JP4961502B2 - Radioactive material storage method - Google Patents

Description

  The present invention relates to a method for storing a radioactive substance accompanied by heat generation and a radioactive substance storage facility therefor.

  After being used at a nuclear power plant, the spent fuel assembly is stored and stored in the fuel storage pool of the nuclear power plant for a predetermined period of time, and then reusable nuclear fuel materials such as uranium and plutonium are used in the spent fuel assembly. Reprocessed at a reprocessing facility for recovery from the body.

  The high-level radioactive waste generated by this reprocessing is produced into a vitrified body and finally buried in a disposal site provided underground. However, since the vitrified body has a high calorific value immediately after production, it is stored while cooling in a dedicated radioactive material storage facility for several decades, and is buried after being reduced to a calorific value that can be buried.

  An example of a storage facility for vitrified bodies is described in Patent Document 1. In the vitrified body storage facility of this example, a plurality of storage tubes for housing the vitrified body are installed in the 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. The cooling air flows through the storage facility by natural circulation using the force by which the warmed air rises.

  Patent Document 2 also describes a radioactive material storage facility in which a plurality of storage tubes for storing radioactive materials are installed in a storage pit, and shows a method for storing the radioactive material in the storage facility. The radioactive material storage method of this example includes storage pits with different storage pipe arrangement intervals in the same storage building, and stores radioactive substances in storage pits with large storage pipe arrangement intervals at the start of storage with a high calorific value. When the calorific value is attenuated to a predetermined value or less after a certain period of time, the radioactive material is transferred and stored in the storage tube in the storage pit where the storage tube is arranged at a small interval.

  Patent Document 3 describes a method for storing a vitrified body in a storage facility. One vitrified storage pit is filled with the vitrified body storage facility having a plurality of storage pits. A method is described in which the outlet temperature of the cooling air is lowered by dispersing the plurality of storage pits and storing them instead of storing them in the next storage pit. In addition, as an example of the storage facility, similarly to Patent Documents 1 and 2, a plurality of storage tubes for storing the vitrified body are installed in the storage pit, and the ventilation tube surrounds the storage tube concentrically, An example of a storage facility is shown in which air taken from outside the storage facility flows between the storage tube and the ventilation tube.

JP 2001-305291 A Japanese Patent Laid-Open No. 9-43384 JP 2001-33588 A

  When cooling air is allowed to flow in the storage pit of a radioactive material storage facility by natural circulation, the air flow rate is determined according to the calorific value of the radioactive material contained in the vitrified material to be stored. Therefore, it is difficult to improve the cooling performance of the vitrified body.

  Thus, for example, in the storage facility described in Patent Document 1, in order to improve the cooling performance without increasing the air flow rate, a structure is provided in which a ventilation pipe is provided and the air flow path on the surface of the storage pipe is narrowed to increase the flow velocity. Yes.

  By flowing the cooling air through a narrow annular passage formed between the storage tube and the ventilation tube, the air flow rate is increased, so that the heat transfer coefficient on the surface of the storage tube is increased. For this reason, this storage facility can also store radioactive materials having a large calorific value. However, it is necessary to provide a ventilation pipe for each storage pipe, which complicates the structure and increases the amount of necessary members and equipment costs.

  When the ventilation pipe is excluded for the simplification of the structure, the wide space between the storage pipes in the storage pit becomes the air flow path, so the air flow rate on the storage pipe surface is slow and the heat transfer coefficient on the storage pipe surface is small. Become. Therefore, the amount of heat removal is limited, and a radioactive substance having a large calorific value cannot be stored as compared with the case where a ventilation pipe is provided.

  On the other hand, since the calorific value of radioactive material decays during storage, facilities that have cooling performance for the calorific value at the start of storage are facilities that have excessive cooling performance for radioactive materials that have been stored for a certain period of time. It becomes. Therefore, as in Patent Document 2, when trying to store radioactive materials in equipment with different cooling performance according to the decay of the calorific value, the equipment can be rationalized, but the work of transferring the radioactive material during storage is not possible. Newly needed.

  As in Patent Document 3, when the storage is distributed and stored in a plurality of storage pits, the total heat generation amount of the entire storage pit is smaller than when the storage pits are concentrated and stored. It is possible to reduce. However, the example of the storage facility structure described in Patent Document 3 is a structure in which a ventilation pipe is provided around the storage pipe in the same manner as Patent Document 1, and the cooling performance required for a radioactive substance to be newly stored is Since it does not change, it is necessary to provide a ventilation pipe so that all the storage pipes have a cooling performance with respect to the amount of heat generated at the start of storage.

  Moreover, patent document 3 does not show the storage order of radioactive materials in the storage pit. Therefore, for example, when Patent Document 3 is applied to a storage facility without a ventilation pipe, and the storage order of radioactive materials in the storage pit is stored in order from the storage pipe on the outlet side or the inlet side of the cooling air, the radioactive material is almost at the same time. There is a possibility that a storage tube surrounded by the storage tube containing the gas will be generated. In that case, there is almost no temperature difference between the storage tube of interest and the surrounding storage tubes, and there is a possibility that radiation heat radiation to the surrounding storage tubes cannot be expected.

  Accordingly, an object of the present invention is to provide a radioactive material storage method and storage facility that can have the cooling performance necessary for a radioactive material immediately after the start of storage with a high calorific value while simplifying the structure in the storage pit of the radioactive material storage facility. Is to provide.

  According to another aspect of the present invention, there is provided a solution for storing a radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed. The radioactive tube is adjacent to a side wall of the storage pit or at least one of the storage tubes adjacent to the storage tube storing the radioactive substance is left empty. After the substance is stored in the storage tube and then stored in the storage pit until the state where the state cannot be maintained, the radioactive substance is left empty in the storage pit. A method for storing a radioactive material, comprising the step of storing the radioactive material in the storage tube.

  Further, in the radioactive material storage method of storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed, When the radioactive material is stored in the storage pipe having a low cooling performance, and the radioactive material is stored in all the storage pipes having a low cooling performance, next, among the plurality of storage pipes, A method for storing a radioactive material comprising the step of storing the radioactive material in the storage tube having a high cooling performance.

  Further, in the radioactive material storage method for storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed, fins are provided as the plurality of storage tubes. When a plurality of storage tubes and storage tubes without fins are employed, the radioactive material is stored in the storage tubes without fins, and when the radioactive material is stored in all of the storage tubes without fins, Next, the radioactive substance storage method is characterized by having a process of storing the radioactive substance in a storage tube provided with the fins.

  Further, in the radioactive material storage method of storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which the cooling air is passed, the heat of the radiation due to radiation is contained in the plurality of storage tubes. Of the second storage pipes that are relatively few adjacent to the first storage pipes that are relatively adjacent to the storage pipes that can be exchanged, the radioactive rays are added to the first storage pipes. A step of storing the radioactive substance in the second storage tube after storing the radioactive material in the first storage tube. This is a method for storing radioactive materials.

  The solution provided by the facility of the present invention includes a storage pit, an intake passage that guides cooling air into the storage pit, an exhaust passage that guides the cooling air from the storage pit to the outside of the storage pit, and the storage pit. In a radioactive material storage facility having a plurality of storage tubes in which the number of rows is arranged in a grid pattern with three or more rows both vertically and horizontally, and in which radioactive materials are stored, the radioactive material is included in the plurality of storage tubes. The stored storage tube directly faces the side wall of the radioactive material storage pit, or at least one of the storage tubes adjacent to the storage tube in which the radioactive material is stored. Is a radioactive substance storage facility characterized by being in an empty state in which the radioactive substance is not accommodated.

  Furthermore, the storage pit, the intake passage for introducing the cooling air into the storage pit, the exhaust passage for guiding the cooling air from the storage pit to the outside of the storage pit, and the number of rows in the storage pit are 3 in both vertical and horizontal directions. In a radioactive material storage facility, the storage tube having a plurality of storage pipes arranged in a grid pattern in rows or more, and storing the radioactive substance therein, wherein the storage pipe in which the radioactive substance is stored among the plurality of storage pipes Is an empty state in which at least one of the storage tubes adjacent to the storage tube in which the radioactive material is stored does not store the radioactive material, and the storage in which the radioactive material is stored A radioactive substance storage facility characterized in that radiant heat transfer is possible between a tube and the empty storage tube.

  A storage pit; an intake passage for guiding cooling air into the storage pit; an exhaust passage for guiding the cooling air from the storage pit to the outside of the storage pit; In the radioactive substance storage facility having a plurality of storage pipes arranged in a grid pattern as described above and containing radioactive substances therein, the first of the radioactive pipes in which the radioactive substances are first stored among the storage pipes Thermal radiation between the first storage tube and the other storage tube is blocked between at least one of the storage tube and the other storage tube adjacent to the first storage tube. And a partition member is disposed in the storage pit so that both surfaces facing the first and other storage tubes are in contact with the cooling air.

  According to the present invention, the structure in the storage pit can be simplified and the cooling performance necessary for the radioactive material immediately after the start of storage with a high calorific value can be obtained.

It is a conceptual diagram which shows the storage method of the radioactive material which is one preferable Example of this invention. 1 is a vertical sectional view of a radioactive substance which is a preferred embodiment of the present invention. FIG. 3 is a horizontal sectional view of FIG. 2. FIG. 3 is an enlarged view in the storage pit of FIG. 2. It is a conceptual diagram which shows the other example of the storage method of a radioactive substance. It is a conceptual diagram which shows the other example of the storage method in the other structural example of a storage building. It is an enlarged view in the storage pit in FIG. In the sectional view of the conventional radioactive substance storage facility, the upper figure shows the vertical section and the lower figure shows the flat section. It is an enlarged view in the storage pit of FIG. It is an example which shows attenuation | damping of the emitted-heat amount of a radioactive substance. It is a figure which shows the heat-transfer form in FIG. It is a conceptual diagram which shows the other example of the storage method in the other structural example of a storage building. It is a conceptual diagram which shows the other example of the storage method in the other structural example of a storage building. It is an enlarged view in the storage pit of FIG. It is a conceptual diagram which shows the other example of the storage method in the other structural example of a storage building. It is a conceptual diagram which shows the other example of the storage method in the other structural example of a storage building.

  In one embodiment for achieving the object of the present invention, the radioactive substance is first stored in the storage tube in such an order that at least one of the adjacent storage tubes is empty, and finally the empty material is stored. The storage method is to store in a storage tube in a state.

  With this feature, if there is an empty storage tube adjacent to the storage tube that stores the radioactive material, the heat generated from the radioactive material is transferred to the cooling air from the surface of the storage tube that stores the radioactive material. In addition to being transmitted, after being transmitted by radiation from the storage tube containing the radioactive substance to the adjacent empty storage tube, it can be transmitted from the empty storage tube surface to the cooling air. For this reason, the heat radiation area to the cooling air is substantially increased, and the cooling performance necessary for the radioactive material at the start of storage with a high calorific value can be obtained without increasing the flow velocity of the cooling air.

  In addition, the storage tube that stores the radioactive substance at the end is in a state where the radioactive substance is already stored in all the adjacent storage pipes. In this case, the radioactive substance stored in the adjacent storage pipe is in the first direction. Since it has been stored, since the amount of heat generation has been attenuated since the start of storage, the temperature of the storage tube is considerably reduced. For this reason, since heat is transferred by radiation from the storage tube containing the new radioactive substance to the adjacent storage tube having a low temperature, the effect of substantially increasing the heat radiation area is obtained, and the radiation at the start of storage with a high calorific value is obtained. It can have the cooling performance required for the substance.

  When storing radioactive material in the storage pit, initially there is little radioactive material stored in the storage pit and there are many empty storage pipes in the surrounding area, so increase the amount of radiation heat radiation to the surrounding storage pipes. However, when it is almost full, there are many storage tubes already containing radioactive materials, and the amount of radiated heat to the surroundings is attenuated. Therefore, the amount of cooling equipment can be reduced by increasing the heat removal performance of the storage pipe that is later in the order in which radioactive materials are stored compared to the storage pipe stored at the beginning. .

  In addition, if the surface of the storage tube or the partition member installed between adjacent storage tubes is surface-treated so that the emissivity is increased by painting or spraying, the amount of heat released by the radiation from the storage tube can be further increased. And the cooling performance of the radioactive substance can be improved.

  Examples of the present invention will be described more specifically below. That is, the radioactive substance storage facility which is a preferred embodiment of the present invention is as described below. In addition, in this example, the example at the time of presuming storing the vitrified body which vitrified the high level radioactive waste generated by reprocessing of a spent nuclear fuel is shown.

  The radioactive substance storage facility 1 of the present embodiment has a storage building 30, and a storage pit 2 and a transport area 6 partitioned by a ceiling slab 5 are provided in the storage building 30. A plurality of storage tubes 4 whose upper ends are attached to the ceiling slab 5 are arranged in the storage pit 2.

  A lower plenum portion 13 is formed between the lower surface of the storage tube 4 in which the glass solidified body 3 (radioactive material) is stored and the floor slab 12, and the storage tube 4 absorbs the elongation due to thermal expansion in the vertical direction. It has a structure to do.

  The upper end of each storage tube 4 is sealed with a plug 10. A movable transport carriage 7 for storing and unloading the glass solidified body 3 in an arbitrary storage tube 4 is provided in the transport area 6.

  This radioactive material storage facility 1 is a facility having six storage pits 2. In each storage pit 2, there are three or more storage tubes 4 in both vertical and horizontal directions, specifically, in 7 vertical columns and 20 horizontal columns. 140 are provided. Furthermore, nine glass vitrified bodies 3 can be stored in one storage tube. 2 to 3 show the storage tube 4 in a simplified number of rows.

  The storage tube 4 is composed of a metal tube such as steel or stainless steel because of its strength and heat resistance. In the case of steel, the outer surface is subjected to anticorrosion treatment such as painting, plating, and thermal spraying.

  An intake passage 8 for taking in cooling air for cooling the vitrified body 3 stored in the storage tube 4 from the outside, and an exhaust passage 9 for cooling the vitrified body 3 and releasing the cooling air whose temperature has risen to the outside. Is provided in the storage building 30. The intake passage 8 communicates with the lower plenum portion 13, and the exhaust passage 9 communicates with the upper plenum portion 14.

  The vitrified body 3 transported from the other building to the storage building 30 by the transport carriage 7 is transported as it is above the predetermined storage tube 4 by the transport cart 7 and stored in the storage tube 4 from which the plug 10 has been removed. And stored. After the glass solidified body 3 is stored, the plug 10 is attached to the upper end portion of the storage tube 4 by the transport carriage 7, and the storage tube 4 is sealed.

  The cooling air is taken into the intake passage 8 from the outside of the storage building 30 and guided to the lower plenum portion 13. The cooling air removes heat released from the vitrified body 3 in the storage tube 4 while rising around the storage tube 4 in the storage pit 2. Here, the warmed cooling air passes through the upper plenum portion 14 and is discharged to the outside of the storage building 30 through the exhaust passage 9. This cooling air flows through the storage building 30 by natural circulation, using the force by which the warmed air rises.

  First, the vitrified body 3 is stored in every other storage tube 4 out of seven storage columns 4 in the storage pit 2 as shown in FIG. Since the vitrified bodies 3 are accommodated every other row, the adjacent rows of the storage tubes 4 in which the vitrified bodies 3 are stored are either the wall surfaces of the storage pits 2 or empty storage tubes 4.

  Therefore, as shown in FIG. 4, heat is transferred from the surface of the storage tube 4 storing the glass solidified body 3 to the cooling air by heat transfer, and heat is transmitted to the empty storage tube 4 in the adjacent row by radiation. The heat is transferred from the surface of the empty storage tube 4 to the cooling air by heat transfer. For this reason, the effect that the heat dissipation area increases is obtained, and the cooling performance for the vitrified body 3 increases.

  When the glass solidified body 3 is stored in order from the storage pipe 4 at the end of the storage pit 2 to the adjacent storage pipe 4 without applying the present invention, the glass solidified body 3 that has just been stored is stored. A storage tube 4 surrounded by the storage tube 4 is generated. In that case, since there is no difference in the amount of heat generated from the surrounding vitrified body 3, there is almost no radiation to the adjacent storage tube, only heat transfer from the surface of the storage tube 4 to the cooling air, and the cooling performance is reduced.

  In this embodiment, since the ventilation pipe that increases the flow velocity around the storage pipe 4 is not installed, the heat transfer rate from the surface of the storage pipe 4 to the cooling air is small, and the cooling performance is high at a high calorific value immediately after the start of storage. Is lacking. However, in addition to heat transfer from the surface of the storage tube 4, if the heat is radiated through the adjacent empty storage tube 4, the necessary cooling performance can be obtained without increasing the flow velocity using the ventilation tube. The structure can be simplified.

  After storing the vitrified bodies 3 in every other row for all the storage pits 2 in the radioactive material storage facility 1, next, the middle row of empty storage tubes shown in the second order in FIG. It will be stored in two rows. At this time, 4/7 of the vitrified body is stored with respect to the storage capacity of the entire storage facility 1. Assuming that the period until the storage facility 1 is full is 7 years, 4 years have already passed since the first vitrified body was stored.

  When storing in the second order, the vitrified bodies 3 are already stored in the storage tubes 4 on both sides in the first order, so that the temperature rises compared to the empty storage tube 4. However, since the vitrified body 3 stored in the first order has passed four years, the calorific value is attenuated and is smaller than the storage start time.

  FIG. 10 shows an example of attenuation of the calorific value from the start of storage of the vitrified body 3. In the example of attenuation in FIG. 10, when four years have passed since storage, the calorific value is attenuated to almost half. For this reason, when the vitrified bodies 3 are stored in the second order, the heat generation amount of the vitrified bodies 3 in the storage tubes on both sides stored in the first order is also almost halved.

  The temperature of the storage tube 4 becomes higher as the calorific value of the stored glass-solidified body 3 increases, and therefore, the glass-solidified body 3 becomes vitrified in the first order than the storage tube 4 that newly stores the glass-solidified body 3 in the second order The temperature of the storage tube 4 storing the body 3 is lower. For this reason, although it is smaller than an empty storage tube, the cooling performance with respect to the newly stored vitrified body 3 is increased due to an increase in heat radiation area due to radiation from the storage tube stored in the second order to the storage tube stored in the first order. Improved compared to the case where there is no radiation to the surrounding storage tube.

  On the other hand, since the storage tube in which the vitrified body 3 is stored in the first order receives radiation from the storage tube stored in the second order, the cooling performance is lowered. However, since the heat generation amount has already decreased and there is room for the limit temperature of the vitrified body 3, even if the temperature rises due to radiation from the storage tube 4 that newly accommodates the vitrified body 3, the limit temperature is reduced. It does not exceed, and there is no problem.

  Further, when the second storage tube 4 is full, it is stored in the remaining storage tubes 4 in the center row. At this time, six years have passed since the vitrified bodies stored in the storage tubes 4 in both adjacent rows, and the amount of heat generation has further decreased.

  As for the storage order of the vitrified body 3, various storage orders other than the order shown in FIG. 1 are conceivable depending on the attenuation of the calorific value of the radioactive substance, the arrangement of the storage tubes, and the like. FIG. 5 shows an example of another storage order in which the first order is stored in every other storage pipe 4 in the front, rear, left and right, and the second order is stored in the remaining storage pipes 4. In this example, radiation heat dissipation to the four adjacent storage tubes can be expected.

  The amount of radiation to the adjacent empty or low heat generating storage tubes 4 varies depending on the radiation rate of the outer surfaces of the storage tubes. In order to increase the amount of radiation to the adjacent storage tube and improve the cooling performance, it is better that the radiation rate of the outer surface of the storage tube is large. Therefore, for example, if the radiation rate is increased by using coating, plating, thermal spraying or the like on the surface of the storage tube, the amount of radiation to the adjacent storage tube 4 is increased, and the cooling performance can be further improved.

FIG. 16 shows an example in which the present invention is applied to the storage pipes 4 arranged in a staggered manner in the storage pit 2.
In the storage tube 4, seven and six rows arranged in the short side direction in the storage pit 2 are alternately arranged. First, in the first order, the vitrified bodies 3 are stored in seven storage tubes 4M in one row.
Since there is an empty storage tube 4N between the rows of storage tubes 4M that store the glass solid bodies 3, in addition to the heat transfer path that is directly transferred from the storage tube 4M to the air, the storage tube 4N is connected to the storage tube 4M. Since heat is transmitted by radiation to the heat transfer path through which heat is transferred from the storage tube 4N to the air, the heat radiation area is increased as compared with the case where the storage tube 4 is sequentially stored from the end storage tube 4, and the cooling performance is improved. .

  When the vitrified material has been stored in the storage pipes 4M in all the storage pits 2 in the storage facility 1, a period of about 0.56 times has elapsed with respect to the period in which the storage facility 1 is full. Will be. If the period for filling the storage facility 1 is 10 years, 5 or 6 years have passed.

  Subsequently, in a second order, the vitrified body is stored in an empty storage tube 4N. In this case, since the storage tubes 4M in the adjacent rows have already stored the vitrified bodies 3 in the first order, the temperature of the storage tubes 4M rises due to heat generated from the vitrified bodies 3 inside. However, compared with the vitrified body 3 of the storage tube 4N immediately after the start of storage, since the vitrified body of the storage tube 4M has passed at least 5 or 6 years, if the calorific value attenuates as shown in FIG. The calorific value of the storage tube 4M is almost half that of the storage tube 4N. Therefore, radiant heat transfer occurs from the storage tube 4N to the storage tube 4M, and the cooling performance is improved.

  In addition, when the cooling performance is insufficient only by the method shown in FIGS. 1 and 5, in order to improve the cooling performance, as shown in FIG. 14, a partition plate 11 is provided between the adjacent storage tubes 4, and the storage tubes Heat can be transmitted from 4 to the partition plate 11 by radiation, and the cooling performance can be improved by dissipating heat from the partition plate 11 to the cooling air.

  The partition plate 11 is a plate-like structure installed so as to partition between the storage pipes 4 and is vertically supported with both ends connected to the floor slab 12 and the ceiling slab 5 of the storage pit 2 as shown in FIG. It is attached to the column 16 or a horizontal support column 17 having both ends connected to the walls on both sides of the storage pit 2 by welding or bolting. Since the partition plate 11 needs sufficient strength and heat resistance, the partition plate 11 is made of metal such as steel, stainless steel, or aluminum alloy. In addition, since long-term durability against corrosion is also required, steel is subjected to surface anticorrosion treatment by painting, spraying, plating, and aluminum alloy by anodization.

  The role of the partition plate 11 is to receive the radiant heat of the storage tube 4 and dissipate heat to the cooling air as described above, and does not completely divide the cooling air flow path. For this reason, as long as it can receive the radiant heat required for cooling of a radioactive substance, some clearance gaps may be vacant. Also, the shape is not a flat plate, and there is no problem even if it is curved or has protrusions.

  Even when the partition plate 11 is used, the cooling performance can be further improved by considering the storage order in the storage tube 4 as in the present invention. An example is shown in FIG. In the example of FIG. 6, two partition plates 11 are installed for every three rows of storage tubes 4. If it does so, it will be divided roughly into the storage tube 4B which faced the partition plate 11 only on one side, and the storage tube 4C which faced the partition plate 11 on both sides.

  When it is assumed that the glass solids having the same heat generation amount are stored in all the storage tubes, the storage tube 4C facing the partition plate 11 on both sides is separated from the partition plate 4B facing the partition plate 11 only on one side. 11 can be said to have high cooling performance because the number of paths for heat dissipation increases through 11.

  Therefore, the first and second orders in which radiation radiation to the surroundings can be greatly expected are stored in the storage tube 4B facing the partition plate 11 only on one side, and finally, the amount of storage increases and radiation radiation to the surroundings is reduced. In order of decreasing 3rd order, it can be stored in a minimum amount of material while maintaining the temperature below the limit of radioactive material efficiently by storing in the storage tube 4C facing the partition plate 11 on both sides with high cooling performance. It becomes.

  This will be described in more detail with reference to FIG. In the first order and the second order, the vitrified body 3X is stored in the storage tube 4B facing the partition plate 11 only on one side. At this time, heat from the vitrified body 3X is transferred from the surface of the storage tube 4B to the air by heat transfer, and transferred from the partition plate 11 to the air by radiation and transferred from the partition plate 11 to the air by heat transfer. Radiated by

  Although the partition plate 11 is only on one side of the storage tube 4B, since the vitrified body is not yet stored in the adjacent storage tube 4C across the partition plate 11, the partition plate 11 can radiate heat to the air from both sides. it can.

  In the third order, the vitrified body 3Y is stored in the storage tube 4C having the partition plates 11 on both sides. Also at this time, the heat from the vitrified body 3Y is transferred to the air from the surface of the storage tube 4C to the air and to the partition plate 11 by radiation, and is transferred from the partition plate 11 to the air by heat transfer. Heat is dissipated by the route.

  Here, the difference from the first and second orders is that the adjacent storage tube 4B across the partition plate 11 is not empty, and the vitrified bodies 3X are already stored in the first and second orders. The amount of heat released to the air is smaller than the first and second orders. Accordingly, since the partition plates 11 are installed on both sides of the storage tube 4C, the vitrified body 3Y can be sufficiently cooled.

  As in the case of the storage tube 4, the greater the radiation rate on the surface of the partition plate 11, the greater the amount of radiation from the storage tube 4 to the partition plate 11. For this reason, the cooling performance of the storage pipe | tube 4 can be improved more by processing the partition plate 11 surface so that the radiation rate of the partition plate 11 surface may become large. For example, the emissivity may be increased by using painting, plating, thermal spraying, anodizing, or the like on the partition plate surface.

  The installation of the partition plate 11 increases the number of structural members in the storage pit 2. However, when the ventilation pipe 15 and the partition plate 11 have the same thickness as compared with the structure in which the ventilation pipe 15 is installed for each storage pipe 4, the amount of members is about 35%, and the structure can be simplified. it can.

  Furthermore, unlike a ventilation pipe, it is not necessary to bend a plate to form a pipe shape, and it is only necessary to install a plate-like member as it is, so that it is possible to reduce labor for processing the member.

  FIG. 15 shows another example of storage using the partition plate 11. In the example of FIG. 15, one partition plate 11 is installed for every other row of storage tubes 4. Then, both sides of the storage tubes 4 in each row face the partition plate 11.

  The first order is stored in the storage pipe 4H facing the storage pit side wall surface 31 and the storage pipe 4J in the center of each of the storage pipes 4 divided by the partition plate 11. In the example of FIG. 15, since the storage tubes 4H to 4J having the same calorific value are arranged across the partition plate 11, the partition plate 11 receives the same amount of radiant heat from the storage tubes on both sides. For this reason, heat radiation from the surface opposite to the partition plate 11 cannot be expected, but the side wall surface 31 of the storage pit or the empty storage tube 4K is located on the side parallel to the partition plate 11, and therefore, due to radiation to that side. Heat dissipation can be expected.

  In the second order, among the storage tube 4 rows divided by the partition plate 11, the storage tubes 4L are stored in the storage tubes 4L adjacent to the storage tube 4J at the center of each row. The storage tube 4L is adjacent to the storage tube 4J already stored in the first order and the empty storage tube 4K. Of course, the storage tube 4J stored first, as well as the empty storage tube 4K, has already passed 3/7 of the period until the storage facility 1 is full, and the amount of heat generated is higher than that of the storage tube 4L. Therefore, heat radiation by radiation from the storage tube 4L to the storage tube 4K and the storage tube 4J can be expected.

In the last third order, they are stored in the storage tube 4K that remains empty. Both sides of the storage tube 4K are adjacent to the storage tube 4H already stored in the first order and the storage tube 4L already stored in the second order.
Since both the storage tube 4H and the storage tube 4L have a longer storage period than the storage tube 4H, the amount of heat generated is small. Therefore, heat radiation from the storage tube 4K to the storage tube 4H and the storage tube 4L can be expected.

  When fins are provided in the storage tube 4 instead of the partition plate 11, for example, as shown in FIG. 12, the storage tubes 4D with fins and the storage tubes 4E without fins are alternately arranged in a row.

  First, as shown in FIG. 12, the vitrified body 3 is stored in a storage tube 4E having low cooling performance and having no fins. Since empty storage tubes 4D with fins arranged in every other row are arranged, heat is transmitted from the storage tube 4E containing the glass solidified body to the empty storage tube 4D by radiation, and from the empty storage tube 4D to the air. And dissipate heat. For this reason, sufficient cooling performance can be obtained without fins.

  In the second order, since it is stored between the storage tubes 4E in which the vitrified bodies are already stored in the first order, radiation to the adjacent storage tubes cannot be expected compared to the first order. Since the storage tube 4D stored in the housing has fins, the cooling performance is higher than that of the storage tube 4E without fins, and sufficient cooling performance can be obtained. By storing in this way, the number of storage tubes 4D with fins can be reduced.

  If the storage order of the vitrified bodies 3 is not specified and if the storage tubes 4 are stored in order from the storage tube 4 at the end of the storage pit 2, radiation to the adjacent storage tubes cannot be expected with certainty. It is necessary to attach a fin to the tube 4.

  On the other hand, by applying the present invention, the number of storage tubes 4D with fins can be reduced, and the structure can be simplified.

  Moreover, as shown in FIG. 13, there is also a method of storing the vitrified body in order from the storage tubes having a large number of adjacent storage tubes. FIG. 13 is an example in which the storage tubes are arranged in 4 rows × 11 rows in the storage pit, unlike the previous examples.

  The storage tube 4F shown in black in the first order in FIG. 13 is surrounded by another storage tube. Therefore, when the vitrified body is first stored prior to the storage tube 4F surrounded by another storage tube, the storage tube 4G with one side facing the wall of the storage pit remains empty. Heat is transferred to 4G and is radiated from the empty storage tube 4G to the air.

  If the storage pipes are stored in order from the storage pipe at the end of the storage pit, the storage pipe 4F in the middle of the storage pit is surrounded by a storage pipe that already stores the glass solidified body. Radiation to the storage tube cannot be expected, and the cooling performance is reduced accordingly.

  When all the storage is completed in the storage tube 4F surrounded by other storage tubes, the one surface is stored in the storage tube 4G facing the wall surface of the storage pit 2 in the second order. Since one side faces the wall surface, heat radiation by radiation to the wall surface can be expected.

  As described above, even when a method of storing before the storage tubes having a large number of adjacent storage tubes is used, it is possible to efficiently cool.

  As described so far, in the period when the amount of heat generated at the start of storage is high, the method of obtaining high cooling performance by transferring heat to the adjacent storage tube 4 or partition plate 11 by radiation and dissipating it to the air, As shown in FIG. 4, when there is almost no structure that blocks radiation between the adjacent storage tubes 4, or as shown in FIG. 7, there is a partition plate 11 between the adjacent storage tubes 4, and the partition A great effect can be obtained by adopting a structure capable of releasing heat to the air from both sides of the plate.

  On the other hand, in the conventional radioactive substance storage facility shown in FIGS. 8 and 9 in which the ventilation pipe 15 is installed around the storage pipe 4, radiation from the storage pipe 4 is blocked by the ventilation pipe 15 around the storage pipe. End up. For this reason, even if the storage tube 4 is empty or the vitrified body 3 having a high calorific value is stored, the cooling performance of the adjacent storage tube 4 is not affected, and the empty storage tube is surrounded. Even if 4 is arranged, the cooling performance is not improved.

  In addition, the present invention defines the storage order of radioactive materials, but does not require the trouble of transferring the radioactive materials during storage, and does not require special equipment during storage, simplifying the structure in the storage pit. In addition, it is possible to efficiently cool a radioactive substance having a high calorific value.

  The storage method and storage facility shown in the examples so far can be applied to the case of storing spent fuel assemblies instead of vitrified bodies.

  The present invention relates to a radioactive material suitable for storing radioactive materials that generate heat, such as vitrified bodies of high-level radioactive waste generated at spent fuel reprocessing facilities for spent fuel assemblies generated at nuclear power plants. There is a field of use in material storage facilities.

DESCRIPTION OF SYMBOLS 1 Radioactive material storage facility 2 Storage pit 3 Vitrified body 4 Storage pipe 5 Ceiling slab 6 Transfer area 7 Transfer carriage 8 Intake passage 9 Exhaust passage 10 Storage pipe plug 11 Partition plate 12 Floor slab 13 Lower plenum part 14 Upper plenum part 15 Ventilation Pipe 16 Vertical support column 17 Horizontal support column 21 Cooling flow path 30 Storage building 31 Storage pit side wall surface

Claims (3)

In the radioactive material storage method of storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed,
Performing a first process of storing the radioactive substance in the storage pipe having a relatively low cooling performance among the plurality of storage pipes;
After storing the radioactive substance in all of the storage pipes with low cooling performance, a second process of storing the radioactive substance into the storage pipe with relatively high cooling performance among the plurality of storage pipes is performed. A method for storing a radioactive material, comprising: In the radioactive material storage method of storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed,
As the plurality of storage tubes, a plurality of storage tubes provided with fins and a storage tube without the fins are adopted,
Performing a first process of storing the radioactive material in the fin-free storage tube;
A storage method of radioactive material, wherein after storing the radioactive material in all of the storage tubes without fins, a second process of storing the radioactive material in the storage tube provided with the fins is performed. . In the radioactive material storage method of storing the radioactive material by storing the radioactive material in a plurality of storage tubes provided in a storage pit through which cooling air is passed,
Of the plurality of storage pipes, the second storage pipes that are relatively few adjacent to the first storage pipes that are relatively adjacent to the storage pipes capable of transferring heat by radiation. A first step of storing the radioactive substance in the first storage tube,
A radioactive substance storage method, wherein after the radioactive material has been stored in all of the first storage tube, a second process of storing the radioactive material in the second storage tube is performed. .