A method for drying transport containers and / or storage containers, and transport containers and / or storage containers

Abstract

To provide a method of drying a transport container and / or a storage container which can remove the remaining water content from a container without difficulty, is simple, not complicated and excellent in the high drying efficiency and is used for radioactive wastes, especially used fuel elements.SOLUTION: A method of drying a transport container and / or a storage container comprises the steps of: performing drainage or machine-drainage of a container 1; and then introducing at least one kind of solid desiccant 4 into a container inner chamber 3 in order to remove the remaining water content from the container inner chamber 3, especially remove the physically and / or chemically-coupled water content. The solid desiccant 4 is the alkaline-earth salt, especially the alkaline-earth oxide.SELECTED DRAWING: Figure 1

Description

[Technical Field] 【0001】 The present invention relates to a method for drying transport and / or storage containers used for radioactive waste, particularly spent fuel elements, and to a method for first draining or mechanically draining the containers. The present invention further relates to the corresponding transport and / or storage containers. Hereinafter, the term "container" will be used as an abbreviation for "transport and / or storage container." [Background technology] 【0002】 Methods for drying transport and / or storage containers of the type described at the beginning are known in practice and in the background art in various forms. Containers used for spent fuel elements are usually loaded with spent fuel elements in water, because water provides an effective shielding medium against the neutrons generated. For further handling, the container is generally drained or mechanically drained first. Subsequently, any remaining moisture in the container is removed by drying, particularly vacuum drying. Removing residual moisture from containers is usually difficult. For this reason, various drying methods are known, but these drying methods are usually time-consuming and costly. Furthermore, these drying methods are notably inefficient. [Overview of the project] [Problems that the invention aims to solve] 【0003】 In contrast, the fundamental technical problem of this invention is to provide the type of method described at the beginning that can remove residual moisture from the container without any problems, is easy, requires little effort, and is outstanding in terms of high drying efficiency. bottom The technical challenge is to provide corresponding transport containers and / or storage containers. [Means for solving the problem] 【0004】 To solve this technical problem, the present invention provides a method for drying transport and / or storage containers used for radioactive waste, particularly spent fuel elements, comprising first draining or mechanically draining the container, and subsequently introducing at least one solid desiccant into the container chamber to remove any remaining moisture from the container chamber, particularly physically and / or chemically bound moisture, wherein the solid desiccant is an alkaline earth salt, particularly an alkaline earth oxide. 【0005】 It is within the scope of the present invention that the solid desiccant is calcium oxide, or that at least 80% by weight, preferably at least 85% by weight, particularly at least 90% by weight, and especially advantageously at least 95% by weight of the solid desiccant consists of calcium oxide. Preferably, the desiccant consists entirely or substantially entirely of calcium oxide. For purposeful purposes, powdered calcium oxide is used as the desiccant. Calcium oxide at 20°C is 800 kg / m³ 3 ~1200kg / m 3 Having a certain bulk density is within the scope of the present invention. 【0006】 The method according to the present invention is preferably used for drying transport and / or storage containers containing spent fuel elements. This method is particularly more suitable for containers with higher or higher thermal output. For the purposes of the invention, the thermal output of the container is 12.5 kW to 42 kW, particularly 15 kW to 40 kW, and preferably 20 kW to 40 kW, for example 25 kW to 40 kW. According to one embodiment, the container has a thermal output of up to 39 kW. In relation to the above, the method according to the present invention has proven to be exceptional. 【0007】 Loading into the container is performed underwater, particularly loading spent fuel elements underwater, and within the scope of the method according to the present invention, the container is first drained or mechanically drained. Preferably, after draining or mechanically draining the container chamber, the container chamber is first vacuum-dried, and only then is any remaining moisture removed from the container chamber using a desiccant according to the present invention. According to a preferred embodiment of the present invention, the container chamber is filled with helium gas after vacuum drying. As demonstrated, the container chamber is filled with helium gas until the internal pressure is 400 hPa to 1000 hPa, preferably 600 hPa to 1000 hPa, and particularly 750 hPa to 950 hPa. 【0008】 The introduction of a desiccant or calcium oxide into the container chamber after vacuum drying is within the scope of the present invention. A particularly important and highly advantageous embodiment within the scope of the present invention is characterized in that the desiccant or calcium oxide is introduced into the container chamber using at least one filter cartridge, and drying is performed using the filter cartridge with the container closed. In this case, the filter cartridge preferably extends in the longitudinal direction of the container chamber. According to one embodiment, the filter cartridge may extend over the entire height or length of the container chamber. According to another advantageous variant, the filter cartridge extends over only a portion of the length or height of the container chamber. 【0009】 A preferred embodiment of the method according to the present invention is characterized in that a desiccant or calcium oxide, and preferably a filter cartridge containing a desiccant or calcium oxide, is placed in the upper third, particularly the upper quarter, of the container chamber. According to a particularly advantageous variation of the method according to the present invention, the placement is made in the upper one-fifth of the container chamber. In this case, the term "upper" is based on the upright state of the container having an upper lid or primary lid. 【0010】 To solve the technical problems, the present invention further teaches a transport container and / or storage container used for radioactive waste, particularly spent fuel elements, wherein the container is provided with at least one drying device containing at least one desiccant to remove residual moisture after mechanical drainage of the container chamber and after vacuum drying, wherein the desiccant is an alkaline earth salt, particularly an alkaline earth oxide, and particularly advantageously calcium oxide. Purposefully, the calcium oxide is present in powder form in the container chamber or the drying device. 【0011】 A particularly advantageous embodiment of the container according to the present invention is characterized in that a desiccant or calcium oxide is contained in at least one, particularly one, filter cartridge. Preferably, the filter cartridge is fixed in the upper third, particularly the upper quarter, particularly the upper fifth of the container chamber, for example, suspended under As already mentioned above, the upper third, upper quarter, and upper fifth are based on the upright state of the container with the upper lid or primary lid. It is within the scope of the present invention that the length of the filter cartridge extends over the upper fifth or approximately the upper fifth of the fuel basket in the container chamber. Such a fuel basket is used to contain spent fuel elements as usual. Preferably, the filter cartridge, including at least one mounting element, has a length of 800 mm to 1200 mm, particularly 900 mm to 1100 mm. 【0012】 It is within the scope of the present invention that the filter cartridge has a containment chamber defined by a water vapor permeable wall for a desiccant, particularly calcium oxide. Purposefully, the water vapor permeable wall of the filter cartridge is made of sintered metal, or substantially made of sintered metal. This is, for example, austenitic stainless steel as the sintered metal. Preferably, the water vapor permeable wall or wall made of sintered metal of the filter cartridge has a pore size of 1 μm to 15 μm, particularly 2 μm to 12 μm, and advantageously 4 μm to 12 μm. Purposefully, the wall thickness of the water vapor permeable wall or wall made of sintered metal of the filter cartridge is 0.5 mm to 6 mm, particularly 1 mm to 5 mm, and advantageously 1.5 mm to 3 mm. The outer diameter of the filter cartridge (which is deemed purposeful when measured horizontally with the filter cartridge fixed) is preferably 25 mm to 60 mm, particularly 30 mm to 50 mm, for example 35 mm to 45 mm. According to a purposeful embodiment of the present invention, the loading volume of the filter cartridge is 600 ml to 1200 ml, particularly 700 ml to 1100 ml, and preferably 800 ml to 1000 ml. 【0013】 The fact that the container is closed by a primary lid is within the scope of the present invention. For the purposes of the invention, the filter cartridge is fixed to the underside of the primary lid. 【0014】 The free volume of the internal chamber of the transport container and / or storage container according to the present invention is preferably 2 m³. 3 ~8m 3 , especially 3m 3 ~6m 3In this case, the free volume of the container means, in particular, the internal chamber volume of the container excluding the fuel basket and fuel elements. It has been demonstrated that 700g to 1200g of desiccant, particularly 700g to 900g of desiccant or calcium oxide is used to remove residual moisture from the container, or in particular from a container having the aforementioned free volume. A filter cartridge introduced into the container is, for the purposes of this invention, to contain 700g to 1200g, particularly 700g to 900g of desiccant or calcium oxide. It is within the scope of this invention that the water vapor absorption capacity of the filter cartridge or such a filter cartridge is 200g to 400g, particularly 210g to 300g of water vapor. For the purposes of this invention, a measurement of the pressure rise is performed with the container closed in order to confirm a sufficient drying rate in the internal chamber of the container. 【0015】 The present invention is based on the understanding that the method and transport and / or storage containers according to the present invention enable easy, low-effort, reliable, and efficient drying of the container's interior. Residual moisture in the container's interior can be removed almost completely without problems, reliably, and with ease. Moisture physically and chemically bound within the container is almost completely absorbed by the desiccant or calcium oxide. The present invention is based on the understanding that the water-binding capacity of calcium oxide is sufficient to absorb the amount of moisture released within the container. It should be emphasized that the implementation of the method according to the present invention is relatively low-cost. In particular, the effort required for the equipment used to dry the container's interior is reduced. Furthermore, the method according to the present invention is characterized by its low failure rate. The method is particularly suitable for containers with higher or higher thermal output. In this respect, the method and container according to the present invention have significant advantages compared to means known in practice. 【0016】 The present invention will be described in detail below based on drawings that show only one embodiment. [Brief explanation of the drawing] 【0017】 [Figure 1]A side sectional view of a transport container and / or a storage container according to the present invention is schematically shown. [Figure 2] A side sectional view of a filter cartridge used in a method according to the present invention or in a container according to the present invention is schematically shown. 【Embodiments for Carrying out the Invention】 【0018】 FIG. 1 shows a transport container and / or a storage container 1 according to the present invention in which a fuel basket (not shown) containing spent fuel elements is stored. The storage is carried out underwater, and first, the drainage or mechanical drainage of the container 1 is performed. Advantageously, in the embodiment, a primary lid 2 for closing the container 1 is attached to the container 1. Preferably, in the embodiment, the inner chamber 3 of the container 1 is vacuum dried for the time being. 【0019】 According to the present invention, a solid desiccant 4 is used to remove the remaining moisture from the inner chamber 3 of the container. The desiccant 4 is, according to an advantageous embodiment, powdered calcium oxide. In this case, preferably, in the embodiment, this desiccant 4 or powdered calcium oxide is accommodated in an accommodation chamber 5 of a filter cartridge 6. This filter cartridge 6 is shown in more detail in FIG. 2. 【0020】 Preferably, in the embodiment, the filter cartridge 6 is arranged in the upper one-fifth of the inner chamber 3 of the container 1. As demonstrated, in the embodiment, the filter cartridge 6 is suspended via an attachment device 7 on the lower surface of the primary lid 2. underIt is. That the wall defining the accommodation chamber 5 of the filter cartridge 6 is steam-permeable is within the scope of the present invention. Advantageously, in the embodiment, this steam-permeable wall is made of sintered metal. In this case, according to a variant of the present invention, the sintered metal can be austenitic stainless steel. The steam-permeable wall 8 of the filter cartridge 6, according to an advantageous embodiment, has a wall thickness of 1 mm to 5 mm and preferably has a pore diameter of 2 μm to 12 μm. As demonstrated, in the embodiment, the filter cartridge 6 including the mounting device 7 has a length of about 800 mm to 1200 mm, particularly 900 mm to 1100 mm. 【0021】 The free volume of the inner chamber 3 of the container 1 according to the present invention is advantageously 2 m 3 ~8 m 3 、particularly 3 m 3 ~6 m 3 That is. In this case, the free volume of the container 1 particularly means the inner chamber volume of the container 1 excluding the fuel basket and the fuel elements. The diameter or outer diameter of the filter cartridge 6 only corresponds to a part of the inner diameter of the inner chamber 3 of the container. In this case, the diameter is advantageously measured horizontally when the container 1 is in a standing state. According to a preferred variant of the present invention, the outer diameter of the filter cartridge 6 is less than one-sixth, advantageously less than one-eighth of the inner diameter of the inner chamber 3 of the container. This application relates to the invention described in the claims, but also includes the following other embodiments. 1. A method for drying transport containers and / or storage containers (1) used for radioactive waste, particularly spent fuel elements, First, drain container (1) or drain it mechanically. A method for drying transport and / or storage containers, wherein, subsequently, at least one solid desiccant (4) is introduced into the container chamber (3) to remove any remaining moisture, particularly physically and / or chemically bound moisture, the solid desiccant (4) being an alkaline earth salt, in particular an alkaline earth oxide. 2. The method of claim 1, wherein the solid desiccant (4) is calcium oxide, or at least 80% by weight, particularly at least 90% by weight, of the solid desiccant (4) consists of calcium oxide. 3. Method 1 or 2 above, wherein after draining or mechanically draining the container chamber (3), the container chamber (3) is then vacuum-dried, and subsequently, any remaining moisture is removed from the container chamber (3) using a solid desiccant (4). 4. One of the methods described in 1 to 3 above, wherein the container chamber (3) is filled with helium gas after vacuum drying. 5. The method of 4 described above, wherein the container chamber (3) is filled with helium gas until the internal pressure reaches 400 hPa to 1000 hPa, and especially 750 hPa to 950 hPa. 6. One of the methods described in 3 to 5 above, wherein a desiccant (4) or calcium oxide is introduced into the container chamber (3) after vacuum drying. 7. One of the methods described in 1 to 6 above, wherein a desiccant (4) or calcium oxide is introduced into the container chamber (3) using at least one filter cartridge (6). 8. One of the methods 1 to 7 above, wherein a desiccant (4) or calcium oxide, and preferably a filter cartridge (6) containing the desiccant (4) or calcium oxide, are placed in the upper third, particularly the upper quarter, of the container (1). 9. A transport container and / or storage container (1) used for radioactive waste, particularly spent fuel elements, wherein the container (1) is provided with at least one drying device containing at least one desiccant (4) to remove residual moisture after mechanical drainage of the container chamber (3) and subsequent vacuum drying, the desiccant (4) being an alkaline earth salt, particularly an alkaline earth oxide. 10. The desiccant (4) is calcium oxide, in the transport container and / or storage container (1) of item 9 above. 11. A desiccant (4), particularly calcium oxide, is present in powder form in the transport container and / or storage container (1) of the above 9 or 10. 12. The desiccant (4) is contained in at least one, particularly one, filter cartridge (6), which is fixed in the upper third, particularly the upper quarter, and advantageously the upper fifth of the container chamber (3) of any one of the transport and / or storage containers (1) described in 9 to 11 above, and particularly suspended. 13. The transport container and / or storage container (1) of the above 12 has a filter cartridge (6) having a containment chamber (5) defined by a water vapor permeable wall (8) for a desiccant (4), particularly calcium oxide, wherein the water vapor permeable wall (8) of the filter cartridge (6) is preferably made of sintered metal or substantially made of sintered metal. 14. The water vapor permeable wall (8) of the filter cartridge (6) has a wall thickness of 0.5 mm to 6 mm, particularly 1 mm to 5 mm, and preferably has a pore size of 1 μm to 15 μm, particularly 2 μm to 12 μm, preferably 4 μm to 12 μm, as described in the transport container and / or storage container (1) of the above 13. [Explanation of symbols] 【0022】 1 container 2 Primary lid 3 Inside the container 4. Desiccant 5 Confinement Rooms 6 filter cartridges 7. Mounting device 8 walls

Claims

[Claim 1] A transport container and / or storage container (1) used for radioactive waste, wherein the container (1) has a separate primary lid (2), a container chamber (3) located below the primary lid (2), and a fuel basket, and the container (1) is provided with at least one drying device containing at least one type of desiccant (4) that is introduced into the container (1) after vacuum drying to remove residual moisture after mechanical draining of the container chamber (3) and subsequent vacuum drying, wherein the desiccant (4) is calcium oxide, and the desiccant (4) is contained in at least one filter cartridge (6), the filter cartridge being fixed to the lower surface of the primary lid (2). [Claim 2] The transport container and / or storage container (1) according to claim 1, wherein the desiccant (4) is present in powder form. [Claim 3] The transport container and / or storage container (1) according to claim 1 or 2, wherein the filter cartridge (6) is fixed or suspended from the upper one-third, upper one-quarter, or upper one-fifth of the container chamber (3). [Claim 4] The transport container and / or storage container (1) according to any one of claims 1 to 3, wherein the filter cartridge (6) has a containment chamber (5) defined by a water vapor permeable wall (8) for a desiccant (4). [Claim 5] The transport container and / or storage container (1) according to claim 4, wherein the water vapor permeable wall (8) of the filter cartridge (6) has a wall thickness of 0.5 mm to 6 mm or 1 mm to 5 mm and has a pore diameter of 1 μm to 15 m or 2 μm to 12 μm or 4 μm to 12 μm.

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