JP5345741B1 - Pretreatment method of incineration ash - Google Patents

Abstract

A radioactive substance contained in incineration ash is efficiently eluted to reduce the volume of incineration ash containing the radioactive substance.
A method of pretreatment of incineration ash that is performed on the incineration ash before final disposal of the incineration ash containing radioactive substances, and incineration is performed by sprinkling water while aeration is performed on the incineration ash. Promotes elution of radioactive substances contained in ash.
[Selection] Figure 1

Description

  The present invention relates to a pretreatment performed prior to final disposal of incinerated ash, and more particularly to a pretreatment method for incinerated ash containing a radioactive substance.

  In general, final disposal sites for waste containing incinerated ash are roughly classified into stable disposal sites, managed disposal sites, and intercepted disposal sites. Waste is finally disposed (generally landfilled) at any of the above-mentioned disposal sites according to a predetermined category, but is pre-treated for the purpose of stabilizing the waste before final disposal. Specifically, organic substances, salts, heavy metals, etc. contained in the waste are washed out and insolubilized (see Patent Documents 1 to 3).

General waste is finally disposed of as described above, but waste containing radioactive materials (mainly cesium (Cs)) is currently disposed of according to the following policy.
(1) Dispose of waste with a radioactive material content of 8,000 Bq / Kg or less in the same way as general waste.
(2) Dispose of radioactive materials with a content of more than 8,000 Bq / Kg to 100,000 Bq / Kg after taking measures to prevent elution of radioactive materials.
(3) Wastes containing more than 100,000 Bq / Kg of radioactive materials shall be stored and managed in an intermediate storage facility or a block-type disposal site.

JP 2002-59106 A JP 2006-281006 A JP 2009-241053 A

  As described above, it is necessary to take some measures to prevent elution of radioactive materials for wastes containing radioactive materials exceeding 8,000 Bq / Kg, which requires time and effort for final disposal. In addition, waste that contains more than 100,000 Bq / Kg of radioactive material must be stored and managed in intermediate storage facilities and isolated disposal sites. The amount of waste that can be processed at such facilities and disposal sites There is a limit.

  Here, incineration ash (main ash and fly ash) discharged from an incineration facility is one of the wastes containing radioactive substances. So far, there are few cases where the amount of radioactive material contained in the main ash, which is the main incinerator ash, exceeds 8,000 Bq / Kg, but depending on the regional characteristics and the properties of the incinerated materials, the radioactive material contained in the main ash There is also a possibility that the amount of slag exceeds 8,000 Bq / Kg.

  According to reports from the National Institute for Environmental Studies, the elution rate of radioactive material (cesium (Cs)) contained in the main ash when solid stirring is performed for 6 hours with a liquid-solid ratio of 10: 1 The (main ash elution rate) is 0 to 2.2%, and the elution rate (fly ash elution rate) of the radioactive substance (cesium (Cs)) contained in the fly ash is 49.0 to 92.9%. That is, it is known that cesium contained in main ash is less likely to elute than cesium contained in fly ash. Such a difference is attributed to the proportion of the easily soluble (water-soluble) water-soluble fraction and the ion exchange state.

  Under the circumstances described above, it is urgent to reduce the volume of incinerated ash containing radioactive materials. In particular, it is urgent to reduce the volume of incinerated ash that contains more than 8,000 Bq / Kg of radioactive materials. .

  An object of the present invention is to efficiently elute radioactive substances contained in incineration ash.

  The pretreatment method of the present invention is a pretreatment method performed on the incinerated ash before final disposal of the incinerated ash containing radioactive substances, and performing both watering and aeration on the incinerated ash. Features.

  In one aspect of the pretreatment method of the present invention, water is intermittently sprinkled while continuously ventilating the incinerated ash.

  In another aspect of the pretreatment method of the present invention, water is sprayed on the incinerated ash from above the incinerated ash, air is supplied to the incinerated ash from the lower end in the bulky direction of the incinerated ash, and the incinerated ash The water that has passed through is recovered.

  In another aspect of the pretreatment method of the present invention, water is sprayed on the incinerated ash from above the incinerated ash, air is supplied to the incinerated ash from the middle of the bulky direction of the incinerated ash, Water that has passed through the incineration ash that is higher than the supply position is absorbed by the incineration ash that is lower than the supply position of the air.

  In another aspect of the pretreatment method of the present invention, the incinerated ash is sprinkled and ventilated while the incinerated ash is contained in a portable container.

  In another aspect of the pretreatment method of the present invention, water and aeration are performed on the incinerated ash while the incinerated ash is contained in a bag-like container having water permeability and air permeability.

  In another aspect of the pretreatment method of the present invention, the gas-liquid ratio, which is the ratio of the aeration amount to the incinerated ash and the water spray amount, is 1000 or more.

  In another aspect of the pretreatment method of the present invention, the gas-liquid ratio is based on elution characteristics of radioactive substances obtained by changing a plurality of aeration amounts and sprinkling amounts in a preliminary test performed by collecting a part of the incinerated ash. To decide.

  ADVANTAGE OF THE INVENTION According to this invention, the radioactive substance contained in incineration ash is wash | cleaned efficiently, and the volume reduction of the incineration ash containing a radioactive substance is attained.

It is a schematic diagram which shows the structure of the test apparatus used for the bench scale test. It is explanatory drawing which shows the result of a 1st bench scale test. It is another explanatory view showing the result of the 1st bench scale test. It is explanatory drawing which shows the result of a 2nd bench scale test. It is a flowchart which shows the process of pre-processing. (A)-(c) is a schematic diagram which shows the container which comprises the stabilization area where pre-processing is performed. It is an expansion schematic diagram of a water seal and water sampling. It is explanatory drawing which shows one of the structural examples of the stabilization area where pre-processing is performed. It is a schematic diagram which shows the other container which comprises the stabilization area where pre-processing is performed. It is explanatory drawing which shows another one of the structural examples of the stabilization area where pre-processing is performed. It is explanatory drawing which shows the implementation state of the pre-process in the stabilization area shown by FIG. It is explanatory drawing which shows another one of the structural examples of the stabilization area where pre-processing is performed. It is explanatory drawing which shows the implementation state of the pre-process in the stabilization area shown by FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that, in all the drawings referred to in the following description, the same members and elements are denoted by the same reference numerals in principle, and repeated description is omitted.

  The present invention relates to a pretreatment performed on incineration ash before final disposal of incineration ash (main ash and fly ash) containing radioactive substances (mainly cesium (Cs) 134, 137). The essence of the present invention is to promote elution of the radioactive substance contained in the incinerated ash by spraying water and ventilating the incinerated ash containing the radioactive substance.

  In order to facilitate understanding of the present invention, two bench scale tests conducted to confirm the effectiveness of the present invention will be described in advance.

(First bench scale test)
A test apparatus 10 having the configuration shown in FIG. 1 was used for the first bench scale test. A test apparatus 10 shown in FIG. 1 includes a column 11, a sprinkler 12, a leachate receiver 13, and a vent 14.

The column 11 has a cross-sectional area of 78.5 cm ² (φ10 cm) and a height of 40 cm. In this test, the incinerated main ash 20 containing stable cesium was packed into the column 11 at a density and height that would not impede water flow and ventilation. Specifically, the incinerated main ash 20 was packed in the column 11 at a density of 1.3 g / cm ³ and a height of 30 cm. However, such density and height are merely examples, and the filling density and height of the incinerated main ash 20 can be arbitrarily set on condition that water passage and ventilation are not hindered.

  The watering device 12 includes a tank 12a, a water supply pipe 12b, a pump 12c, and a timer 12d. The tank 12a is a container for storing water sprayed to the incinerated main ash 20. A pump 12c is provided in the middle of the water supply pipe 12b, and the operation of the pump 12c is controlled by a timer 12d. With the watering device 12, a predetermined amount of water is sprinkled from above the incinerated main ash 20 in the column 11 at a predetermined timing.

  The leachate receiver 13 is disposed directly under the column 11 and is connected to the bottom surface of the column 11. The water sprayed on the incineration main ash 20 by the water sprinkler 12 is drained from the column 11 after permeating the incineration main ash 20 and stored in the leachate receiver 13 as leachate.

  The ventilation device 14 includes a compressor 14a, an air supply pipe 14b, and a mass flow controller 14c. With this aeration device 14, a predetermined amount of air is sent into the column 11 at a predetermined timing. Here, the pipe end of the supply pipe 14b is connected to the lower part of the side surface of the column 11, and the air fed into the column 11 through the supply pipe 14b enters the incineration main ash 20 from the middle of the bulk of the incineration main ash 20 in the bulk direction. Supplied. In the following description, the incinerated main ash 20 filled in the column 11 is divided into upper and lower portions with the air supply position as a boundary, the upper side above the air supply position being “upper layer 20a” and the lower side being “lower layer 20b”. May be distinguished. That is, the air is supplied to the boundary between the upper layer 20a and the lower layer 20b of the incineration main ash 20, and the supplied air moves in the upper layer 20a of the incineration main ash 20 from below to above.

In the first bench scale test, three test apparatuses 10 shown in FIG. 1 were prepared, and the amount of air supplied to each column 11 (aeration amount to the incinerated main ash) was varied. Specifically, air was supplied to the column 11 (first treatment section) of the first test apparatus 10 at a rate of 1 L / min. Similarly, air is supplied to the column 11 (second treatment section) of the second test apparatus 10 at a rate of 2 L / min, and 4 L is supplied to the column 11 (third treatment section) of the third test apparatus 10. Air was supplied at a rate of / min. In other words, the daily ventilation rate for the incinerated main ash in the first treatment zone is 1.4 m ³ , the daily ventilation rate for the incineration main ash in the second treatment zone is 2.8 m ³ , and the incineration in the third treatment zone The daily ventilation rate for the main ash is 5.6 m ³ .

On the other hand, the amount of water supplied to each treatment area (the amount of water sprayed to the incinerated main ash of each treatment area) was the same. Specifically, the amount of water sprayed per incineration main ash in each treatment area was 1.5 mm, and the amount of water sprayed per day was 36 mm. Here, when water is sprayed into a container having the same cross-sectional area as the water spray area, the amount of water sprayed is shown using the height of the water accumulated in the container. That is, the amount of water spray was shown using the standard similar to the standard which shows rainfall. Therefore, in other words, the watering amount per day for the incinerated main ash in each treatment area is 0.000283 m ³ (78.5 × 3.6 = 282.6 cm ³ ≈0.000283 m ³ ).

  The test was continued for 6 days under the above conditions. During the test, leachate was collected over time and analyzed for water quality. Specifically, the amount of cesium contained in the leachate was analyzed by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry). The analysis results are shown in FIGS.

  As shown in FIGS. 2 and 3, the elution rate (elution amount / content) of cesium in the first treatment section was 1.7%. Here, as described above, the elution rate of the main ash is 0 to 2.2% when the solid stirring process is performed for 6 hours in a state where the liquid-solid ratio is 10: 1. That is, in the first treatment section where the liquid-solid ratio (cumulative leachate amount / incinerated ash amount) is 0.6: 1, an elution rate substantially equal to that obtained when the liquid-solid ratio is 10: 1 was obtained.

  Further, focusing on the relationship between the amount of water sprayed and the amount of air flow, it was also found that when the water spray amount is the same, the elution rate is improved by increasing the air flow rate. This is considered to be caused by a decrease in the pH of the incinerated ash and the retained water due to an increase in the aeration amount. Specifically, the gas-liquid ratio (aeration amount / watering amount) in the first treatment section where the elution rate was about 2% was about 5000 (1.4 / 0.000283). Further, the gas-liquid ratio (aeration amount / watering amount) in the second treatment section where the elution rate was 2.9% was about 10,000 (2.8 / 0.000283). In the third treatment zone, the elution rate is 3.5%, which is twice that of the first treatment zone, and the gas-liquid ratio at that time is about 20,000 (5.6 / 0.000283).

(Second bench scale test)
The test apparatus 10 shown in FIG. 1 was also used in the second bench scale test. In the second bench scale test, two test apparatuses 10 shown in FIG. 1 are prepared, the column 11 of the first test apparatus 10 is supplied with air, and the column 11 of the second test apparatus 10 is supplied with air. I didn't care. Specifically, air was supplied only to the column 11 (first treatment section) of the first test apparatus 10 at a rate of 1 L / min.

On the other hand, the amount of water supplied to each treatment area was the same. Specifically, the watering amount per time for each treatment area was 1.5 mm, and the watering amount per day was 150 mm. In other words, the amount of water per day for each treatment area is 0.00118 m ³ (78.5 × 1.5 = 117.75 cm ³ ≈0.00118 m ³ ).

  In the second bench scale test, instead of the incinerated main ash 20 shown in FIG. 1, incinerated fly ash containing stable cesium is applied to the column 11 of each test apparatus 10 under the same conditions as in the first bench scale test. Filled.

  The test was continued for 1.3 days under the above conditions. During the test, the quality of the leachate was analyzed under the same conditions and techniques as in the first bench scale test. The analysis results are shown in FIG.

  As shown in FIG. 4, the elution rate of cesium is improved in the first treatment section where watering and aeration are performed, compared to the second treatment section where only watering is performed. In addition, the gas-liquid ratio (aeration amount / sprinkling amount) in the first treatment section is about 1000 (1.4 / 0.00118).

  From the above test results, it was confirmed that elution of radioactive substances contained in incinerated ash is promoted according to the pretreatment method of the present invention using a combination of watering and aeration. The pretreatment method of the present invention whose effectiveness has been confirmed by a bench scale test can be carried out, for example, as follows.

(First embodiment)
First, a stabilization area for carrying out the pretreatment method of the present invention is prepared. The stabilization area will be installed in the building where rainwater can be removed. After preparing the stabilization area, preprocessing is performed according to the order shown in FIG.

First, the incinerated ash that is the object of the pretreatment is sprinkled out at a predetermined density in the stabilization area (step S1). The density is, for example, 1.3 g / cm ³ . Such seeded out density, for ^example, can be set within the range of ^{0.5g / cm 3 ~1.8g / cm 3} . In addition, although the spreading thickness (= bulkiness of incineration ash) can be set arbitrarily, it is desirable that it is in the range of 0.3 m to 2.0 m.

  Thereafter, the amount of water spray per incineration ash is determined (step S2). Specifically, the watering amount per time is determined using the following formula based on the thickness of the spread. The amount of water spray Y (mm) per one time is proportional to the spreading thickness X (m) through a proportional coefficient A that varies depending on the radioactive substance content of the incinerated ash. That is, it is expressed as Y = AX. As described above, the proportionality coefficient A varies depending on the characteristics of the incinerated ash (such as the content of radioactive material), but is set within a range of 0.4 to 4.0, for example.

  In the present embodiment, it is assumed that the watering amount per time is 1.5 mm, the watering amount per day is 36 mm, and the number of watering times per day is 24 times. However, this watering condition is an example, and for example, the amount of watering per day is determined within a range of 36 to 2160 mm. In this case, if the watering amount per time is maintained at 1.5 mm, the number of watering times per day is 24 to 1440 times.

Next, the air flow rate for the incinerated ash is determined (step S3). Specifically, the aeration amount at which the gas-liquid ratio (aeration amount / amount of water) becomes a predetermined value is determined according to the amount of water determined as described above. In the present embodiment, it is assumed that the ventilation rate is determined so that the gas-liquid ratio is about 5000. That is, it is assumed that the air flow per day is determined to be 1.4 m ³ (= 1 L / min). As described above, in the first bench scale test, an elution rate of about 2% was obtained when the gas-liquid ratio was about 5000.

  Here, the order of determining the amount of water spray and the amount of ventilation is not limited to the above order. That is, it is only necessary to set the water spray amount and the air flow rate so that the gas-liquid ratio becomes a predetermined value, and the water spray amount may be determined after the air flow rate is determined.

  Then, according to the watering conditions and ventilation conditions set as mentioned above, the watering process and ventilation process with respect to incineration ash are performed (step S4). Specifically, intermittently supplied from above the incineration ash while continuously supplying air to the incineration ash sprinkled into the stabilization area at a rate of 2 mm / sec (equivalent to about 1 L / min in the bench scale test). Do watering. Specifically, water of 1.5 mm is sprinkled every other hour. Such watering treatment and aeration treatment are continued for a predetermined number of days (for example, 6 days). During the period, the quality of the leachate is appropriately evaluated based on a predetermined index (step S5). Such indicators include electrical conductivity (EC), pH value, air dose rate, radioactivity concentration, cesium content and the like. As a result of the analysis / evaluation in step S5, if the pretreatment end criteria (for example, the criteria set in the prior treatability test) are not cleared, the pretreatment period is extended or the watering / venting conditions are re-established. Make settings to stabilize the state of incinerated ash after pretreatment. Here, the water content (moisture content) of the incinerated ash can be adjusted in advance before the start of the watering treatment in order to drain substantially the same amount of leachate as the watering amount. For example, by adjusting the moisture content to 30 to 40%, approximately the same amount of leachate as the amount of water sprayed can be drained.

  Next, a configuration example of the stabilization area will be described. The stabilization area can be configured using, for example, a portable container 100 as shown in FIGS.

  The container 100 is formed in a box shape with an insertion port 110 provided above, and includes a cover (not shown) that opens and closes the insertion port 110. When the incineration ash is stored in the container 100, the container 100 is moved below the discharge hopper provided in the incineration facility or the like to open the inlet 110, and the incineration ash is put into the container 100 from the discharge hopper. Eject (drop).

  A bottom member 120 is disposed on the bottom of the container 100. On the upper surface of the bottom member 120, a downward slope is provided from one side in the longitudinal direction of the container 100 toward the other side. Further, a water collecting pipe 130 is provided on the inclined lower end side of the bottom member 120. A large number of water collecting holes are provided in the pipe wall of the water collecting pipe 130, and the pipe end 130 a of the water collecting pipe 130 penetrates the side wall of the container 100 as shown in FIG. Protruding outside. The water sprayed and infiltrated into the incinerated ash in the container 100 flows down along the upper surface (inclined surface) of the bottom member 120 and then flows into the water collecting pipe 130 from the water collecting hole, and as the leachate, the container 100 Drained outside.

  An air supply pipe 140 is laid on the bottom member 120. As shown in FIG. 5C, the air supply pipe 140 is provided on the branch line over the entire bottom surface of the container 100 in a plan view. The air supply pipe 140 is provided with a number of air supply holes, and the pipe end 140 a of the air supply pipe 140 penetrates the side wall of the container 100 and protrudes out of the container 100. The air sent into the air supply pipe 140 flows out from the air supply hole and moves in the incineration ash from below to above. That is, the penetration direction of the water sprayed on the incineration ash is opposite to the ventilation direction of the air supplied to the incineration ash. Here, since the air pipe 140 is laid on the bottom member 120, air is supplied to the incineration ash from the lower end in the bulky direction of the incineration ash.

  As shown in FIG. 5A, a part of the side wall of the container 100 is configured to be rotatable, and by rotating the side wall (opening / closing door 150), a part of the side surface of the container 100 is formed. It can be opened to discharge incineration ash. Further, a hook 160 is provided on the side wall opposite to the side wall constituting the open / close door 150. The hook 160 is locked to the truck or the like when the container 100 is loaded on the truck or the like.

  The container 100 having the above configuration is loaded on a truck or the like and carried to an incineration facility or the like, and incineration ash is loaded in the incineration facility or the like. The container 100 loaded with the incineration ash is loaded on a truck or the like and carried into a predetermined pretreatment dedicated section. A large number of small sections in which the container 100 is installed are provided in the preprocessing dedicated section, and the container 100 carried into the preprocessing dedicated section is placed in an arbitrary or predetermined small section. The pretreatment dedicated section is provided with a water supply pipe, an air supply pipe, and a drain pipe that go around two or more small sections.

  Each small section is provided with a sprinkler connected to a water supply pipe, and the container 100 is placed under the sprinkler with the input port 110 opened. Further, each small section is provided with a water seal / sampling tank 200 connected to the drain pipe 210, and the water collecting pipe 130 of the container 100 is connected to the water seal / sampling tank 200. Furthermore, the air supply pipe 140 of the container 100 is connected to the air supply pipe.

  When the container 100 is placed in the small section as described above, the watering process and the aeration process are started. Specifically, water sent out from a water supply device (for example, a pump) is sprinkled from above the container 100 toward the incinerated ash in the container 100 via a water supply pipe and a sprinkler. At the same time, the air sent out from the air supply device (for example, a compressor) is supplied to the incineration ash through the air supply pipe and the air supply pipe 140. Here, the water sprayed on the incineration ash moves from the upper side to the lower side in the incineration ash, and the air supplied to the incineration ash moves from the lower side to the upper side. In addition, the watering conditions and the ventilation conditions, particularly the method for determining the gas-liquid ratio are as described above. In addition, in order to prevent radioactive materials adsorbed on water, dust, etc. from being scattered by ventilation of the incineration ash, a water-permeable sheet (for example, non-woven fabric) may be covered on the upper surface of the incineration ash, and a filter is provided. A suction device may be provided.

  Water sprayed on the incineration ash and passed through the incineration ash is drained into a water seal / sampling tank 200 through a water collecting pipe 130. FIG. 7 shows an outline of the water sealing / dispensing mast 200. A pipe end 130 a of a water collecting pipe 130 is inserted into the water seal / collecting pipe 200. Further, a pipe end 210 a of a drain pipe 210 is connected to the side wall of the water seal / collecting water tank 200. Here, the pipe end 210 a of the drain pipe 210 is at a higher position than the pipe end 130 a of the water collection pipe 130. More specifically, the height from the bottom surface of the water seal / collecting pipe 200 to the pipe end 210a of the drain pipe 210 is higher than the height from the bottom face of the water seal / collecting pipe 200 to the pipe end 130a of the water collecting pipe 130. Is higher. Therefore, when the level of leachate in the water seal / sample 200 gradually increases and reaches the height of the pipe end 210a of the drain pipe 210, the leachate flows into the drain pipe 210. The leachate flowing into the drain pipe 210 is sent to a leachate treatment apparatus (not shown) via the drain pipe 210.

  A water collection valve 220 is provided in the middle of the water collecting pipe 130 so that leachate can be collected as needed and analyzed. Further, a radiation sensor 230 is provided in the vicinity of the water collecting pipe 130 so that the elution status of the radioactive substance can be monitored. As the radiation sensor 230, it is desirable to use a sensor capable of measuring γ rays, such as a GM tube or a scintillation meter. When using a scintillation meter, it is desirable to block radiation from the surroundings by using a collimator. Furthermore, the water seal / sample 200 is provided with a pH / EC sensor 240 so that the elution status of salts other than radioactive substances can be monitored. The detection results obtained by the radiation sensor 230 and the pH / EC sensor 240 are wirelessly transmitted or wired via a signal converter (not shown). That is, it is possible to monitor the elution status of radioactive materials and the like at a remote location.

  When the pretreatment process in the pretreatment dedicated section is completed, the process proceeds to the final disposal process. In the final disposal step, the container 100 shown in FIG. 6 is moved from the pretreatment dedicated section to the final disposal site, and the incineration ash that has been stabilized (pretreated) in the container 100 is finally disposed (for example, landfill disposal). To do.) That is, the container 100 forms a stabilization area for performing pretreatment, and is also a dedicated container for carrying in and out the incinerated ash to and from the pretreatment dedicated section.

  As described above, according to the pretreatment method according to the present embodiment, the radioactive substance contained in the incineration ash can be washed out in a short time with a small amount of water, and thus the volume of the incineration ash containing the radioactive substance can be efficiently reduced. It can be made. In particular, incinerated ash that requires special final disposal (for example, storage / management at an intermediate storage facility or a block-type disposal site) due to a high content of radioactive substances can be reduced in volume.

  The stabilization area can be configured without using the container 100 shown in FIG. For example, as shown in FIG. 8, the preprocessing dedicated section 300 is divided into a plurality of small sections 310. As shown in the enlarged view, the incinerated ash carried into each small section 310 is sprinkled out with a predetermined thickness by a heavy machine 320 such as a bulldozer. The incinerated ash sprinkled out to the small section 310 is sprinkled with water from a sprinkler 330 provided above the small section 310, and is also ventilated by a ventilation device (not shown). Each sub-compartment 310 is provided with a water seal / sampler similar to the water seal / sample 200 shown in FIG. 7, and the leachate passes through the water seal / sample and drainage pipe. And collected in the leachate pit 340 provided at the corner of the pretreatment dedicated section 300. The pretreatment section 300 is provided with a flush water collecting side groove so that the leachate and the wash water can be separated.

(Second Embodiment)
According to the pretreatment method according to the first embodiment, incinerated ash from which radioactive substances are washed out is obtained, and leachate containing high concentrations of radioactive substances is generated. Therefore, in the first embodiment, leachate is collected, and the collected leachate is treated by a leachate treatment apparatus having a radioactive substance removal function.

  However, if the leachate is absorbed and adsorbed onto a solid and concentrated, the leachate treatment process is omitted, and a significant cost reduction is expected. In this respect, the pretreatment method of the present invention is characterized in that elution of radioactive substances is promoted by aeration in addition to watering the incinerated ash. Therefore, incineration ash can be separated into two layers using such characteristics. Specifically, the incineration ash is separated into a layer where the radioactive material is washed out and a layer where the washed out radioactive material is concentrated by adjusting the ventilation position (air supply position) for the incineration ash. Can do. This will be specifically described below.

  When the incinerated ash is separated into two layers as described above, for example, pretreatment is performed in a stabilization area configured using the portable container 400 shown in FIG. A container 400 shown in FIG. 9 has the same basic configuration as the container 100 shown in FIG. However, in the container 400 shown in FIG. 9, the air supply pipe 140 is disposed above the bottom surface of the container 400 by a predetermined distance, and when the incineration ash 410 is accommodated in the container 400, the air supply pipe 140 is embedded in the incineration ash 410. Is done. Therefore, the air flowing out from the air supply holes of the air supply pipe 140 is supplied to the incineration ash 410 from the middle of the bulk of the incineration ash 410. In the following description, the incineration ash 410 accommodated in the container 400 is divided into upper and lower portions with the air supply position as a boundary, the upper side from the air supply position being “upper layer 410a” and the lower side being “lower layer 410b”. Call and distinguish. That is, the air is supplied to the boundary between the upper layer 410a and the lower layer 410b of the incineration ash 410, and the supplied air moves in the upper layer 410a of the incineration ash 410 from below to above. That is, ventilation is performed on the upper layer 410a of the incineration ash 410, but ventilation is not performed on the lower layer 410b.

  On the other hand, as in the case of the first embodiment, watering by the sprinkler 420 is performed from above the incineration ash 410. That is, the water sprayed on the incineration ash 410 penetrates the lower layer 410b after passing through the upper layer 410a of the incineration ash 410.

  In short, the upper layer 410a of the incinerated ash 410 is sprinkled and ventilated, while water that has passed through the upper layer 410a penetrates into the lower layer 410b. As a result, the radioactive substance is efficiently washed out in the upper layer 410a of the incineration ash 410, and the water containing the radioactive substance washed out from the upper layer 410a is absorbed, adsorbed and concentrated in the lower layer 410b. Note that a water absorbing material or an adsorbing material (for example, zeolite) may be included in advance in the lower layer 410b of the incineration ash 410. Moreover, drainage can be started simultaneously with the start of watering by adjusting the moisture content of the upper layer 410a of incineration ash in advance. On the other hand, by not adjusting the moisture content of the lower layer 410b of the incineration ash 410, it becomes possible to absorb and concentrate more water discharged from the upper layer 410a.

  When the incinerated ash 410 is formed in two layers as described above, the content of the radioactive material in the upper layer 410a and the elution risk are reduced, so that normal final disposal (for example, landfill in a stable disposal site) can be performed. . On the other hand, since the content and elution risk of the radioactive material in the lower layer 410b are increasing, special final disposal (for example, storage / management at an intermediate storage facility or a block-type disposal site) is performed.

  According to the pretreatment method according to the present embodiment, since it is not necessary to collect and treat leachate, it is necessary to provide the bottom member 120 and the water collecting pipe 130 (FIG. 6) in the container 400 shown in FIG. Absent. Moreover, it is not necessary to provide the water sealing / collecting tank 200 (FIGS. 6 and 7) in the pretreatment dedicated section where the container 400 shown in FIG. 9 is placed, and it is not necessary to provide the leachate treatment apparatus.

  As described above, according to the pretreatment method according to the present embodiment, the ratio of incineration ash requiring special final disposal to the total amount of incineration ash can be reduced. Furthermore, according to the pretreatment method according to the present embodiment, it is not necessary to treat leachate, and the disposal cost of the incinerated ash containing radioactive substances is greatly reduced.

  Note that the preprocessing method according to the present embodiment can also be implemented in the stabilization area having the configuration shown in FIG.

(Third embodiment)
In 1st Embodiment, the stabilization area was comprised by the container 100 (FIG. 6) which is an exclusive container for carrying in / out incineration ash to / from the pre-processing exclusive area. On the other hand, in this embodiment, the incineration ash accommodated in the bag-like container is carried into the stabilization area provided in the pretreatment dedicated section, and pretreatment is performed.

  The pretreatment dedicated section is divided into a large number of small sections, and a stabilization area shown in FIG. 10 is provided in each small section. In addition, the pre-treatment dedicated section is provided with a water supply pipe and an air supply pipe that go around two or more small sections.

  The stabilization area shown in FIG. 10 includes a gantry 501 supported by four legs 500 and a processing chamber 502 provided on the gantry 501. The mount 501 has a rectangular planar shape, and an opening 501a is formed at the center thereof. The processing chamber 502 is surrounded on all sides by side walls 503 rising from the respective sides of the gantry 501 and open upward.

  In the opening 501a of the gantry 501, a plurality of air supply pipes 504 having a large number of air supply holes formed in the tube wall are arranged. The total length of each air supply tube 504 is longer than the diameter of the opening 501a, and each air supply tube 504 straddles the opening 501a. In addition, the respective air supply pipes 504 merge and are connected to an air supply pipe (not shown).

  A water receiving tank 505 is disposed under the gantry 501. In other words, the water receiving tank 505 is disposed below the processing chamber 502. On the other hand, a sprinkler 506 is disposed above the processing chamber 502, and a water supply pipe (not shown) is connected to the sprinkler 506.

  In the processing chamber 502 shown in FIG. 10, a bag-like container having water permeability and air permeability (in this embodiment, incinerated ash accommodated in the flexible container bag 600 is carried in. Specifically, an incineration facility, etc. The flexible container bag 600 filled with the incinerated ash is carried into the pre-processing section, and the flexible container bag 600 carried into the pre-processing section is lifted by a crane, a forklift, or the like, and is opened above the processing chamber 502. 502a is put into the processing chamber 502. That is, it is placed on the mount 501 (see FIG. 11), and more specifically, a flexible container bag is placed on the opening 501a so as to close the opening 501a of the mount 501. 600. In other words, the area of the opening 501a is the flexible container bag. Smaller than the bottom area of 600, the flexible container bag 600 is placed on the pedestal 501, the opening 501a is closed by a flexible container bag 600.

  When the flexible container bag 600 is placed in the processing chamber 502 as described above, the watering process and the aeration process are started. Specifically, water supplied through the water supply pipe is discharged from the sprinkler 506. At the same time, the air supplied to the air supply pipe 504 through the air supply pipe is released from the air supply holes of the air supply pipe 504. That is, water is sprayed from above the flexible container bag 600 and air is supplied from below the flexible container bag 600. The sprinkled water permeates the incineration ash through the flexible container bag 600, and moves in the incineration ash from above to below. On the other hand, the supplied air passes through the flexible container bag 600 and moves in the incineration ash from below to above. Sprinkling conditions and aeration conditions, particularly the method for determining the gas-liquid ratio are as described above.

  In this embodiment, incineration ash is filled in a bag-like flexible container bag 600. Therefore, the incineration ash is not raised by the air moving from the lower side to the upper side in the incineration ash, and the pretreatment can be performed while the upper opening 502a of the processing chamber 502 is kept open.

  The water that has passed through the incineration ash mainly passes through the bottom surface of the flexible container bag 600 and flows out of the flexible container bag 600. The water that has flowed out of the flexible container bag 600 falls into the water receiving tank 505 through the opening 501a of the mount 501 and is stored as leachate.

  When the preprocessing is completed as described above, the flexible container bag 600 in the processing chamber 502 is lifted by a crane, a forklift, or the like and taken out of the processing chamber 502, and a new flexible container bag 600 is put in the processing chamber 502. That is, preprocessing is performed in a batch system.

  A modification of the stabilization area shown in FIG. 10 is shown in FIG. In the stabilization area shown in FIG. 12, a cover plate 507 for opening and closing the upper opening 502a is rotatably attached to one of the side walls 503 of the processing chamber 502. A sprinkler 506 is mounted on the inner surface of the cover plate 507, and a joint (not shown) for connecting the water supply pipe and the sprinkler 506 is provided. The upper opening 502a of the processing chamber 502 is opened and closed as necessary. For example, when the flexible container bag 600 is taken in and out of the processing chamber 502, the upper opening 502a is opened. On the other hand, when the upper opening 502a is closed by the cover plate 507, the inside of the processing chamber 502 is hermetically sealed.

  Further, a joint 508 to which an air supply pipe is connected is provided at the upper part of the other side wall 503 of the processing chamber 502, and air is supplied into the processing chamber 502 through the air supply pipe connected to the joint 508. 12 is not provided in the processing chamber 502 shown in FIG. 12, and a punching metal 509 is fitted in the opening 501a of the gantry 501.

  As shown in FIG. 13, after the flexible container bag 600 is placed in the processing chamber 502, the upper opening 502 a (FIG. 12) of the processing chamber 502 is closed by the cover plate 507. That is, the inside of the processing chamber 502 is sealed. Further, a water supply pipe is connected to a joint (not shown) provided on the lid plate 507. Next, watering treatment and aeration treatment are started. Specifically, water supplied via the water supply pipe and the joint is discharged from the sprinkler 506. At the same time, air is supplied into the processing chamber 502 via the air supply pipe and the joint 508. That is, water is sprayed from above the flexible container bag 600 and air is supplied from above the flexible container bag 600. The sprinkled water permeates the incineration ash through the flexible container bag 600, and moves in the incineration ash from above to below. Further, the air supplied into the processing chamber 502 also passes through the flexible container bag 600 and moves in the incineration ash from above to below. Sprinkling conditions and aeration conditions, particularly the method for determining the gas-liquid ratio are as described above.

  The water that has passed through the incineration ash mainly passes through the bottom surface of the flexible container bag 600 and flows out of the flexible container bag 600. The water flowing out from the flexible container bag 600 falls into the water receiving tank 505 through the through hole of the punching metal 509 (FIG. 12) and is stored as leachate. But the member which closes the opening part 501a of the mount frame 501 should just be a member which does not prevent drainage and exhaust_gas | exhaustion, and is not limited to the punching metal 509. FIG. For example, the opening 501a may be closed with a mesh member. If the bottom surface of the flexible container bag 600 can be sufficiently supported without closing the opening 501a, it is not necessary to close the opening 501a.

  In this modified example, since air is supplied to the sealed processing chamber 502, the pressure in the processing chamber 502 increases, and the movement of water in the incinerated ash is promoted. Moreover, since the moving direction of the water in the incineration ash and the moving direction of the air are the same, there is no possibility that the water and the air interfere with each other, and the movement of both is performed smoothly. Furthermore, since air moves mainly from top to bottom in the incineration ash, the incineration ash can be raised by the airflow even if the pretreatment is performed with the incineration ash contained in a container with an open top. It is suitable for pretreatment of incinerated fly ash having a particle size smaller than that of incinerated main ash without being lifted up.

  In the embodiment described so far and the modifications thereof, air is supplied to the incineration ash. However, carbon dioxide may be supplied instead of air, and even in that case, the effect of improving the elution rate of the radioactive substance can be obtained. Further, as a method of supplying air to the incineration ash, air may be supplied to the incineration ash not only by supplying air by a blower fan or the like but also by suctioning with a vacuum pump or the like.

  As mentioned above, although some embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary. For example, a sample of incinerated ash that is the object of pretreatment may be obtained, a treatability test as a preliminary test (same as the treatability test) may be performed, and watering conditions and aeration conditions may be determined based on the results. .

  By the way, as for the treatability test, an appropriate Japanese translation established in the industry has not yet been defined. Therefore, in this specification, it is broadly defined as a preliminary test. Such a definition means, for example, preliminary examination on applicability of technology. Narrower means analysis and experiments performed in advance with samples. Any test within the scope of such a definition can naturally be regarded as a treatability test as used herein.

  A treatability test for determining watering conditions and aeration conditions can be performed using the same or substantially the same test apparatus as the test apparatus 10 shown in FIG. The treatability test is performed through a series of steps. The series of steps includes, for example, a moisture content adjusting step, a filling step, and a setting step for the amount of sprinkling / aeration.

  In the moisture content adjusting step, the moisture content of the incinerated ash as a sample is adjusted so that leachate can be obtained simultaneously with watering. The moisture content is defined as {(waste weight−dry waste weight) / waste weight} × 100, and is adjusted by adding water to the incinerated ash as a sample. What is necessary is just to set the standard of the moisture content to adjust to 25% or more-45% or less. Exactly, the moisture content varies depending on the target incineration ash, but the incineration ash within the range of the experiment has a moisture content in the range of 10% to 50%. That is, when water is contained in the incineration ash at such a moisture content, it can be considered that the incineration ash contains water to an extent that saturates water. Therefore, in that state, it can be said that almost no leachable water comes out. It can be said that when the incinerated ash in such a state is started to be sprinkled, leachate substantially corresponding to the sprinkled amount can be obtained. It is preferable to adjust the moisture content in order to shorten the period of the treatability test.

  The dry waste weight here corresponds to the total evaporation residue. The measurement is performed in the same way as the method specified for measuring the solid content in the “Remarks” of the preparation of the first test solution of the Environmental Agency Notification No. 13, and the measured value of the dried sample is dried and discarded. Used as an object weight.

  By the way, in the “Remarks” for the preparation of the first test solution of the Environment Agency Notification No.13, “The industrial waste is 20 grams or more and 100 grams or less (a gram) of a flat balance (with a capacity of 50 milliliters or more, Pre-dried) or evaporation pestle (capacity over 100 milliliters, pre-dried), evaporate to dryness with care not to boil. After drying for 2 hours, it is allowed to cool for 30 minutes in a desiccator.As a result, the weight (b gram) of the material remaining on the flat balance or evaporation pan is accurately determined, and this is the weight of the solid part. To the effect.

  In the packing step, the incinerated ash whose water content is adjusted as described above is packed into the column of the test apparatus so as to have a predetermined density. At the time of packing, a predetermined weight of incinerated ash is added to a predetermined volume in the column to adjust to a predetermined density. Basically, no compaction is performed during filling. Therefore, the incinerated ash in a state where the moisture content has been adjusted is in a state where the state is maintained and placed in the column. That is, this state can be said to be a state in which the test apparatus is filled with incinerated ash at a density that does not impede ventilation and water flow.

  After incineration ash as a sample is packed in the column in this way, a plurality of watering conditions and aeration conditions are set in the watering amount / aeration amount setting step. Watering conditions and ventilation conditions are set separately and independently. Basically, the watering conditions and the ventilation conditions are set while checking the respective elution characteristics by setting a plurality of watering quantities and aeration quantities. It is only necessary to analyze the elution characteristics acquired with a plurality of sprinkling amounts and aeration amounts, and finally set an appropriate sprinkling amount and aeration amount to be applied to the actual incinerated ash, that is, a gas-liquid ratio.

DESCRIPTION OF SYMBOLS 10 Test apparatus 11 Column 12 Sprinkling apparatus 13 Leaching water receiver 14 Aeration apparatus 20 Incineration main ash 100,400 Container 130 Catchment pipe 140,504 Air supply pipe 210 Drainage pipe 230 Radiation sensor 240 pH / EC sensor 300 Pretreatment dedicated section 310 Section 330, 420, 506 Sprinkler 410 Incinerated ash 500 Leg 501 Base 501a Opening 502 Processing chamber 502a Upper opening 503 Side wall 505 Water receiving tank 507 Cover plate 508 Joint 509 Punching metal 600 Flexible container back

Claims (6)

Both watering and aeration The method of line power sale preprocessing on the ash prior to final disposal of ash containing radioactive materials,
Watering the incineration ash from above the incineration ash,
Supply air to the incineration ash from the middle of the bulky direction of the incineration ash,
A pretreatment method for incineration ash, wherein water that has passed through the incineration ash that is above the air supply position is absorbed by the incineration ash that is below the air supply position . In the pretreatment method of incineration ash according to claim 1 ,
A pretreatment method for incineration ash, wherein water and aeration are performed on the incineration ash while the incineration ash is contained in a portable container. A pretreatment method for performing both watering and aeration on the incinerated ash before final disposal of the incinerated ash containing radioactive substances,
A pretreatment method for incineration ash, wherein water and aeration are performed on the incinerated ash while the incinerated ash is contained in a bag-like container having water permeability and air permeability . In the pretreatment method for incineration ash according to any one of claims 1 to 3 ,
A pretreatment method for incinerated ash, wherein water is intermittently sprinkled while continuously ventilating the incinerated ash. In the pretreatment method of the incinerated ash according to any one of claims 1 to 4 ,
A pretreatment method for incineration ash, wherein a gas-liquid ratio, which is a ratio of an aeration amount to an incineration ash and a water spray amount, is 1000 or more. In the pretreatment method of incineration ash according to claim 5 ,
Before the incinerated ash, wherein the gas-liquid ratio is determined based on the elution characteristics of the radioactive material obtained by changing a plurality of aeration amounts and sprinkling amounts in a preliminary test performed by collecting a part of the incinerated ash Processing method.

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