JP2009008436A - Radioactive material storage facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radioactive material storage facility capable of simplifying the structure in a storage pit without lowering cooling performance of the radioactive material. <P>SOLUTION: Storage tubes 3 for storing a vitrified waste (radioactive material) 2 are arranged in the storage pit 4. A porous body 6 is installed in a space around the storage tubes 3. A decay heat of the vitrified waste 2 is removed by cooling air 7 through the storage tubes 3. Then, mixing of the cooling air 7 is accelerated by the porous body 5, and a thermal conductivity of the storage tubes 3 is improved. The heat is transferred by radiation from the storage tubes 3 to the porous body 5. The decay heat of the vitrified waste 2 is removed efficiently into the cooling air 7 by the effects. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to radioactive material storage facilities, and in particular, radioactive materials with heat generation such as spent fuel assemblies generated at nuclear power plants and high-level radioactive waste vitrified bodies generated at spent fuel reprocessing facilities. It is related with the radioactive substance storage facility suitable for storing.

  The spent fuel assembly after being used in the nuclear power plant is stored in the fuel storage pool of the nuclear power plant. Spent fuel assemblies stored in the fuel storage pool for a predetermined period are reprocessed in a reprocessing facility to recover reusable nuclear fuel materials such as uranium and plutonium. By this reprocessing, a vitrified body of high-level radioactive waste (hereinafter referred to as a vitrified body) is generated.

  The vitrified body is finally buried in a disposal site provided underground. However, since the vitrified body has a high calorific value immediately after production, it is stored in a dedicated storage facility while being cooled for several decades, and is disposed of after being reduced to a disposable calorific value. A part of the spent fuel assembly is stored in an intermediate storage facility such as a metal cask or vault for several decades before being reprocessed in the reprocessing facility.

  Patent Document 1 discloses a conventional example of a vitrified body storage facility. In this conventional example of the vitrified body storage facility, a plurality of storage tubes for storing the vitrified body are installed in a storage pit. A ventilation pipe concentrically surrounds the storage pipe, and air taken from outside the storage facility flows between the storage pipe and the ventilation pipe. The vitrified body is cooled by this air. The air that has cooled the vitrified body is heated and discharged to the outside through an exhaust passage formed in the storage facility. This cooling air flows in the storage facility by natural circulation using the force (draft force) that warmed air rises in the exhaust duct.

In the storage facility described in Patent Document 1, the flow rate of the cooling air is increased by flowing the cooling air through a narrow annular passage formed between the storage tube and the heat removal ventilation tube. The heat transfer coefficient on the surface increases. For this reason, this storage facility can also store radioactive materials having a large calorific value.
Further, as another conventional example showing a vitrified body storage facility, for example, in Patent Document 2, the structure is simplified by eliminating the ventilation pipe, thereby reducing the amount of members and equipment costs. However, when there is no ventilation pipe, since the cooling air adds a component flowing in the horizontal direction in addition to a component flowing in the vertical direction, the flow becomes complicated. Thereby, there exists a possibility that the cooling efficiency of a storage pipe may become non-uniform | heterogenous. Therefore, the storage facility described in Patent Document 2 is provided with an air dispersion wall at the lower end of the storage pipe to make the air flowing into the storage pit uniform.

  Moreover, in patent document 2, since the wide space between the storage pipes in a storage pit becomes an air flow path, since the air flow rate on a storage pipe surface is slow, the heat transfer coefficient of a storage pipe surface becomes small. Therefore, it is necessary to take measures to improve some heat removal performance such as fins and heat sinks.

In addition, as a configuration example in which a fluid is flowed in a flow path and heat exchange is performed, for example, according to Patent Document 3, cooling is performed by inserting a porous body in which a specific metal is thinned into a flow path heated from the surroundings. It has been shown that the amount of heat removed by air increases by 20% or more compared to a circular tube having a smooth surface. This is because the porous body is inserted into the space heated from the surroundings, so that the fluid in the vicinity of the heat transfer surface and the fluid in the center of the flow are mixed. This is probably because radiant heat transfer can be expected from the hot surface to the porous body.
JP 2001-305291 A JP 2001-27695 A JP 2002-130975 A

  However, in the storage facility disclosed in Patent Document 1, since it is necessary to provide a ventilation pipe for each storage pipe, the structure is complicated, and the amount of members and equipment costs required to hold the ventilation pipe increase. The problem arises.

  Further, in the storage facility disclosed in Patent Document 2, since a wide space between the storage pipes in the storage pit serves as an air flow path, the air flow velocity on the storage pipe surface is slow, so that heat transfer on the storage pipe surface is performed. The rate is small. Therefore, for example, it is necessary to take measures such as installing a radiation fin in the storage tube. This makes it technically possible to store radioactive materials with a large calorific value even if there is no ventilation pipe and the cooling air flow velocity on the surface of the storage pipe is small, but it complicates the structure of the building, and reduces the cost of equipment and equipment. There is a problem of increasing costs.

  In addition, in Patent Document 3 described above, the insertion of a porous body in which a specific metal is thinned into a flow path is disclosed, but there is no viewpoint of achieving both a heat removal effect and a fluid pressure loss. Lack of consideration for uniform cooling efficiency throughout the storage facility.

  An object of the present invention is to provide a radioactive substance storage facility that can simplify the structure in the storage pit without lowering the cooling efficiency for each storage pipe, and can make the cooling efficiency for each storage pipe uniform.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A radioactive substance storage area, an intake duct that guides cooling air into the radioactive substance storage area, an exhaust duct that guides the cooling air discharged from the radioactive substance storage area to the outside, and a radioactive substance storage area A radioactive material storage facility comprising a plurality of storage pipes in which radioactive material is stored, wherein an upward cooling air flow rate increases as the distance from the intake duct decreases in the lower part of the radioactive material storage region. The cooling air passage is formed, and a porous body unit including a thin metal wire is laminated and installed in a portion where the cooling air around the storage tube flows.

  Also, a radioactive substance storage area, an intake duct for guiding cooling air into the radioactive substance storage area, an exhaust duct for guiding the cooling air discharged from the radioactive substance storage area to the outside, and the radioactive substance storage area A radioactive material storage facility comprising a plurality of storage pipes disposed therein and storing radioactive materials therein, wherein an upward cooling air flow rate increases with increasing distance from the intake duct in a lower portion of the radioactive material storage region The cooling air passage is formed, a porous body containing a thin metal wire is installed in a portion where the cooling air flows around the storage pipe, and an upward cooling air flow velocity in the lower part of the radioactive substance storage region is A porous body in which the porosity of the porous body decreases with increasing distance so as to be substantially uniform regardless of the distance away from the intake duct. A structure in which to place.

  Further, in the radioactive substance storage facility, the porosity of the porous body arranged along the side wall surface of the radioactive substance storage area is made larger than the porosity of the porous body arranged at other positions, and the side The flow rate of the cooling air rising along the wall surface is increased.

  According to the present invention, it is possible to achieve uniform cooling efficiency of the storage tube and simplification of the structure in the storage pit while improving the cooling performance of the radioactive substance.

  The radioactive substance storage facility according to the first to third embodiments of the present invention will be described in detail below.

“First Embodiment”
The radioactive substance storage facility according to the first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view showing the overall configuration of the radioactive substance storage facility according to the first embodiment of the present invention. FIG. 2 is a plan view of the lower end portion of the storage tube according to the first embodiment. FIG. 3 is a plan view of a storage pit in which a porous body is installed around the storage tube according to the first embodiment. FIG. 4 is a perspective view showing the detailed structure of the unit frame of the porous body according to the first embodiment. FIG. 5 is a diagram showing the flow of cooling air in the storage pit when the porous body according to the first embodiment is not installed. FIG. 6 is a diagram showing the flow of cooling air in the storage pit when the porous body according to the first embodiment is installed.

  1 to 6, 1 is a radioactive material storage facility, 2 is a solidified glass body, 3 is a storage tube, 4 is a storage pit, 5 is an intake duct, 6 is an exhaust duct, 7 is cooling air, and 8 is a porous body. A unit unit, 9 is a support lattice, 10 is a storage tube support guide, 11 is a porous unit unit, and 12 is a thin line.

  In the radioactive substance storage facility 1 shown in FIG. 1, the upper end portion of the storage tube 3 storing a plurality of vitrified bodies (radioactive substances) 2 is attached to the ceiling of the storage pit 4. This suspension structure absorbs the thermal expansion in the vertical direction of the storage tube caused by the heat generation of the vitrified body 2. An intake duct 5 is formed on the upstream side of the storage pit, an exhaust duct 6 is formed on the downstream side, and a porous body 8 (described in detail in FIG. 4) in which cooling air 7 is arranged in a space around the storage pipe. By flowing through the inside, the vitrified body 2 stored in the storage tube 3 is cooled. The warmed air flows into the exhaust duct 6 and the cooling air flows through the building by the draft force of the air generated here.

  2 and 3 are views of the storage pit 4 as viewed from above. FIG. 3 is a plan view before the porous body 8 is attached and FIG. 4 is a plan view after the porous body 8 is attached. In the illustrated example, the storage tube 3 is in contact with the support grid 9 at four locations and fixed in position. The support grid 9 is attached to a storage tube support guide 10 fixed to the wall surface of the storage pit 4. Here, when the storage tubes 3 are arranged uniformly in the vertical and horizontal directions, the shape of the space surrounded by the storage tubes 3 is the same at any position, and thus the porous body 8 is configured by the unit unit 11.

  FIG. 4 is a perspective view showing the entire configuration of the unit unit 11 of the porous body 8, and the horizontal cross section of the porous body 8 in the configuration example shown in FIG. 4 is such that four vertices of a square are hollowed out with a circle. It becomes a shape (see also FIG. 3). The unit unit 11 of the porous body 8 is a dodecahedron formed from a frame body composed of a wire-shaped portion having a diameter of 9.0 mm representing the thick outer frame shown in FIG. A net is formed on all surfaces (10 surfaces) forming the unit unit 11, and the net has a configuration in which the diameter of the wire is 1.0 mm and the pitch is 20 mm.

  A thin wire 12 having a diameter of 0.5 mm is inserted into the unit unit 11 by 500 m. The porosity of the porous body 8 at this time is 0.994. These fine wires and unit units 11 are all made of stainless steel. Even when another unit unit is stacked on the unit unit 11 of the porous body 8, the shape of the porous body can be maintained without being compressed and deformed by the frame of the porous body. In addition, a thin wire having a diameter of 0.5 mm inserted into the porous body 8 is held inside the porous body 8 by a net having a diameter of 1.0 mm installed on all surfaces of the unit unit 11. Thereby, the porosity inside the unit unit 11 is kept constant.

  The porous body 8 is formed by laminating unit units 11 on the storage tube support guide 10 from above before constructing the concrete of the ceiling of the storage pit 4 (the storage tube support guide 10 and the unit unit 11 in FIG. The porous body having a uniform porosity can be formed in a vertically long space having a height of about 10 m formed outside the storage tube 3. In addition, the critical buckling stress of the unit unit 11 can be calculated by the following equation in the case of the terminal conditions fixed at both ends.

(Critical buckling stress) = (Terminal condition coefficient) × 3.14 ² × Young's modulus / (length of rod / secondary radius of section) ^0.5
Substituting into the above equation 4 as the terminal condition coefficient in the terminal condition fixed at both ends, the Young's modulus of stainless steel 206 GPa, the rod length 1 m, the secondary radius of the cross section = the secondary moment of the cross section / the cross sectional area of the rod = 0.00225, The critical buckling stress is calculated to be 41 MPa. Next, the buckling stress of the lowermost unit unit to which the load is most applied is calculated. The unit unit has a weight of about 9 kg. When ten layers are stacked, a load of nine steps is applied to the lowest unit unit. The buckling stress at this time can be calculated by the following equation.

(Stress on unit) = (weight of unit) × (gravity acceleration) × (number of product steps of unit unit−1) / (cross-sectional area of 8 bars)
Weight of the unit unit 11 90 kg, the acceleration of gravity 9.8 kg / ^{m 2,} the product number 9 units units, and substituting the cross-sectional area 0.00051M ² eight bars in the above equation, the stress applied to the unit obtained 1.7MPa It is done. Since this is very small at 1/20 or less of the buckling stress, even if the unit units 11 are stacked in 10 stages, the shape of the unit units is maintained without buckling. That is, by stacking unit units, it is possible to construct a porous body having a constant porosity in a vertically long space of about 10 m in height.

  Further, the weight of one ventilation tube used in the prior art is approximately 2200 kg, assuming that the diameter of the ventilation tube is 0.6 m, the thickness is 0.015 m, the height is 10 m, and the product is SUS. On the other hand, the weight of one row of porous bodies, that is, 10 units of unit units is about 90 kg as described above, and is very light, about 1/25 of the ventilation pipe. Therefore, the load applied to the storage tube support guide 10 is also small. That is, when the porous body according to the present embodiment is installed, the weight applied to the storage tube support guide 10 is small, so that the strength of the support guide 10 can be reduced.

  Moreover, when attaching the fin used by a prior art, since a long welding operation | work about 10 m in length is needed, a processing cost becomes high. Furthermore, at the time of installation, a storage pipe welded with fins is inserted into the storage pit 4 from above, but a storage pipe in which fins are welded is installed in a narrow space so as not to interfere with the fins of adjacent storage pipes. The work to do takes time and installation costs. On the other hand, in this embodiment, it is only necessary to stack the unit units 11 of the porous body 8 in order from the upper part after installing the cylindrical storage pipe without fins, so that the installation cost can be kept low.

  Although the material of the porous body 8 is stainless steel, a material obtained by performing anticorrosion measures such as plating, coating, and thermal spraying on carbon steel or copper, or chromium-containing steel can also be used.

  The decay heat of the vitrified body 2 is removed by the cooling air 7 through the storage tube 3. At this time, mixing of the cooling air is promoted by the porous body 5 and the heat transfer coefficient of the storage tube is improved. In addition, heat is transferred from the storage tube 3 to the porous body 5 (metal mesh or fine wire) by radiation. By these effects, the decay heat of the vitrified body 2 is efficiently removed to the cooling air 7. According to Patent Document 3 described above, when the porosity is 0.993 or more, the amount of heat removal is improved by 20% compared to the case of a circular tube having a smooth surface. Therefore, also in this embodiment, the heat removal performance is reliably improved.

  Thus, by providing the porous body 8 in the flow path through which the cooling air flows, heat transfer is improved by mixing the air in the vicinity of the heat transfer plate surface, and radiation heat transfer between the heat transfer surface and the porous body. Therefore, heat transfer from the heat transfer surface to the cooling air is promoted.

  As disclosed in Patent Document 2 of the above-described prior art, when the ventilation pipe is excluded for simplification of the structure, the air is easily affected by the connection position of the intake duct 5, the exhaust duct 6 and the storage pit 4. For this reason, the flow of the cooling air 7 becomes uneven.

  FIG. 5 shows the analysis result of the air flow velocity in the storage pit when the ventilation pipe is excluded for the simplification of the structure. In the lower part of the storage pit 4, as the distance from the intake duct 5 increases, the inside of the storage pit The upward flow rate of the cooling air in the tank becomes faster (see the length of the upward arrow at the lower part of the storage pit). This is because the inertial force in the flow direction (horizontal direction) when the cooling air flowing in from the intake duct 5 flows into the storage pit 4 (A in FIG. 5) is warmed by the storage pit 4 and rises in the vertical direction. This is because it is very strong against the flow velocity component. In other words, since the cross-sectional area of the inlet entering the storage pit 4 from the intake duct 5 is very small compared to the cross-sectional area of the middle stage of the storage pit, the flow rate of the cooling air in the horizontal direction when flowing into the storage pit is increased, Since the cooling air with the increased flow velocity hits the pit wall facing the inlet, the flow velocity in this portion increases.

  In addition, the air flow velocity in B in FIG. 5 is relatively low due to the effect of the high air flow velocity in the portion far from the intake duct 5. Thus, it can be seen that when the ventilation pipe is excluded, the flow becomes non-uniform. Thus, when the horizontal component of the velocity distribution of the cooling air differs depending on the location in the storage pit, the heat removal performance is also unevenly distributed, which causes a problem that the design of the building becomes very difficult.

  In the present embodiment, by arranging the porous body 8 around the storage tube 3, the generation of horizontal flow components is suppressed, and the periphery of the storage tube is moved from the bottom to the top even if there is no structure such as a ventilation tube. Cooling air can flow uniformly. Thus, the cooling efficiency of each storage pipe can be made uniform by preventing the cooling air flow in the storage pit from being biased.

  FIG. 6 shows the analysis result of the air flow rate in the storage pit 4 when the porous body 8 is installed around the storage tube 3, and it can be seen that the air flow rate in the storage pit 4 is substantially uniform. In other words, when the horizontal axis is the position between the entrance side of the storage pit and the opposite wall surface, and the upward flow velocity at the lower part of the storage pit is the vertical axis, in the case of FIG. However, there is a considerable difference between the vertical values of the opposite wall surface and the inlet side. However, if a porous body having the same structure is arranged as shown in FIG. 6, the tendency of FIG. It will appear, but not so much difference. Incidentally, if the porous body shown in FIG. 7 described later is disposed, the above-described difference can be almost eliminated.

  Moreover, since the radiant heat transmitted from the surface of the storage tube to the ceiling and floor of the storage pit is reduced by the porous body, the temperature rise of the storage pit ceiling and floor can be suppressed, and consequently installed on the ceiling and floor of the storage pit. The structure of the heat insulating member and the side wall channel can be simplified. In addition, since the weight of the porous body 5 is very light, it is possible to ensure the seismic strength without fixing the porous body 5 with a strong member, so the necessity of newly installing a strength member is not necessary. Does not occur.

  As described above, the heat transfer promoting effect by the insertion of the porous body is caused by radiant heat transfer between the heat transfer surface and the porous body or mixing of air. Therefore, a material having high emissivity and thermal conductivity is preferable as the porous body. On the other hand, the radioactive substance storage facility is assumed to store radioactive substances for about 50 years. Here, when the cooling air contains salt, it is necessary to select a material having high corrosion resistance for the porous body. As described above, stainless steel is used as the material of the porous body, but a material that has been subjected to anticorrosion measures such as plating, painting, and thermal spraying on chromium-containing steel, carbon steel, or copper may be used. Moreover, although the case where the porous body 5 has a mesh shape has been shown, a metal plate having a large number of small holes may be used.

“Second Embodiment”
A radioactive substance storage facility according to a second embodiment of the present invention will be described below with reference to FIG. FIG. 7 is a longitudinal sectional view showing the entire configuration of the radioactive substance storage facility according to the second embodiment of the present invention, and is a longitudinal sectional view of the storage pit when the porosity distribution of the porous body is adjusted. The second embodiment is characterized in that the porosity distribution of the porous bodies arranged in the storage pits is different. However, since the other configurations are the same as those in the first embodiment, The description regarding 1 embodiment is used.

  In the radioactive substance storage facility of FIG. 1, in the first embodiment of the present invention in which the porous body 5 having a uniform porosity is installed, the cooling air 7 is substantially uniform as shown in FIG. In the embodiment, in order to further increase the effect, the porosity of the porous body 13 is reduced as the distance from the intake duct 5 decreases, so that the pressure loss of the porous body 13 increases as the distance from the intake duct 5 increases. Give it.

  According to the configuration of the second embodiment, if a porous body with a reduced porosity is arranged so that the pressure loss is applied to the porous body as much as possible from the entrance, the gap is reduced so that the pressure loss is not applied so much in the vicinity. It is possible to make the upward flow velocity at the lower portion of the storage pit substantially equal on the inlet side and the opposite wall surface side. Here, the porosity of the porous body is changed by changing the density of the mesh in the net connecting the porous body frames, or by changing the length and amount of the fine wires 12 included.

“Third Embodiment”
A radioactive substance storage facility according to a third embodiment of the present invention will be described below with reference to FIG. FIG. 8 is a longitudinal sectional view showing the overall configuration of the radioactive substance storage facility according to the third embodiment of the present invention, in which the porosity of the porous body in the vicinity of the storage pit wall surface is increased to increase the air flow velocity in the vicinity of the wall surface. It is a longitudinal cross-sectional view of a storage pit.

  The third embodiment shows a configuration when it is desired to lower the temperature of the wall of the storage pit 4 in the radioactive substance storage facility of FIG. That is, in the storage pit, the porosity of the porous body 15 in the vicinity of the side wall surface where the temperature is to be lowered is shown as the porous body 14 in another part (FIG. 8 shows an example using a porous body having a uniform porosity as in FIG. However, the present invention is not limited to this, and it may be a porous body whose porosity changes as shown in FIG. 7) and increases along the wall surface by reducing the pressure loss of the porous body in the vicinity of the wall surface. The cooling effect is enhanced by increasing the air flow rate. Similarly, when there is a region where the temperature is to be decreased, the temperature can be decreased for the same reason by increasing the porosity of the porous body in the region.

  As described above, the embodiment of the present invention has the following configuration, and is characterized by having functions or actions. That is, in the part where the cooling air around the storage pipe arranged in the storage pit flows, a porous body group in which a porous body made by thinning metal or a porous body of a unit unit is arranged is arranged around the storage pipe. By disposing the porous body in the horizontal direction, the generation of flow components in the horizontal direction can be suppressed, and the cooling air can be made to flow uniformly from the bottom to the top around the storage tube without a structure such as a ventilation tube. Thus, the cooling efficiency of each storage pipe can be made uniform by preventing the cooling air flow in the storage pit from being biased. In addition, by arranging a porous body having a high porosity by thinning a specific metal in a portion where the cooling air flows around the storage tube, heat transfer from the radioactive substance to the cooling air is promoted, It is possible to suppress a decrease in cooling efficiency that occurs when the ventilation pipe is deleted.

  Moreover, since the radiant heat transmitted from the surface of the storage tube to the ceiling and floor of the storage pit is reduced by the porous body, the temperature rise of the storage pit ceiling and floor can be suppressed, and consequently installed on the ceiling and floor of the storage pit. The structure of the heat insulating member and the side wall channel can be simplified.

  In addition, when it is desired to reduce the temperature rise of the members constituting the side wall surface, the porosity of the porous body should be made larger than that of the porous body at other sites so that the pressure loss of the porous body near the side wall surface is reduced. Thus, it can be dealt with by increasing the flow velocity of the air rising along the side wall surface.

  Furthermore, the porous body installed around the storage tube is not made to have a uniform shape, but by adjusting the porosity of the porous body so that the pressure loss in the portion where the flow velocity becomes high is increased, The cooling air flowing from the bottom to the top can be made more uniform.

  The storage tubes of the vitrified storage facility are generally about 50 cm in diameter and about 10 m in height, and are arranged at intervals of about 1 m. Since the space in which the porous body is installed is a space between the storage tubes, the space is a vertically long space having a height of 10 m or more. The porous body is preferably installed uniformly in the space between the storage tubes. Therefore, a porous unit unit having a height of about 1 m into which a thin wire having a predetermined length is inserted is laminated on a storage tube support guide having a guide function for supporting the storage tube. By making the diameter and length of the thin wire inserted into the unit unit equal in all the porous bodies, the uniformity of the porosity can be ensured.

  Since the frame of the porous unit unit needs to have strength capable of supporting its own weight, the diameter is generally thicker than the thin line inserted into the porous unit unit. Thereby, the porosity of the porous body installed in the vertically long space can be made uniform.

  As described above, the heat transfer enhancement effect by insertion of the porous body is caused by radiant heat transfer and air mixing between the heat transfer surface and the porous body. Therefore, the porous body is a metal with high emissivity and thermal conductivity. It is preferable to be comprised with a material. On the other hand, the radioactive substance storage facility is assumed to store radioactive substances for about 50 years. Here, when the cooling air contains salt, it is necessary to select a material having high corrosion resistance for the porous body. From the above, as the material of the porous body, a material in which anticorrosion measures such as plating, painting, spraying, etc. are applied to stainless steel, chromium-containing steel, carbon steel or copper is used.

It is a longitudinal cross-sectional view which shows the whole structure of the radioactive substance storage facility which concerns on the 1st Embodiment of this invention. It is a top view in the lower end part of the storage pipe regarding a 1st embodiment. It is a top view of the storage pit which installed the porous body around the storage tube regarding a 1st embodiment. It is a perspective view which shows the detailed structure of the unit unit of the porous body regarding 1st Embodiment. It is a figure which shows the flow of the cooling air in the storage pit when not installing the porous body regarding 1st Embodiment. It is a figure which shows the flow of the cooling air in a storage pit at the time of installing the porous body regarding 1st Embodiment. It is a longitudinal cross-sectional view which shows the whole structure of the radioactive substance storage facility which concerns on the 2nd Embodiment of this invention, and is a longitudinal cross-sectional view of the storage pit at the time of adjusting the porosity distribution of a porous body. It is a longitudinal cross-sectional view which shows the whole structure of the radioactive substance storage facility which concerns on the 3rd Embodiment of this invention, and raises the porosity of the porous body near the storage pit wall surface, and the storage pit which raised the air flow velocity near the wall surface It is a longitudinal cross-sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radioactive substance storage facility 2 Vitrified body 3 Storage pipe 4 Storage pit 5 Intake duct 6 Exhaust duct 7 Cooling air 8 Unit unit of porous body 9 Support grid 10 Storage pipe support guide 11 Unit unit 12 Fine line 13 As it becomes far from the intake duct Porous body with small porosity 14 Porous body with uniform porosity

Claims (5)

A radioactive substance storage area, an intake duct that guides cooling air into the radioactive substance storage area, an exhaust duct that guides the cooling air discharged from the radioactive substance storage area to the outside, and a radioactive substance storage area A radioactive material storage facility comprising a plurality of storage tubes in which radioactive material is stored,
In the lower part of the radioactive substance storage area, a passage of the cooling air is formed such that the upward cooling air flow velocity increases as the distance from the intake duct increases.
A radioactive substance storage facility, wherein a porous body unit including a thin metal wire is laminated and installed in a portion where cooling air flows around the storage tube. A radioactive substance storage area, an intake duct that guides cooling air into the radioactive substance storage area, an exhaust duct that guides the cooling air discharged from the radioactive substance storage area to the outside, and a radioactive substance storage area A radioactive material storage facility comprising a plurality of storage tubes in which radioactive material is stored,
In the lower part of the radioactive substance storage area, a passage of the cooling air is formed such that the upward cooling air flow velocity increases as the distance from the intake duct increases.
A porous body containing a fine metal wire is installed in a portion where cooling air flows around the storage tube,
Disposing a porous body in which the porosity of the porous body decreases as the distance increases, so that the upward cooling air flow velocity in the lower portion of the radioactive substance storage region is substantially uniform regardless of the distance away from the intake duct. A radioactive material storage facility. In claim 1 or 2,
The porosity of the porous body arranged along the side wall surface of the radioactive substance storage region is made larger than the porosity of the porous body arranged at other positions, and the cooling air rising along the side wall surface is increased. A radioactive material storage facility characterized by increasing the flow velocity. In claim 2 or 3,
The radioactive substance storage facility according to claim 1, wherein the porosity of the porous body is determined by changing a density of a net connected to a frame body of the porous body or changing a length of a metal thin wire included therein. In any one of claims 1 to 4,
The radioactive substance storage facility, wherein the porous body is made of a corrosion-resistant material.

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