A radioactive waste disposal container and method of making the same

Abstract

The application discloses a radioactive waste disposal container and a preparation method thereof. The preparation method comprises the following steps: step 1, a barrel body is obtained by casting according to the volume of the radioactive waste to be treated; step 2, a transition coating layer is obtained by spraying a tungsten-based powder on the outer surface of the barrel body, and a first shielding layer is obtained by filling a filler into the pores of the transition coating layer through vacuum impregnation; step 3, a second shielding layer is obtained by brushing a shielding resin on the outer surface of the first shielding layer and drying; step 4, a shielding rubber mixture is prepared, the shielding rubber mixture is pressed into a shielding rubber shell according to the volume and shape of the second shielding layer, and a shielding barrel body is obtained after vulcanization treatment; and step 5, the barrel body treated in step 3 is placed in the shielding barrel body to obtain the disposal container. The radioactive waste disposal container can realize the composite shielding of neutrons and gamma rays under the premise of minimizing the volume of the radioactive waste disposal container.

Description

Technical Field

[0001] This invention specifically relates to a method for preparing a radioactive waste disposal container and the radioactive waste disposal container prepared using this method. Background Technology

[0002] Currently, these radioactive wastes are stored in temporary or storage containers to allow them to decay to a safe dose range before being deregulated. The temporary storage, transfer, or storage of these radioactive wastes utilizes containers made of cement, lead, or carbon steel to shield the waste and reduce the collective dose received by personnel during these processes.

[0003] Existing disposal containers, such as cement drums, lead drums, and carbon steel drums, are characterized by their large size and poor shielding effectiveness. Even when achieving adequate shielding, their volume is enormous, failing to meet the principle of minimizing radioactive waste disposal. Conversely, reducing container volume does not effectively shield radioactive waste, increasing the radiation dose to workers. While some researchers have attempted to reduce container volume by using layered designs with different materials, the sleeve-type cover design requires multiple layers for installation, increasing on-site work time and offering less than ideal shielding. Another approach involves filling shielding material between two clamps, but this method does not effectively reduce container volume. Furthermore, both of these designs only shield against single neutron or gamma rays, failing to achieve comprehensive shielding against neutron or gamma rays while minimizing volume. Summary of the Invention

[0004] In view of this, in order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a radioactive waste disposal container and its preparation method, which can achieve efficient composite shielding against neutron rays and gamma rays while minimizing the radioactive waste disposal.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: One object of the present invention is to provide a method for preparing a radioactive waste disposal container, wherein the disposal container comprises, from the inside out, a barrel body, a first shielding layer, a second shielding layer, and a shielded barrel body, and the preparation method includes the following steps: Step 1: The volume of the barrel body is designed according to the volume of the radioactive waste to be processed, and then the barrel body is cast. Step 2: Spray tungsten-based powder onto the outer surface of the barrel body to obtain a transition coating, and then fill the pores of the transition coating with filler through vacuum impregnation to obtain the first shielding layer; Step 3: After brushing and drying the shielding resin on the outer surface of the first shielding layer, the second shielding layer is obtained, and the volume of the second shielding layer is determined. Step 4: Prepare the shielding rubber mixture, press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer, and obtain the shielding barrel body after vulcanization treatment; Step 5: Place the barrel body with the first shielding layer and the second shielding layer on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the disposal container.

[0006] By employing a multi-layered shielding structure and filling the transition coating obtained by spraying tungsten-based powder with filler, neutron and gamma rays can be effectively shielded. Furthermore, the layers of the prepared disposal container are tightly bonded and not easily detached. The volume of the innermost layer of the disposal container is designed based on the volume of the radioactive waste to be treated, which helps to minimize the volume of the disposal container. In addition, the thickness of the disposal container in this invention is less than or equal to 100 mm.

[0007] According to some preferred embodiments of the present invention, the barrel body is made of high-boron steel, wherein the mass percentage of boron in the high-boron steel is 2% to 6%; the thickness of the barrel body is greater than 5 mm. The barrel body being made of high-boron steel, wherein the mass percentage of the lightweight element boron is 2% to 6%, provides a good shielding effect against neutron rays; and setting the thickness of the barrel body to be greater than 5 mm ensures the overall structural strength of the disposal container.

[0008] According to some preferred embodiments of the present invention, the method for obtaining a transition coating by spraying tungsten-based powder onto the outer surface of the barrel body in step 2 is as follows: Tungsten-based powder is sprayed onto the outer surface of the barrel body using plasma spraying under the conditions of a current of 400-800 A, a hydrogen flow rate of 6-12 SCFH, an argon flow rate of 10-20 SCFH, and a spraying distance of 100-150 mm; the tungsten-based powder is tungsten powder, tungsten-boron powder, or tungsten-nickel powder. The transition coating is prepared using tungsten-based powder via plasma spraying technology, resulting in a metal framework structure containing heavy metal elements.

[0009] According to some preferred embodiments of the present invention, the thickness of the transition coating is 0.5 to 10 mm, and the porosity of the transition coating is 10% to 60%.

[0010] According to some preferred embodiments of the present invention, the method for obtaining the first shielding layer by filling the pores of the transition coating with filler through vacuum impregnation in step 2 is as follows: A barrel body with a transition coating on its outer surface is placed in an impregnation tank, and an impregnation liquid containing filler is added until the impregnation liquid covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is drawn until the vacuum degree is less than or equal to -0.099 MPa. The impregnation time is 30~120 min. After impregnation, the outer surface of the transition coating is wiped to obtain the first shielding layer. The transition coating pores are filled with an organic filler with a high hydrogen content (5%~20% by mass) using vacuum impregnation technology. This filler contains the light element hydrogen, thus forming a composite material of light elements and heavy metal elements, which has a composite shielding effect and can simultaneously provide highly efficient shielding against neutron rays and gamma rays.

[0011] According to some preferred embodiments of the present invention, the filler is selected from one or more of hydroxyethyl methacrylate, tetradecyl methacrylate, 1,6-hexanediol dimethacrylate, or 2-hydroxypropyl methacrylate. The filler containing a large amount of hydrogen has a good shielding effect against neutron rays, and when combined with a transition coating containing heavy metal elements, the first shielding layer can simultaneously provide highly efficient shielding against both neutron rays and gamma rays.

[0012] According to some preferred embodiments of the present invention, the method for obtaining the second shielding layer after brushing and drying the shielding resin on the outer surface of the first shielding layer in step 3 is as follows: first, a layer of shielding resin with a thickness of 0.3~0.5mm is brushed onto the outer surface of the first shielding layer, and after an interval of 10~20 minutes, another layer of shielding resin with a thickness of 0.3~0.5mm is brushed onto the outer surface. The above operation is repeated until the total thickness of the multiple layers of shielding resin is 1~5mm. Finally, the second shielding layer is obtained after drying at room temperature.

[0013] According to some preferred embodiments of the present invention, the raw material components of the shielding resin, by weight, comprise 60% to 80% epoxy resin and 20% to 40% filler; the filler is a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder. In some embodiments of the present invention, the raw material components of the shielding resin further include a curing agent and an accelerator, wherein the volume of the curing agent accounts for 1% to 3% of the volume of the epoxy resin, and the volume of the accelerator accounts for 1% to 3% of the volume of the epoxy resin. A second shielding layer is prepared using materials containing light elements and heavy metal elements for shielding against neutron rays and gamma rays.

[0014] According to some preferred embodiments of the present invention, the method for preparing the shielding barrel body in step 4 is as follows: rubber is melted at 100-120°C, additives are added, and the mixture is stirred at 30-40 rpm for 30-60 minutes to ensure uniform mixing of the melted rubber and additives, thereby obtaining the shielding rubber mixture; the shielding rubber mixture is pressed into a shielding rubber shell according to the volume and shape of the second shielding layer; the shielding rubber shell is then vulcanized at 140-180°C for 30-60 minutes; the thickness of the shielding barrel body is 5-50 mm.

[0015] According to some preferred embodiments of the present invention, the raw material components of the shielding rubber mixture include 85% to 95% rubber and 5% to 15% additives, wherein the rubber is natural rubber, silicone rubber, styrene-butadiene rubber, or butyl rubber; and the additives are a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder. After uniformly mixing heavy metal element powder and light element powder into molten rubber, a shielding barrel with a certain degree of flexibility is prepared and wrapped around the barrel body, the first shielding layer, and the outer side of the second shielding layer. This not only protects the entire disposal container from impacts and reduces damage caused by other physical collisions, but also provides shielding against neutron rays and gamma rays. Furthermore, it possesses halogen-free, flame-retardant, and corrosion-resistant properties, extending the service life of the disposal container and preventing environmental pollution during post-processing.

[0016] According to some preferred embodiments of the present invention, in step 1, the volume of the radioactive waste to be treated is equal to the volume of the barrel body; in step 4, the volume of the second shielding layer is less than or equal to the volume of the shielding barrel body. The shielding barrel body has a certain elasticity, and under the action of its own weight, the barrel body having the first shielding layer and the second shielding layer can be inserted into the shielding barrel body, ensuring that the inner wall of the shielding barrel body is in contact with the second shielding layer.

[0017] Another object of the present invention is to provide a radioactive waste disposal container, which is prepared by the above-described preparation method. The disposal container includes, from the inside out, a barrel body, a first shielding layer, a second shielding layer and a shielded barrel body. The inner surface of the first shielding layer is attached to the outer surface of the barrel body, the outer surface of the first shielding layer is attached to the inner surface of the second shielding layer, and the outer surface of the second shielding layer is attached to the inner surface of the shielded barrel body.

[0018] Due to the adoption of the above technical solutions, compared with the prior art, the advantages of the present invention are as follows: the radioactive waste disposal container and its preparation method of the present invention can minimize the volume of the radioactive waste disposal container and have excellent shielding effect, achieving composite shielding against neutron rays and gamma rays, reducing the radiation dose received by operators in the disposal of radioactive waste in temporary storage, transfer and storage and other disposal methods, and ensuring the safety of operators and the environment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a top view of the radioactive waste disposal container in a preferred embodiment of the present invention; The attached diagram is labeled as follows: barrel body-1, first shielding layer-2, second shielding layer-3, shielding barrel body-4. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] The present invention provides a method for preparing a radioactive waste disposal container, comprising the following steps: Step 1: After designing the volume of the barrel body 1 according to the volume of the radioactive waste to be treated, the barrel body 1 is integrally cast using high boron steel, so that the volume of the barrel body 1 is equal to the volume of the radioactive waste. The mass percentage of boron in the high boron steel is 2%~6%.

[0023] Step 2: Using plasma spraying, under conditions of 400~800A current, 6~12SCFH hydrogen flow rate, 10~20SCFH argon flow rate, and 100~150mm spraying distance, tungsten-based powder is sprayed onto the outer surface of the barrel body 1 to obtain a transition coating with a thickness of 0.5~10mm. The barrel body 1 with the transition coating on its outer surface is then placed in an impregnation tank, and an impregnation liquid containing filler is added until the impregnation liquid covers the top surface of the barrel body 1. The impregnation tank is then sealed, and a vacuum is drawn until the vacuum degree is less than or equal to -0.099MPa. The impregnation time is 30~120min. After impregnation, the outer surface of the transition coating is wiped to obtain the first shielding layer 2. The obtained first shielding layer 2 is a transition coating with filler filling the pores. The tungsten-based powder is tungsten powder, tungsten boron powder, or tungsten nickel powder; the filler is selected from one or more of hydroxyethyl methacrylate, tetradecyl methacrylate, 1,6-hexanediol dimethacrylate, or 2-hydroxypropyl methacrylate.

[0024] Step 3: First, brush a layer of shielding resin with a thickness of 0.3~0.5mm onto the outer surface of the first shielding layer 2. After an interval of 10~20 minutes, brush another layer of shielding resin with a thickness of 0.3~0.5mm onto the outer surface. Repeat the above operation until the total thickness of the multiple layers of shielding resin is 1~5mm. Finally, after drying at room temperature, the second shielding layer 3 is obtained and the volume of the second shielding layer 3 is determined.

[0025] The shielding resin comprises, by weight, 60%–80% epoxy resin and 20%–40% filler. It also includes a curing agent and an accelerator, with the curing agent and accelerator each accounting for 1%–3% of the epoxy resin volume. The filler is a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder. For the mixture of boron powder and tungsten powder, the mass ratio of boron powder to tungsten powder is 1:1.

[0026] Step 4: Melt the rubber at 100~120℃, add the additive, and stir at 30~40rpm for 30~60min to make the melted rubber and additives evenly mixed to obtain a shielding rubber mixture; press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer 3, and then vulcanize the shielding rubber shell at 140~180℃ for 30~60min to obtain a shielding barrel 4 with a thickness of 10~50mm.

[0027] The raw material components of the shielding rubber mixture, by weight, include 85% to 95% rubber and 5% to 15% additives. The rubber is natural rubber, silicone rubber, styrene-butadiene rubber, or butyl rubber. The additives are a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder. For the mixture of boron powder and tungsten powder, the mass ratio of boron powder to tungsten powder is 1:1.

[0028] Step 5: Place the barrel body 1, which has been treated in Step 3 and has the first shielding layer 2 and the second shielding layer 3 on its outer surface, into the shielded barrel body 4 to obtain the treatment container.

[0029] like Figure 1 As shown, the radioactive waste disposal container prepared using the above-described method comprises, from the inside out, a container body 1, a first shielding layer 2, a second shielding layer 3, and a shielded container body 4. The inner surface of the first shielding layer 2 is bonded to the outer surface of the container body 1, the outer surface of the first shielding layer 2 is bonded to the inner surface of the second shielding layer 3, and the outer surface of the second shielding layer 3 is bonded to the inner surface of the shielded container body 4.

[0030] Example 1 Step 1: Design a radioactive waste disposal container with an outer diameter of 500 mm, a height of 500 mm, and a total thickness of 13 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 150 mSv / h. The container body is made of high boron steel in one piece by casting, with a thickness of 5 mm. The mass ratio of boron in the high boron steel is 3.0%.

[0031] Step 2: Using plasma spraying at a current of 500A, a hydrogen flow rate of 8 SCFH, an argon flow rate of 12 SCFH, and a spraying distance of 150mm, tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a 2mm thick transition coating with a porosity of 40%. The barrel body with this transition coating is then placed in an impregnation tank, and an impregnation solution containing filler is added until it covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is applied until the vacuum level is less than -0.099MPa. The impregnation time is 60 minutes. After impregnation, the barrel body is removed and wiped to obtain the first shielding layer. In this embodiment, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0032] Step 3: First, brush a layer of shielding resin with a thickness of 0.5mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5mm onto the outer surface. Repeat the brushing process twice to make the total thickness of the multiple layers of shielding resin 1mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0033] The shielding resin comprises, by weight, 70% epoxy resin and 30% filler. It also includes a curing agent and an accelerator, with the curing agent accounting for 1% of the volume of the epoxy resin and the accelerator accounting for 1% of the volume of the epoxy resin. The filler is a mixture of boron powder and tungsten powder in a 1:1 mass ratio. Furthermore, the curing agent is potassium peroxide acetone, and the accelerator is cobalt isooctanoate.

[0034] Step 4: Melt the rubber at 100℃, add the additive, and stir at 35 rpm for 40 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture; press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer, and then vulcanize the shielding rubber shell at 160℃ for 40 minutes to obtain a shielding barrel with a thickness of 5mm.

[0035] The raw material components of the shielding rubber mixture, by weight, include 90% rubber and 10% additives. The rubber is natural rubber, and the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0036] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the treatment container.

[0037] Example 2 Step 1: Design a radioactive waste disposal container with an outer diameter of 900 mm, a height of 550 mm, and a total thickness of 23.5 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 160 mSv / h. The container body is made of high boron steel in one piece by casting, with a thickness of 8 mm. The mass ratio of boron in the high boron steel is 3.8%.

[0038] Step 2: Using plasma spraying at a current of 550A, a hydrogen flow rate of 10 SCFH, an argon flow rate of 14 SCFH, and a spraying distance of 180mm, tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a transition coating with a thickness of 2.5mm and a porosity of 36%. The barrel body with this transition coating is then placed in an impregnation tank, and an impregnation solution containing filler is added until it covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is drawn until the vacuum degree is less than -0.099MPa. The impregnation time is 60 minutes. After impregnation, the barrel body is removed and wiped to obtain the first shielding layer. In this embodiment, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0039] Step 3: First, brush a layer of shielding resin with a thickness of 0.5 mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5 mm onto the outer surface. Repeat this process 6 times to make the total thickness of the multiple layers of shielding resin 3 mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0040] The shielding resin comprises, by weight, 72% epoxy resin and 28% filler. It also includes a curing agent and an accelerator, with the curing agent and accelerator each accounting for 1.8% of the epoxy resin volume. The filler is a mixture of boron powder and tungsten powder in a 1:1 mass ratio. Furthermore, the curing agent is potassium peroxide acetone, and the accelerator is cobalt isooctanoate.

[0041] Step 4: Melt the rubber at 110℃, add the additive, and stir at 35 rpm for 60 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture; press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer, and then vulcanize the shielding rubber shell at 160℃ for 60 minutes to obtain a shielding barrel with a thickness of 10 mm.

[0042] The raw material components of the shielding rubber mixture, by weight, include 92% rubber and 8% additives. The rubber is natural rubber, and the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0043] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the treatment container.

[0044] Example 3 Step 1: Design a radioactive waste disposal container with an outer diameter of 1000 mm, a height of 600 mm, and a total thickness of 34 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 200 mSv / h. The container body with a thickness of 10 mm is made by integral casting of high boron steel, and the mass ratio of boron in the high boron steel is 3.5%.

[0045] Step 2: Using plasma spraying at a current of 600A, a hydrogen flow rate of 10 SCFH, an argon flow rate of 15 SCFH, and a spraying distance of 120mm, a 2mm thick transition coating of tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a transition coating with a porosity of 30%. The barrel body with this transition coating is then placed in an impregnation tank, and an impregnation solution containing filler is added until it covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is drawn until the vacuum level is less than -0.099MPa. The impregnation time is 60 minutes. After impregnation, the barrel body is removed and wiped to obtain the first shielding layer. In this embodiment, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0046] Step 3: First, brush a layer of shielding resin with a thickness of 0.5 mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5 mm onto the outer surface. Repeat this process 4 times to make the total thickness of the multiple layers of shielding resin 2 mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0047] The shielding resin comprises, by weight, 75% epoxy resin and 25% filler; in addition, the raw material components of the shielding resin also include a curing agent and an accelerator, with the curing agent accounting for 1.5% of the volume of the epoxy resin and the accelerator accounting for 1.5% of the volume of the epoxy resin; the filler is a mixture of boron powder and tungsten powder with a mass ratio of 1:1; furthermore, the curing agent is potassium peroxide acetone, and the accelerator is cobalt isooctanoate.

[0048] Step 4: Melt the rubber at 120℃, add the additive, and stir at 40 rpm for 60 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture. Press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer. Then, vulcanize the shielding rubber shell at 160℃ for 60 minutes to obtain a shielding barrel with a thickness of 20 mm.

[0049] The raw material components of the shielding rubber mixture, by weight, include 85% rubber and 15% additives. The rubber is natural rubber, and the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0050] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in Step 3 into the shielded barrel body to obtain the treatment container.

[0051] Example 4 Step 1: Design a radioactive waste disposal container with an outer diameter of 1200 mm, a height of 500 mm, and a total thickness of 57 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 220 mSv / h. The container body with a thickness of 20 mm is made by integral casting of high boron steel. The mass percentage of boron in the high boron steel is 4.0%.

[0052] Step 2: Using plasma spraying at a current of 620A, a hydrogen flow rate of 12SCFH, an argon flow rate of 16SCFH, and a spraying distance of 150mm, tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a 3mm thick transition coating with a porosity of 25%. The barrel body with this transition coating is then placed in an impregnation tank, and an impregnation solution containing filler is added until it covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is applied until the vacuum level is less than -0.099MPa. The impregnation time is 60 minutes. After impregnation, the barrel body is removed and wiped to obtain the first shielding layer. In this embodiment, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0053] Step 3: First, brush a layer of shielding resin with a thickness of 0.5 mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5 mm onto the outer surface. Repeat this brushing process 8 times to make the total thickness of the multilayer shielding resin 4 mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0054] The shielding resin comprises, by weight, 65% epoxy resin and 35% filler. It also includes a curing agent and an accelerator, with the curing agent and accelerator each accounting for 2.5% of the epoxy resin volume. The filler is a mixture of boron powder and tungsten powder in a 1:1 mass ratio. Furthermore, the curing agent is potassium peroxide acetone, and the accelerator is cobalt isooctanoate.

[0055] Step 4: Melt the rubber at 120℃, add the additive, and stir at 40 rpm for 60 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture. Press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer. Then, vulcanize the shielding rubber shell at 180℃ for 60 minutes to obtain a shielding barrel with a thickness of 30 mm.

[0056] The raw material components of the shielding rubber mixture, by weight, include 95% rubber and 5% additives. The rubber is natural rubber; the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0057] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in Step 3 into the shielded barrel body to obtain the treatment container.

[0058] Example 5 Step 1: Design a reflective waste disposal container with an outer diameter of 1500 mm, a height of 800 mm, and a total thickness of 81 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 3 Sv / h. The container body is made of high boron steel in one piece by casting, with a thickness of 30 mm. The mass ratio of boron in the high boron steel is 4.8%.

[0059] Step 2: Using plasma spraying at a current of 800A, a hydrogen flow rate of 12SCFH, an argon flow rate of 15SCFH, and a spraying distance of 120mm, tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a transition coating with a thickness of 8mm and a porosity of 50%. The barrel body with this transition coating is then placed in an impregnation tank, and an impregnation solution containing filler is added until the solution covers the top surface of the barrel body. The impregnation tank is then sealed, and a vacuum is applied until the vacuum level is less than -0.099MPa. The impregnation time is 120min. After impregnation, the barrel body is removed and wiped to obtain the first shielding layer. In this embodiment, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0060] Step 3: First, brush a layer of shielding resin with a thickness of 0.5 mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5 mm onto the outer surface. Repeat this process 6 times to make the total thickness of the multiple layers of shielding resin 3 mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0061] The shielding resin comprises, by weight, 70% epoxy resin and 30% filler; in addition, the raw material components of the shielding resin also include a curing agent and an accelerator, with the curing agent accounting for 2% of the volume of the epoxy resin and the accelerator accounting for 2% of the volume of the epoxy resin; the filler is a mixture of boron powder and tungsten powder with a mass ratio of 1:1; furthermore, the curing agent is potassium peroxide acetone and the accelerator is cobalt isooctanoate.

[0062] Step 4: Melt the rubber at 120℃, add the additive, and stir at 40 rpm for 60 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture. Press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer. Then, vulcanize the shielding rubber shell at 180℃ for 60 minutes to obtain a shielding barrel with a thickness of 40 mm.

[0063] The raw material components of the shielding rubber mixture, by weight, include 85% rubber and 15% additives. The rubber is natural rubber, and the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0064] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the treatment container.

[0065] Comparative Example 1 A radioactive waste disposal iron drum with a thickness of 13mm, an outer diameter of 500mm, and a height of 500mm was obtained by integral casting of metal iron.

[0066] Comparative Example 2 A radioactive waste disposal iron drum with a thickness of 23.5 mm, an outer diameter of 900 mm, and a height of 550 mm was obtained by integral casting of metal iron.

[0067] Comparative Example 3 A radioactive waste disposal iron drum with a thickness of 34 mm, an outer diameter of 1000 mm, and a height of 600 mm was obtained by integral casting of metal iron.

[0068] Comparative Example 4 A radioactive waste disposal drum with a thickness of 57 mm, an outer diameter of 1200 mm, and a height of 500 mm was obtained by integral casting of metal iron.

[0069] Comparative Example 5 A radioactive waste disposal iron drum with a thickness of 81 mm, an outer diameter of 1500 mm, and a height of 800 mm was obtained by integral casting of metal iron.

[0070] Comparative Example 6 Step 1: Design a radioactive waste disposal container with an outer diameter of 500 mm, a height of 500 mm, and a total thickness of 13 mm based on the volume of the radioactive waste to be processed. This container will be used to store radioactive metal waste with a radioactive dose of 150 mSv / h. The container body is made of high boron steel in one piece by casting, with a thickness of 5 mm. The mass ratio of boron in the high boron steel is 3.0%.

[0071] Step 2: Using plasma spraying at a current of 500A, a hydrogen flow rate of 8 SCFH, an argon flow rate of 12 SCFH, and a spraying distance of 150mm, tungsten-based powder is sprayed onto the outer surface of the barrel body to obtain a 2mm thick transition coating with a porosity of 40%. After brushing a filler onto the outer surface of this transition coating and allowing it to stand for 60 minutes, it is wiped to obtain the first shielding layer. In this comparative example, the tungsten-based powder is tungsten powder, and the filler is hydroxyethyl methacrylate.

[0072] Step 3: First, brush a layer of shielding resin with a thickness of 0.5mm onto the outer surface of the first shielding layer. After an interval of 20 minutes, brush another layer of shielding resin with a thickness of 0.5mm onto the outer surface. Repeat the brushing process twice to make the total thickness of the multiple layers of shielding resin 1mm. Finally, after drying at room temperature, the second shielding layer is obtained and its volume is determined.

[0073] The shielding resin comprises, by weight, 70% epoxy resin and 30% filler. It also includes a curing agent and an accelerator, with the curing agent accounting for 1% of the volume of the epoxy resin and the accelerator accounting for 1% of the volume of the epoxy resin. The filler is a mixture of boron powder and tungsten powder in a 1:1 mass ratio. Furthermore, the curing agent is potassium peroxide acetone, and the accelerator is cobalt isooctanoate.

[0074] Step 4: Melt the rubber at 100℃, add the additive, and stir at 35 rpm for 40 minutes to ensure that the melted rubber and the additive are mixed evenly to obtain a shielding rubber mixture; press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer, and then vulcanize the shielding rubber shell at 160℃ for 40 minutes to obtain a shielding barrel with a thickness of 5mm.

[0075] The raw material components of the shielding rubber mixture, by weight, include 90% rubber and 10% additives. The rubber is natural rubber, and the additives are a mixture of boron powder and tungsten powder with a mass ratio of 1:1.

[0076] Step 5: Place the barrel body with the first and second shielding layers on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the treatment container.

[0077] Table 1. Shielding efficiency test results of the disposal containers prepared in Examples 1 to 5 and Comparative Examples 1 to 6.

[0078] As shown in Table 1 above, the disposal container prepared using the method of the present invention has a higher shielding efficiency for radioactive waste compared to an iron drum of the same thickness. In other words, to achieve the same shielding efficiency, the volume of the disposal container prepared according to the method of the present invention can be effectively reduced, and it will not cause environmental pollution during the post-processing. Furthermore, comparing Example 1 with Comparative Example 6, it can be seen that the first shielding layer obtained by filling the pores of the transition coating with filler using the vacuum impregnation method has a higher shielding efficiency than the first shielding layer obtained by directly brushing a layer of filler onto the outer surface of the transition coating. This is mainly because the vacuum impregnation method can ensure that the filler is filled into the pores of the transition coating and has a high pore filling rate, while the brushing method cannot guarantee this, resulting in a difference in shielding efficiency.

[0079] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a radioactive waste disposal container, characterized in that, The treatment container comprises, from the inside out, a barrel body, a first shielding layer, a second shielding layer, and a shielded barrel body. The layers of the treatment container are tightly bonded together, and the thickness of the treatment container is less than or equal to 100 mm. The preparation method includes the following steps: Step 1: After designing the volume of the barrel body according to the volume of the radioactive waste to be processed, the barrel body is cast. Step 2: Spray tungsten-based powder onto the outer surface of the barrel body to obtain a transition coating, and then fill the pores of the transition coating with filler through vacuum impregnation to obtain the first shielding layer; Step 3: After brushing and drying the shielding resin on the outer surface of the first shielding layer, the second shielding layer is obtained, and the volume of the second shielding layer is determined; Step 4: Prepare the shielding rubber mixture, press the shielding rubber mixture into a shielding rubber shell according to the volume and shape of the second shielding layer, and obtain the shielding barrel body after vulcanization treatment; Step 5: Place the barrel body with the first shielding layer and the second shielding layer on the outer surface after the treatment in step 3 into the shielded barrel body to obtain the disposal container; The method for obtaining a transition coating by spraying tungsten-based powder onto the outer surface of the barrel body in step 2 is as follows: Tungsten-based powder is sprayed onto the outer surface of the barrel body using plasma spraying under the conditions of a current of 400-800A, a hydrogen flow rate of 6-12 SCFH, an argon flow rate of 10-20 SCFH, and a spraying distance of 100-150mm; the tungsten-based powder is tungsten powder, tungsten boron powder, or tungsten nickel powder; the thickness of the transition coating is 0.5-10mm, and the porosity of the transition coating is 10%-60%; The method for obtaining the first shielding layer by filling the pores of the transition coating with filler in step 2 through vacuum impregnation is as follows: Place the barrel body with a transition coating on the outer surface into an impregnation tank and add an impregnation liquid containing filler until the impregnation liquid covers the top surface of the barrel body. Then seal the impregnation tank and evacuate until the vacuum degree is less than or equal to -0.099 MPa. The impregnation time is 30~120 min. After the impregnation is completed, wipe the outer surface of the transition coating to obtain the first shielding layer. The method for obtaining the second shielding layer by brushing and drying the shielding resin on the outer surface of the first shielding layer in step 3 is as follows: First, brush a layer of shielding resin with a thickness of 0.3~0.5mm on the outer surface of the first shielding layer. After an interval of 10~20 minutes, brush another layer of shielding resin with a thickness of 0.3~0.5mm. Repeat the above operation until the total thickness of the multiple layers of shielding resin is 1~5mm. Finally, after drying at room temperature, the second shielding layer is obtained.

2. The preparation method according to claim 1, characterized in that, The barrel body is made of high-boron steel, and the boron content in the high-boron steel is 2% to 6% by mass; the thickness of the barrel body is greater than 5mm.

3. The preparation method according to claim 1, characterized in that, The filler is selected from one or more of hydroxyethyl methacrylate, tetradecyl methacrylate, 1,6-hexanediol dimethacrylate, or 2-hydroxypropyl methacrylate.

4. The preparation method according to claim 1, characterized in that, By weight, the raw material components of the shielding resin include 60% to 80% epoxy resin and 20% to 40% filler; the filler is a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder.

5. The preparation method according to claim 1, characterized in that, The method for preparing the shielding barrel body in step 4 is as follows: Rubber is melted at 100-120℃, and additives are added. The mixture is stirred at 30-40 rpm for 30-60 minutes to ensure uniform mixing of the melted rubber and additives, thus obtaining the shielding rubber mixture. The shielding rubber mixture is then pressed into a shielding rubber shell according to the volume and shape of the second shielding layer. The shielding rubber shell is then vulcanized at 140-180℃ for 30-60 minutes. The thickness of the shielding barrel body is 5-50 mm.

6. The preparation method according to claim 5, characterized in that, By weight, the raw material components of the shielding rubber mixture include 85% to 95% rubber and 5% to 15% additives, wherein the rubber is natural rubber, silicone rubber, styrene-butadiene rubber or butyl rubber; and the additives are a mixture of boron powder and tungsten powder or a mixture of boron powder and tantalum powder.

7. The preparation method according to claim 1, characterized in that, In step 1, the volume of the radioactive waste to be processed is equal to the volume of the barrel body; in step 4, the volume of the second shielding layer is less than or equal to the volume of the shielding barrel body.

8. A radioactive waste disposal container, characterized in that, The treatment container is prepared by any one of the preparation methods described in claims 1 to 7. The treatment container comprises, from the inside out, a barrel body, a first shielding layer, a second shielding layer, and a shielded barrel body. The inner surface of the first shielding layer is attached to the outer surface of the barrel body, the outer surface of the first shielding layer is attached to the inner surface of the second shielding layer, and the outer surface of the second shielding layer is attached to the inner surface of the shielded barrel body.

Images