JP3054728B2 - Waste treatment facility - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a facility for treating waste such as radioactive waste and general waste.

[0002]

2. Description of the Related Art Radioactive wastes are classified into high-level radioactive wastes and medium-low-level radioactive wastes. Among them, high-level radioactive wastes 6 are vitrified as shown in FIGS. Into a steel container 5 and cast it into a rock layer 10 several hundred meters underground.
A horizontal shaft 12 is provided on the lower side of 11, holes 13 are formed in the horizontal shaft 12 at appropriate intervals, and properties such as low water permeability and high ion exchange capacity around the vessel 5 are formed in the holes 13. It is being considered to contain high levels of radioactive waste 6 in a form wrapped in clay 15 having it.

[0003] Further, in order to ensure isolation, it has been considered that the shaft 11 and the horizontal shaft 12 are backfilled with clay-like material. Since the clay-based material is required to have high erosion resistance and low water permeability as a highly stable substance, it is necessary to use bentonite and a bentonite-mixed soil containing sand and the like in this bentonite. Is common.

[0004]

However, the vertical shaft 11 and the horizontal shaft
The backfilling of 12 has no construction experience, and the use of bentonite or bentonite-mixed soil as its material has not been sufficiently studied, and there is a problem in particular in terms of density. Further, if a large amount of expensive bentonite is used as it is, the construction cost will increase accordingly.

On the other hand, as shown in FIG. 15, medium- and low-level radioactive wastes 8 are put in a container 7 such as a drum and the like, and the depth reaching the upper part of the bedrock 10 is cut and cut.
A closed chamber 14 made of reinforced concrete is provided at the top of the container, and the container 7 is accommodated in the closed chamber 14, and the surroundings of the closed chamber are covered with bentonite mixed soil to cover the soil. And the construction of this bentonite mixed soil is carried out by rolling with a vibrating roller, but the vibrating roller is suitable for a wide and flat part, but it rolls well when there is a slope or narrow part I couldn't do that.

[0006] In general waste treatment facilities, underground 8
The ground is cut to a depth of about 15m and a vinyl sheet is laid on the bottom surface to prevent water leakage. Instead of this vinyl sheet, bentonite mixed soil may be used. However, the treatment facility for general waste using the bentonite mixed soil has a poor track record of construction, and has the same problems of density and construction cost as the treatment facility for the radioactive waste 8 at the medium and low levels.

An object of the present invention is to eliminate the disadvantages of the prior art, to obtain sufficient shielding properties, to keep the amount of expensive bentonite small, to reduce the cost of construction, and to make the construction quick and easy. And to provide a waste treatment facility that can be completed.

[0008]

In order to achieve the above object, the present invention firstly provides gravel (G _max = 5 to 20 mm): sand: bentonite = 50: 20 to 40:30 to 10 (dry weight ratio) %) And sealed with a gravel-mixed bentonite mixed soil consisting of

Second, the sealing is performed in a horizontal shaft formed in the bedrock layer. Third, the sealing is formed by compaction of the gravel-mixed bentonite mixed soil, or the gravel-mixed bentonite mixed soil. Compressed to a water content of 7-20%, compressive stress 25-50kg / cm
² to form a block having a dry density ρd = 1.76 to 2.0 t / m ^3, and perform this by stacking the blocks, or by spraying bentonite-mixed bentonite mixed soil. The gist of the invention is to perform the combination of pressure, stacking of blocks, and spraying.

Thirdly, on the bottom, gravel (G _max = 5~20m
m): Sand: bentonite = 50:20 to 40: 30 to 10 (dry weight ratio%), compacted bentonite-mixed bentonite mixed soil, repeated as appropriate, laminated, and mixed gravel-mixed bentonite on the slope The soil is compressed to dry density ρd = 1.76-2.0 at a water content of 7-20% and a compressive stress of 25-50 kg / cm ² .
The gist of the present invention is that blocks having t / m ³ are stacked, and voids such as the slopes and the spaces between the blocks are sprayed with the bentonite-mixed soil mixed with gravel.

According to the first aspect of the present invention, the gravel-mixed soil used for sealing as an industrial waste treatment facility is a gravel (G).
_max = 5 to 20 mm): Sand: bentonite = 50:20 to 40:30
-10 (dry weight ratio%), the water permeability k = 1
^{X10 -8 to} 5x10 ^-9 cm / sec, and a layer excellent in radioactivity and shielding property that is difficult to pass water can be obtained. Further, even if the amount of bentonite is smaller than that of the conventional bentonite-mixed soil, the same shielding properties can be obtained, and the cost can be reduced.

According to the second aspect of the present invention, in addition to the above-mentioned operation, since the sealing is performed in the horizontal shaft formed in the bedrock layer, the entire horizontal shaft becomes the shielding layer, and the shielding effect can be improved accordingly.

[0013] Claims 3 to 6 relate to a sealing method, and the compaction according to claim 3 is the simplest method for obtaining the density, but according to the present invention described in claim 4, Because of the block, it is easy to make the density uniform. Moreover, the blocks can be piled up in a brick manner even in a non-planar place where rolling cannot be performed, and the construction can be completed easily and quickly. In addition, each block compresses the bentonite mixed soil mixed with gravel to have a water content of 7 to 20% and a dry density ρd of 1.76 to 2.0 t / m ³ at a compressive stress of 25 to 50 kg / cm ^2, so that the hydraulic conductivity k = 5 × 10 ^-9 to 1 × 10 ^-9 cm / sec, and the shielding effect is superior to that of the case where rolling is performed by a vibrating roller. According to the fifth aspect of the present invention, sealing can be achieved even in a very narrow gap.

According to the present invention, even when the horizontal shaft is an arch-shaped tunnel, it is possible to fill the bentonite-mixed soil with gravel into every corner up to the arch portion above the tunnel. , The whole having a permeability coefficient k = 1 × 10
An excellent shielding effect of ^{-8 to} 5 × 10 ^-9 cm / sec can be maintained. In addition, efficient construction can be performed in a short time.

According to the seventh aspect of the present invention, as a non-planar place where compaction cannot be performed, a medium-low level radioactive waste or general waste disposal facility is cut and ground with a slope on the ground. Can also be applied, and the permeability k =
An excellent shielding effect of 1 × 10 ^{−8 to} 5 × 10 ⁻⁹ cm / sec can be secured.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal sectional side view of a main part showing a first embodiment of a waste treatment facility of the present invention, and FIG. 2 is a front view of the main part. The same components as those in the conventional example are denoted by the same reference numerals.

This embodiment is a method of constructing a treatment facility for high-level radioactive waste 6, and, like the above-mentioned conventional example, a horizontal shaft is provided on the lower side of a shaft 11 reaching a bedrock layer several hundred meters underground.
12, holes 13 are formed in the horizontal shaft 12 at appropriate intervals, and a container 5 containing high-level radioactive waste 6 in the hole 13.
Is placed around clay 15 around it. The horizontal shaft 12 is a tunnel whose upper part is the arch 4.

The gravel-mixed bentonite mixed soil used for sealing in the present invention has a composition ratio of gravel (G _max = 5 to 20 mm): sand: bentonite = 50: 20 to 40:30 to 10 (dry weight ratio%). You do it. Comprehensively determine the water blocking effect expected in this range and the availability and cost of materials at the site. It is well known that increasing the blending ratio of bentonite improves the water blocking effect but increases the cost.

[0019] The gravel-mixed bentonite mixed soil used for sealing in the present invention has a blending ratio of gravel (G _max = 5 to 20 mm): sand:
Bentonite = 50: 20-40: 30-10 (dry weight ratio%)
That is. Comprehensively determine the water blocking effect expected in this range and the availability and cost of materials at the site. It is well known that increasing the blending ratio of bentonite improves the water blocking effect but increases the cost. It should be noted, gravel _(G max = _5~20mm) is
Indicates the range of particle size of gravel material.

Next, a bentonite-mixed soil mixed with gravel is compressed into the part of the arch 4 so as to have a water content of 7 to 20% and a compressive stress of 25%.
Dry density ρd at 5050 kg / cm ² = 1.76-2.0 t / m
^The blocks 2 formed to be ³ are combined and laminated. At this time, bentonite is laid in the gap between the compression blocks, and the compression blocks are combined in such a manner that a gap is not formed between the blocks 2 and 2 as much as possible.

As shown in FIG. 3, the block 2 has a stepped notch 2a on one side and a notch 2b corresponding to the notch 2a on the other side, or FIG. As shown in FIG.
c and the recess 2d are formed, and as shown in FIG. 5, the protrusion 2c is shorter than the protrusion 2c or the recess 2d.
Various shapes such as a tenon-shaped tenon with an e and a concave portion 2f, or an arc-shaped with the arch 4 as shown in FIG.

As shown in FIGS. 7 and 8, a method of forming the block 2 is to mix a bentonide mixed soil with a predetermined water content into a compression chamber 17 of a rotating body 18 and to adjust the rotation. The bent-nite mixed soil is forcibly dropped into the compression chamber 17 by being pressed by the pushing device 16 which moves up and down, or by blowing air by an air injection device 19 shown in FIG. 9 (wet method). Alternatively, either of the methods of producing bentonite mixed soil at a natural water content and injecting water with a water injection device so as to have a predetermined water content (dry method) may be used.

Further, in a portion where the blocks 2 are difficult to be piled up, that is, in a very narrow spraying portion 3 such as between the inner surface of the horizontal shaft 12 and the block 2, a bentonite mixed soil mixed with gravel is sprayed using a spraying machine such as a need gun. Spraying completes the sealing. The gravel-mixed bentonite mixed soil for this spraying is
As in the case of compaction, the compounding ratio is gravels (G _max = 5 to 20 m).
m): Sand: bentonite = 50:20 to 40:30 to 10 (dry weight ratio%). Therefore, after drying, the dry density ρd =
The 1.76~2.0 t / m ^3. Hereinafter, the stacking of the blocks 2 and the spraying to the spraying part 3 are repeated to fill the inside of the horizontal shaft 12 with the gravel-mixed bentonite mixed soil, and the entire horizontal shaft 12 is sealed as a shielding layer.

FIG. 10 shows a second embodiment of the present invention, which is a method for constructing a treatment facility for a medium- to low-level radioactive waste 8, which is a lower part of a shaft 11 reaching a bedrock layer 10. A horizontal shaft 12 is provided at a lower portion of the horizontal shaft 12, and a closed chamber 14 surrounded by a clay 15 is provided below the horizontal shaft 12. In this closed chamber 14, a large number of containers 7 such as drums in which radioactive waste 6 of a medium to low level is enclosed are stored. The filling of the inside of the horizontal shaft 12 with the gravel-mixed bentonite mixed soil is the same as in the first embodiment.
Note that the clay 15 may be the bentonite-mixed soil mixed with gravel.

FIG. 11 shows a third embodiment of the present invention, which is a modified example of the second embodiment. The ground is cut off until it reaches a bedrock layer 10 so as to have a slope 9. On the bottom surface, a compacted bentonite-mixed soil composed of gravel (G _max = 5 to 20 mm): sand: bentonite = 50: 20 to 40: 30 to 10 (dry weight ratio%) 1
Was formed.

Further, where the slope 9 is located, the bentonite-mixed soil mixed with gravel is compressed to dryness ρd = 1.76-2.0 at a water content of 7-20% and a compressive stress of 25-50 kg / cm ² .
The block 2 formed so as to have a thickness of t / m ³ is placed, and the gap between the slope portion 9 and the block 2 and the gap between the blocks 2 and 2 are sprayed with a gravel-mixed bentonite mixed soil by a spraying machine. .

When the compaction unit 1 is stacked to a predetermined height, a plurality of sealed chambers 14 are constructed in parallel, and a drum having a low-level radioactive waste 6 sealed inside the sealed chamber 14 is constructed. Many containers 7 are stored.

Blocks 2 are continuously stacked on the front, rear, left and right sides of the closed chamber 14, and the gap between the slope 9 and the blocks 2 and the gap between the blocks 2 and 2 are sprayed with bentonite-mixed soil mixed with gravel using a spraying machine. Spray. On the top surface of the closed chamber 14, a compaction part 1 of bentonite mixed soil mixed with gravel is
Stack up to the position matching the top of 10. Finally, soil covering 22 is applied with normal earth and sand to complete the process.

FIG. 12 shows a fourth embodiment of the present invention, which is a method of constructing a treatment facility for general waste 21 and having a slope of about 8 to 15 m underground. Cut and lay a bentonite mixed soil instead of a vinyl sheet.

[0030] First, gravel in digging the bottom (G _max = 5~20m
m): Sand: bentonite = 50:20 to 40:30 to 10 (dry weight ratio%), the compacted bentonite mixed soil composed of gravel is rolled to form this compacted part 1, and the end of the compacted part 1 Then, a pebble-mixed bentonite mixed soil having the same composition as above is sprayed into the gap 3 between the slope 9.

When the compacted portion 1 is appropriately laminated, the gravel-mixed bentonite mixed soil is compressed along the slope portion 9 and dried at a water content of 7 to 20% and a compressive stress of 25 to 50 kg / cm ² . The blocks 2 formed so as to have a density ρd = 1.76 to 2.0 t / m ³ are placed in combination. And, the gap 3 between the block 2 and the slope portion 9 is sprayed with the gravel-mixed bentonite mixed soil having the same composition as described above. The blocks 2 are stacked until they are at the same height as the ground. Finally, the same gravel-mixed bentonite-mixed soil is sprayed on the inside of the stacking surface of the block 2 to finish the surface, thereby completing the construction.

[0032]

【Example】

<Embodiment 1> An embodiment of the compression force of the block 2 used in the present invention will be described. 1. Purpose To understand the compression force of the compression block of bentonite mixed soil mixed with gravel. 2. Test Description (1) Materials used gravel ...... G _max = 20 mm of the concrete for the coarse aggregate sand ...... concrete fine aggregate bentonite · · · Na type bentonite (Kunigel V1) water (2 ) Formulation Gravel: sand: bentonite = 50: 37.5: 12.5 (dry weight ratio%) Water content: W = 7, 10, 15, 20% (3) Compressor 5t uniaxial compression tester (4) Specimen φ10cm × h13cm (Compressed with a φ10cm × h20cm mold) (5) Compression test result W = 7 ~ 15% ・ ・ When compressive stress 25kgt / cm ² ρd = 95% × ρd _max W = 20% ・ ・··· ρd = 90% × ρd _max at a compressive stress of 25 kgt / cm ² With such a dry density (ρd), the permeability coefficient of the compressed block is k = 5 × 10 ⁻⁹ to 1 × 10 ⁻⁹ cm / sec. As a result, an excellent water shielding effect can be obtained.

<Example 2> An example of a sprayed portion of the bentonite mixed soil mixed with gravel according to the present invention will be described. 1. Objective To understand the workability and construction quality of the gravel-mixed bentonite mixed soil by the spraying method. 2. Test Description (1) Materials used gravel ...... No. 6 crushed stone (G _max = 20 mm) sand ...... concrete fine aggregate bentonite · · · Na type bentonite (Kunigel V1) Water (2) Mixing (one example of experimental mixing) Gravel: sand: bentonite = 50:35:15 (dry weight ratio%) Water content ... (a) W = 9% (optimum water content W _DPt ) (b) W = 11 use percent (optimally water content ratio _{W DP + 2%) (c} ) W = 13% ( optimum water content ratio _{W DP + 4%) (3} ) use mechanical Nidogan (pneumatic 5kgf / cm ^2). (4) Specimen Spray into a mold 80 cm long x 80 cm wide x 30 cm deep. (5) Construction status Although the rebound was 30-40%, the formwork (80cm × 80cm ×
Spraying to a depth of 30cm) was done without any problems. (6) Result of construction quality (a) Dry density (ρd) ρd = (90-95%) × ρd _max . ρ
d _max is ρd _max = 1.95 t / m ³ in the formulation of this with the maximum dry density obtained by the compaction test chamber. (b) Permeability coefficient (k) k = 1 × 10 ⁻⁸ to 1 × 10 ⁻⁹ cm / sec. This value is the water permeability when the bentonite content is 15%, and the bentonite content may be increased or decreased according to the target water permeability.

[0034]

As described above, the waste disposal facility of the present invention can obtain sufficient shielding properties, and can reduce the cost of bentonite by keeping the amount of expensive bentonite to a small amount. And can be easily completed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a main part showing a first embodiment of a waste treatment facility of the present invention.

FIG. 2 is a front view of a main part showing a first embodiment of the waste treatment facility of the present invention.

FIG. 3 is a perspective view showing an example of a combination of blocks.

FIG. 4 is a perspective view showing another example of a block.

FIG. 5 is a perspective view showing another example of another block.

FIG. 6 is a perspective view showing still another example of the block.

FIG. 7 is a plan view showing a block manufacturing apparatus.

FIG. 8 is a partially cutaway side view showing the block manufacturing apparatus.

FIG. 9 is a partially cutaway side view showing another manufacturing apparatus of the block.

FIG. 10 is a vertical sectional side view of a main part showing a second embodiment of the waste treatment facility of the present invention.

FIG. 11 is a vertical sectional side view of a main part showing a third embodiment of the waste treatment facility of the present invention.

FIG. 12 is a vertical sectional side view of a main part showing a fourth embodiment of the waste treatment facility of the present invention.

FIG. 13 is a vertical side view showing a conventional high-level radioactive waste treatment facility.

FIG. 14 is a vertical sectional side view of a main part showing a conventional high-level radioactive waste treatment facility.

FIG. 15 is a perspective view showing a conventional medium and low level radioactive waste treatment facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Compression part 2 ... Block 2a, 2b ... Notch 2c, 2e ... Convex part 2d, 2f ... Concave part 3 ... Spray part 4 ... Arch 5 ... Container 6 ... Radioactive waste 7 ... Container 8 ... Radioactive waste 9 … Slope section 10… Boulder bed 11… Stand shaft 12… Side shaft 13… Hole 14… Closed room 15… Clay 16… Pushing device 17… Compression room 18… Rotating body 19… Air injection device 21… General waste 22… Soil

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhiro Suyama 2-9-1, Tobita-Ki, Chofu-shi, Tokyo Kashima Construction Co., Ltd. Technical Research Institute (72) Inventor Yoshihiro Kondo 2--19, Tobita-Kiyita, Chofu-shi, Tokyo No. 1 Kashima Construction Co., Ltd. Technical Research Institute (56) References JP-A-58-131600 (JP, A) JP-A-61-97599 (JP, A) JP-A-61-230098 (JP, A) JP JP-A-64-28600 (JP, A) JP-A-9-33698 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21F 9/36 G21F 9/34

Claims (7)

(57) [Claims] (1) Gravel (G _max = 5 to 20 mm): sand: bentonite = 50: 20 to 40: 30 to 10 (dry weight ratio%) sealed with gravel mixed bentonite mixed soil Waste treatment facility. 2. The waste treatment facility according to claim 1, wherein the sealing is performed in a horizontal shaft formed in a bedrock layer. 3. The waste disposal facility according to claim 1, wherein the sealing is formed by compaction of the gravel-mixed bentonite mixed soil. 4. Sealing is performed by compressing the gravel-mixed bentonite mixed soil to form a block having a water content of 7 to 20% and a dry density ρd of 1.76 to 2.0 t / m ^{3 at} a compressive stress of 25 to 50 kg / cm ² . The waste disposal facility according to claim 1, wherein the blocks are stacked. 5. The waste treatment facility according to claim 1, wherein the sealing is performed by spraying a bentonite-mixed soil mixed with gravel. 6. The waste treatment facility according to claim 1, wherein the sealing is performed by a combination of compaction of the gravel-mixed bentonite mixed soil, stacking of the blocks, and spraying. The method according to claim 7 bottom, gravel (G _max = 5~20mm):
Sand: bentonite = 50:20 to 40: 30 to 10 (dry weight ratio%), rolled the gravel-mixed bentonite-mixed soil consisting of 50 to 20 to 40: 30 to 10 (dry weight ratio%), repeated this as appropriate, and laminated the gravel-mixed bentonite-mixed soil on the slope. Water content 7 ~ 20%, compressive stress 25 ~
Dry density ρd at 50 kg / cm ² = 1.76 to 2.0 t / m ³
A waste disposal facility characterized by stacking blocks, and spraying bentonite-mixed soil with gravel into gaps such as the slopes and the blocks.