JP2015190761A - storage container of radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage container of a radioactive material capable of discharging hydrogen gas generated inside the storage container by radiolysis or corrosion, to the outside of the storage container surely, efficiently and inexpensively with a simple constitution at low cost.SOLUTION: A storage container of a radioactive material includes a tubular part 3 provided inside the storage container 1 of the radioactive material 2, and having at least one end opened to the outside of the storage container 1, and a hydrogen permeable membrane 4 provided on the tubular part 3. The hydrogen permeable membrane 4 is provided on a position where at least a part of the periphery of the hydrogen permeable membrane 4 is enclosed by the radioactive material 2, when the radioactive material 2 is stored in the storage container 1.

Description

  The present invention relates to a storage container for storing, storing, transferring, and burying radioactive materials.

  Radioactive materials generated in nuclear power plants, nuclear fuel reprocessing plants, decommissioning plants, and the like are stored in containers for storage, transfer, embedding, and disposal. At this time, the radioactive substance in the container has a high dose, and when water coexists, hydrogen gas is generated due to radiolysis of water, and the pressure and concentration of hydrogen in the container may increase, which is not preferable. In addition, when metal ions in the decontamination waste liquid are treated, high doses of cationic resin, anion resin, and the like are generated as secondary waste. It is known that hydrogen gas is generated from this high dose of cationic resin or anion resin. For these reasons, the high-dose resin used in the treatment of the decontamination waste liquid is not allowed to be buried. It is also known that hydrogen gas is generated when a radioactive substance containing an amphoteric metal such as aluminum or zinc is solidified with a cement-based material (see, for example, Patent Document 1). Hydrogen gas is also generated by the corrosion reaction of amphoteric metals.

  In Patent Document 2, a high-dose resin is generated by treatment of metal ions in the decontamination waste liquid, and as a countermeasure against hydrogen gas generated from the resin, a chemical liquid such as an oxidizing agent or a reducing agent is used in the decontamination waste liquid. A waste liquid treatment method that suppresses the generation of hydrogen by pretreating metal ions is described.

  In Patent Document 3, in order to avoid generation of hydrogen in a container containing a radioactive substance, the radioactive waste is removed by dehydrating or warming the container after the radioactive substance is cemented and solidified. An article processing method is disclosed. In this method, a pretreatment is performed to remove water itself that causes hydrogen generation.

  Patent Document 4 discloses a radioactive waste processing method in which a hydrogen oxidation catalyst is installed in a storage container. In this method, hydrogen generated in the storage container is combined with oxygen by an oxidation catalyst and returned to water to remove hydrogen.

Japanese Patent Laid-Open No. 6-102397 JP2013-221898A JP 2007-132787 A JP 2002-286893 A

  In a radioactive material storage container, it is necessary to release or remove hydrogen gas generated in the storage container due to radiolysis or corrosion from the storage container to prevent an increase in hydrogen concentration or pressure in the storage container.

  In the waste liquid treatment method for suppressing the generation of hydrogen from a high-dose resin as described in Patent Document 2, a chemical liquid for pretreating metal ions in the decontamination waste liquid is required. A complicated piping system, heating equipment, filter equipment, ultraviolet irradiation equipment, and the like are also required. Moreover, in the radioactive waste processing method which performs the pre-processing which removes a water | moisture content as described in patent document 3, the heating equipment of a storage container, the pressure reduction equipment, an off-gas processing equipment, etc. are required. Thus, in order to suppress or avoid the generation of hydrogen, the conventional technique has a problem that the processing system becomes complicated and the processing cost increases.

  On the other hand, in the radioactive waste processing method in which a hydrogen oxidation catalyst is installed as described in Patent Document 4, oxygen gas that reacts with hydrogen gas is present in a limited amount in the storage container, so that there is a slight amount. There is a problem that only an amount of hydrogen can be removed, and it is difficult to reliably remove hydrogen.

  The present invention provides a radioactive substance storage container that can reliably and efficiently release hydrogen gas generated inside a storage container due to radiolysis or corrosion to the outside of the storage container with a simple configuration and low cost. Objective.

  The radioactive substance storage container according to the present invention has the following characteristics. A tubular part is provided inside the radioactive substance storage container, and at least one end is open to the outside of the storage container, and a hydrogen permeable membrane provided in the tubular part. The hydrogen permeable membrane is provided at a position where at least a part of the periphery of the hydrogen permeable membrane is surrounded by the radioactive substance when the storage container stores the radioactive substance.

  The radioactive substance storage container according to the present invention can reliably and efficiently release the hydrogen gas generated inside the storage container due to radiolysis and corrosion to the outside of the storage container with a simple configuration and low cost.

It is a schematic diagram which shows the structure of the storage container of the radioactive substance by Example 1 of this invention. In Example 1, it is a figure which shows the hydrogen permeability coefficient of a palladium alloy membrane, and the relationship of temperature. In Example 1, it is a figure which shows the relationship between the hydrogen permeation | transmission flow rate N from the inside of a storage container to the exterior, and the hydrogen concentration inside a storage container. In Example 1, it is a longitudinal cross-sectional view of the tubular part of a storage container, and is a figure in case a hydrogen permeable film comprises a part of side surface of a tubular part. In Example 1, it is a longitudinal cross-sectional view of the tubular part of a storage container, and is a figure in case a hydrogen permeable film comprises a part of bottom face of a tubular part. In Example 1, it is a longitudinal cross-sectional view of the tubular part of a storage container, and is a figure at the time of providing a hydrogen permeable film in the inside of a tubular part along the cross section of the internal space of a tubular part. In Example 1, it is a schematic diagram which shows the structure of the storage container provided with a some tubular part inside. In Example 1, it is a longitudinal cross-sectional view of the tubular part of a storage container, and is a figure at the time of providing a plurality of hydrogen permeable membranes in the length direction of the tubular part. It is a schematic diagram which shows the structure of the storage container of the radioactive substance by Example 2 of this invention. It is a longitudinal cross-sectional view of the tubular part of the storage container of the radioactive substance by Example 3 of this invention. It is a longitudinal cross-sectional view of the tubular part of another structure of the storage container of the radioactive substance by Example 3 of this invention.

  The radioactive substance storage container according to the present invention is a container used for storing, storing, transferring, and embedding radioactive substances while maintaining hermeticity so as not to leak the radioactive substances to the outside. It is suitable for use when hydrogen is generated inside the storage container due to corrosion reaction of metal or metal.

  The radioactive substance storage container according to the present invention includes a tubular part provided inside the storage container and having at least one end opened to the outside of the storage container, and the tubular part has a property of selectively transmitting hydrogen gas. A hydrogen permeable membrane which is a member is provided. The hydrogen permeable membrane is heated by the decay heat of the radioactive material. For this reason, the radioactive substance storage container according to the present invention can release the hydrogen gas generated inside the storage container to the outside reliably, safely and efficiently without impairing the hermeticity. It is possible to prevent an increase in the concentration and pressure of hydrogen in the inside.

  It is well known that radioactive materials stored in radioactive material storage containers generate decay heat, and the temperature of the storage container rises due to the decay heat. For example, in Japanese Patent Laid-Open No. 2000-249789, a copper alloy used in a radioactive material storage container is tested at 200 ° C., assuming a heat resistance temperature of 300 ° C. to 650 ° C. and a temperature increase due to decay heat. The test which performed the heating of is carried out. Therefore, although the radioactive substance storage container depends on the amount of radioactive substance contained therein, it can be generally estimated that the temperature rises to 200 ° C. or higher due to the decay heat of the radioactive substance. In the radioactive substance storage container according to the present invention, the hydrogen permeable membrane is heated by the decay heat of the radioactive substance.

  As the hydrogen permeable film used in the radioactive material according to the present invention, a metal film such as a palladium alloy film, a polymer film such as polyimide, and a ceramic film such as silicon nitride can be used. Metal films and polymer films have been put into practical use for general industries, and ceramic films are in the development stage for practical use. Hydrogen permeable membranes are used to purify hydrogen gas used in the fields of semiconductor manufacturing, petroleum refining industry, and chemical industry. A method for separating hydrogen gas using a palladium alloy membrane is described in, for example, Japanese Patent Application Laid-Open No. 2008-289948. The characteristics of the palladium alloy film are that the metal palladium adsorbs hydrogen molecules, the adsorbed hydrogen molecules dissociate, the hydrogen atoms generated by the dissociation move in the palladium, move through the film, and move to the film surface. They are bonded to each other on the film surface to form hydrogen molecules, so that hydrogen gas is selectively permeated. On the other hand, a feature of the polymer film and the ceramic film is that only hydrogen gas is selectively permeated by molecular sieve (separation by molecular size). The hydrogen permeable membrane is used for purifying hydrogen gas, but can also be applied to remove hydrogen gas.

  It is known that the hydrogen permeation membrane (hydrogen permeation efficiency) is improved when used at a temperature higher than room temperature. A preferable temperature for using the hydrogen permeable membrane is 50 ° C. or more in consideration of hydrogen permeation efficiency of the hydrogen permeable membrane and embrittlement by hydrogen gas. The metal film and the ceramic film are more preferably 200 ° C. or higher, and the polymer film is more preferably 50 ° C. or higher and 150 ° C. or lower. The storage container according to the present invention is characterized in that the hydrogen permeation efficiency of the hydrogen permeable membrane is improved by heating the hydrogen permeable membrane using the decay heat of the radioactive substance to raise the temperature of the hydrogen permeable membrane. As described above, it can be assumed that the temperature of the radioactive material storage container generally rises to at least 200 ° C. due to the decay heat of the radioactive material, so that the hydrogen permeable membrane is heated to a temperature of 50 ° C. or higher. The hydrogen permeation efficiency can be expected to improve.

  It is also possible to configure a part of the outer wall (for example, lid) of the radioactive substance storage container with a hydrogen permeable membrane so that only hydrogen gas is released from the inside of the storage container to the outside. However, in order to efficiently release hydrogen gas, a configuration that improves the hydrogen permeation efficiency of the hydrogen permeable membrane by actively heating the hydrogen permeable membrane as in the storage container according to the present invention is extremely effective.

  As described above, the storage container according to the present invention has a simple configuration, and can release the hydrogen gas inside the storage container to the outside reliably, safely and efficiently at low cost.

  Hereinafter, a configuration of a radioactive substance storage container according to an embodiment of the present invention will be described with reference to the drawings. Note that in the drawings for describing the following embodiments, the same reference numerals are given to the same elements, and repeated description thereof may be omitted.

The configuration of the radioactive substance storage container according to the first embodiment of the present invention will be described. In the storage container, for example, waste sludge such as cation resin and anion resin generated by processing metal ions in the decontamination waste liquid generated at nuclear power plants, etc. is stored, and radiation such as in-furnace structures is stored. It is possible to store a solidified metallized cementitious material. Radioactive metals generated as operational waste at commercial nuclear power plants are evaluated to contain radioactive materials such as Co-60 (approximately 4 × 10 ¹⁴ Bq / ton) (Japan Atomic Energy Society standard, marginal disposal) Basic requirements for production of target waste: 2009).

  FIG. 1 is a schematic view showing a configuration of a radioactive substance storage container according to the present embodiment. The metal storage container 1 stores a high-dose radioactive substance 2 and the like, and includes a tubular portion 3 inside.

  The tubular portion 3 can be formed by piping, for example, and only one end is opened to the outside of the storage container 1 and has a bottom surface at the other end. One end of the opening of the tubular portion 3 may or may not protrude to the outside of the storage container 1, but in FIG. 1, when it does not protrude to the outside (the opening 8 of the tubular portion 3 is the outer surface of the storage container 1. Is provided). The inside of the tubular portion 3 is a cavity, is continuous with the outside of the storage container 1, and does not contain the radioactive substance 2. The shape of the cross section of the tubular portion 3 is arbitrary, and can be, for example, a circle, an ellipse, or a polygon. The size of the tubular portion 3 (the length in the length direction, the area of the cross section of the internal space, the thickness, etc.) is the size of the storage container 1 and the amount of the radioactive substance 2 stored in the storage container 1 (estimated amount). ) Can be determined arbitrarily. The tubular portion 3 is preferably formed of the same material as the storage container 1, but may be formed of a material different from that of the storage container 1.

  The tubular portion 3 includes a hydrogen permeable membrane 4 having a property of selectively transmitting hydrogen gas. When the storage container 1 stores the radioactive substance 2, the hydrogen permeable membrane 4 is provided at a position lower than the uppermost surface of the radioactive substance 2 (so as to be located inside the radioactive substance 2). That is, the hydrogen permeable membrane 4 is provided at a position where at least a part of the periphery of the hydrogen permeable membrane 4 is surrounded by the radioactive material 2 when the storage container 1 stores the radioactive material 2. Although details will be described later with reference to FIGS. 4A to 4C, the hydrogen permeable membrane 4 may constitute a part of the side surface of the tubular part 3 or may constitute at least a part of the bottom surface of the tubular part 3. Alternatively, it may be provided inside the tubular portion 3 along the cross section of the internal space of the tubular portion 3. For example, when the hydrogen permeable membrane 4 constitutes a part of the side surface of the tubular portion 3, it is provided so that one surface of the hydrogen permeable membrane 4 faces the radioactive substance 2 (see FIGS. 1 and 4A). . Since the hydrogen permeable membrane 4 is surrounded at least partially by the radioactive material 2 and is close to or adjacent to the radioactive material 2, the hydrogen permeable membrane 4 is heated by the decay heat of the radioactive material 2, and the temperature is increased. Performance is improved.

  Inside the storage container 1, hydrogen gas is generated by water radiolysis. The hydrogen gas inside the storage container 1 permeates the hydrogen permeable membrane 4 and flows into the tubular portion 3, flows inside the tubular portion 3, and is open at one end (opening portion 8) of the tubular portion 3. To the outside of the storage container 1. Since the hydrogen permeable membrane 4 selectively transmits only hydrogen gas, the radioactive substance 2 does not flow out of the storage container 1. That is, the storage container 1 selectively releases only hydrogen gas to the outside. The hydrogen gas that has permeated the hydrogen permeable membrane 4 and released to the outside of the storage container 1 is mixed with air in the atmosphere, diluted, and discharged.

  The hydrogen gas that has flowed into the tubular portion 3 flows toward the upper portion of the storage container 1. For this reason, it is preferable that the open end of the tubular portion 3 opens on the upper surface of the storage container 1. However, the tubular portion 3 may be opened on the side surface of the storage container 1.

  In the storage container 1 containing the high-dose radioactive material 2, the amount of hydrogen gas generated by radiolysis of water depends on the shape of the storage container 1, the type of waste sludge, the filling amount, and the water content To do. Under typical conditions, it is evaluated that hydrogen gas of 1 to 500 L / year may be generated per year.

FIG. 2 is a graph showing the relationship between the hydrogen permeability coefficient and temperature of the palladium alloy membrane. The temperature characteristics shown in FIG. 2 are as follows: the membrane type is Pd-5% Au, the thickness is 100 μm, the membrane area is 12 cm ² , and the hydrogen permeability coefficient is 1.2 × 10 ⁻⁸ mol · s when the membrane temperature is 300 ° C. ^This is a characteristic of a palladium alloy film of ⁻¹ · m ⁻¹ · Pa ^−0.5 . In this embodiment, an example in which this palladium alloy film is used as the hydrogen permeable film 4 will be described. In the following, the hydrogen permeation performance of the palladium alloy membrane is evaluated.

In general, the hydrogen permeation flow rate of the hydrogen permeable membrane is calculated by the equation (1) using the hydrogen permeation coefficient.
J = φ · S / L × ((P ₁ ) ^0.5 − (P ₂ ) ^0.5 ) (1)
In the formula (1), J is a hydrogen permeation flow rate (mol · s ⁻¹ ), φ is a hydrogen permeation coefficient (mol · m ⁻¹ · s ⁻¹ · Pa ^−0.5 ), and S is a membrane area (m ² ). , L represents the film thickness (m), P ₁ represents the hydrogen partial pressure (MPa) inside the storage container 1, and P ₂ represents the hydrogen partial pressure (MPa) outside the storage container 1. Since the hydrogen concentration outside the storage container 1 can be evaluated as almost zero under atmospheric conditions, P ₂ = 0 can be set in Equation (1).

  FIG. 3 shows the hydrogen permeation from the inside of the storage container 1 to the outside, obtained by using the formula (1), in the storage container 1 according to the present embodiment (the above-described palladium alloy film is used as the hydrogen permeable film 4). It is a figure which shows the relationship between the flow volume N (L / year) and the hydrogen concentration (%) inside the storage container.

  As can be seen from FIG. 3, when the hydrogen concentration inside the storage container 1 is 4% of the flammability limit concentration, the hydrogen permeation flow rate N of the hydrogen permeable membrane 4 is 5600 L / year. In recent years, it has been known that the hydrogen permeability coefficient tends to be smaller by one digit than the ideal hydrogen permeability coefficient in a region where the hydrogen concentration is low. Taking this knowledge into consideration, assuming that the hydrogen permeation performance of the hydrogen permeable membrane 4 is 1/10 and the value obtained from FIG. 3 is 1/10, the hydrogen permeation flow rate N is estimated to be 560 L / year. The value 560 L / year of the hydrogen permeation flow rate N exceeds the maximum hydrogen generation rate of 500 L / year when the waste sludge is stored in the storage container 1 described above. That is, in the storage container 1 according to the present embodiment, a larger amount of hydrogen than the amount generated inside can be discharged to the outside, and the hydrogen concentration inside the storage container 1 is always higher than 4% of the flammability limit concentration. Can also be kept low.

In FIG. 3, as a comparative example, a palladium alloy film having a film type of Pd-5% Au, a thickness of 25 μm, a film area of 12 cm ² , and a film temperature of 20 ° C. was obtained using the formula (1). The relationship between the hydrogen permeation flow rate N (L / year) and the hydrogen concentration (%) is also shown. In the comparative example, the hydrogen permeation coefficient at a temperature of 20 ° C. was determined as 3.0 × 10 ⁻¹⁰ mol · s ⁻¹ · m ⁻¹ · Pa ^{−0.5 by} extrapolating the graph of FIG. As can be seen from FIG. 3, the hydrogen permeation flow rate N of the hydrogen permeable membrane of the comparative example is 560 L / year when the hydrogen concentration inside the storage container is 4% of the flammability limit concentration. Also in the case of the comparative example, when the hydrogen permeation flow rate is estimated to be 1/10 as in the case of this example, the hydrogen permeation flow rate N is 56 L / year, which is the maximum hydrogen when waste sludge is stored in the storage container. The generation rate is less than 500L / year. Therefore, in the case of a palladium alloy film having a film temperature of 20 ° C., hydrogen generated inside the storage container 1 may not be sufficiently discharged to the outside. In the comparative example, the thickness of the membrane was set to 25 μm so as to make the hydrogen gas permeate easily by making it thinner than the thickness (100 μm) in this embodiment, but the hydrogen permeable membrane of the comparative example still has a low temperature. Therefore, the hydrogen permeation flow rate N is smaller than that of the hydrogen permeable membrane of this example.

  As described above, the hydrogen permeable membrane 4 has a large change in the hydrogen permeation flow rate depending on the temperature. In the radioactive material storage container according to the present embodiment, the hydrogen permeation flow rate of the hydrogen permeable membrane 4 can be maintained large by utilizing the decay heat of the radioactive material 2 and maintaining the temperature of the hydrogen permeable membrane 4 high. Further, if a sufficient hydrogen permeation flow rate can be obtained by keeping the temperature of the hydrogen permeable membrane 4 high, the thickness of the hydrogen permeable membrane 4 can be increased. By increasing the thickness of the hydrogen permeable membrane 4, the mechanical strength of the hydrogen permeable membrane 4 can be improved and the hydrogen permeable membrane 4 can be prevented from being damaged.

  Further, according to the equation (1), when the thickness L and area S of the hydrogen permeable membrane 4 are changed, the hydrogen permeation flow rate of the hydrogen permeable membrane 4 can be changed. Therefore, when the thickness and area of the hydrogen permeable membrane 4 are set to appropriate values according to the amount (estimated amount) of hydrogen gas generated inside the storage container 1, the hydrogen gas inside the storage container 1 is reduced to the flammable limit concentration. It is possible to suppress to the following.

  FIG. 4A is a view showing the configuration of the tubular portion 3 of the storage container 1 and is a longitudinal sectional view of the tubular portion 3. The hydrogen permeable membrane 4 constitutes a part of the side surface of the tubular portion 3 and is provided so that one surface faces the radioactive substance 2. One hydrogen permeable membrane 4 or a plurality of hydrogen permeable membranes 4 may be provided in the circumferential direction of the tubular portion 3. When one hydrogen permeable membrane 4 is provided in the circumferential direction of the tubular portion 3, the hydrogen permeable membrane 4 may be provided in the entire circumferential direction of the tubular portion 3 (see FIG. 1). You may provide in a part. Further, when a plurality of hydrogen permeable membranes 4 are provided in the circumferential direction of the tubular portion 3, the hydrogen permeable membrane 4 may be provided continuously in the circumferential direction of the tubular portion 3 or may be provided discontinuously. .

  The tubular portion 3 may include an aperture plate 5 that contacts the radioactive substance 2 and a reinforcing plate 6 that contacts the internal space of the tubular portion 3. The perforated plate 5 and the reinforcing plate 6 are supporting members for the hydrogen permeable membrane 4 and hold the hydrogen permeable membrane 4 therebetween. The aperture plate 5 forms the outer peripheral surface of the tubular portion 3, the reinforcing plate 6 forms the inner peripheral surface of the tubular portion 3, and the hydrogen permeable membrane 4 is installed between the aperture plate 5 and the reinforcing plate 6. Is done. The aperture plate 5 has a plurality of holes that allow one surface of the aperture plate 5 to communicate with the other surface, and the reinforcing plate 6 includes a plurality that communicates one surface of the reinforcement plate 6 with the other surface. Of holes. The hydrogen gas flows from the radioactive substance 2 to the hydrogen permeable membrane 4 through these holes, and passes through the hydrogen permeable membrane 4 and flows into the tubular portion 3.

  By holding the hydrogen permeable membrane 4 between the aperture plate 5 and the reinforcing plate 6, the possibility of damage to the hydrogen permeable membrane 4 can be extremely reduced. Further, by providing an aperture plate 5 to form a space between the radioactive substance 2 and the hydrogen permeable membrane 4, the hydrogen permeable membrane 4 can be prevented from being deteriorated or convection of hydrogen gas can be performed in the vicinity of the hydrogen permeable membrane 4. To improve the flow of hydrogen gas.

  The aperture plate 5 and the reinforcing plate 6 can be formed of the same material, for example, using a metal mesh sheet, a punching metal, a porous ceramic layer, or the like. The size (hole diameter) of the holes of the aperture plate 5 and the reinforcing plate 6 can be arbitrarily determined. However, the size of the hole of the aperture plate 5 is preferably smaller than the size of the radioactive material 2 so that the radioactive material 2 does not enter the hole of the aperture plate 5. The thicknesses of the perforated plate 5 and the reinforcing plate 6 can be arbitrarily determined. For example, the thickness can be determined in consideration of the strength when the hydrogen permeable membrane 4 is held therebetween.

  FIG. 4B is a diagram showing another configuration of the tubular portion 3 of the storage container 1, and is a longitudinal sectional view of the tubular portion 3. The hydrogen permeable membrane 4 constitutes a part of the bottom surface of the tubular portion 3 and is provided so that one surface faces the radioactive substance 2. The hydrogen permeable membrane 4 may constitute the entire bottom surface of the tubular portion 3. The hydrogen permeable membrane 4 may be held between the aperture plate 5 and the reinforcing plate 6. In FIG. 4B, as an example, a case where the hydrogen permeable membrane 4 is provided between the aperture plate 5 and the reinforcing plate 6 is shown. In the hydrogen permeable membrane 4, the aperture plate 5 and the reinforcing plate 6, The bottom surface of the tubular portion 3 is configured.

  FIG. 4C is a view showing another configuration of the tubular portion 3 of the storage container 1, and is a longitudinal sectional view of the tubular portion 3. The hydrogen permeable membrane 4 is provided inside the tubular portion 3 along the cross section of the internal space of the tubular portion 3. The hydrogen permeable membrane 4 may be held between the aperture plate 5 and the reinforcing plate 6. FIG. 4C shows a case where the hydrogen permeable membrane 4 is provided between the aperture plate 5 and the reinforcing plate 6 as an example.

  As shown in FIGS. 4A to 4C, when the storage container 1 stores the radioactive substance 2, the hydrogen permeable membrane 4 is located at a position lower than the uppermost surface of the radioactive substance 2 (so that it is located inside the radioactive substance 2. ) Is provided. That is, the hydrogen permeable membrane 4 is provided at a position where at least a part of the periphery of the hydrogen permeable membrane 4 is surrounded by the radioactive material 2 when the storage container 1 stores the radioactive material 2. Since the hydrogen permeable membrane 4 is surrounded at least partially by the radioactive material 2 and is close to or adjacent to the radioactive material 2, the hydrogen permeable membrane 4 is heated by the decay heat of the radioactive material 2, and the temperature is increased. Performance is improved.

  In this embodiment, the case where a palladium alloy film is used as the hydrogen permeable film 4 has been described. Besides palladium alloy films, hydrogen permeable platinum, nickel, niobium, vanadium, zirconium, tungsten, titanium, and an alloy film containing at least one of ruthenium, and a polymer containing polyimide as a main component Even if a membrane or a ceramic membrane containing silicon nitride as a main component is used as the hydrogen permeable membrane 4, the same effect as in this embodiment can be expected.

  The inside and outside of the storage container 1 are partitioned by the hydrogen permeable membrane 4, and the radioactive substance 2 does not migrate to the outside of the storage container 1.

  In this embodiment, the case where hydrogen is generated by radiolysis has been described as an example. However, when hydrogen is generated by corrosion of miscellaneous solid waste containing amphoteric metals such as aluminum and zinc generated at a nuclear power plant. In addition, the present invention is applicable.

  FIG. 5 is a schematic diagram showing a configuration of the storage container 1 having a plurality of tubular portions 3 therein. As shown in FIG. 5, the storage container 1 can also include a plurality of tubular portions 3 inside. The plurality of tubular parts 3 are preferably arranged at equal intervals inside the storage container 1 in order to efficiently release hydrogen gas from the storage container 1. Further, the position of the hydrogen permeable membrane 4 in the tubular portion 3 may be the same or different in the plurality of tubular portions 3.

  FIG. 6 is a view showing the configuration of the tubular portion 3 of the storage container 1, and is a longitudinal sectional view of the tubular portion 3. The hydrogen permeable membrane 4 constitutes a part of the side surface of the tubular portion 3 and is provided so that one surface faces the radioactive substance 2. In the storage container 1 shown in FIG. 6, a plurality of hydrogen permeable membranes 4 are provided in the length direction of one tubular portion 3. The hydrogen permeable membrane 4 may be provided continuously in the length direction of the tubular portion 3 or may be provided discontinuously. In the example shown in FIG. 6, the two hydrogen permeable membranes 4 are discontinuously provided in the length direction of the tubular portion 3.

  The storage container 1 shown in FIGS. 5 and 6 has an advantage that the hydrogen gas inside the storage container 1 can be discharged to the outside more efficiently.

  The configuration of the radioactive substance storage container according to the second embodiment of the present invention will be described. The storage container of the present embodiment has the same configuration as the storage container of Embodiment 1, but the tubular portion is different. In the following, differences from the first embodiment will be mainly described.

  FIG. 7 is a schematic diagram showing a configuration of a radioactive substance storage container according to the present embodiment. The storage container 1 includes a tubular portion 13 inside. Both ends of the tubular portion 13 are open to the outside of the storage container 1. That is, the tubular portion 13 includes openings 8 at both ends, and the atmosphere outside the storage container 1 can flow through the storage container 1 through the tubular portion 13. The openings 8 at both ends of the tubular portion 13 are provided on the outer surface of the storage container 1. The hydrogen permeable membrane 4 may constitute a part of the side surface of the tubular portion 13 (FIG. 4A), or may be provided inside the tubular portion 13 along the cross section of the internal space of the tubular portion 13 (FIG. 4C). Since the hydrogen permeable membrane 4 is surrounded at least partially by the radioactive material 2 and is close to or adjacent to the radioactive material 2, the hydrogen permeable membrane 4 is heated by the decay heat of the radioactive material 2, and the temperature is increased. Performance is improved.

The hydrogen gas inside the storage container 1 passes through the hydrogen permeable membrane 4 and flows into the tubular portion 13, flows inside the tubular portion 13, and is released to the outside of the storage container 1. Since the tubular portion 13 and the hydrogen permeable membrane 4 are heated by the decay heat of the radioactive substance 2, natural convection of the atmosphere occurs inside the tubular portion 13. For this reason, the hydrogen gas that has passed through the hydrogen permeable membrane 4 is diluted with the air in the atmosphere by natural convection of the atmosphere inside the tubular portion 13, and is easily discharged to the outside of the storage container 1. Further, since the hydrogen gas is diluted and easily discharged, the hydrogen partial pressure P ₂ in the equation (1) becomes smaller, and the hydrogen permeation flow rate of the hydrogen permeable membrane 4 increases. Therefore, the radioactive substance storage container 1 according to the present embodiment can discharge the hydrogen gas inside the storage container 1 more efficiently.

  In the radioactive substance storage container 1 according to the present embodiment, both ends of the tubular portion 13 are opened to the outside of the storage container 1, so that the hydrogen gas that has permeated through the hydrogen permeable membrane 4 is more efficiently and efficiently generated by natural convection in the atmosphere. It can be safely diluted and discharged.

  A configuration of the radioactive substance storage container according to the third embodiment of the present invention will be described. The storage container of the present embodiment has the same configuration as the storage container of Embodiment 1, but the tubular portion is different. In the following, differences from the first embodiment will be mainly described.

  FIG. 8 is a view showing the configuration of the tubular portion of the radioactive substance storage container according to the present embodiment, and is a longitudinal sectional view of the tubular portion. The storage container 1 includes a tubular portion 23 inside. The tubular portion 23 includes the hydrogen recombination catalyst layer 7 inside. The hydrogen recombination catalyst layer 7 is filled with a hydrogen recombination catalyst, and recombines hydrogen gas with oxygen gas to convert it into water vapor. The hydrogen gas that has permeated through the hydrogen permeable membrane 4 is converted into water vapor by the hydrogen recombination catalyst layer 7, mixed with air in the atmosphere, and discharged from the inside of the tubular portion 23 to the outside of the storage container 1.

  The hydrogen recombination catalyst layer 7 is installed between the hydrogen permeable membrane 4 and the opening 8 of the tubular portion 23 inside the tubular portion 23 in order to convert the hydrogen gas that has permeated the hydrogen permeable membrane 4 into water vapor. Is preferred. In the example shown in FIG. 8, the hydrogen recombination catalyst layer 7 is a surface of the hydrogen permeable membrane 4 that does not face the radioactive substance 2 (opposite to the face that faces the radioactive substance 2). It is installed at a position facing the surface.

  The hydrogen recombination catalyst filled in the hydrogen recombination catalyst layer 7 includes a catalyst composed of a carrier made of cerium oxide or a mixed oxide of cerium oxide and zirconium oxide, and palladium supported on the carrier. It can be illustrated.

  FIG. 9 is a view showing another configuration of the tubular portion of the radioactive substance storage container according to the present embodiment, and is a longitudinal sectional view of the tubular portion. The storage container 1 includes a tubular portion 33 inside. The tubular portion 33 includes the hydrogen recombination catalyst layer 7 therein, and both ends open to the outside of the storage container 1 (that is, the tubular portion 13 has both ends as in the storage container of the second embodiment (FIG. 7)). Provided with an opening 8). The configuration, function, and installation position of the hydrogen recombination catalyst layer 7 are the same as described above with reference to FIG.

  The radioactive substance storage container 1 according to the present embodiment removes hydrogen gas that has permeated through the hydrogen permeable membrane 4 using a chemical reaction called hydrogen recombination. Therefore, the radioactive substance storage container 1 according to the present embodiment has the effects of the storage containers 1 of the first embodiment and the second embodiment, and converts the hydrogen gas that has permeated the hydrogen permeable membrane 4 into water vapor. Radioactive materials can be stored, stored, transported, and buried safely.

  In addition, this invention is not limited to said Example, Various modifications are included. For example, the above-described embodiments are described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to an aspect including all the configurations described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, with respect to a part of the configuration of each embodiment, the configuration of another embodiment can be added, deleted, or replaced.

  DESCRIPTION OF SYMBOLS 1 ... Storage container, 2 ... Radioactive material, 3, 13, 23, 33 ... Tubular part, 4 ... Hydrogen permeable membrane, 5 ... Opening plate, 6 ... Reinforcement plate, 7 ... Hydrogen recombination catalyst layer, 8 ... Opening part .

Claims (13)

A tubular portion provided inside the storage container of radioactive material, at least one end opening to the outside of the storage container;
A hydrogen permeable membrane provided in the tubular portion,
The hydrogen permeable membrane is provided at a position where at least a part of the periphery of the hydrogen permeable membrane is surrounded by the radioactive substance when the storage container stores the radioactive substance. .   The radioactive hydrogen storage container according to claim 1, wherein the hydrogen permeable membrane forms part of a side surface of the tubular portion. The tubular portion has only one end opened to the outside of the storage container and has a bottom surface at the other end,
The radioactive hydrogen storage container according to claim 1, wherein the hydrogen permeable membrane constitutes at least a part of the bottom surface.   2. The radioactive substance storage container according to claim 1, wherein the hydrogen permeable membrane is provided inside the tubular portion along a transverse section of the internal space of the tubular portion.   2. The radioactive substance storage container according to claim 1, wherein both ends of the tubular portion are open to the outside of the storage container. The tubular portion includes two support members having a plurality of holes,
The radioactive hydrogen storage container according to claim 1, wherein the hydrogen permeable membrane is provided between the two support members.   The radioactive substance storage container according to claim 1, comprising a plurality of the tubular portions.   The radioactive tubular storage container according to claim 1, wherein the tubular portion includes a plurality of the hydrogen permeable membranes. The tubular portion includes a hydrogen recombination catalyst layer inside,
2. The radioactive substance storage container according to claim 1, wherein the hydrogen recombination catalyst layer is filled with a hydrogen recombination catalyst and is provided between the hydrogen permeable membrane and the opening of the tubular portion. .   The radioactive hydrogen storage container according to claim 1, wherein the hydrogen permeable film is an alloy film including at least one of palladium, platinum, nickel, niobium, vanadium, zirconium, tungsten, titanium, and ruthenium.   10. The radioactive substance storage container according to claim 9, wherein the hydrogen recombination catalyst is composed of a carrier made of cerium oxide or a mixed oxide of cerium oxide and zirconium oxide, and palladium supported on the carrier.   The radioactive substance storage container according to claim 1, wherein the hydrogen permeable membrane is a polymer membrane containing polyimide.   The radioactive hydrogen storage container according to claim 1, wherein the hydrogen permeable membrane is a ceramic membrane containing silicon nitride.

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