JP2019002824A - Method and apparatus for compressing and molding radioactive waste - Google Patents

Abstract

To provide a method and apparatus for compressing and molding radioactive waste, capable of forming a molding having a radioactive waste content of 75 mass% or more at low pressure force and normal temperature.SOLUTION: A method for compressing and molding radioactive waste comprises: a mixing step S2 of mixing powdery radioactive waste 1 of 75 mass% or more and a hydraulic inorganic solidifying material 2 and water 3 of 25 mass% or less in total with a mixed powder 4 of 100 mass% in an amount of 0.9:1.1 to 1.1:0.9 at a mass ratio represented by the hydraulic inorganic solidifying material 2:the water 3; a storage step S3 of storing the mixed powder 4 in a storage container 17; a temporary compression step S4 of temporarily compressing the mixed powder 4 in the storage container 17 in the state of holding the storage container 17 by a storage container retainer 19; and a compressing and molding step S5 of finally compressing the mixed powder 4 in the storage container 17 in the state of holding the storage container 17 by the storage container retainer 19.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radioactive waste compression molding method and compression molding apparatus.

  Radioactive waste generated in facilities such as nuclear power plants is reduced and stabilized by various treatments. Among radioactive wastes, combustible wastes are incinerated in a dedicated incinerator to reduce the volume, and a cement solidification method in which the generated incineration ash is solidified using cement has been put into practical use.

  According to the cement solidification method, there is an advantage that radioactive waste such as incineration ash can be stably fixed, but it is necessary to adjust the fluidity suitable for kneading the mixture of cement paste and radioactive waste. The content of radioactive waste in the cement solid body is low and is only about 15% by mass.

  In addition, as a cement solidification method, a method of solidifying cement by mixing cesium adsorbent such as zeolite, ferrocyanide salt, manganese compound, silicotitanate and incineration ash has been proposed, and calcium hydroxide or sodium hydroxide is proposed. It has also been proposed to accelerate the reaction by using an alkali such as, or to perform compression molding using a blending condition with a reduced water / cement ratio if necessary (see, for example, Patent Document 1). According to this method, the waste content in the cement solidified body can be increased, but is about 20% by mass.

  In addition, a method has been proposed in which radioactive incineration ash is compression-molded into a cement solidified body by adding an adsorbent that adsorbs radioactive substances to radioactive incinerated ash, cement-based solidifying material, and water-expandable clay (for example, (See Patent Document 2). In this method, the waste content in the cement solidified body is increased to 70% by mass or more. However, the pressure applied during compression molding is 15 MPa or more, or 4 t / cm (continuous roll type), and the pressure is relatively high. is there.

JP 2013-234881 A JP2013-79810A

  The present invention has been made to solve the above-described problems, and is a radioactive waste that can form a molded body having a radioactive waste content of 75% by mass or more at a low pressure and normal temperature. An object is to provide a compression molding method and a compression molding apparatus.

  One aspect of the method for compressing and molding radioactive waste according to the present invention is a method for compressing and molding powdered radioactive waste, wherein the radioactive waste, a hydraulic inorganic solidifying material, and water are mixed to obtain a mixed powder. And 75% by mass or more of the radioactive waste, and 25% by mass or less of the hydraulic inorganic solidified material and water, and 100% by mass of the mixed powder and 100% by mass of the mixed powder. A mixing step of mixing in an amount of 0.9: 1.1 to 1.1: 0.9 in a mass ratio represented by water, a storing step of storing the mixed powder in a storing container, and the storing A temporary compression step of temporarily compressing the mixed powder in the storage container in a state where the container is held by the storage container holding device; and a state in which the storage container is held in the storage container by the storage container holding device. The mixed powder is subjected to main compression in a longer time than the temporary compression step. And a compression molding step of obtaining a molded body Te.

  One aspect of the compression molding apparatus of the radioactive waste of the present invention is a mixer for producing a mixed powder by mixing powdered radioactive waste, a hydraulic inorganic solidifying material, and water, and the mixer. The radioactive waste supply device for supplying the radioactive waste in an amount of 75% by mass or more with respect to 100% by mass of the mixed powder, and the mixer with respect to 100% by mass of the mixed powder. The total amount of the hydraulic inorganic solidified material and water is 25% by mass or less, and the mass ratio represented by the hydraulic inorganic solidified material: water is 0.9: 1.1 to 1.1: 0.9, A hydraulic inorganic solidified material supply device that supplies the hydraulic inorganic solidified material, a water supply device that supplies the water, a mixed powder transfer device that transfers the mixed powder in the mixer and stores it in a storage container; A storage container holding device that holds the storage container, and a mixed powder in the storage container, Having a compression device for pressurizing the following more pressure 10 MPa 13 MPa.

  ADVANTAGE OF THE INVENTION According to this invention, the compression molding method and compression molding apparatus of a radioactive waste which can form the molded object whose content of a radioactive waste is 75 mass% or more at low pressure and normal temperature can be provided. .

It is a figure which shows typically the compression molding apparatus of the radioactive waste used for the compression molding method of embodiment. It is a flowchart which shows the compression molding method of embodiment. It is sectional drawing which shows typically the storage container holding | maintenance apparatus of embodiment. It is a figure for demonstrating the clearance of a storage container. It is a graph showing the relationship between Portland cement: water mass ratio and the compression strength of a molded object when not performing temporary pressing.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a radioactive waste compression molding apparatus 10 used in the present embodiment. The compression molding apparatus 10 is connected to a mixer 15 that mixes the powdered radioactive waste 1, the hydraulic inorganic solidified material 2, and the water 3 to produce a mixed powder, and is connected to the mixer 15, and is in the form of powdered radioactive waste. A radioactive waste supply device 11 that measures a predetermined amount of the product 1 and supplies it to the mixer 15, and water that is connected to the mixer 15 and measures a predetermined amount of the hydraulic inorganic solidifying material 2 to be supplied to the mixer 15. A hard inorganic solidifying material supply device 12 and a water supply device 13 connected to the mixer 15 and measuring a predetermined amount of water 3 and supplying the water 3 to the mixer 15 are provided.

  In addition, the compression molding apparatus 10 includes a mixed powder transfer device 18 that transfers the mixed powder in the mixer 15 to the outside and stores it in the storage container 17, a compression device 16 that pressurizes the contents of the storage container 17, A storage container holding device 19 that holds the storage container 17 is provided. The compression device 16 includes a pressurizing piston 21 that pressurizes the contents of the storage container 17. The container 17 is disposed in the compression device 16.

  FIG. 2 is a flowchart showing the compression molding method of the present embodiment. The compression molding method shown in FIG. 2 includes a measuring step S1 for measuring powdered radioactive waste 1, a hydraulic inorganic solidified material 2 as a solidified material, and water 3 in a predetermined amount, and a measured radioactive content. There are a mixing step S2 for obtaining the mixed powder 4 by mixing the waste 1, the hydraulic inorganic solidifying material 2 and the water 3, and a storage step S3 for storing the mixed powder 4 in the storage container 17. The compression molding method of the present embodiment further includes a temporary compression step S4 for temporarily compressing the mixed powder 4 in the container 17 and a compression molding step for obtaining a molded body 5 by subjecting the temporarily compressed mixed powder 4 to main compression. S5.

  The radioactive waste 1 to be treated is powdered radioactive waste, for example, radioactive waste generated from nuclear facilities or incinerated ash obtained by incineration or heat treatment of combustible radioactive waste. Or incineration fly ash. The “powder” here is, for example, a particle size of about 2.5 mm or less by a sieving method. In addition to the incineration ash and incineration fly ash, the radioactive waste 1 may be, for example, sand or soil, or an inorganic salt generated by treating an acidic or alkaline radioactive chemical by a neutralization reaction. In addition, the radioactive waste 1 has a particle size of 2.1, as long as it does not impair the effects of the present invention, such as radioactive waste 1 other than powder, such as agglomerated aggregates of powdered incineration ash and unburned residue during incineration. Coarse material of 5 mm or more may be included. Moreover, the radioactive waste 1 should just have radioactive at least one part, and may contain the non-radioactive waste.

  In the compression molding method of the present embodiment, the molded body 5 containing 75% by mass or more of the radioactive waste 1 is formed. Even if the amount of radioactive waste 1 is less than 75% by mass, for example, 70% by mass, a molded body 5 with good strength can be obtained. However, the amount of water 3 increases, and the fluidity of the mixed powder 4 increases. If the amount of the radioactive waste 1 is less than 75% by mass, the volume reduction of the radioactive waste is inferior.

  In the weighing step S1, 75% by mass or more of the radioactive waste 1 is weighed with respect to the total amount (100% by mass) of the mixed powder 4. The amount of the radioactive waste 1 is preferably 77 to 85% by mass. As the amount of radioactive waste 1 is increased, the volume can be reduced. However, if the amount is too large, sufficient strength may not be obtained.

  Moreover, in the measurement process S1, the hydraulic inorganic solidified material 2 and the water 3 which are components other than the radioactive waste 1 among the components of the molded object 5 are respectively measured. The total amount of the hydraulic inorganic solidifying material 2 and the water 3 is 25% by mass or less with respect to the remainder of the mixed powder 4 other than the radioactive waste 1, that is, the total amount of the mixed powder 4. Moreover, the ratio of the quantity of the hydraulic inorganic solidification material 2 and the water 3 is 0.9: 1.1-1.1: 0.9 in mass ratio shown by the hydraulic inorganic solidification material 2: water3. When the mass ratio of the hydraulic inorganic solidifying material 2 and the water 3 is within the above range, the molded body 5 has sufficient strength.

  Next, the weighed radioactive waste 1, the hydraulic inorganic solidified material 2, and the water 3 are supplied to the mixer 15 shown in FIG. 1 and mixed by the mixer 15 to obtain a mixed powder 4 (mixing step S2). ). When the radioactive waste 1, the hydraulic inorganic solidifying material 2, and the water 3 are in the above amounts, the mixed powder 4 becomes, for example, a powder having high fluidity. Therefore, workability is excellent and sufficient strength can be imparted to the molded body 5.

  As the hydraulic inorganic solidifying material 2, various portland cements such as ordinary portland cement, early-strength portland cement, medium heat portland cement, low heat portland cement, various mixed cements such as blast furnace cement and fly ash cement, various cements such as alumina cement Can be used. The hydraulic inorganic solidifying material 2 may be used alone or in combination of two or more.

  The water 3 is not particularly limited, and may contain an alkaline or acidic drug or additive as long as the effects of the present invention are not impaired.

  Next, the mixed powder 4 is transferred from the mixer 15 to the compression device 16 by a mixed powder transfer device 18 such as a vibration feeder or a screw feeder, and is stored in a storage container 17 disposed in the compression device 16. (Accommodating step S3).

  The container 17 is, for example, a cylindrical container having an inner diameter of about 250 mm to 300 mm made of a metal plate or the like. The mixed powder 4 is compression molded in the container 17 to form a molded body 5.

  Next, a temporary compression step S <b> 4 is performed in which the mixed powder 4 in the container 17 is temporarily compressed (temporarily pressed) in a time shorter than the subsequent main compression time. By passing through temporary compression process S4, the molded object 5 excellent in intensity | strength can be obtained even at normal temperature and low pressurization force.

  The temporary compression step S4 may be performed a plurality of times. In this case, the accommodation step S3 is performed a plurality of times in accordance with the temporary compression step S4. That is, the accommodating step S3 is performed a plurality of times so that the predetermined amount of the mixed powder 4 is accommodated in the accommodating container 17 in a plurality of times. The temporary compression process S4 is performed after each accommodation process S3, and the next accommodation process 3 is performed. The number of times of temporary pressing in this way is also referred to as “temporary pressing number”.

  For example, when the number of temporary pressing is three, in the first storing step S3, a predetermined amount of one-third of the radioactive waste 1 is stored in the storage container 17, and then temporarily pressed. After this operation is performed twice, the remaining portion (one third of the predetermined amount) is accommodated in the accommodating container 17 and temporarily pressed. According to the method for compressing and molding radioactive waste according to the present embodiment, the molded body 5 having higher strength can be obtained even at a normal temperature and a low applied pressure by performing a plurality of temporary compression steps S4.

  In the temporary compression step S4, the temporary pressing can be performed at a low pressure, for example, a pressure of 10 MPa to 13 MPa, preferably 11 MPa to 12 MPa. The temporary pressing time is shorter (approximately 0.1 to 5 seconds) than the subsequent main compression time. The temperature at the time of temporary pressing is not particularly adjusted, and may be room temperature (5 to 40 ° C.). The number of temporary pressings is one or more, and a molded body 5 having excellent strength can be obtained even at room temperature and low pressure. In terms of molding efficiency, the number of temporary pressings is preferably about 15 times or less, and more preferably 3 times in terms of increasing molding efficiency while obtaining the excellent strength of the molded body 5.

  After the temporary compression step S4, a compression molding step S5 is performed in which the mixed powder 4 in the container 17 is subjected to main compression (main pressing). In the compression molding step S5, in order to sufficiently compress the precursor of the molded body 5 obtained in the temporary compression step S4, pressurization is performed for a longer time than the temporary pressing time. The main pressing time in the compression molding step S5 is, for example, 1 hour or more. The main pressing time may be a time sufficient to form the molded body 5 depending on the type of the radioactive waste 1 or the blended powder 4. The main pressing can be performed at a low pressure and at a normal temperature, similarly to the temporary pressing.

  In the compression molding method of the present embodiment, the storage container 17 is held by the storage container holding device 19 through the temporary compression step S4 and the compression molding step S5. 3A to 3C are cross-sectional views schematically showing the container holding device 19 and the container 17. FIG. 3A is a diagram illustrating a state in which the storage container 17 is held by the storage container holding device 19. FIG. 3B is a diagram illustrating a state in which the contents of the storage container 17 are pressurized by the pressurizing piston 21 provided in the compression device 16 in the state of FIG. FIG. 3C is a diagram illustrating a state in which the storage container 17 is removed from the storage container holding device 19.

  For example, as shown in FIGS. 3A and 3B, in the temporary compression step S <b> 4 and the compression molding step S <b> 5, when the contents of the storage container 17 are pressurized by the pressurizing piston 21, the storage container 17 is configured. If the metal plate is thin, depending on the strength of the storage container 17 and the pressure applied by the pressure piston, the storage container 17 may be deformed or may be damaged by the deformation and the contents may be scattered.

  Therefore, in this embodiment, the storage container holding device 19 that surrounds and holds the outer periphery so as to suppress deformation of the storage container 17 is used. Further, the container holding device 19 aligns the positions of the container 17 and the pressure piston 21 so that the pressurizing piston 21 is inserted into the container 17 and fixes the upper part of the container 17. Thereby, it can prevent that the storage container 17 deform | transforms or is damaged by a deformation | transformation. Further, as shown in FIG. 3C, the storage container holding device 19 is configured so that the storage container 17 can be removed, so that the molding efficiency can be improved when the compression molding apparatus 10 repeatedly produces a plurality of molded bodies 5. Can be increased. In addition, the container holding device 19 can be composed of, for example, a metal plate.

  FIG. 4 is a view for explaining the clearance of the storage container 17 in the temporary compression step S4 and the compression molding step S5, and is a diagram showing a horizontal section of the storage container 17 held by the storage container holding device 19. As shown in FIG. 4, in the temporary compression step S <b> 4 and the compression molding step S <b> 5, when the contents of the storage container 17 are pressurized by the pressurization piston 21 of the compression device 16, the inner wall of the storage container 17 and the pressurization piston 21. It is preferable to provide a clearance (gap) C between the outer circumferences. By providing the clearance C, the air contained in the mixed powder 4 is likely to escape to the outside during compression. For this reason, since air hardly remains in the molded body 5, the strength of the molded body 5 can be improved.

  The width of the clearance C is preferably about 0.5 mm to 3 mm, and more preferably about 1 mm to 2 mm. When the clearance width is 0.5 mm or more, the air contained in the mixed powder 4 is easily extracted to the outside at the time of compression. When the clearance width is 3 mm or less, the contents are not easily protruded to the outside, and the deposit is formed. Easy to suppress. When the inner wall of the container 17 and the outer periphery of the pressure piston 21 are cylindrical, the width of the clearance C is calculated as a half value of the difference between the inner diameter of the container 17 and the outer diameter of the pressure piston 21. can do.

  In this way, the mixed powder 4 is compression molded in the storage container 17 to obtain a molded body 5. The ratio L / D of the height L to the diameter D of the molded body 5 is preferably 1.5 or less. L / D is 1.5 or less and it is easy to suppress a decrease in strength of the molded body 5. L / D can be adjusted by the amount of the inner diameter of the container 17, the radioactive waste 1, the hydraulic inorganic solidifying agent 2, and the water 3. The obtained molded body 5 is taken out of the compression device 16 together with the container 17 and cured or stored.

  According to the method for compressing and molding radioactive waste according to the present embodiment described above, a molded body having excellent strength can be formed at room temperature and with a relatively low pressure without applying heat.

  Next, the present invention will be described in more detail using examples.

(Examples 1 and 2)
In the examples, incineration ash (hereinafter also simply referred to as “incineration ash”) of municipal waste incinerators was used as simulated radioactive waste. 75% by mass of incinerated ash, 12.5% by mass of Portland cement (OPC) and 12.5% by mass of water were weighed, and then mixed to obtain a mixed powder. Incinerated ash has a volume-based average particle diameter of about 100 μm by laser diffraction scattering.

  Next, a part of the obtained mixed powder was collected and accommodated in a metal cylindrical container having an inner diameter of 250 mmφ. At this time, the amount of the mixed powder to be used was adjusted so that the finally obtained molded body had a height of 375 mm, that is, L / D was about 1.5.

  In Example 1, the entire amount of the mixed powder was accommodated in a container, then temporarily pressed, and then pressed (temporary pressing once). In Example 2, the mixed powder was divided into three parts and each was sequentially accommodated in a container. After each accommodation, the mixed powder was temporarily pressed, and after a total of three temporary pressings, the main pressing was performed (the number of temporary pressings was 3 times). ).

  The temporary pressing time was instantaneous (about 0.5 seconds), and the main pressing time was 6 hours in Example 1 and 4 hours in Example 2. The applied pressure was 10 MPa for all, and the temperature was not adjusted for all, and the test was performed at room temperature. Moreover, when performing temporary pressing and main pressing, the outer periphery and upper part of the container were held with a thick metal plate to prevent deformation. The clearance was 1 mm. After the resulting molded body was cured for 7 days, the compressive strength was measured. The results are shown in Table 1 together with the blending of each component in the mixed powder and the compression conditions.

(Examples 3 and 4)
In Examples 3 and 4, the relationship between the blending of each component in the mixed powder and the compression strength of the molded body was examined. The amount of incinerated ash was 80% by mass in Example 3, 85% by mass in Example 4, and the remainder was mixed at a Portland cement / water mass ratio of 1: 1 to obtain a mixed powder. Otherwise, a molded body was obtained under the same operation and conditions as in Example 2. The results are shown in Table 1 together with the blended powder and compression conditions.

(Examples 5-7)
In Examples 5 to 7, the relationship between the clearance width and the compression strength of the molded body was examined. In Example 1, a rod having a different diameter (pressure piston) is used, and the clearance is 0.5 mm in Example 5, 1 mm in Example 6, 2 mm in Example 7, and the other operations are the same as in Example 1. And the molding was obtained on condition. The results are shown in Table 1 together with the blended powder and compression conditions.

(Experimental Examples 1 and 2)
In Experimental Examples 1 and 2, the influence on the compression strength of the molded body when the value of L / D was changed was examined. L / D was set to 1 in Experimental Example 1 and 1.5 in Experimental Example 2, and was temporarily pressed under the same operation and conditions as in Example 1. The compressive strength of the molded body precursor after one temporary pressing was measured. The results are shown in Table 1 together with the blended powder and compression conditions.

(Comparative Examples 1-3)
As simulated radioactive waste, incinerated ash was used in Comparative Examples 1 and 3, and inorganic powder mainly composed of calcium phosphate was used in Comparative Example 2. In each case, 75% by mass of radioactive waste and the remainder were mixed with Portland cement and water at a mass ratio of 1: 1 to obtain mixed powders. The incinerated ash and the inorganic powder have a volume-based average particle diameter of about 100 μm by a laser diffraction scattering method. Thereafter, without pressing, in Comparative Examples 1 and 2, the pressure was 10 MPa for 1 hour, and in Comparative Example 3 the pressure was 10 MPa for 6 hours and the temperature was not adjusted to obtain a molded body. In Comparative Examples 1 to 3, the clearance is 1 mm and L / D is approximately 1.5. The obtained molded body was cured for 7 days, and then the compressive strength was measured. The results are shown in Table 1 together with the blended powder and compression conditions.

  From Table 1, it can be seen that in Examples 1 and 2 where the temporary pressing was performed once or more, compared to Comparative Examples 1 to 3 where the temporary pressing was not performed, the strength of the molded body was increased four times or more. For example, when the standard value of the strength of the molded body is 1.47 MPa or more of the low-level radioactive waste disposal standard, there is no tolerance without temporary pressing, but the standard strength is sufficiently satisfied by the effect of temporary pressing. A good molded body was obtained. This is considered to be the effect by the same effect | action as overprinting a molded object with small L / D. However, the molded body adhesion portion for each temporary pressing was not peeled off, and was integrated as a molded body.

  Moreover, from Examples 3 and 4, it can be seen that a molded body with excellent strength can be obtained by temporary pressing at a radioactive waste mixing ratio of 75% by mass or more.

  In addition, it can be seen from Experimental Examples 1 and 2 that the smaller the L / D, the higher the compression strength of the molded body precursor after temporary pressing and the higher the strength of the molded body.

(Reference Examples 1-3)
In the reference example, the influence on the compressive strength of the molded product when the ratio of the amount of Portland cement (OPC) and water was changed was examined for the case where temporary pressing was not performed. As simulated radioactive waste, the same incinerated ash and inorganic powder as in Comparative Examples 1 and 2 were used, and the amount of simulated radioactive waste was 75% by mass with respect to 100% by mass of the mixed powder. (OPC mass%, water mass%) is (19.6, 5.4), (13.75, 11.25), (12.5, 12.5) with respect to 100 mass% of the mixed powder. ), (11.25, 13.75), (7.5, 17.5), (0, 25). Mixed powders were prepared with the respective blends, accommodated in a container similar to the above so that the L / D was approximately 1.5, and pressed at 10 MPa for 1 hour with a clearance of 1 mm. About the obtained molded object, after curing like Example 1, compressive strength was measured. The results are shown in FIG.

  From FIG. 5, when the temporary pressing is not performed, the amount of OPC is 7.5 to 13.75% by mass, and any of incinerated ash and inorganic powder is used, which satisfies the standard value of the compression strength of the molded body. I understand that. Even when temporary pressing is performed, it is considered that the relationship between the mass ratio of OPC and water and the compression strength of the molded body shows the same tendency as when temporary pressing is not performed. Therefore, the mass ratio of OPC to water in the case of temporary pressing is the measurement error range from the median OPC: water = 1: 1 (12.5 mass%: 12.5 mass%) satisfying the above-mentioned standard value. A range of ± 10% in which is included was adopted.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Radioactive waste, 2 ... Hydraulic inorganic solidification material, 3 ... Water, 4 ... Mixed powder, 5 ... Molded object, 10 ... Compression molding apparatus, 11 ... Radioactive waste supply apparatus, 12 ... Hydraulic inorganic solidification material Supply device, 13 ... water supply device, 15 ... mixer, 16 ... compression device, 17 ... accommodating container, 18 ... mixed powder transfer device, 19 ... accommodating container holding device, 21 ... pressurizing piston, S1 ... metering step, S2 ... Mixing step, S3 ... Housing step, S4 ... Temporary compression step, S5 ... Compression molding step, C ... Clearance.

Claims (7)

A method for compression molding powdered radioactive waste,
A step of mixing the radioactive waste, a hydraulic inorganic solidifying material, and water to obtain a mixed powder, wherein the radioactive waste is 75% by mass or more with respect to 100% by mass of the mixed powder; The hard inorganic solidified material and water are mixed in an amount of 25% by mass or less in total and 0.9: 1.1 to 1.1: 0.9 in terms of mass ratio represented by the hydraulic inorganic solidified material: water. A mixing step;
A storage step of storing the mixed powder in a storage container;
A temporary compression step of temporarily compressing the mixed powder in the storage container in a state where the storage container is held by a storage container holding device;
A compression molding step of obtaining a molded body by subjecting the mixed powder in the storage container to a main compression in a longer time than the temporary compression step in a state where the storage container is held by the storage container holding device. A feature of a compression molding method for radioactive waste.   The method for compression molding radioactive waste according to claim 1, wherein the hydraulic inorganic solidifying material is Portland cement.   In the temporary compression step and the compression molding step, the contents of the container are pressurized by a pressure piston, and the width is 0.5 mm or more and 3 mm or less between the inner wall of the container and the outer periphery of the pressure piston. The method for compression molding radioactive waste according to claim 1 or 2, wherein a clearance is provided.   The ratio L / D of the height L with respect to the diameter D of the said molded object is 1.5 or less, The compression molding method of the radioactive waste of any one of Claim 1 thru | or 3 characterized by the above-mentioned. The pressurization time in the temporary compression step is instantaneous,
The pressurization time in the compression molding step is 1 hour or more,
The method for compressing and molding radioactive waste according to any one of claims 1 to 4, wherein the applied pressure in the temporary compression step and the compression molding step is 10 MPa or more and 13 MPa or less. A mixer for producing a powder mixture by mixing powdered radioactive waste, a hydraulic inorganic solidifying material, and water;
A radioactive waste supply device for supplying the radioactive waste in an amount of 75% by mass or more with respect to 100% by mass of the mixed powder to the mixer;
In the mixer, the total amount of the hydraulic inorganic solidified material and water is 25% by mass or less with respect to 100% by mass of the mixed powder, and the mass ratio of the hydraulic inorganic solidified material: water is 0.9. : 1.1 to 1.1: 0.9, a hydraulic inorganic solidified material supply device that supplies the hydraulic inorganic solidified material, and a water supply device that supplies the water;
A mixed powder transfer device for transferring the mixed powder in the mixer and storing it in a storage container;
A container holding device for holding the container;
A compression molding apparatus for radioactive waste, comprising: a compression apparatus that pressurizes the mixed powder in the container at a pressure of 10 MPa to 13 MPa. The compression device includes a pressure piston,
7. The radioactive waste compression molding apparatus according to claim 6, wherein a clearance having a width of not less than 0.5 mm and not more than 3 mm is provided between the inner wall of the container and the outer periphery of the pressure piston.

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