivalent by simulating the infiltration direction of groundwater in deep layers.

After permeating the sample water as described above, the soil sample 3 to which the radionuclide has been transferred is removed from the storage container 1 by removing the upper lid 1b, and the concentration of radioactive substances attached to the soil sample 3 is detected. By doing so, it becomes possible to grasp the state of simulating soil in the geological disposal environment.

The pressure inside the upper space 17 can be maintained at a predetermined pressure by interlocking the sensor 26 for detecting the pressure in the upper space 17 of the storage container 1 and the pressure relief valve 25. The pressure in the space 17 can be set to the same level as the atmospheric pressure.

[0027]

As described above, the present invention has the following effects. Since the sample water can be used for pressurizing the soil sample, the fluid supplied to the storage container may be one type of sample water,
Therefore, the entire structure of the device can be simplified and the economical efficiency can be improved. By preparing various rupture discs and selectively assembling them on the pressure plate and using pressurized water as sample water, it is possible to perform simulation tests on soil samples under various set pressures, and a wide range of simulation tests can be realized. Practicality increases.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a formation simulation device according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an overall view showing an embodiment of a formation simulation device according to the present invention.

[Explanation of symbols]

 1 Storage Container 1d Sample Water Supply Opening (Nozzle) 1e Sample Water Discharging Opening (Nozzle) 2 Soil Storage Section 3 Soil Sample 4 Perforated Plate 5 Pressurizing Plate 5a Hole 6 Bellows 7 Rupture Disc 8 Sample Water Supply Means 10 Top Filter 11 Lower filter 13 Connecting rod (connecting bolt) 16 Collar 19 Sample water tank 21 Pressurizing pump

Claims (1)

[Claims] 1. A stratum simulation device used for testing the migration status of radionuclides in soil in the vicinity of a geological disposal target site, the storage container having upper and lower sample water injection openings and sample water discharge openings, respectively. A soil storage part formed by covering the top and bottom with a filter in the storage container, and a perforated plate arranged above the upper filter forming the soil storage part and pressing the upper filter downward. A pressure plate that is connected to the perforated plate via a connecting rod in the storage container, and is vertically interposed between the pressure plate and the inner peripheral surface of the storage container, and the storage container can be moved up and down. A bellows that is supported in an airtight state on the inner peripheral surface of the rupture disc, a rupture disc that is assembled in a hole formed in the pressure plate and is broken when a predetermined load or more is applied, and a sample water injection opening. By formation simulation apparatus characterized by comprising a sample water supply means for supplying the water sample under pressure to the interior of the container.