JPH0246119B2 - HOSHASEIHAIKIBUTSUNOGENYOKOKASHORIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a volume reduction and solidification treatment method for radioactive waste generated from radioactive material utilization facilities such as nuclear power plants.

Conventionally, the solidification treatment method for radioactive waste is as follows:
Commonly used methods include adding cement, asphalt, or plastic to radioactive waste and solidifying it homogeneously, but this treatment method is an excellent volume reduction method because the mixing ratio of radioactive waste in the solidified material is small. There are disadvantages that cannot be obtained sexually. Recently, dry waste is solidified into granules either alone or with the addition of a binder, and the resulting granules are stored as an interim storage method until the final disposal method is decided. Methods for disposing of radioactive waste by storing it in containers such as tanks and drums have been developed and are being put into practical use. When radioactive waste that has been solidified into particles by this method is finally solidified, a solidifying material such as asphalt or plastic is injected into the gaps between the solidified particles already filled in a drum can, etc. Filling is commonly done. However, when using this method, the granules are simply filled into a container and the solidifying material is injected to form the final solidified material, so the filling rate of the particles is low, and 35 to 60% of the container volume is filled with the solidifying material. Therefore, the volume reduction properties are poor and do not meet today's demands for volume reduction properties in solidification processing.

Also, recently, according to Japanese Patent Application Laid-Open No. 57-17900,
A technology for treating radioactive waste using a solidified material consisting of 100 parts by weight of chlorinated polyethylene resin and 100 to 500 parts by weight of radioactive waste has been developed. Since this solidified material is dumped into the ocean, the range of the mixing ratio of radioactive waste is set so that the density is 1.2 or more and the unconfined compressive strength is 150 kg/cm ² or more. It is also said that it is effective to mold a chlorinated polyethylene resin while crosslinking it using an organic peroxide or an organic peroxide and a crosslinking aid in order to increase the unconfined compressive strength of the solidified product. However, this solidified product also has the drawback that the mixing ratio of radioactive waste to chlorinated polyethylene resin is low and the amount of chlorinated material used is not small, so it is extremely difficult to use this solidified material as a solidified material for intermediate storage. It is disadvantageous. Furthermore, the solidified material cross-linked by adding organic peroxide or cross-linking aid is brittle and easily destroyed, so the amount of radioactive waste mixed must be kept small, and it must be treated at high temperatures for cross-linking. It has drawbacks and is not a sufficient technology for producing solidified materials.

The present invention was made in order to eliminate the above-mentioned drawbacks of the prior art, and an object of the present invention is to be able to stably solidify radioactive waste at a high volume reduction rate, and also to solidify radioactive waste within a storage container. It is an object of the present invention to provide a method for volume reduction and solidification of radioactive waste, which allows obtaining a homogeneous and strong solidified body with a small porosity.

That is, the present invention provides rubber-like elastic polymeric material 100
parts by weight and 550 to 1500 parts by weight of dry radioactive waste,
Without adding crosslinking agent, and above 30℃ and 120℃
granulation by mixing, kneading, or kneading without melting at a temperature below 120°C, and compressing the resulting granulated aggregate at a temperature below 120°C to form a strong and homogeneous solidified body. This is a method for volume reduction and solidification of radioactive waste.

According to the method of the present invention, waste liquids and slurries generated from facilities such as nuclear power plants can be completely reduced in volume and solidified, and the target wastes for the method of the present invention include the following.

(1) Used ion exchange resin There are two types of used ion exchange resin: one with a particle size of approximately 0.5m/mφ and the other called powderex (product name). , condensate desalination systems, fuel pool water desalination systems, radioactive waste liquid treatment systems, etc., and pressurized water reactors (PWRs).
Bypass purification system (purification desalination, deboronization),
These occur in fuel pit desalination, extracted coolant processing systems, etc.

(2) Concentrated waste liquid Refers to chemical waste liquid (resin recycling waste liquid, etc.) that has been evaporated and concentrated, and has a moisture content of around 80%.
The main component is Na ₂ SO ₄ (sodium sulfate or borax).

(3) Waste liquid containing corrosion products generated from equipment and piping (referred to as crud) Generated from equipment and piping that come into contact with fluids.

The main component is Fe ₂ O ₃ .

(4) Filter sludge Occurs from equipment drains, floor drains, etc.
The main ingredient is a pulp-like fine powder filter aid.

(5) Incineration ash Exit the incinerator.

The rubber-like elastic polymer substance used as a binder for dried radioactive waste in the method of the present invention is:
It refers to a group of polymeric substances called elastomers that exhibit rubber-like elastic behavior in a physical sense within the operating temperature range. 500
It is preferable to use Kg/ ^cm2 . Some types of plastics exhibit Young's modulus values within the above range due to their amorphous nature or chlorination ratio; for example, chlorinated polyethylene (chlorinated polyethylene), which is usually treated as a thermoplastic resin. At a chlorine content of 20 to 50%, the crystalline one is plastic-like, but the amorphous one has rubber-like elasticity and can be used as a binder in the process of the invention.

Examples of rubber-like elastic polymeric substances that can be used as binders in the method of the invention are natural rubbers and synthetic rubbers, and more specifically the following: natural rubbers, hydrochloric acid rubbers, etc. Derivatives: Olefin-based synthetic rubbers such as isoprene, isobutylene, butyl rubber, chlorinated polyethylene, ethylene-propylene copolymer elastomer, etc.;
Butadiene-based synthetic rubbers, such as butadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, methylbutadiene, chloroprene, styrene-butadiene-acrylonitrile copolymer, and the like. In addition to this, urethane rubber, silicone rubber, etc. can also be used. These rubbery elastic polymeric materials can be used alone or in combination.

According to the method of the present invention, the contamination rate of waste with rubber-like elastic polymer substances alone is higher than that of thermoplastic resins and thermosetting resins, and it can be used as a binder as it is, but dioctyl phthalate can be used as a binder. When used together when filling a rubber-like elastic polymer material, it is possible to highly fill the dry waste into the rubber-like elastic polymer material without reducing the compressive strength of the obtained pellets, so it is particularly preferably added. The blending ratio is 10 to 100 parts by weight, preferably 100 parts by weight of the rubber-like elastic polymer material.
30 to 70 parts by weight.

In addition, a plasticizer such as liquid rubber, such as nitrile rubber, and a lubricant such as lead stearate can be added. Particularly in the case of chlorinated synthetic rubber, it is preferable to add a stabilizer such as tribasic lead sulfate. These additives are common plasticizers, lubricants, and stabilizers in synthetic rubber, and their preferred blending ratio is 10 to 10% of the rubber-like elastic polymer material.
100% by weight, more preferably 30-70% by weight plasticizer, 0.5-2% by weight lubricant and 5-20% by weight stabilizer.

In the method of the present invention, a crosslinking agent such as an organic peroxide or a crosslinking agent such as an organic peroxide and a crosslinking aid such as triallyl isocyanurate must not be added. A granulated material obtained by kneading and granulating with a binder containing such a crosslinking agent and a crosslinking aid has too high a hardness and becomes brittle, and therefore is not suitable for the volume reduction solidification treatment method of the present invention.

The optimum blending ratio of the rubber-like elastic polymer material and radioactive waste in the method of the present invention will be explained. In the case of dried concentrated waste liquid from nuclear power plants, 550~
1500 parts by weight, preferably 1200 to 1300 parts by weight can be blended. By adding as much dried concentrated waste liquid as possible, the blending ratio of the dried product in the resulting solidified product can be increased, and the treatment effect of the rubber-like elastic polymer substance can be enhanced. however
Addition of 1,500 parts by weight or more of the dry matter is not preferable because the mechanical strength of the granules produced by a kneading granulator, a preketting machine, etc. will decrease.
If the amount of the dried material is less than 550 parts by weight, the volume reduction properties will be poor, the processing efficiency of the rubber-like elastic polymeric material will be reduced, and the amount used will be increased. In addition, instead of concentrated waste liquid, used ion exchange resin (granular and powder) generated from nuclear power plants, dried products such as filter sludge, and incineration ash can be used for 100 parts by weight of rubber-like elastic polymer substances. 550
~1200 parts by weight, preferably 900 to 1000 parts by weight can be blended. Addition of 1,200 parts by weight or more of the dry material is not preferable because the mechanical strength of the granulated product produced by a kneading granulator or the like decreases.

The granulated material obtained by the method of the present invention has a smooth surface and is strong and resistant to impact, so during the process of transporting it to a storage tank, during storage, and during the process of taking it out from the storage tank and transporting it to a compressor for compression treatment. It is easy to handle and is highly safe as it prevents the generation of dust at the operational stage such as putting it into a compressor mold and filling it into a storage container such as a drum can. In other words, if waste material is simply kneaded with rubber-like elastic polymer material without granulation, it will be flaky and prone to chipping and peeling, and scattering of these chips and peelings will be a problem, making it unsuitable for storage and transportation. . When storing or compressing the granulated material obtained by the method of the present invention, it is necessary to store a material that is simply kneaded with a rubber-like elastic polymer material and dry radioactive waste but is not shaped into particles. This has the advantage that there is very little powder scattering at each step of the operation compared to the case of compressing or compressing.

Further, the granulated material according to the present invention itself has a dense structure, and when it is filled into a mold and compressed, the pressurizing time can be shortened.

Furthermore, the particulate material according to the present invention itself has a better volume reduction rate than conventional products and has a high radioactive waste contamination rate.

Particulate materials for intermediate storage of radioactive waste must have sufficient compressive strength and drop strength during transportation and storage, as well as fire resistance, temperature resistance, abrasion resistance, and radiation resistance. Must be. The properties of the particulate material made of 100 parts by weight of a rubber-like elastic polymeric material and 550 to 1,500 parts by weight of dried radioactive waste according to the present invention are extremely good as shown below, and the solidified material is suitable for intermediate storage. It has favorable properties for obtaining.

(1) Compressive strength Since the particulate material of the present invention has the properties of a rubber-like elastic substance, the pellets do not break due to compression. Furthermore, deformation due to its own weight during storage is minimal, being less than 3% even when stored at a height of 20 m.

(2) Drop strength The granulated material of the present invention does not break due to the impact of dropping from a height considered in the treatment process, and the weight loss due to breakage is extremely small. The weight loss due to damage when dropped from a height of 20 m is 0 to 0.01%.

(3) Fire resistance Particulates of concentrated waste liquid and incineration ash are nonflammable, and particulates of other radioactive wastes are flame retardant, so there is no problem with fire resistance when storing pellets.

(4) Moisture Resistance Since the particulate material according to the present invention contains a rubber-like elastic polymer substance as a binder, it has excellent moisture resistance, and even if it absorbs moisture, no cracks will occur.

(5) Wear resistance Although it is undesirable for dust to be generated due to abrasion during transfer, approximately 50 particles were placed in a ball mill and rotated at 100 rpm for 30 minutes to simulate the process of transferring granules according to the present invention. It was found that the abrasion loss rate was 0.01% of the purchased amount, which caused no problems in transportation.

(6) Radiation resistance Even when the particulate material of the present invention is irradiated with radiation of 10 ⁷ rad, no decrease in strength is observed, and the radiation dose absorbed from ordinary radioactive waste is sufficiently safe.

Therefore, 100 parts by weight of a rubber-like elastic polymer material, such as a chlorinated polyethylene resin, is mixed with dried concentrated waste liquid.
The granulated material according to the present invention containing 550 to 1,500 parts by weight or 550 to 1,200 parts by weight of used ion exchange resin (granules and powders), filter sludge and incineration ash can be used as a solidified material for intermediate storage. It has favorable physical properties.

These particulate products according to the present invention are made by adding 100 parts by weight of conventional chlorinated polyethylene resin to 100 parts by weight of dry waste.
It is extremely superior in treatment efficiency and volume reduction properties to compositions containing ~500 parts by weight.

In the method of the present invention, the aggregate of these particulates is compacted at a temperature below 120° C. to form a strong and homogeneous solid, either after intermediate storage to reduce the radioactivity or without intermediate storage. In this compression process, the magnitude of the compression force to be applied to the aggregate of the granules depends on the type of radioactive waste contained in the granules and the mixing ratio of the rubber-like elastic polymer material and radioactive waste. It's different. Generally about 200-300Kg/cm ²
Homogeneous solidification can be obtained with a compression force of
In order to obtain a strength higher than that of the granulated product, a pressure of about 400 to 500 Kg/cm 2 or higher, preferably 1000 Kg/cm ² or higher than the granulation pressure at which the granulated product was obtained using a kneading granulator etc.
It is necessary to compress with a compression force of Kg/cm ² or more, and depending on the type of waste, it may be desirable to compress it to a compression force of 2000 Kg/cm ² or more.

The higher the temperature in the above compression process, the lower the compression force can be used for the compression process, but if it exceeds 120℃, the decomposition of radioactive waste and the plasticity of the rubber-like elastic polymer material will increase more than necessary. It's not appropriate. Furthermore, when amorphous polyethylene resin chloride with a chlorine content of 20 to 50% is used as a rubber-like elastic polymer material, it loses its rubber-like elasticity and becomes plastic-like at -20 to -35°C.
In order to maintain rubber-like elasticity, it is necessary to carry out the compression process at a temperature of -20 to -35°C or higher. Generally, the compression step of the present invention is carried out at a temperature of 10-120°C, preferably 50-90°C.

Embodiments of the method of the present invention will be described with reference to process diagrams.

A solution or slurry containing radioactive waste generated at a nuclear power plant or the like is once stored in a stock solution supply tank 1 and then guided to a dryer 4 by a stock solution supply pump 2. Granular used ion exchange resin is difficult to dry as it is, so in order to improve performance after drying, an in-line crusher 3 is installed between the stock solution supply pump and the dryer to crush the resin particles in a slurry state. You can also do that. In the dryer 4, it is generally preferable to dry a waste solution or slurry with a concentration of 5 to 20% by weight to a moisture content of 5% by weight or less, but for wastes that are difficult to dry, such as filter sludge, the moisture content is There is no particular problem in kneading and granulating even if the amount is about 30% by weight. The dryer 4 is preferably a vacuum thin film dryer or a vacuum drum type dryer, for example. A moisture meter 5 checks whether the waste dried in the dryer has reached a predetermined moisture content. High moisture content dry waste that has not been dried to a predetermined moisture content is returned to the return tank 6, diluted with water, discharged from the system by the return pump 7, and returned to the stock solution supply tank 1. The waste dried to a predetermined moisture content is once stored in a storage tank 20 and then periodically transferred to a weighing device 8. On the other hand, the rubber-like elastic polymer material mixed with the stabilizer is transferred from the rubber-like elastic polymer material hopper 9 to the meter 8. A liquid plasticizer, such as dioctyl phthalate, is then supplied from the plasticizer reservoir 22 to the meter 8 . In this manner, a mixture consisting of dry waste, a rubber-like elastic polymer material containing additives, and a plasticizer is weighed in a predetermined weight ratio in the weighing device, and then allowed to fall naturally into the mixer 10. The mixture consisting of the dry waste and the rubber-like elastic polymer material, etc., thoroughly mixed in the mixer is then granulated in the kneading and granulating machine 11. At this time, the kneaded material is preferably heated to 30 to 120°C, more preferably 40 to 100°C, without being melted.
Since the kneaded material is heated to about 90° C. by frictional heat, heating of the kneaded material can be achieved without any particular external heating. In the illustrated granulation process, the cutter 12 performs granulation. The shape of the granulated particles is 0.5 to 3.0 cm in diameter and 0.5 to 3.0 cm in height, which is convenient for storage and transportation.
The granulation process is 3.0cm long and has a cylindrical shape.
〓Various methods are adopted depending on the type of Japanese machine, and the particulate material may be shaped like a plate or a filament.
In short, any shape suitable for transportation and storage may be used.

The granulated material created in this way is used in the switching damper 1.
Vibration feeder 1 by switching 8 and 19
7 to the storage tank 21 for intermediate storage. A drum can can also be used instead of the storage tank 21. After intermediate storage and radioactive decay, the particulate material is taken out by a discharge device 13 and conveyed to a compressor 14 to be compressed and reduced in volume. Next, the solidified body (compressed volume-reduced solidified body) is stored in a drum can 15 to form a solidified body. The drum can 15 may be lined with a resin lining several mm thick in advance, or a solidifying agent such as plastic or asphalt may be injected after the volume reduction body is stored. The shape of the volume reducing body is such that it can be inserted into a drum, and it may be an integral block or divided into several blocks. Alternatively, the pellets can be conveyed to the compressor 14 by the vibrating feeder 16 and compressed and reduced in volume to form a solidified product without intermediate storage.

The compressor mold can be used at room temperature or heated above room temperature to 120°C.

By keeping the surface pressure applied for 1 to 10 minutes, the voids in the volume-reduced body can be reduced and a dense structure can be formed. In addition, when compressing particles of used ion exchange resin that have spring back, it is possible to suppress spring back of the volume reduction body by compressing while heating and then cooling while maintaining compression pressure. .

The present invention will be explained in more detail with reference to the following examples.

Example 1 Amorphous chlorinated polyethylene with 30% chlorine content
Mix 100 parts by weight of concentrated waste liquid from nuclear power plants with 1290 parts by weight of dried waste (moisture content 0.2%). Further 50 parts by weight of dioctyl phthalate, 10 parts by weight of tribasic lead as a stabilizer and 1 part by weight of lead stearate as a lubricant are added. These compositions were mixed and kneaded and then granulated to produce pellets. The pellet has a specific gravity of 2.26 and a cylindrical shape with a diameter of 13 mm and a height of 15 mm.

The above pellet aggregate was placed in a cylindrical mold and compression molded while heating to produce a reduced volume solidified product. When these pellets were filled irregularly into a cylindrical mold with an inner diameter of 5.08 cm, a height of 8.2 cm, and an inner volume of ¹⁶⁶ cm, 37 pellets were filled. The weight of the pellet is 175.2g and the specific gravity is 2.26.
Therefore, the actual volume is ^77.5cm3 . Since this actual volume corresponds to 47% of the internal volume of the cylindrical mold, 53% of the void space exists within the mold. The pellet aggregate in the mold was heated to 80°C and compressed with a surface pressure of 400 kg/cm ² , and held for 5 minutes to produce a homogeneous volume-reduced solidified product. The specific gravity of this volume-reduced solidified material is 2.30, which is higher than the specific gravity of the pellets. The filling rate increased and the volume of the solidified body decreased to 46% of the mold volume.

In addition, the pellet aggregate was compressed using the same equipment as above at room temperature with a surface pressure of 500 kg/cm ² ,
A volume-reduced solidified body was produced by holding for 5 minutes. This volume-reduced solidified material has a specific gravity of 2.30, is compressed more than the specific gravity of pellets, and has a homogeneous and dense structure.
The volume of the volume-reduced solidified body was reduced to 46% of the mold volume.

Example 2 Amorphous chlorinated polyethylene with 30% chlorine content
100 parts by weight of dried waste ion exchange resin from nuclear power plants (granular resin, moisture content)
5.9%) in a proportion of 970 parts by weight. 50 more
parts by weight of dioctyl phthalate, 10 as stabilizer
Part by weight of tribasic lead and 1 part by weight of lead stearate are added as a lubricant. These compositions were mixed and kneaded and then granulated to produce pellets. The specific gravity of the pellet is 1.24, and the shape is cylindrical with a diameter of
13mm and height 15mm.

The above pellet aggregate was placed in a cylindrical mold and compressed while heating to produce a reduced volume solidified product. When these pellets were filled irregularly into a cylindrical mold with an inner diameter of 5.08 cm, a height of 8.2 cm, and an inner volume of ¹⁶⁶ cm, 37 pellets were filled. Since the weight of the pellet is 100 g and the specific gravity is 1.24, the actual volume is 80.6 cm ³ . Since this actual volume corresponds to 49% of the internal volume of the cylindrical mold, 51% of the void space exists within the mold. The pellet aggregate in the mold was heated to 80°C and compressed with a surface pressure of 400 kg/cm ² , and held for 5 minutes to produce a homogeneous volume-reduced solidified product. The specific gravity of this volume-reduced solidified material is 1.31, which is higher than the specific gravity of the pellets. The filling rate increased and the volume of the solidified material decreased to 46% of the mold volume.

The above pellet aggregate was compressed using the same equipment as above at room temperature with a surface pressure of 500 kg/cm ² .
A volume-reduced solidified body was produced by holding for a minute. This volume-reduced solidified material has a specific gravity of 1.31, which is higher than that of pellets, and has a homogeneous and dense structure. The volume of the volume-reduced solidified body was reduced to 46% of the mold volume.

Example 3 Amorphous chlorinated polyethylene with 30% chlorine content
100 parts by weight of dried waste ion exchange resin from nuclear power plants (powdered resin, moisture content)
4.8%) in a proportion of 970 parts by weight. 50 more
parts by weight of dioctyl phthalate, 10 as stabilizer
Part by weight of tribasic lead and 1 part by weight of lead stearate are added as a lubricant. These compositions were mixed and kneaded and then granulated to produce pellets. The specific gravity of the pellet is 1.46, and the shape is cylindrical with a diameter of
13mm and height 15mm.

Put the above pellet collection into a cylindrical mold,
A volume-reduced solidified product was produced by compression molding while heating.
When these pellets were filled irregularly into a cylindrical mold with an inner diameter of 5.08 cm, a height of 8.2 cm, and an inner volume of ¹⁶⁶ cm, 38 pellets were filled. The weight of the pellet is 117.0g and the specific gravity is 1.46
Therefore, the actual volume is ^80.1cm3 . Since this actual volume corresponds to 49% of the internal volume of the cylindrical mold, there is a void area of 51% within the mold. The pellet aggregate in the mold was heated to 80°C and compressed with a surface pressure of 400 kg/cm ² , and held for 5 minutes to produce a homogeneous volume-reduced solidified product. The specific gravity of this volume-reduced solidified material is 1.48, which is greater than the specific gravity of the pellets. As the filling rate increased, the volume of the solidified material decreased to 48% of the mold volume.

The pellet polymer was compressed using the same equipment as above at room temperature with a surface pressure of 500 kg/cm ² .
A volume-reduced solidified body was prepared by holding the mixture for a minute. This volume-reduced solidified material has a specific gravity of 1.48, which is higher than that of pellets, and has a homogeneous and dense structure. The volume of the volume-reduced solidified material was reduced to 48% of the mold volume.

Example 4 Amorphous chlorinated polyethylene with 30% chlorine content
For every 100 parts by weight, 966 parts by weight of waste obtained by drying nuclear power plant filter sludge is mixed. Further 50 parts by weight of dioctyl phthalate, 10 parts by weight of tribasic lead as a stabilizer and 1 part by weight of lead stearate as a lubricant are added.
These compositions were mixed and kneaded and then granulated to produce pellets. The specific gravity of the pellet is 1.52,
The shape is cylindrical with a diameter of 13 mm and a height of 15 mm.

Put the above pellet collection into a cylindrical mold,
A volume-reduced solidified product was produced by compression molding while heating.
When these pellets were filled irregularly into a cylindrical mold with an inner diameter of 5.08 cm, a height of 8.2 cm, and an inner volume of ¹⁶⁶ cm, 38 pellets were filled. The weight of the pellet is 116 g and the specific gravity is 1.52, so the actual volume is 76.2 cm ³ . Since this actual volume corresponds to 46% of the internal volume of the cylindrical mold, there is a void area of 54% within the mold. The pellet aggregate in the mold was heated to 80°C and compressed with a surface pressure of 400 kg/cm ² , and held for 5 minutes to produce a homogeneous volume-reduced solidified product. The specific gravity of this volume-reduced solidified material is 1.54, which is greater than the specific gravity of the pellets. The filling rate increased and the volume of the solidified body decreased to 45% of the mold volume.

The above pellet aggregate was compressed using the same equipment as above at room temperature under a surface pressure of 500 kg/cm ² .
A volume-reduced solidified body was produced by holding for a minute. This volume-reduced solidified material has a specific gravity of 1.54, which is higher than that of pellets, and has a homogeneous and dense structure. The volume of the volume-reduced solidified body was reduced to 45% of the mold volume.

Example 5 Amorphous chlorinated polyethylene with 30% chlorine content
Add incineration ash from a nuclear power plant at a ratio of 970 parts by weight to 100 parts by weight. Further 50 parts by weight of dioctyl phthalate, 10 parts by weight of tribasic lead as a stabilizer and 1 part by weight of lead stearate as a lubricant are added. These compositions were mixed and kneaded and then granulated to produce pellets. The specific gravity of pellets is
2.23, and the shape is cylindrical with a diameter of 13 mm and a height of 15 mm.
It is.

Put the above pellet collection into a cylindrical mold,
A volume-reduced solidified product was produced by compression molding while heating.
When these pellets were filled irregularly into a cylindrical mold with an inner diameter of 5.08 cm, a height of 8.2 cm, and an inner volume of ¹⁶⁶ cm, 37 pellets were filled. The weight of the pellet is 169.9g and the specific gravity is
2.23, so the actual volume is 7.62 ^cm3 . Since this actual volume corresponds to 46% of the internal volume of the cylindrical mold, there is a void area of 54% within the mold. 400℃ while heating the pellet aggregate in the mold to 80℃
It was compressed with a surface pressure of Kg/cm ² and held for 5 minutes to produce a homogeneous volume-reduced solidified body. The specific gravity of this volume-reduced solidified material is
2.25, which is greater than the specific gravity of pellets. The filling rate increased and the volume of the solidified body decreased by 45% of the mold volume.

The above pellet aggregate was compressed using the same equipment as above at room temperature with a surface pressure of 500 kg/cm ² .
A volume-reduced solidified body was produced by holding for a minute. This volume-reduced solidified material has a specific gravity of 2.25, which is higher than that of pellets, and has a homogeneous and dense structure. The volume of the volume-reduced solidified body was reduced to 45% of the mold volume.

As explained above, in the present invention, a solidified particulate material consisting of 100 parts by weight of a rubber-like elastic polymer material and 550 to 1,500 parts by weight of radioactive waste is compressed at room temperature or in a heated state. First, compared to the most widely used cement solidification method, the volume of the volume-reduced body compressed after granulation according to the present invention is 1/7th the volume.
The volume reduction of the present invention is extremely large. Secondly, compared to the conventional method of mixing radioactive waste with chlorinated polyethylene resin, the proportion of waste in the mixture is significantly larger, so the amount of chlorinated polyethylene resin, which is a rubber-like elastic polymer, can be reduced. It has the advantage of high processing efficiency. Furthermore, due to the properties of the rubber-like elastic polymer used as the binder, the granulated product generates very little crushed pieces or dust when compressed, and is highly stable. Furthermore, since the compressed solidified body according to the present invention is homogeneous and strongly integrated, it can be handled more safely and easily. Furthermore, when compressed volume reduction bodies are filled and stored in a container such as a drum can, the filling rate can be increased by 25 to 50% compared to a method in which a solidifying material such as asphalt or plastic is injected and solidified after storing the granulated material. .

Furthermore, in the present invention, when obtaining the granulated material or compressing the granulated material to obtain the solidified material, it is carried out at an extremely low temperature without melting, so there is no decomposition of radioactive waste, and moreover, unlike conventional synthetic resins, Unlike methods that are carried out in a molten state such as those described above, there is no need for an extra quenching step, and there is no problem with cooling water contaminated with radioactivity.

According to the present invention, radioactive waste is filled into a rubber-like elastic polymer material at a high mixing ratio, and the mixing ratio is limited to a specific range to form particles, making it suitable for storage and transportation. This effect and the effect of compressing the particulate material to obtain a strong and dense solidified material work synergistically, and as a result, it can be stored in a storage container with an excellent volume reduction rate, and the procedure is consistent. The volume reduction performance of the method of the present invention is excellent compared to conventional methods for volume reduction and solidification of radioactive waste, and the present invention is a novel and useful method for volume reduction and solidification of radioactive waste. This is a solidification treatment method.

[Brief explanation of the drawing]

The drawings are process diagrams for explaining embodiments of the method of the present invention. Codes in the figure: 1...Stock solution supply tank, 2...Stock solution supply pump, 3...In-line crusher, 4...Dryer, 5...Moisture meter, 6...Return tank, 7...
Return pump, 8... Measuring device, 9... Hopper for rubber-like elastic polymer substance, 10... Mixer, 11...
Kneading and granulating machine, 12... Cutter, 13... Carrying out device, 14... Compressor, 15... Drum can, 16,
17... Vibration feeder, 18, 19... Switching damper, 20... Storage tank, 21... Storage tank, 2
2...Plasticizer storage tank.

Claims (1)

[Claims] 1. Mixing, kneading, and mixing 100 parts by weight of a rubber-like elastic polymeric substance and 550 to 1500 parts by weight of dry radioactive waste without adding a crosslinking agent and without melting at a temperature of 30°C or more and less than 120°C. Alternatively, a method for volume reduction and solidification treatment of radioactive waste, which comprises kneading and granulating, and compressing the resulting granulated material aggregate at a temperature of less than 120°C to form a strong and homogeneous solidified body.