JP5413974B2 - Method for measuring pore surface area inside rock using radon and device for measuring pore surface area inside rock using radon - Google Patents

Description

  The present invention relates to a method for measuring a pore surface area inside a rock using radon and a device for measuring a pore surface area inside a rock using radon.

When isolating radioactive waste in the ground, the larger the surface area (gap surface area) of the rock in the ground, the easier the radionuclide will adhere, and the influence of the radionuclide on the living environment can be eliminated. In addition, when carbon dioxide (CO ₂ ) is stored underground, the influence of the acidic water in which CO ₂ is dissolved on the rock depends on the reaction area of the rock. For this reason, grasping the surface area (gap surface area) of the rock in the ground means whether or not stable disposal or storage can be performed when underground disposal of radioactive waste or underground storage of CO ₂ is performed. It is an important evaluation item to judge.

  A mercury intrusion method is known in which pressure is applied to mercury covering a sample, mercury is pressed into fine pores of the sample, and the pore distribution of the sample is measured based on the amount of change in pressure and mercury. It has been conventionally known to verify the state of pores in a compound powder by measuring the pore distribution of a sample by this mercury intrusion method (see, for example, Patent Document 1). The surface area (pore surface area) of the rock can be evaluated by verifying the condition of the pores in the ground rock by the mercury intrusion method.

  Further, a gas adsorption method is known in which gas molecules such as nitrogen and helium are adsorbed on a sample and gas is adsorbed in small holes of the sample to measure the pore distribution of the sample (PET method). It is conceivable to use this gas adsorption method to adsorb gas to powdered rock and to evaluate the surface area (gap surface area) of the rock based on the amount of adsorbed gas.

  When the surface area (pore surface area) of the ground rock is evaluated by the mercury intrusion method, mercury is intruded into the rock fragment, but since the mercury is intruded into the hole as a sphere, all of the rock flow gap The surface area (gap surface area) corresponding to the actual flow space cannot be evaluated. Moreover, when evaluating the surface area (gap surface area) of a rock using the gas adsorption method, it is not suitable as a method for estimating the flow gap of the rock because the rock is powdered.

  On the other hand, a small amount of uranium is contained in the rock, and radon as a decay product is released from the rock. Radon is an element that emits radiation to lead with a half-life of about 3.8 days. Rocks have a gap, and radon is released from the surface of the rock's fluid gap. For this reason, it is considered that the surface area of the rock flow gap can be evaluated by measuring the amount of radon released.

JP 2009-289758 A

  The present invention has been made in view of the above circumstances, and provides a method for measuring the pore surface area inside a rock using radon, which can measure the pore surface area inside the rock by evaluating the flow gap of the rock using radon. With the goal.

  Further, the present invention has been made in view of the above situation, and provides an apparatus for measuring a gap surface area inside a rock by using radon, which can measure the gap surface area inside the rock by evaluating the flow gap of the rock using radon. The purpose is to do.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a method for measuring the surface area of pores inside a rock using radon. To determine the amount of radon released from the total gap amount, and dividing the determined radon amount by the unit radon amount released per unit area of the rock sample, the pore surface area of the rock sample is obtained. It is characterized by calculating.

  In the present invention according to claim 1, the amount of radon contained in the fluid obtained by circulating the rock sample is defined as the amount of radon released from the entire gap of the rock sample, and the amount of radon is calculated per unit area of each rock solid. The surface area (gap surface area) of the total pore volume is obtained by dividing by the amount of unit radon released into the rock. Therefore, the surface area (gap surface area) corresponding to the flow gap of the rock is evaluated and the pore surface area inside the rock is measured. be able to. Because radon has a half-life of about 3.8 days, when measuring the amount of stable radon in the fluid, the fluid is circulated for about a month to obtain a radiation equilibrium between the released radon and the destroyed radon. It is preferable to make it.

  The total amount of pores in a rock sample is the volume in the range surrounded by the surface area of the gap through which fluid can flow.For example, the rock sample can be saturated by submerging the rock sample in water. Obtained by subtracting the weight of the dry rock sample from the weight of the sample.

  According to a second aspect of the present invention, there is provided a method for measuring a pore surface area inside a rock using radon according to the present invention, wherein the fluid circulated through the rock sample is water. It is characterized by.

  In the present invention according to claim 2, since water is circulated as a fluid, radon permeation from the fluid can be suppressed, and the surface area (gap surface area) corresponding to the flow gap of the rock can be accurately evaluated. .

  According to a third aspect of the present invention, there is provided a method for measuring a pore surface area inside a rock using radon according to the present invention. The amount of unit radon released is determined by filling the unit sample, which is cut out from the rock sample and whose surface is flattened and the total surface area is grasped, with water, and the radon amount contained in the water filled with the unit sample is the total area. It is the amount of the divided value.

  In the present invention according to claim 3, the amount of radon released per unit area specific to the rock sample can be easily obtained.

  According to a fourth aspect of the present invention for achieving the above object, there is provided an apparatus for measuring a surface area of a gap inside a rock using radon according to the present invention, a flow container in which a rock sample in which the total gap amount is grasped is accommodated in a fluid, A circulating means for circulating the fluid, a radon amount measuring means for measuring a stable radon amount in the fluid circulated by the circulating means, and a unit radon amount which is a radon release amount per unit area of the rock sample is obtained. A radon flux detecting means; and a surface area deriving means for determining a pore surface area of the rock sample by dividing the radon amount measured by the radon amount measuring means by a unit radon amount determined by the radon flux detecting means. It is characterized by that.

  In the present invention according to claim 4, the fluid is circulated by the circulating means to the rock sample whose total gap amount is grasped, the radon amount contained in the circulated fluid is measured by the radon amount measuring means, and the measured radon amount is measured. Is the amount of radon released from the total amount of pores in the rock sample, and by the surface area deriving means, the amount of radon is divided by the amount of radon released per unit area of the rock solids. The surface area (gap surface area) is determined. For this reason, the surface area (gap surface area) corresponding to the flow gap of the rock can be evaluated to measure the gap surface area inside the rock. Since radon has a half-life of about 3.8 days, when measuring the amount of stable radon in the fluid, in order to obtain a radiation equilibrium state between the released radon and the destroyed radon, the fluid is reduced by circulation means. It is preferable to circulate for one month.

  The total gap amount is determined by the total gap amount deriving means based on the dry weight and fluid saturation weight of the rock sample.

  According to a fifth aspect of the present invention, there is provided a device for measuring the surface area of a gap inside a rock using radon according to the present invention. The device for measuring a surface area of a rock inside a rock according to claim 4 wherein the circulating means circulates water as a fluid. It is characterized by.

  In the present invention according to claim 5, since the circulating means circulates water as a fluid, it is possible to suppress the permeation of radon from the fluid and accurately evaluate the surface area (gap surface area) corresponding to the rock flow gap. be able to.

  According to a sixth aspect of the present invention, there is provided the device for measuring the surface area of the pores inside the rock using radon according to the present invention, wherein the device for measuring the surface area of the pores inside the rock according to claim 4 or 5, wherein the radon flux detecting means comprises: An airtight container that is filled with water and contains a unit sample that has been cut out from a rock sample and whose surface has been flattened to determine the total surface area, and the amount of radon contained in the water extracted from the airtight container is detected. And a radon flux calculating means for obtaining a unit radon amount per unit area by dividing the detected radon amount by the total surface area of the unit sample.

  In the present invention according to claim 6, since the unit sample is stored in an airtight container filled with water and the amount of radon released per unit surface is obtained, the amount of radon released per unit area specific to the rock sample can be easily reduced. Can be requested.

  The method for measuring the pore surface area inside a rock using radon according to the present invention makes it possible to measure the pore surface area inside the rock by evaluating the flow gap of the rock using radon.

  Moreover, the gap surface area measuring apparatus inside the rock using radon according to the present invention can measure the gap surface area inside the rock by evaluating the flow gap of the rock using radon.

It is a whole block diagram of the pore surface area measuring device inside the rock by radon concerning one example of the present invention. It is a conceptual diagram of a radon flux detection means. It is a whole processing figure explaining the crevice surface area measuring method inside the rock by radon concerning one example of the present invention.

  FIG. 1 shows the overall conceptual configuration of an apparatus for measuring the surface area of a gap inside a rock according to an embodiment of the present invention, and FIG. 2 shows the concept of a radon flux detecting means. FIG. 3 shows a processing flow for explaining the processing of the method for measuring the pore surface area inside the rock by radon according to an embodiment of the present invention over time.

  Based on FIG. 1 and FIG. 2, an apparatus for measuring a pore surface area inside a rock using radon will be described.

As shown in FIG. 1, a circulation container 2 that contains a rock sample 1 is provided, and a circulation path 3 is connected to the circulation container 2. The rock sample 1 accommodated in the circulation container 2 has been measured in advance for a dry weight (W _D ) and a weight in which water is saturated in the gap (saturated weight: W _S ). The circulation path 3 is provided with a pump (for example, a Mono pump) 4 as a circulation means, and the water in the circulation container 2 is circulated through the circulation path 3 by driving the pump 4.

  By circulating the water in the circulation container 2 in which the rock sample 1 is accommodated, radon is released from the rock sample 1 into the circulating water and becomes a circulating water containing radon. Since radon has a half-life of about 3.8 days, when measuring the amount of stable radon contained in water, the pump 4 is used to obtain a radiation equilibrium state between the released radon and the destroyed radon. It is circulated for about one month.

  A radon amount measuring means 11 is connected to the circulation path 3 on the downstream side of the circulation container 2 via a valve member 5, and the circulating water circulated for about one month is sent to the radon amount measuring means 11 to reduce the radon amount. It is drained after being measured.

Total gap amount deriving means 12 for calculating the total gap amount (P _V ) of the rock sample 1 is provided. The total gap amount deriving means 12 derives the total gap amount of the rock sample 1 (volume in a range surrounded by the surface area of the gap through which the fluid can flow). The total gap amount deriving means 12 receives the dry weight (W _D ) and saturation weight (W _S ) of the rock sample 1 measured in advance. In total the gap amount deriving means 12, the total clearance volume of rock samples 1 _{(P V)} is calculated by subtracting the dry weight _{(W D)} from the saturation weight _{(W S) (P V =} W S -W D) .

Although are described as an example of calculating the total clearance volume of rock samples 1 (P _V) with total clearance amount deriving means 12 by P _{V =} W _S -W _D, the total clearance volume of rock samples 1 other If it has been grasped in advance by the technique, the total gap amount deriving means 12 can be omitted.

The total gap amount (P _V ) of the rock sample 1 calculated by the total gap amount deriving means 12 is sent to the radon amount measuring means 11, and in the radon amount measuring means 11, the radon amount relative to the total gap amount (P _V ), that is, Then, the amount of radon contained in the circulating water that has been circulated for about one month and the amount of radon is stable (the amount of radon after passing through the rock sample 1: R _np ) is measured. Information on the radon amount (R _np ) measured by the radon amount measuring means 11 is sent to the surface area deriving means 13.

On the other hand, a radon flux detecting means 14 for obtaining a unit radon amount (radon flux: R _nF ) which is a radon emission amount per unit area of the rock sample 1 is provided. The radon flux detecting means 14 includes the same rock as the rock sample 1. The radon amount passing through the unit area, that is, the radon flux (R _nF ) of the rock sample 1 is determined.

  The outline of the radon flux detection means 14 will be described based on FIG.

As shown in the figure, the unit sample 21 is cut out from the rock sample 1 (see FIG. 1), the surface is flattened, and the surface area (S _R ) is grasped. The unit sample 21 is accommodated in an airtight container 22 filled with water and immersed for a predetermined period (for example, one month). When the unit sample 21 is immersed in the airtight container 22 for a predetermined period, radon that passes (releases) the surface of the unit sample 21 is stably contained in the water inside the airtight container 22.

The water inside the hermetic container 22 after a predetermined period of time is extracted, and radon in the immersion water is analyzed by the radon flux calculating means 23 to measure the radon amount (R _nR ). In addition to the surface area (S _R ) information of the unit sample 21, individual information such as physical characteristics and volume is input to the radon flux calculating means 23, and the amount of radon released from the surface of the unit sample 21, that is, the unit sample. A unit radon amount (Radon flux: R _nF ) passing through the surface of 21 is calculated. That is, the radon flux (R _nF ) is calculated by dividing the radon amount (R _nR ) in the immersion water by the surface area (S _R ) of the unit sample 21 (R _nF = R _nR / S _R ).

In the radon flux detecting means 14 described above, since the unit sample 21 is accommodated in the airtight container 22 filled with water and the amount of radon released per unit area is obtained, the radon released per unit area unique to the rock sample 1 is obtained. The amount (Radon flux: R _nF ) can be easily determined.

Returning to FIG. 1, the surface area deriving means 13 is based on the radon amount (R _np ) after _{passing the} rock sample 1 and the radon flux (R _nF ) of the rock sample 1, and the total pore amount (P _The pore surface area (S _F ), which is the surface area of _V ), is calculated. That is, the pore surface area (S _F ) is calculated by dividing the radon amount (R _np ) after passing through the rock sample 1 by the radon flux (R _nF ) of the rock sample 1 (S _F = R _np / _RnF ).

  The gap surface area measuring method using the gap surface area measuring apparatus described above will be described with reference to FIG.

In step S1, the dry weight (W _D ) of the rock sample 1 is measured, and in step S2, the saturated weight (W _S ) of the rock sample 1 is measured. The dry weight (W _D ) is subtracted from the measured saturated weight (W _S ) to calculate the total gap amount (P _V ) of the rock sample 1 in Step S3, and water is passed for one month in Step S4. In the embodiment, water is passed through the rock sample 1 to release radon into the water, but it is also possible to ventilate the rock sample 1 to release radon into the gas (air). .

After one month of water flow in step S4, the radon amount (R _np ) after the water flow is measured in step S5. That is, the amount of radon contained in the circulating water in which the amount of radon has been stabilized after the passage of water for about one month is measured, and the amount of radon released from all the gaps in the rock sample 1 is measured.

On the other hand, in step S6, the same rock as the rock sample 1 is shaped into a rectangular parallelepiped to form the unit sample 21, and in step S7, the surface area (S _R ) of the unit sample 21 is measured. In step S8, the unit sample 21 is immersed in the airtight container 22 for one month, and in step S9, radon in the immersion water is analyzed and the radon amount (R _nR ) is measured. After the radon amount (R _nR ) is measured in step S9, the radon flux (R _nF ) released from the surface of the unit sample 21 is calculated in step S10.

Then, the process of dividing the radon amount (R _np ) measured in step S5 by the radon flux (R _nF ) calculated in step S10 is performed in step S11, and the total gap amount corresponding to the radon amount (R _np ) is performed. The area (according to (P _V )), that is, the gap surface area (S _F ) which is the area of the entire gap surface of the rock sample 1 is calculated in step S11.

Therefore, in the above-described device and method for measuring the surface area of the pores inside the rock using radon, the total void amount (P _V ) of the rock sample 1 is obtained by the total void amount deriving means 12, and water is circulated through the rock sample 1 by the pump 4. The amount of radon contained in the water is measured by the radon amount measuring means 11 to be the amount of radon (R _np ) released from the total pore amount (P _V ) of the rock sample 1. Then, the surface area deriving means 13 _divides the radon amount (R _np ) by the unit radon amount (radon flux: R _nF ) released per unit area of the individual rock, thereby obtaining the surface area ( The gap surface area (S _F ) is determined.

For this reason, the pore surface area (S _F ) can be obtained based on the radon amount (R _np ) contained in the water passed through the rock, and the surface area corresponding to the actual flow gap is evaluated to evaluate the gap inside the rock. It becomes possible to measure the surface area (S _F ).

Moreover, since water is circulated by the pump 4 as a circulation means, the permeation | transmission of radon from water can be suppressed and the gap surface area (S _F ) corresponding to the flow gap of rock can be evaluated accurately. .

  INDUSTRIAL APPLICABILITY The present invention can be used in the industrial field of an apparatus for measuring a pore surface area inside a rock using radon that measures the pore surface area inside the rock by evaluating the flow gap of the rock using radon.

  In addition, the present invention can be used in the industrial field of a method for measuring a pore surface area inside a rock using radon, in which the pore surface area inside the rock is measured by evaluating the flow gap of the rock using radon.

1 Rock sample 2 Distribution container 3 Circulation path 4 Pump (Mono pump)
5 Valve member 11 Radon amount measuring means 12 Total gap amount deriving means 13 Surface area deriving means 14, 23 Radon flux detecting means 21 Unit sample 22 Airtight container

Claims (6)

Circulate fluid through a rock sample for which the total amount of pores is known,
Measuring the amount of stable radon in the fluid to determine the amount of radon released from the total gap,
Dividing the determined radon amount by the unit radon amount released per unit area of the rock sample to calculate the pore surface area of the rock sample. In the method of measuring the pore surface area inside the rock by radon according to claim 1,
The fluid to be circulated in the rock sample is water. In the method for measuring the pore surface area inside the rock by radon according to claim 1 or 2,
The amount of unit radon released per unit area of the rock sample is
A unit sample that has been cut out from the rock sample and whose surface has been flattened and the total surface area has been grasped is filled with water, and the amount of radon contained in the water filling the unit sample is divided by the total area. A method for measuring pore surface area inside rocks using radon. A distribution container in which a rock sample in which the total amount of pores is grasped is contained in a fluid;
Circulating means for circulating the fluid in the flow container;
Radon amount measuring means for measuring a stable radon amount in the fluid circulated by the circulation means;
A radon flux detecting means for obtaining a unit radon amount which is a radon emission amount per unit area of the rock sample;
A surface area deriving unit for determining a pore surface area of the rock sample by dividing the radon amount measured by the radon amount measuring unit by a unit radon amount determined by the radon flux detecting unit. A device for measuring the surface area of pores inside rocks. In the device for measuring the pore surface area inside the rock by radon according to claim 4,
The said circulation means distribute | circulates water as a fluid. The pore surface area measuring device inside the rock by radon characterized by the above-mentioned. In the gap surface area measuring device inside the rock by radon according to claim 4 or claim 5,
The radon flux detecting means is
An airtight container in which a unit sample cut out from the rock sample and whose surface is flattened and whose total surface area is grasped is filled with water and stored;
Radon flux calculating means for detecting the amount of radon contained in the water extracted from the airtight container and calculating the radon amount per unit area by dividing the detected radon amount by the total surface area of the unit sample; A device for measuring pore surface area inside rocks using radon, characterized by comprising.

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