JPH06331796A - Method, apparatus and tool for cementing miscellaneous solid state radioactive waste - Google Patents

Abstract

PURPOSE:To allow positive cementation by placing miscellaneous solid state radioactive wastes in a metal mesh cage contained in a drum, evacuating the drum, and then injecting mortar, thereby restraining light waste from floating. CONSTITUTION:A metal net cage 2A of such mesh as passing the mortar is provided with stretching parts 3B and set in a drum 1A and miscellaneous solid state radioactive wastes are placed therein. A metal net cover is then placed thereon while a doughnut type temporary cover 4 is placed on the drum 1A which is sealed airtightly for a while. At the same time, a piping block 5 comprising an evacuation pipe 51 and a mortar injection pipe 53 is brought into airtight contact with the central opening of the temporary cover 4. After evacuating the drum 1A, mortar is injected therein and the drum 1A is vibrated to spread the mortar. The mortar is cured while applying the temporary cover 4 which is removed after setting of mortar and the mortar is additionally injected. Upon setting of the additional mortar, the cover is applied and the drum IA is enclosed by wrapping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for solidifying cement, which is a low-level but radioactive radioactive solid waste generated during the construction and operation of a nuclear facility, and an apparatus and solidification treatment therefor. It also relates to the tools used.

[0002]

BACKGROUND OF THE INVENTION So-called radioactive miscellaneous solid waste is a metal,
Since it covers a wide range from fibers to plastic molded products, its shape varies and its density also has a wide range. This waste is stored in a drum and treated by solidification with cement mortar.

However, as described above, since the density of the waste is large and small, some of them sink into the mortar and some of them float.
There is no problem with heavy ones, but the issue is how to suppress the floating of light ones to form a solidified body.

Various methods for solidifying low-level radioactive solid waste have been considered so far. First, a container was proposed in which waste and mortar were mixed to form a solidified product (Shokai Sho 58-162100). For pellet-shaped waste, press it with a lid having a sufficient weight (Japanese Patent Laid-Open No. 61-62899), or put pellets of low specific gravity in the lower part of the container first, and pellets of higher specific gravity. In the upper part (Japanese Patent Laid-Open No. 63-204200), or use a container that is designed to pass through the filler but stop at the filler injection port even if the pellet floats (Japanese Patent Laid-Open No. 4 (1998) -04200).
No. 34398) was proposed.

From the idea of reducing the difference in specific gravity between mortar and waste, use of lightweight aggregate (having a bulk specific gravity of 2 or less) has also been disclosed (Japanese Patent Laid-Open No. 63-167297).
In order to further secure the effect, it has been considered to use artificial ultra-lightweight aggregate selected according to the specific gravity of waste (Japanese Patent Laid-Open No. 3-189600).

[0006] However, the above techniques cannot be universally applied to miscellaneous solid waste mixed with arbitrary shapes and specific gravities. Therefore, regardless of the specific gravity of waste,
In addition, the advent of a cement solidification treatment technology that can be applied to a mixture of solids having different specific gravities has been desired.

[0007]

SUMMARY OF THE INVENTION In response to the above demands, an object of the present invention is to dispose of radioactive solid waste having a wide range of density from metal (specific gravity 3 to 7) to heat insulating material (specific gravity 0.04). An object of the present invention is to provide a treatment method that can be applied to a mixture of substances and can suppress the floating of light solids to surely form a cement-solidified body. It is also within the scope of the present invention to provide an apparatus used to carry out the method and a tool for containing miscellaneous solid waste within a drum.

[0008]

The method of cement solidification of radioactive miscellaneous solid waste according to the present invention comprises the following steps shown in FIG. 1: a) A wire mesh made of mesh sized to pass mortar Arrange in the drum can (1A) what is provided with the overhanging part (2B) on the side surface and the bottom surface of the bottom cylindrical basket (2A) so that the basket keeps a required distance from the inner surface of the drum can (Fig. 1A), b) Storing radioactive miscellaneous solid waste (10) in a basket in a drum can (FIG. 1B) c) Cylindrical spacer (3) for passing mortar on top
B), and put a mesh wire mesh lid (3A) through which the mortar passes over the basket (2A), d) cover the drum can with a donut-shaped temporary lid (4), and use the temporary lid to attach the spacer ( 3B) Hold the upper edge, and remove the temporary lid and drum (1
A) A temporary airtight seal is made between the upper edge and
Vacuum suction pipe (51) and mortar injection pipe (5
The piping block (5) having 3) is brought into air-tight contact with the central opening of the temporary lid, e) The inside of the drum can (1A) is vacuum-sucked, mortar (7A) is injected, and the drum can is vibrated. Spreading the mortar in the can, f) curing by leaving still with the temporary lid (4), and hardening the mortar into a cured product (7B), g) removing the temporary lid (4) and adding After injecting the mortar (8), and h) curing the additional mortar (8), the drum can is covered (1
Do B) and wrap and tighten.

In the above step e), it is preferable to perform a porosity measurement in the drum can by a vapor phase replacement method as described later with reference to FIG. 4 between vacuum suction and mortar injection in the drum can. .

Prior to placement of the basket, the drum can is preferably coated on the bottom and corners of the can by installing a cement block and / or painting mortar, as shown in FIGS. 2A and 2B. The block is prefabricated and placed on the bottom of the drum, as shown in FIG.
And a ring-shaped molded product as shown in 3B.

The apparatus for cement treatment of radioactive waste according to the present invention for carrying out the above-mentioned treatment method comprises the following means shown in FIG. 1: (a) At the time of injecting and hardening mortar into a drum can. A temporary lid (4) for use in a doughnut-shaped cylindrical basket (2A) with a bottom made of wire mesh, which is arranged in a drum can.
The spacer (3
B) A temporary lid that has a thickness capable of pressing the upper edge of the drum can (1A) and can hermetically seal the upper edge of the drum can (1A), (b) The temporary lid (4) is pressed against the upper edge of the spacer, and the temporary lid and the drum can are A means for temporarily airtightly sealing the upper edge, c) a vacuum suction pipe (51) and a valve (52), and a mortar injection pipe (53) and a shutter (54), and the temporary lid ( 4) A pipe block (5) that comes into air-tight contact with the central opening, d) A means for performing vacuum suction through the above-mentioned pipes (51, 53), and a means for performing mortar injection, and (e) A vibration of a drum can during the injection of mortar. Shaking means (6), and (f) means for tightening the lid of the drum can (not shown).

In a preferred embodiment for measuring the porosity inside the drum by the above-mentioned vapor phase substitution method, the apparatus for carrying out the measurement is also a constituent part, which is connected to the piping block.

The cement solidification treatment tool for radioactive miscellaneous solid waste used in the present invention comprises the following parts.

I) On a side surface and a bottom surface of a bottomed cylindrical basket (2A) made of a wire mesh having a size that allows the mortar to pass through, an overhanging portion (2B) is provided so as to keep the basket at a required distance from the inner surface of the drum can. ) A basket provided with), ii) a mesh made of mesh having a size that allows mortar to pass therethrough (3A), and iii) a cylindrical spacer (3B) that is integral with or separate from the lid and allows mortar to pass therethrough.

[0015]

[Operation] A basket made of wire mesh (2
A) and the lid with spacer (3A) are
A mesh that does not pass most of 0) and allows mortar to pass. The size of the mesh is usually 10 to 30 mm
The degree is appropriate. The whole size is a drum (1
Select from the inner surface of A) about 30 mm, and select the overhanging portion (2B) so that the basket is located at the center of the drum can with this distance secured and that the basket can be easily inserted into the drum can. The spacer (3B) attached to the lid has a diameter of 100 mm,
A height of 10 to 50 mm is suitable.

The above mesh allows fine solids close to powder, such as incinerated ash and heat insulating material, to pass therethrough, and falls to the bottom of the drum. Since this may cause corrosion and impair the durability of the solidified body, it is recommended to coat the bottom corner and bottom of the drum can with cement as described above. This cement coating is also useful for avoiding direct impact on the drum can when placing the wire netting basket in the drum can or when throwing miscellaneous solid waste into it.

After accommodating radioactive miscellaneous solid waste, covering the wire mesh with a lid, a temporary lid is placed. Since the water evaporated from the cement mortar condenses and condenses on the inner surface of the temporary lid, it is preferable that the temporary lid be inclined downward toward the center on the back surface so as to drop the generated water drops.

As long as the temporary lid is heavy within a range where there is no problem in operation, an appropriate packing is provided on the peripheral edge where it comes into contact with the upper edge of the drum can, so that the temporary lid is hermetically sealed. A seal can be secured. Depending on the convenience of the operation, the temporary lid may be made lightweight, and a means capable of locking the upper edge of the drum and the peripheral edge of the temporary lid to keep airtightness may be used.

The method for measuring the porosity by the vapor phase substitution method is known, and an apparatus therefor is commercially available (for example, "High-precision automatic volume meter VM-10 manufactured by STEC").
0 ”). The principle will be briefly described. First, as shown in FIG. 4, a wire netting basket (2A) is placed in a drum (1A) having a known volume Vs, and miscellaneous solid waste (1A) is placed therein.
Insert 0) and cover with a temporary lid. The vacuum pump (VP) sucks the air in the drum to reduce the pressure, and the valve (V ₁ ) is closed to measure the pressure (the value is P ₁ ). next,
An inert gas having an initial pressure Pa contained in a tank (T) having a known volume Vex is introduced into the drum by opening the valve (V ₂ ), and the pressure is measured when the pressure equilibrium is reached. the value and P _2). Then, the volume Vx of what was put in the drum (wire mesh basket and solid waste)
Is calculated by the following formula.

Vx = Vs−Vex · (Pa−P ₁ ) / (P ₁ −P ₂ ) Depending on the amount of the content thus obtained, the amount of mortar to be injected can be appropriately determined. it can.

The vibration at the time of injecting the mortar can be carried out according to the method already known in this field, using known equipment.

The curing may be carried out by leaving the temporary cover for an appropriate time, usually for one day.

Light and fine powder in miscellaneous solid waste may be exposed on the surface of the mortar that has been set and hardened by curing. If the lid is left open, the next time the lid is opened and closed. There is a concern that this radioactive material will scatter, so additional mortar should be injected to condition it. Conditioning is also necessary or useful to ensure that the porosity in drums meets the legal regulations for radioactive waste disposal.

The porosity in the drum after the mortar injection and solidification can be determined as follows. That is, if the weight of an empty drum can is Wo (kg) and the weight after containing the wire netting basket and miscellaneous solids is W (kg), the weight of the contents W _G (k
g) = W-Wo, and the ratio W _G / Vx to the porosity Vx calculated as described above is the true density of the contents.

Letting n (cm) be the height of the space left unfilled in the upper part of the drum after the mortar injected first is cured, the volume of the space remaining in the upper part (V upper part) is the inner diameter R (cm) of the drum can. 56.7 cm), V (top) = R ² × 0.785 × n / 10 (cm ³ ), and the amount of mortar for conditioning, that is, additionally injected is V (mortar). ), The void V (void) that remains in the drum after conditioning is
It is expressed by the following formula: V (void) = [Vs−V (upper)] − [Vx + V (mortar)] The porosity of the solidified body is [V (void) + V (upper)] / Vs × 100 (%) It is represented by.

The additional mortar for conditioning is
As it is clear from the fact that it is not necessary to permeate into a miscellaneous solid, it is possible to use one having a low water mixing rate. In order to avoid breathing of water on the surface of the mortar, it is preferable that the water mixing ratio is as low as possible. The drum can into which the additional mortar has been poured is further cured to harden the mortar, and then a steel lid is put on the drum and the mortar is sealed by winding.

[0027]

EFFECTS OF THE INVENTION In the cement solidification treatment of the present invention, even if the shape, size or density of radioactive miscellaneous solid waste varies within a wide range, or if they are a mixture of different ones,
Floating during mortar injection can be prevented and solidification can be reliably performed. If fine, light waste is mixed in and may emerge through the mesh of the wire, it can be trapped by conditioning or additional mortar injection.

In a preferred embodiment in which the bottom corner or bottom of the drum can is coated with cement in advance, incineration ash or the like leaks through the mesh and solidifies while contacting with the drum can, leaving a risk of corrosion. Can also be prevented.

Further, if the preferred embodiment of measuring the porosity after containing the miscellaneous solids is carried out, the amount of mortar to be injected can be appropriately calculated, and at the same time, the appropriate amount of the mortar for conditioning can be known. It is easy to match the porosity of the body with the legal standards.

The device for carrying out the present invention has neither a newly constructed structure nor expensive parts, and is a combination of a device commonly used in this field and a known device used in another field. It can be configured by.

Further, the processing tool of the present invention can be easily manufactured by a metal net woven of stainless steel wire, a perforated plate punched on a steel plate, and the like, and the cost thereof is not expensive.

[Brief description of drawings]

FIG. 1 is a conceptual cross-section of a drum and its contents, showing the steps of the cement solidification treatment method for radioactive miscellaneous solids of the present invention, where A is a wire mesh basket placed in the drum,
B is a case where miscellaneous solid waste is stored in a basket, C is a cover with a spacer attached to the basket, D is a temporary cover and a piping block is in contact with the temporary cover, and E is a drum can. After vacuum suction, mortar is injected and the drum is vibrated, F is standing and cured with the temporary lid, G is the temporary lid removed and additional mortar is injected, and H is The results are shown when the lid is fixed to the drum can by winding and tightly closed.

FIG. 2 is a view showing a step preceding A in FIG. 1 showing a preferred embodiment of the present invention, where A is a cement coating on the corner of the drum can, and B is a cement coating on the bottom surface. Where, respectively.

FIG. 3 is a diagram showing a concrete block used for carrying out the preferred embodiment shown in FIG. 2, in which A is a plan view;
B is a sectional view.

FIG. 4 is an explanatory view showing a principle of measuring a void volume by a vapor phase substitution method, which is carried out in another preferable embodiment of the present invention.

[Explanation of symbols]

 1A Drum can 1B Lid 2A Wire netting basket 2B Overhanging part 3A Wire netting lid 3B Spacer 4 Temporary lid 5 Piping block 51 Vacuum suction piping 52 Vacuum valve 53 Mortar injection piping 54 Shutter 6 Vibrating means 7A Cement mortar 7B Hardened body 8 Addition Mortar 9 Block for coating 10 Radioactive miscellaneous solid waste

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[Procedure amendment]

[Submission date] April 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

The method of cement solidification of radioactive miscellaneous solid waste according to the present invention comprises the following steps shown in FIGS. 1 to 8: a) A wire mesh of a size that allows mortar to pass through. Place the inside of the drum can (1A) on the side surface and bottom surface of the bottomed cylindrical basket (2A) that was manufactured so that the basket was provided with an overhanging portion (2B) so as to keep a required distance from the inner surface of the drum can. (Fig. 1), b) contain radioactive solid waste (10) in a basket in a drum (Fig. 2), and c) a cylindrical spacer (3) through which mortar passes.
B), and put the mesh wire mesh lid (3A) through which the mortar passes over the basket (2A) (Fig. 3), d) cover the drum can with a donut-shaped temporary lid (4), and temporarily Hold the upper edge of the spacer (3B) with the lid, and remove the temporary lid and drum (1
A) A temporary airtight seal is made between the upper edge and
Vacuum suction pipe (51) and mortar injection pipe (5
The piping block (5) having 3) is brought into airtight contact with the central opening of the temporary lid (Fig. 4). E) Vacuum suction is applied to the inside of the drum can (1A), and then mortar (7A) is injected into the drum can. Applying vibration to spread the mortar in the can (Fig. 5), f) curing by leaving still with the temporary lid (4), and hardening the mortar to give a cured product (7B) (Fig. 6), g) removing the temporary lid (4) and injecting additional mortar (8) (FIG. 7), and h) after curing the additional mortar (8), cover the drum (1).
B) and wrap it to seal (Fig. 8).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

In the above step e), it is preferable to perform the porosity measurement in the drum can by the gas phase replacement method as described later with reference to FIG. 11 between the vacuum suction in the drum can and the mortar injection. .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Prior to placement of the basket, the drum can is preferably coated at the bottom and corners of the can with a cement block and / or mortar coating, as shown in FIGS. 9A and 9B. The block is manufactured in advance and placed on the bottom of the drum.
A ring-shaped molded product (9) as shown in A and B of FIG.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The apparatus for cementing radioactive waste according to the present invention for carrying out the above treatment method comprises the following means shown with reference to FIGS. 1 to 8: a) Mortar in a drum can (4) A temporary lid (4) used for injecting and curing the dough, which has a donut shape and is a bottomed cylindrical basket (2A) made of wire mesh and arranged in a drum can.
The spacer (3
B) A temporary lid that has a thickness capable of pressing the upper edge of the drum can (1A) and can hermetically seal the upper edge of the drum can (1A), (b) The temporary lid (4) is pressed against the upper edge of the spacer, and the temporary lid and the drum can are A means for temporarily airtightly sealing the upper edge, c) a vacuum suction pipe (51) and a valve (52), and a mortar injection pipe (53) and a shutter (54), and the temporary lid ( 4) A pipe block (5) that comes into air-tight contact with the central opening, d) A means for performing vacuum suction through the above-mentioned pipes (51, 53), and a means for performing mortar injection, and (e) A vibration of a drum can during the injection of mortar. Shaking means (6), and (f) means for tightening the lid of the drum can (not shown).

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The method for measuring the porosity by the vapor phase substitution method is known, and an apparatus therefor is commercially available (for example, "High-precision automatic volume meter VM-10 manufactured by STEC").
0 ”). The principle will be briefly described. First, as shown in FIG. 11, a wire netting basket (2A) is placed in a drum (1A) having a known volume Vs, and miscellaneous solid waste (1A) is placed therein.
Insert 0) and cover with a temporary lid. The vacuum pump (VP) sucks the air in the drum to reduce the pressure, and the valve (V ₁ ) is closed to measure the pressure (the value is P ₁ ). Next, the inert gas having the initial pressure Pa, which had been put in the tank (T) having a known volume Vex, was introduced into the drum by opening the valve (V ₂ ), and the pressure was measured when the pressure equilibrium was reached. (That value is P ₂ ). Then, the volume Vx of what is put in the drum (the wire netting basket and the solid waste) is calculated by the following formula.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1 to 8 are conceptual cross-sectional views of a drum and its contents, showing the steps of the method for cementing radioactive radioactive solids according to the present invention. FIG. 1 shows a wire mesh basket arranged in the drum. Indicates the stage at which

FIG. 2 shows a stage of storing miscellaneous solid waste in a basket.

FIG. 3 shows a stage in which a lid with a spacer is placed on the basket.

FIG. 4 shows a stage where a temporary lid is put on and a piping block is brought into contact with the temporary lid.

FIG. 5 shows a stage in which mortar is injected and vibration is applied to the drum after vacuum suction inside the drum.

FIG. 6 shows a stage of stationary curing with a temporary lid.

FIG. 7 shows the stage where the temporary lid is removed and additional mortar is injected.

FIG. 8 shows a stage in which a lid is fixed to a drum can by winding it, and the drum can is closed.

FIG. 9 is a view showing a step preceding FIG. 1, showing a preferred embodiment of the present invention, where A is a cement coating on the corner of the drum can, B is a cement coating on the bottom surface, and FIG. Are shown respectively.

FIG. 10 is a diagram showing a concrete block used for carrying out the preferred embodiment shown in FIG. 9, in which A is a plan view and B is a sectional view.

FIG. 11 is an explanatory view showing the principle of measurement of void volume by the vapor phase substitution method, which is carried out in another preferred embodiment of the present invention.

[Explanation of Codes] 1A Drum can 1B Lid 2A Wire netting basket 2B Overhanging portion 3A Wire netting lid 3B Spacer 4 Temporary lid 5 Piping block 51 Vacuum suction piping 52 Vacuum valve 53 Mortar injection piping 54 Shutter 6 Shaking means 7A Cement mortar 7B Hardened body 8 Additional mortar 9 Block for coating 10 Radioactive miscellaneous solid waste

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

[Figure 9]

[Figure 10]

FIG. 11

Claims (6)

[Claims] 1. A method for solidifying cement of radioactive miscellaneous solid waste, which comprises the following steps: a) On a side surface and a bottom surface of a bottomed cylindrical basket made of a wire mesh of a size that allows mortar to pass through, Is provided with an overhanging portion so as to keep a required distance from the inner surface of the drum can, and is placed in the drum can. B) The radioactive solid waste is stored in the basket in the drum can. C) Mortar is placed on the upper part. Place a lid made of mesh wire mesh with a cylindrical spacer that allows passage of mortar on the basket, d) cover the drum can with a donut-shaped temporary lid, and use the temporary lid to cover the spacer upper edge. And temporarily seal the space between the temporary lid and the upper edge of the drum can, and airtightly connect the piping block with the vacuum suction piping and the mortar injection piping to the central opening of the temporary lid. Thereby, e) within the drum by injecting mortar After vacuum suction,
Applying vibration to the drum to spread the mortar into the can; f) curing the mortar with the temporary lid still standing, and g) removing the temporary lid and injecting additional mortar, and h) After hardening the additional mortar, cover the drum with a lid and wrap it tightly. 2. The step e) further includes a step of measuring a porosity in the drum can by a gas phase replacement method between vacuum suction and mortar injection in the drum can.
Processing method. 3. The step a) above, further comprising the step of placing a cement block and / or coating mortar on the bottom and corners of the can prior to placing the basket in the drum. The processing method of 1. 4. An apparatus for solidifying cement for radioactive miscellaneous solid waste, which comprises the following means: (a) A temporary lid used when pouring and hardening mortar into a drum can, and having a donut shape, With a thickness to press the upper edge of the spacer provided on the top of the wire mesh lid that covers the bottomed cylindrical basket made of wire mesh placed in the drum can,
Temporary lid that can seal airtightly with the upper edge of the drum, b) A means for pressing the temporary lid against the upper edge of the spacer and temporarily sealing the space between the temporary lid and the upper edge of the drum, c) Vacuum A pipe block having a suction pipe and a valve, and a mortar injection pipe and a valve, which come into air-tight contact with the central opening of the temporary lid, d) means for performing vacuum suction through the pipe, and means for performing a mortar injection, ) Vibrating means for vibrating the drum during mortar injection,
And f) A means for tightening the lid of the drum. 5. The device according to claim 4, wherein a device for measuring the porosity inside the drum by the vapor phase replacement method is connected to the piping block. 6. A tool for solidifying cement for radioactive miscellaneous solid waste, which comprises the following parts: i) On a side surface and a bottom surface of a bottomed cylindrical basket made of a wire mesh having a size that allows mortar to pass through, Is a basket provided with an overhanging portion so as to keep a required distance from the inner surface of the drum, ii) a lid made of a mesh wire mesh of a size that allows the mortar to pass through, and iii) a mortar that is integral with or separate from the above lid. Cylindrical spacer to pass through.