Method and system for forming waste body

Abstract

To reduce the generation of hydrogen gas in waste.SOLUTION: A waste forming method includes the steps of: mixing a solidification material and a boron compound into a mixture; and filling the mixture into a container storing radioactive waste, forming waste comprising solidified matter; and heating the waste to adjust the average pore diameter of the solidified matter to 10 nm or more and 50 nm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to methods and systems for forming waste bodies. [Background technology]

[0002] Low-level radioactive waste with relatively high radioactivity concentrations, such as metals activated by long-term neutron irradiation, such as control rods used in nuclear reactors, is being considered for burial disposal in an area about 50 to 100 meters below the ground surface. In its standards, the Atomic Energy Society of Japan assumes that the basic disposal method will be to place a solidified mixture of pore size control material and solidification material, including the treated radioactive waste, into a container, which is then sealed to form a waste body.

[0003] There is a concern that the sealing of the container may cause the moisture in the container to decompose due to radiation from radioactive waste with high radioactivity concentration, generating hydrogen gas, which may reach the lower limit of hydrogen combustion. In general, the hydrogen gas concentration is required to be 4% or less by volume in order to prevent combustion caused by hydrogen gas in the presence of oxygen. The Society's standard also restricts the hydrogen gas concentration to 4% or less by volume in the container. In other words, in addition to restrictions on the total radioactivity and moisture content of the radioactive waste, attention must also be paid to the generation of hydrogen from the radioactive waste and solidified materials in the container. This limits the amount of radioactive waste and solidified materials that can be stored, reducing the amount of radioactive waste that can be filled per waste body and causing an increase in the number of waste bodies. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5661492 specification [Patent Document 2] Patent No. 5807785 specification [Non-patent literature]

[0005] [Non-Patent Document 1] Atomic Energy Society of Japan Standard: Manufacturing requirements and inspection methods for waste packages for subsurface disposal: 2015 ISBN978-4-89047-383-0 [Non-Patent Document 2] Takahashi et al., "Effect of water state in cement hydrate samples on hydrogen gas generation," Report of the Central Research Institute of Electric Power Industry L (11020), 1-18, Intro 1-3, March 2013 [Non-Patent Document 3] Frederic Chupin et al, Water content and porosity effect on hydrogen radiolytic yields of geopolymers, Journal of Nuclear Materials, 494 (2017) 138-146 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to reduce the moisture content of radioactive waste, it is possible to dry the radioactive waste before placing it in a container. However, for example, containers with a capacity of 200 L or more or containers with a capacity of 1 m 3 It is difficult to dehydrate solidified bodies with a volume larger than this, and there is a risk of cracking and damage due to drying, as well as insufficient drying.

[0007] In an embodiment of the present invention, one of the objectives is to reduce the amount of hydrogen gas generated in the waste body. [Means for solving the problem]

[0008] The method for forming a waste body according to the embodiment includes: Pore ​​size adjustment material Boron compounds and By kneading the pore size adjusting material at a mass ratio of more than 0% and less than 5% to the solidifying material, Mixed The pore size adjusting material penetrates into the network of the solidified material. forming a mixture; filling a container for containing radioactive waste with the mixture to form a waste body including a solidified body; The container is not completely sealed, and the evaporated water vapor can be released to the outside. Heat it up Remove moisture, A step of adjusting the average pore size of the solidified body to 10 nm or more and 50 nm or less; sealing the waste body with a lid prior to burial disposal of the waste body; Equipped with: [Brief description of the drawings]

[0009] [Figure 1] 4 is a flowchart for explaining an example of a method for forming a waste body according to the first embodiment. [Diagram 2] FIG. 1 is a schematic diagram illustrating an example of a waste body formation system. [Diagram 3] FIG. 13 shows the results of a uniaxial compressive strength test of the solidified body after a one-month curing period. [Figure 4] FIG. 13 shows the results of a uniaxial compressive strength test of the solidified body after a curing period of six months. [Diagram 5] FIG. 1 shows the amount of hydrogen generated when solidified bodies of samples A, B, and C were irradiated with gamma rays for 17 hours. [Figure 6] FIG. 1 shows the results of measuring the average pore diameters of solidified bodies of samples A, B, and C. [Figure 7] FIG. 1 is a graph showing the relationship between the solidified body heating temperature and the average pore diameter for samples A, B, and C. [Figure 8] FIG. 1 is a graph showing the relationship between the G value of hydrogen gas generation and the average pore diameter when crushed and heated samples A to C are irradiated with gamma rays for 17 hours. [Figure 9] FIG. 13 is a diagram showing the results of comparing the relationship between the average pore diameter and the G value of hydrogen gas generation between samples A to C and a reference example. [Figure 10] FIG. 13 is a graph showing the water content of a solidified body after heat treatment and the G value of hydrogen gas generation. [Figure 11] FIG. 13 is a diagram showing the results of comparing the relationship between the water content and the G value of hydrogen gas generation between samples A to C and a reference example. [Figure 12] 10 is a flowchart for explaining an example of a method for forming a waste body according to the second embodiment. [Figure 13] FIG. 1 is a schematic diagram illustrating an example of a waste body formation system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described with reference to the drawings. In each embodiment, substantially the same components are denoted by the same reference numerals, and the description thereof may be omitted. The drawings are schematic, and the relationship between the thickness of each part and the planar dimensions, the thickness ratio of each part, etc. may differ from the actual ones.

[0011] (First embodiment) 1 is a flow chart for explaining an example of a method for forming a waste body according to the first embodiment. The example of the method for forming a waste body according to the first embodiment includes a mixing step S1-1, a filling step S1-2, and a heating step S1-3.

[0012] The waste body of the first embodiment can be formed, for example, by using a forming system 1A shown in Fig. 2. Fig. 2 is a schematic diagram showing an example of a waste body forming system. The forming system 1A shown in Fig. 2 includes a material supplying section 100 having a storage tank 101 and a storage tank 102, a mixing section 200 having a kneading tank 201 and an agitating blade 202, and a heating section 300 having a heating device 301 or a heating chamber 302.

[0013] The mixing step S1-1 includes mixing a solidification material and a pore size adjusting material to form a mixture.

[0014] The solidification material functions as a binder for forming a solidified body. The solidification material includes, for example, a geopolymer composition. The geopolymer is one of inorganic polymers. The geopolymer is obtained by a reaction including a Si-based material such as silicon dioxide, a Si-Al-based material such as metakaryon, and an alkaline material such as potassium silicate (K2SiO3) or potassium hydroxide (KOH). The reaction may be performed by adding moisture such as water.

[0015] The solidification material is not limited to geopolymers, and may include compositions of materials such as cement, ceramics, which are fired by heat treatment of inorganic materials, glass, asphalt, or plastics. The solidified body formed using the solidification material includes the above materials.

[0016] The solidification material is supplied from a storage tank 101 to a kneading tank 201. The storage tank 101 is provided to store the solidification material. The storage tank 101 is connected to the kneading tank 201 via, for example, a pipe. When the solidification material is composed of a plurality of materials, each material may be stored in a different storage tank and supplied to the kneading tank 201.

[0017] The pore size adjusting material is a material for adjusting the pore size of the solidified body formed by solidifying the solidification material. Examples of the pore size adjusting material include boron compounds such as boric acid (H3BO3). The material is not limited to boron compounds, and other materials may be used as long as they can control the pore size of the solidified body.

[0018] The average particle size of the pore diameter adjusting material is preferably, for example, 355 μm or less. The finer the particle size is, for example, 355 μm or less, the easier it is to mix and the more reactive it is. The average particle size of the pore diameter adjusting material can be measured, for example, by using a 355 μm sieve or a particle size distribution meter.

[0019] The pore diameter adjusting material is supplied from the storage tank 102 to the kneading tank 201. The storage tank 102 is provided to store the pore diameter adjusting material. The storage tank 102 is connected to the kneading tank 201 via, for example, a pipe.

[0020] FIG. 1 shows a configuration in which the storage tank 101 and the storage tank 102 are connected to the kneading tank 201 via a single pipe, but this is not limited thereto, and the storage tank 101 and the storage tank 102 may be connected to the kneading tank 201 via separate pipes.

[0021] The solidification material and the pore diameter adjusting material are mixed by kneading them in a kneading tank 201 using an agitator 202. In the mixture, the mass ratio of the pore diameter adjusting material to the solidification material is preferably greater than 0% and less than 5%, and more preferably greater than 1% and less than 5%. If it is greater than 5%, the strength of the solidified body may be significantly reduced.

[0022] In the filling step S1-2, the mixture is filled into a container 12 that contains radioactive waste 11, thereby forming a waste body 10A having the radioactive waste 11, the container 12, and a solidified body 13A. The mixture is filled into the container 12 from a kneading tank 201 through piping in a filling section provided in the formation system 1A, for example.

[0023] Examples of the radioactive waste 11 include activated metals and high-dose resins (radioactive waste with a high concentration of radioactive nuclides, such as activated metals activated by long-term neutron irradiation of control rods, channel boxes, etc. used in a reactor, and used resins generated in reactor water purification systems of nuclear reactors, etc.). The shape of the radioactive waste 11 is not particularly limited, and may be, for example, granular, powdery, plate-like, tubular, lump-like, or liquid. Examples of the container 12 include drums and the like.

[0024] The solidified body 13A is a semi-hardened or hardened body of the mixture obtained in the filling step S1-2. The solidified body 13A preferably covers the radioactive waste 11.

[0025] Although the forming system 1A shown in FIG. 2 shows an out-drum type, the present invention is not limited to the out-drum type, and an in-drum type in which a stirring blade is provided in a container and there is no kneading tank may be used.

[0026] The heating step S1-3 includes a process of heating the solidified body 13A. The heating step S1-3 is performed by heating the waste body 10A, for example, in a heating device 301 for heating one by one or continuously, or in a batch-type heating chamber 302 for simultaneously heating multiple waste bodies.

[0027] The heating temperature can be controlled in the heating device 301 and the heating chamber 302. The waste body 10A is transported from the loading section to the heating device 301 or the heating chamber 302 by using, for example, a transport mechanism. The heating chamber 302 can heat a plurality of waste bodies 10A in the same process, as shown in FIG.

[0028] The waste body 10A may be heated in a state where the water vapor evaporated by heating can be released to the outside without being completely sealed in the container. For example, the above state can be achieved by attaching an openable lid to the container. This allows the solidified body 13A to be heated to remove moisture from the waste body 10A. The container is then sealed with a lid before the waste body is buried.

[0029] The solidified body 13A has a porous structure. The average pore size of the solidified body 13A can be adjusted by heating the solidified body 13A. This is because, by adding a pore size adjuster, the pore size adjuster penetrates into the network of the solidified material to increase the average pore size of the solidified body 13A, or because the solidification speed of the solidified body decreases, generating bubbles.

[0030] By increasing the average pore size, the contact area between the water in the solidified body 13A and the solidified body 13A can be reduced, thereby suppressing the energy transfer from the solidified body 13A and reducing the amount of hydrogen gas generated in the waste body 10A.

[0031] The average pore diameter of the solidified body 13A is preferably 10 nm or more and 50 nm or less, more preferably 12 nm or more and 50 nm or more and 50 nm or less, and even more preferably 16 nm or more and 50 nm or less. If the average pore diameter is less than 10 nm, the contact area between the water in the solidified body 13A and the solidified body 13A increases, and the amount of hydrogen gas generated increases. If the average pore diameter exceeds 50 nm, the strength decreases and the function for solidifying radioactive waste becomes insufficient. The average pore diameter can be measured, for example, by measuring the pore size distribution using a nitrogen gas adsorption method.

[0032] The heating temperature in the heating step S1-3 is preferably 120°C or higher and 1000°C or lower. The heating time in the heating step S1-3 is preferably 12 hours or longer. There is no particular upper limit to the heating time, but it is believed that physical properties such as pore size will not change if the heating is performed for 12 hours or longer. By controlling the heating temperature and heating time in the heating step S1-3 within the above ranges, the average pore size of the solidified body 13A can be adjusted to 10 nm or higher and 50 nm or lower.

[0033] The example of the method for forming the waste body of the first embodiment may further include a curing step. The curing step allows the waste body 10A after the heating step S1-3 to be cured, so that the reaction of the solidified body can be further promoted. The curing step is performed, for example, by leaving the waste body 10A in a room temperature and pressure environment.

[0034] As described above, in the waste body forming method of the embodiment, the pore size adjuster is added to the solidified material in the mixing step, and the waste body is then heated to adjust the average pore size of the solidified body to 10 nm or more and 50 nm or less. This reduces the amount of hydrogen generation from the solidified body.

[0035] Here, an example of the evaluation results of the characteristics of the solidified body containing the solidification material and the pore diameter adjusting material, but not containing radioactive waste, will be described. Table 1 shows each material of the solidified body sample used in the evaluation and its mass ratio (%).

[0036] [Table 1]

[0037] In Samples A to C, the solidification material includes metakaolin, silica fume which is an amorphous porous material containing silicon oxide (SiO2), potassium silicate solution (K2SiO3) having a mass percent concentration of 30%, potassium hydroxide (KOH), and water.

[0038] Samples B and C contain boric acid (H3BO3) added as a pore size adjuster to Sample A as the standard solidified material. The mass ratio of boric acid to the solidified material in this case is 1% for Sample B and 5% for Sample C.

[0039] FIG. 3 is a diagram showing the results of an uniaxial compressive strength test of the solidified body after a one-month curing period. The uniaxial compressive strength shown in FIG. 3 is a value measured using a compressive strength tester. It can be seen from FIG. 3 that sample C does not have sufficient strength and the uniaxial compressive strength cannot be measured. This shows that the mass ratio of the pore size adjusting material to the solidification material is preferably less than 5%. Furthermore, FIG. 4 is a diagram showing the results of an uniaxial compressive strength test of the solidified body after a six-month curing period. It can be seen from FIG. 4 that sample C also hardens when the curing period is six months.

[0040] FIG. 5 shows the amount of hydrogen generated when the solidified bodies of Samples A, B, and C were irradiated with gamma rays for 17 hours. Comparing Samples A, B, and C, the amount of hydrogen gas generated relative to the absorbed dose per mass of the solidified body (G value of hydrogen gas generation (10 -7 It can be seen that the hydrogen gas generation rate (mol / J) decreases as the addition rate of boric acid increases. The amount of hydrogen gas generated was measured using a gas chromatograph. Figure 6 shows the results of measuring the average pore diameter of the solidified body at this time. The average pore diameter was measured by pore size distribution measurement using the nitrogen gas adsorption method. The higher the addition rate of boric acid, the larger the average pore diameter becomes, and a comparison with Figure 5 confirms a tendency for the amount of hydrogen gas generated to decrease as the average pore diameter increases.

[0041] Next, the changes in the solidified bodies of Sample A, Sample B, and Sample C due to heating will be described. Figure 7 is a diagram showing the relationship between the heating temperature and the average pore size of the solidified bodies of Sample A, Sample B, and Sample C. Figure 7 shows the average pore size of each sample after crushing Sample A, Sample B, and Sample C to a particle size of 355 μm or less and heating for 12 hours. The heating temperatures are 120°C, 200°C, 300°C, and 1000°C. From Figure 7, it can be confirmed that the average pore size increases not only when Sample C but also when Sample B is used by performing heating treatment at a temperature of 120°C or more and 1000°C or less.

[0042] FIG. 8 shows the relationship between the G value of hydrogen gas generation and the average pore size of the solidified bodies when samples A to C, which were subjected to the above-mentioned crushing and heat treatment, were irradiated with gamma rays for 17 hours. It can be seen from FIG. 8 that the G value decreases as the average pore size increases. For example, when the G value is 0.05×10 -7 In order to achieve a concentration of mol / J or less, it is preferable that the average pore size of the solidified body is 10 nm or more.

[0043] FIG. 9 is a diagram showing the comparison results of the relationship between the average pore size and the G value of hydrogen gas generation between Samples A to C and the Reference Example. The literature values ​​in FIG. 9 show the relationship between the average pore size and the G value of the sample described in the non-patent document (Frederic Chupin et al, Water content and porosity effect on hydrogen radiolytic yields of geopolymers, Journal of Nuclear Materials, 494 (2017) 138-146). The experimental values ​​in FIG. 9 show the relationship between the average pore size and the G value of Samples A to C shown in FIG. 8. It can be seen from FIG. 9 that Samples A to C can reduce the G value more than the samples described in the non-patent document.

[0044] Figure 10 shows the relationship between the moisture content of the solidified body after heat treatment and the G value of hydrogen gas generation. From Figure 10, it can be seen that when the heating temperature is 1000°C, there is a large decrease in moisture content, but when the heating temperature is 300°C or less, the effect of heat treatment on the moisture content is minor. This shows that the decrease in moisture content due to heat treatment is not the main cause of the decrease in the G value of hydrogen gas generation. On the other hand, this does not mean that there is no correlation at all between the moisture content and the G value of hydrogen gas generation.

[0045] FIG. 11 is a diagram showing the results of comparing the relationship between the moisture content and the G value of hydrogen gas generation between Samples A to C and the Reference Example. The literature values ​​in FIG. 11 show the relationship between the average pore diameter and the G value of the samples described in the above non-patent document. The experimental values ​​in FIG. 11 show the relationship between the average pore diameter and the G value of Samples A to C. It can be seen from FIG. 11 that the experimental values ​​have a gentler gradient in the data distribution than the literature values. This shows that the moisture content dependency of the amount of hydrogen gas generated is reduced by adjusting the average pore diameter in Samples A to C.

[0046] Second Embodiment 12 is a flow chart for explaining an example of a method for forming a waste body according to the second embodiment. The example of the method for forming a waste body according to the second embodiment includes a mixing step S2-1, a filling step S2-2, and a heating step S2-3.

[0047] The waste body of the second embodiment can be formed, for example, by using a forming system 1B shown in FIG. 13. FIG. 13 is a schematic diagram showing an example of a forming system for a waste body. The forming system 1B shown in FIG. 13 includes a material supplying section 100 having a storage tank 101, a storage tank 102, and a storage tank 103, a mixing section 200 having a kneading tank 201 and an agitating blade 202, and a heating section 300 having a heating device 301 or a heating chamber 302. Note that, for the same parts of the forming system 1B as those of the forming system 1A, the description of the forming system 1A can be appropriately used.

[0048] The mixing step S2-1 includes a process of mixing a solidification material, a pore diameter adjusting material, and radioactive waste to form a mixture. The explanation of the solidification material, the pore diameter adjusting material, and the radioactive waste can be appropriately referred to the explanation of the first embodiment.

[0049] The radioactive waste is supplied from the storage tank 103 to the kneading tank 201. The storage tank 103 is provided to store the radioactive waste. The storage tank 103 is connected to the kneading tank 201 via, for example, a pipe.

[0050] FIG. 13 shows a configuration in which the storage tanks 101 to 103 are connected to the kneading tank 201 via a single pipe, but this is not limited to this, and the storage tanks 101 to 103 may be connected to the kneading tank 201 via separate pipes.

[0051] The solidification material, the pore size adjusting material, and the radioactive waste are mixed in a kneading tank 201 by kneading with an agitator 202 .

[0052] In the filling step S2-2, the mixture is filled into the container 12 to form a solidified body 13B, thereby forming a waste body 10B having the container 12 and the solidified body 13B. The mixture may be filled into the container 12 in a filling section provided in the formation system 1B, for example. The description of the container 12 can be appropriately cited from the description of the first embodiment.

[0053] The solidified body 13B is a semi-hardened or hardened body of the mixture in the filling step S2-2.

[0054] Although the forming system 1B shown in FIG. 12 shows an out-drum type, the present invention is not limited to the out-drum type, and an in-drum type in which a stirring blade is provided in a container and there is no kneading tank may be used.

[0055] The heating step S2-3 includes a process of heating the solidified body 13B. The solidified body 13B is heated, for example, by heating the waste body 10B in the heating device 301 or the heating chamber 302. The description of the heating device 301 or the heating chamber 302 of the first embodiment can be appropriately used for the description of the heating device 301 or the heating chamber 302.

[0056] The waste body 10B may be heated in a state where the water vapor evaporated by heating can be released to the outside without being completely sealed in the container. For example, the above state can be achieved by attaching an openable lid to the container. This allows the solidified body 13B to be heated to remove moisture from the waste body 10B. The container 12 is then sealed with a lid before the waste body 10B is buried.

[0057] The solidified body 13B has a porous structure. The average pore size of the solidified body 13B can be adjusted by heating the solidified body 13B. The explanation of the solidified body 13A can be used for the rest of the explanation of the solidified body 13B. The explanation of the heating step S2-3 can be used for the rest of the explanation of the heating step S1-3.

[0058] The example of the method for forming the waste body of the second embodiment may further include a curing step. The curing step allows the waste body 10B after the heating step S2-3 to be cured, so that the reaction of the solidified body can be further promoted. The curing step is performed, for example, by leaving the waste body 10B in a room temperature and pressure environment.

[0059] As described above, in the waste body forming method of the embodiment, the solidification material, the pore size adjuster, and the radioactive waste are mixed in the mixing step, and then the heat treatment is performed, so that the average pore size of the solidified body can be adjusted to 10 nm or more and 50 nm or less. This makes it possible to reduce the amount of hydrogen generated in the waste body. For other explanations, the explanations of the first embodiment can be used as appropriate.

[0060] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0061] Reference Signs: 1A...forming system, 1B...forming system, 10A...waste body, 10B...waste body, 11...radioactive waste, 12...container, 13A...solidified body, 13B...solidified body, 100...material supply section, 101...storage tank, 102...storage tank, 103...storage tank, 200...mixing section, 201...kneading tank, 202...agitating blade, 300...heating section, 301...heating device, 302...heating chamber.

Claims

1. A step of mixing the solidification material and the boron compound as a pore diameter adjusting material by kneading the solidification material in a mass ratio of the pore diameter adjusting material to the solidification material that is greater than 0% and less than 5% to form a mixture in which the pore diameter adjusting material has penetrated into the network of the solidification material; Filling a container containing radioactive waste with the mixture to form a waste body including a solidified body; a step of heating the waste body in a state where the waste body is not completely sealed in the container and evaporated water vapor can be released to the outside to remove moisture, and adjusting the average pore size of the solidified body to 10 nm or more and 50 nm or less; sealing the waste body with a lid prior to burial disposal of the waste body; A method for forming a waste body, comprising:

2. A step of mixing a solidification material, a boron compound as a pore diameter adjusting material, and radioactive waste by kneading the solidification material with a mass ratio of the pore diameter adjusting material to the solidification material being greater than 0% and less than 5%, to form a mixture in which the pore diameter adjusting material has penetrated into the network of the solidification material; filling a container with the mixture to form a waste body including a solidified mass; a step of heating the waste body in a state where the waste body is not completely sealed in the container and evaporated water vapor can be released to the outside to remove moisture, and adjusting the average pore size of the solidified body to 10 nm or more and 50 nm or less; sealing the waste body with a lid prior to burial disposal of the waste body; A method for forming a waste body, comprising:

3. The method of claim 1 or claim 2, wherein the waste body is heated to a temperature of 120° C. or higher.

4. The method of claim 1 , wherein the solidified body comprises a geopolymer, a cement, a ceramic, a glass, an asphalt, or a plastic.

5. A material supply source having a first tank for containing a solidification material and a second tank for containing a boron compound which is a pore size adjusting material; a mixing section for mixing the solidified material supplied from the first tank and the boron compound supplied from the second tank by kneading the solidified material with a mass ratio of the pore diameter control material to the solidified material being greater than 0% and less than 5%, thereby forming a mixture in which the pore diameter control material has penetrated into the network of the solidified material; a filling section for filling the mixture supplied from the mixing section into a container for accommodating radioactive waste to form a waste body including a solidified body; a heating unit for heating the waste material in a state where the waste material is not completely sealed in the container and the evaporated water vapor can be released to the outside to remove moisture and adjust the average pore size of the solidified material to 10 nm or more and 50 nm or less; a waste sealing section for sealing the waste with a lid before the waste is buried; A waste body forming system comprising:

6. A material supply source having a first tank for containing a solidification material, a second tank for containing a boron compound which is a pore size adjusting material, and a third tank for containing radioactive waste; a mixing section for mixing the solidified material supplied from the first tank, the boron compound supplied from the second tank, and the radioactive waste supplied from the third tank by kneading the solidified material with a mass ratio of the pore diameter adjusting material to the solidified material being greater than 0% and less than 5%, thereby forming a mixture in which the pore diameter adjusting material has penetrated into the network of the solidified material; a filling section for filling a container with the mixture supplied from the mixing section to form a waste body including a solidified body; a heating unit for heating the waste material in a state where the waste material is not completely sealed in the container and the evaporated water vapor can be released to the outside to remove moisture and adjust the average pore size of the solidified material to 10 nm or more and 50 nm or less; a waste sealing section for sealing the waste with a lid before the waste is buried; A waste body forming system comprising:

7. The system according to claim 5 or claim 6, wherein the heating section heats the waste body to a temperature of 120° C. or higher.

8. The system of claim 5 , wherein the solidified body comprises a geopolymer, a cement, a ceramic, a glass, an asphalt, or a plastic.

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