JP2013104794A - Storage method for radiation contamination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage method for a radiation contamination capable of shielding a radiation with simple structure.SOLUTION: A storage method for a radiation contamination encloses the outside of a first radiation contamination 46 with a second radiation contamination 48 whose radiation concentration is lower than that of the first radiation contamination 46.

Description

  The present invention relates to a method for storing radiation contaminants for storing radiation contaminants.

  We will remove radiation pollutants such as soil, sand, plants and sludge that have been contaminated so that people can live again in the radiation-contaminated area. These removed radioactive contaminants (hereinafter “removables”) are stored for a long time in intermediate storage facilities and final disposal sites, but it takes a long time to construct and operate these facilities. Therefore, as a preliminary step, it is considered to temporarily store the removed material in a temporary storage area.

  As a technique for shielding radiation, a radiation shielding structure made of concrete is often used. For example, the radiation shielding structure of Patent Document 1 is composed of opposing steel plates and concrete placed between the steel plates.

  However, when a temporary storage site is constructed by surrounding the outer periphery with such a radiation shielding structure, a considerable amount of work is required for the construction. In particular, the temporary storage area is a temporary storage facility, so construction in a short time is desired.

JP 2004-317242 A

  This invention considers the fact concerned, and makes it a subject to provide the storage method of the radiation contaminant which can shield a radiation with a simple structure.

  Invention of Claim 1 is the storage method of the radiation contaminant which surrounds the outside of a 1st radiation contamination with the 2nd radiation contamination whose radiation density is lower than the said 1st radiation contamination.

  In invention of Claim 1, the radiation radiated | emitted from a 1st radiation contaminant can be shielded with a 2nd radiation contaminant, and it can suppress that this radiation leaks outside the 2nd radiation contaminant. Therefore, radiation emitted from the first radiation contaminant can be shielded with a simple structure in which the outside of the first radiation contaminant is simply surrounded by the second radiation contaminant.

  According to a second aspect of the present invention, the second radiation contaminant is covered above the first radiation contaminant.

  In the second aspect of the present invention, the second radiation contaminant shields the scattered radiation (sky shine) that is a part of the radiation emitted from the first radiation contaminant, and the scattered radiation is the second radiation contaminant of the second radiation contaminant. Leakage to the outside can be suppressed.

  According to a third aspect of the present invention, the outer periphery of the second radiation contaminant is surrounded by a radiation shield.

  In invention of Claim 3, the radiation radiated | emitted from a 2nd radiation contaminant can be shielded with a radiation shield. Further, since the second radiation contaminant surrounding the outside of the first radiation contaminant has a lower radiation concentration than the first radiation contaminant, the configuration of the radiation shield surrounding the outer periphery of the second radiation contaminant can be simplified.

  According to a fourth aspect of the present invention, the first radiation contaminant and the second radiation contaminant are packed and stacked in a container, and the radiation shield is stored in soil that is not contaminated with radiation. It is composed of stacked bodies.

  In the invention according to claim 4, the first radiation contaminant and the second radiation contaminant can be easily moved by packing the first radiation contaminant and the second radiation contaminant in the container, It is possible to prevent the first radiation contaminant and the second radiation contaminant from being scattered by the wind.

  Moreover, since concrete is not used for formation of a radiation shield, the cost of constructing a radiation shield can be reduced.

  Since the present invention has the above configuration, radiation can be shielded with a simple structure.

It is a top view which shows the storage facility which concerns on embodiment of this invention. It is front sectional drawing which shows the storage facility which concerns on embodiment of this invention. It is explanatory drawing which shows the arrangement | positioning condition of the container which concerns on embodiment of this invention. It is explanatory drawing which shows the arrangement | positioning procedure of the container which concerns on embodiment of this invention. It is explanatory drawing which shows the arrangement | positioning procedure of the container which concerns on embodiment of this invention. It is sectional drawing which shows the modification of the arrangement | positioning method of the container which concerns on embodiment of this invention. It is sectional drawing which shows the modification of the arrangement | positioning method of the container which concerns on embodiment of this invention. It is front sectional drawing which shows the modification of the storage facility which concerns on embodiment of this invention. It is front sectional drawing which shows the modification of the storage facility which concerns on embodiment of this invention. It is explanatory drawing which shows the model of the numerical simulation which concerns on the Example of this invention. It is explanatory drawing which shows the model of the numerical simulation which concerns on the Example of this invention. It is a diagram which shows the amount of scattered radiation with respect to the distance from the removal thing which concerns on the Example of this invention.

  Embodiments of the present invention will be described with reference to the drawings. First, the storage method of the radiation contaminant which concerns on embodiment of this invention is demonstrated.

  A plan view of FIG. 1 shows a storage facility (hereinafter referred to as “storage facility”) 10 for radioactive contaminants according to an embodiment of the present invention. In the storage facility 10, the removed material brought from the radiation-contaminated area (hereinafter referred to as “decontamination area”) is temporarily stored. The removed material stored in the storage facility 10 is later transferred to an intermediate storage facility or a final disposal site.

  Here, the removed material is radiation contaminants removed so that people can live again in the decontamination area.For example, soil from which the ground surface layer has been stripped, earth and sand such as gravel, cutting dust such as concrete and asphalt, etc. And dirt such as sludge and incinerated ash deposited in the gutter, and dead leaves of plants, grasses, epidermis, trunks, branches, roots and the like.

  In the decontamination area or the storage facility 10, the removed material is stored in a removed material storage yard 12 provided in the storage facility 10 in a state of being packed in containers L, M, and H described later. When the removal objects are packed in the containers L, M, and H in the decontamination area, the containers L, M, and H packed with the removal objects are loaded on a transport vehicle such as a truck and transferred to the storage facility 10 for storage. When the removal object is packed in the containers L, M, and H in the facility 10, the removal object is transferred to the storage facility 10 by a transport vehicle such as a truck loaded with the removal object.

  The storage facility 10 includes a removed material storage yard 12, a peripheral wall 14 as a radiation shield, a temporary storage yard 16 before soil treatment, a soil treatment yard 18, a temporary storage yard 20 before incineration, an incineration yard 22, a parking lot 24, A management building 26 is provided.

  In the soil treatment yard 18, the soil carried into the storage facility 10 as a removed material is washed to remove radioactive substances from the soil. The soil from which radioactive material has been removed is returned to the decontamination area. In the incineration processing yard 22, combustible removals such as dead leaves of plants, grasses, epidermis, trunks, branches, roots, etc. are burned. Thereby, since the volume of the removed product can be reduced and stored in the removed product storage yard 12, a large amount of the removed product can be stored in the removed product storage yard 12.

  The temporary storage yard 16 before the soil treatment is a yard for temporarily placing the removed material to be treated in the soil treatment yard 18, and the temporary yard 20 before the incineration treatment temporarily places the removed material to be treated in the incineration facility yard 22. For the yard.

  In the removed matter storage yard 12, the removed matter is stored by the radiation contaminant storage method of the present invention. As shown in FIG. 1, the removed material storage yard 12 is divided into three regions (a low concentration removed material storage region 28, a medium concentration removed material storage region 30, and a high concentration removed material storage region 32). In plan view, the high-concentration removed matter storage area 32 is disposed at a substantially central portion of the removed substance storage yard 12, and the medium-concentration removed substance storage area 30 surrounds the entire outer periphery of the high-concentration removed substance storage area 32. The low-concentration removed material storage area 28 is disposed so as to surround the entire outer periphery of the medium-concentration removed material storage area 30.

  As shown in FIG. 2 which is an AA cross-sectional view of FIG. 1, a zeolite layer 38 is formed on an excavated ground surface 36 obtained by excavating the surface layer of the ground 34 by about 50 cm. Further, a floor slab 40 made of reinforced concrete is provided. That is, the floor slab 40 directly constitutes the foundation.

  On the upper surface of the floor slab 40, a drainage gradient of about 1/150 that decreases from the center of the floor slab 40 toward the outer periphery is formed. The outer periphery of the floor slab 40 is integrated with the floor slab 40. A water shielding wall 42 made of reinforced concrete is erected. A drainage groove 44 is formed on the upper surface of the floor slab 40 adjacent to the inner wall surface of the water shielding wall 42.

  As shown in FIG. 2, when viewed from the front and the side (FIG. 2 is a cross-sectional view as viewed from the front), the high-concentration removed material storage area 32 is disposed at a substantially central portion of the floor slab 40. The removed substance storage area 30 is disposed so as to surround the side and the upper side of the high concentration removed substance storage area 32, and the low concentration removed substance storage area 28 is disposed on the side and upper side of the medium concentration removed substance storage area 30. It is arranged to surround.

  As shown in FIGS. 1 and 2, a plurality of containers H filled with high-concentration removal products 46 are arranged in the high-concentration removal material storage area 32. A plurality of containers H are arranged and stacked in a container 52 installed on the upper surface of the substantially central portion of the floor slab 40.

  The container 52 is formed by stacking up and down a plurality of cylinders formed of reinforced concrete. The bottom member is provided with a bottom member integrally with the cylinder so as to close the bottom opening of the cylinder, and the opening on the top surface of the cylinder located at the top is made of concrete. It is detachably closed by a lid member 54 composed of a plate (in particular, a concrete plate that has been reduced in weight), an iron plate, a lead plate, or the like.

  In the medium-concentration removed substance storage area 30, a plurality of containers M packed with medium-concentration removal objects 48 are arranged and stacked on the floor slab 40 and the lid member 54 (see FIG. 2). In this example, the container M for one step is laid on the lid member 54).

  In the low-concentration removed material storage region 28, a plurality of containers L packed with the low-concentration removed products 50 are laid on the floor slab 40 and the container M placed on the lid member 54. They are arranged in a stack.

  The containers L, M, and H only need to be able to accommodate the high concentration removed product 46, the medium concentration removed product 48, and the low concentration removed product 50 in a lump. For example, the containers L, M, and H may be formed as a bag-like packaging material formed by a sheet woven from strong chemical fibers such as polyethylene and polypropylene, or may be a drum can or other container.

  Here, the low concentration removed product 50 is a removed product having a radiation concentration of 8000 Bq / kg or less, and the medium concentration removed product 48 is a removed product having a radiation concentration greater than 8000 Bq / kg and less than or equal to 100000 Bq / kg. The high-concentration removed product 46 is a removed product having a radiation concentration greater than 100,000 Bq / kg.

  As shown in FIG. 1, the peripheral wall 14 surrounds the outer periphery of the removed matter storage yard 12 (low concentration removed matter storage region 28, medium concentration removed matter storage region 30, and high concentration removed matter storage region 32) in plan view. It is arranged like that. Further, as shown in FIG. 2, the peripheral wall 14 is configured by laying and stacking a plurality of containers N filled with soil 56 (hereinafter referred to as “non-contaminated soil”) that is not contaminated with radiation.

  The container N is not particularly limited as long as it can store soil in a lump shape, and the same packaging materials, drums, containers, and the like as the containers L, M, and H can be used. In addition, it is preferable to use the surface layer of the ground 34 excavated for installing the floor slab 40 as the non-contaminated soil 56 to be packed in the container N because the material for forming the peripheral wall 14 can be effectively used. Soil that is not contaminated by radiation can be obtained from the ground 34 at a position deeper than about 5 cm.

  As shown in FIG. 2, the height of the peripheral wall 14 is higher than the heights of the medium concentration removed matter storage region 30 and the high concentration removed matter storage region 32. As shown in FIG. 1, the peripheral wall 14 is partially interrupted with respect to the circumferential direction of the peripheral wall 14, and the interrupted portion serves as an entrance / exit 58 of the storage facility 10. The entrance / exit 58 is provided with an openable / closable gate 60 that regulates the entry and exit of people, vehicles, and the like to the storage facility 10.

  As described above, in the storage method for radiation contaminants of the present invention, when the high-concentration remover 46 is the first radiation contaminant, the outside of the high-concentration remover 46 as the first radiation contaminant is A medium-concentration removal object 48 as a second radiation contamination whose radiation concentration is lower than that of the first radiation contamination is surrounded, and an outer periphery of the medium-concentration removal object 48 is surrounded by a peripheral wall 14 as a radiation shield, and a high-concentration removal object 46 Is covered with a medium-concentration removal product 48.

  Further, in the method for storing radiation contaminants according to the present invention, when the medium concentration removed matter 48 is the first radiation contaminant, the outside of the medium concentration removed matter 48 as the first radiation contaminant is disposed outside the first radiation contaminant. Is surrounded by a low-concentration removal object 50 as a second radiation contaminant having a lower radiation concentration, and the outer periphery of the low-concentration removal object 50 is surrounded by a peripheral wall 14 as a radiation shield, and the medium concentration removal object 48 is surrounded by a low concentration. It is configured to be covered with the removed object 50.

  The size of each yard provided in the storage facility 10 may be appropriately determined in consideration of the storage amount of the low concentration removed product 50, the medium concentration removed product 48, and the high concentration removed product 46, the ratio of these storage amounts, and the like. Good. For example, in the planar dimensions, the outer shape of the storage facility 10 is 200 m × 200 m, the outer shape of the removed material storage yard 12 is 80 m × 120 m, the outer shape of the high concentration removed material storage region 32 is 20 m × 16 m, and the intermediate concentration removed material storage region 30 The outer shape may be 90 m × 50 m, and the outer shape of the low concentration removed material storage area 28 may be 120 m × 80 m.

  As shown in FIG. 2, the containers L are stacked so that the upper part has a mountain shape, and a roof is formed by covering the upper part with a water shielding sheet 62.

  As shown in FIG. 2, ground 34 such as rainwater generated when the containers L, M, and H are carried into the removed matter storage yard 12 and arranged, and spring water that has flowed out of the containers L, M, and H is provided. The leakage to the inside is prevented by the floor slab 40 and the water shielding wall 42, and water is collected in the drainage groove 44 by the drainage gradient of the floor slab 40. Then, the collected water is drained after the radioactive substance is properly removed.

  As shown in FIG. 1, a removal hole storage yard 12 is provided with a measurement hole 64. The measurement hole 64 measures the radiation concentration of the wastewater accumulated in the drainage groove 44 and monitors whether radioactive substances are leaking from the containers L, M, and H. A measurement hole 66 is provided in the ground 34 near the peripheral wall 14. The measurement hole 66 measures the radiation concentration of the groundwater accumulated in the lower part of the measurement hole 66 and monitors whether radioactive material has leaked from the removed material storage yard 12 to the nearby ground 34. The arrangement and number of the measurement holes 64 and 66 may be determined as appropriate.

  In addition, on the outside near the peripheral wall 14, the air dose of radiation is measured, and it is monitored whether the radiation leaks from the storage facility 10 to the outside of the storage facility 10.

  The procedure for arranging the containers L, M, and H in the removed matter storage yard 12 may be appropriately determined according to the amount and type of the removed matter to be stored. An example of the procedure for placing the containers L, M, and H in the removed matter storage yard 12 is as follows. First, as shown in FIGS. 1 and 3, the surface layer of the ground 34 is excavated to form the zeolite layer 38 and the floor slab 40. After forming the temporary road 70 in which the rough terrain crane 68 can be run and installed in the removed matter storage yard 12, a plurality of containers N filled with non-contaminated soil 56 are laid and stacked on the ground 34, The peripheral wall 14 is constructed. The containers L, M, H, and N are moved by the rough terrain crane 68 installed on the temporary road 70.

  Next, as shown in FIGS. 4A and 4B, the first-stage containers L, M, and H are laid out on the floor slab 40.

  Next, as shown in FIG. 4 (c), the operation of stacking the containers L, M, H for one stage on the lower containers L, M, H is performed by the containers L, M, H. Repeat until the desired height is reached.

  Next, as shown in FIG. 4 (d), after the upper surface opening of the container 52 is closed by the lid member 54, one stage of the container L is laid and stacked on the container L, and the container M and On the lid member 54, one-stage containers M are laid and stacked.

  Next, the operation of laying and stacking one-stage containers L and M on the lower containers L and M is repeated until the containers L and M reach a predetermined height.

  Next, as shown in FIG. 4 (e), one stage of the container L is laid and stacked on the container M.

  Next, the operation of laying and stacking one stage of the container L on the container L is repeated until the container L reaches a predetermined height.

  As described above, in the arrangement procedure of the containers L, M, and H shown in FIG. 4, the container L is stored in the removed matter storage yard 12 by repeating the work of laying and stacking a plurality of containers L, M, and H for one stage. , M and H are arranged.

  Introducing another example of the procedure for placing the containers L, M, H in the removed matter storage yard 12, first, as shown in FIGS. 1 and 3, the surface layer of the ground 34 is excavated to form the zeolite layer 38 and the floor slab. 40, and a temporary road 70 on which the rough terrain crane 68 can be run and installed is provided in the removed matter storage yard 12, and a plurality of containers N filled with non-contaminated soil 56 are laid and stacked on the ground 34. Thus, the peripheral wall 14 is constructed. The containers L, M, H, and N are moved by the rough terrain crane 68 installed on the temporary road 70.

  Next, as shown in FIGS. 5 (a) and 5 (b), all the containers L arranged outside the medium concentration removed substance storage area 30 in plan view are laid on the floor slab 40 and stacked. To do.

  Next, as shown in FIG. 5 (c), all containers M to be placed outside the high concentration removed matter storage area 32 in plan view are laid on the floor slab 40 and stacked.

  Next, as shown in FIG. 5 (d), the container H is laid and stacked in the container 52, and then the upper surface opening of the container 52 is closed by the lid member 54.

  Next, as shown in FIG. 5 (e), the remaining containers M and L are laid out and stacked.

  In the procedure shown in FIGS. 4 and 5, the influence of scattered rays (sky shine) from the containers H and M (the high-concentration removal object 46 and the medium-concentration removal object 48) in the middle of the placement work is a problem. In this case, the upper surface opening of the container 52 is closed with the lid member 54, and the upper portion of the container M is appropriately cured with a sheet material having radiation shielding properties.

  Next, the operation and effect of the storage method for radiation contaminants according to the embodiment of the present invention will be described.

  In the method for storing radioactive contaminants according to the embodiment of the present invention, as shown in FIG. 2, the radiation radiated from the high concentration removed matter 46 packed in the container H arranged in the high concentration removed matter storage region 32. The shielding layer formed by the medium-concentration removal material 48 packed in the container M arranged in the medium-concentration removal material storage area 30 and the container L arranged in the low-concentration removal material storage area 28. It is possible to prevent the radiation from leaking to the outside of the removed matter storage yard 12 because the shielding layer formed by the packed low concentration removed matter 50 is shielded.

  Further, the radiation radiated from the medium-concentration removal object 48 packed in the plurality of containers M arranged in the medium-concentration removal material storage area 30 is packed into the container L arranged in the low-concentration removal substance storage area 28. The shielding layer formed by the low-concentration removed material 50 is shielded, and this radiation can be prevented from leaking outside the removed material storage yard 12.

  Therefore, the medium concentration removal in which a plurality of containers M packed with the medium concentration removal object 48 are arranged outside the high concentration removal object storage area 32 where the plurality of containers H packed with the high concentration removal object 46 are arranged. A plurality of containers L packed with low-concentration removal substances 50 are arranged outside the medium-concentration removal substance storage area 30 surrounded by the substance storage area 30 and arranged with a plurality of containers M packed with medium-concentration removal substances 48. The high-concentration removal product 46 and the medium-concentration removal product storage region packed in the container H arranged in the high-concentration removal product storage region 32 with a simple structure that only surrounds the low-concentration removal product storage region 28. The radiation radiated from the medium concentration removed matter 48 packed in the container M arranged in the plurality 30 can be shielded. Moreover, the radiation dose in the storage facility 10 can be kept low.

  Further, the peripheral wall 14 can prevent radiation from leaking to the outside of the peripheral wall 14 from the low-concentration removed objects 50 packed in the containers L arranged in the low-concentration removed substance storage region 28. In particular, the low-concentration removal product 50 packed in a plurality of containers L arranged in the low-concentration removal product storage region 28 arranged outside the high-concentration removal product storage region 32 and the medium-concentration removal product storage region 30 From high-concentration removals 46 packed in a plurality of containers H arranged in the concentration-removed substance storage area 32 and medium-concentration removal objects 48 packed in a plurality of containers M arranged in the medium-concentration removal substance storage area 30. Since the radiation concentration is low, the configuration of the peripheral wall 14 as a radiation shield surrounding the outer periphery of the low concentration removed matter storage region 28 can be simplified.

  As a result, a high concentration removed product 46 packed in a plurality of containers H arranged in the high concentration removed material storage region 32 and a medium concentration removal packed in a container M arranged in a plurality of medium concentration removed material storage regions 30. The radiation radiated from the low-concentration removal object 50 packed in the container 48 arranged in the object 48 and the low-concentration removal object storage region 28 can be shielded with a simple structure.

  Further, scattered radiation (sky shine), which is a part of radiation radiated from the high-concentration removal material 46 packed in the container H arranged in the high-concentration removal material storage region 32, is converted into the medium-concentration removal material storage region. A shielding layer that is formed by the medium-concentration removal material 48 packed in a plurality of containers M arranged in 30 and covers the upper portion of the high-concentration removal material storage area 32; and a plurality of containers that are arranged in the low-concentration removal material storage area 28. The shield layer formed by the low-concentration removal material 50 packed in the L and covering the upper portion of the medium-concentration removal material storage region 30 is shielded, and this scattered ray (sky shine) leaks outside the removal material storage yard 12. Can be suppressed.

  Further, scattered radiation (sky shine), which is a part of radiation radiated from the medium-concentration removal object 48 packed in the container M arranged in the medium-concentration-removal object storage area 30, is converted into the low-concentration removal object storage area. The shielding layer formed by the low-concentration removal material 50 packed in the container L arranged in the number 28 covers the medium-concentration removal material storage area 30 and shields the scattered radiation (skyshine) from the removal material storage yard. 12 can be prevented from leaking to the outside.

  Further, by packing the low-concentration removal product 50, the medium-concentration removal product 48, and the high-concentration removal product 46 into the containers L, M, and H, these removal products are lifted by a rough terrain crane, a forklift, or a truck, It can be easily moved by a transport vehicle or the like. Moreover, it is possible to prevent these removed objects from being scattered by the wind.

  Moreover, since concrete is not used for formation of the surrounding wall 14 as a radiation shield, the cost for constructing the radiation shield can be reduced.

  Further, since the containers H and M packed with the high concentration removed matter 46 and the medium concentration removed matter 48 having a high radiation concentration are arranged inside the removed matter storage yard 12, the outer peripheral portion of the removed matter storage yard 12 is provided. To the containers H and M can be increased. Accordingly, since the effect of weakening the energy of radiation can be expected by separating the distance, the containers H and M can be accommodated without increasing the distance from the outer periphery of the removed matter storage yard 12 to the outer periphery of the storage facility 10. It is possible to prevent the leakage of radiation to the outside of the storage facility 10 by weakening the energy of the radiation emitted from the packed high concentration removal product 46 and the medium concentration removal product 48. That is, the site of the storage facility 10 can be reduced.

  Moreover, the shielding effect of the radiation radiated | emitted from the high concentration removal thing 46 can be heightened by arrange | positioning the high concentration removal thing 46 with a high radiation concentration in the container 52 which has radiation shielding property.

  Further, as shown in FIG. 2, the floor slab 40 is provided on a ground-bearing excavated ground surface 36 excavating the surface layer of the ground 34. 40 can be prevented from cracking. Further, even if a crack occurs in the floor slab 40, radioactive material contained in spring water or the like to enter the ground 34 from this crack is absorbed by the zeolite layer 38 and leaks into the ground 34. Can be prevented.

  In addition, the storage facility 10 can prevent radiation radiated from the stored radiation contaminant (removed material) from leaking outside the storage facility 10 and collectively manage the radiation contaminant (removed material). it can.

  The embodiment of the present invention has been described above.

  In the embodiment of the present invention, the removed material storage yard 12 is divided into three regions (a low concentration removed material storage region 28, a medium concentration removed material storage region 30, a high concentration removed material storage region 32), and a high concentration removal is performed. The medium concentration removed material storage region 30 is disposed so as to surround the outside of the material storage region 32, and the low concentration removed material storage region 28 is disposed so as to surround the outside of the medium concentration removed material storage region 30. Although an example in which the outside of the object 46 is surrounded by the medium-concentration removal object 48 and the outside of the medium-concentration removal object 48 is surrounded by the low-concentration removal object 50 is shown, the outside of the removal object having a certain radiation concentration is more than this removal object The removal object storage yard 12 may be divided into any number of regions as long as it has a configuration surrounded by a removal object having a low radiation concentration.

  For example, the removal product storage yard 12 is divided into two regions (low concentration removal material storage region and high concentration removal material storage region), and the low concentration removal material storage region is arranged so as to surround the outside of the high concentration removal material storage region. Alternatively, the removal product storage yard 12 is divided into four regions (first to fourth concentration removal material storage regions), and the second concentration removal is performed so as to surround the outside of the first concentration removal material storage region. An object storage area is arranged, a third concentration removed substance storage area is arranged so as to surround the outside of the second concentration removed substance storage area, and a fourth concentration removed substance is stored so as to surround the outside of the third concentration removed substance storage area. You may make it arrange | position an area | region.

  Further, in the embodiment of the present invention, an example is shown in which the removed materials are sorted into three groups (high concentration removed material 46, medium concentration removed material 48, and low concentration removed material 50) based on the radiation concentration. May be classified into any number of groups, and the range of the value of the radiation density of each group may be set in any manner.

  Further, this sorting may be performed at any timing from the removal of the removed matter in the decontamination area to the placement in the removed matter storage yard 10. For example, in the decontamination area, the removal objects are packed in the containers H, M, and L, and the radiation concentration of the removal objects packed in the containers H, M, and L is measured in the decontamination area or the storage facility 10. The group may be determined, and when the removed objects are packed in the containers H, M, and L in the storage facility 10, the radiation concentration of the removed objects packed in the containers H, M, and L is determined. You may make it measure and determine a group.

  Moreover, you may perform the measurement of a radiation density | concentration before stuffing in the accommodating bodies H, M, and L. FIG. For example, before removing the removed substance, the radiation density at the place to be removed may be measured to make a group determination, and the removed substance removed from the place may be made into this group.

  In the embodiment of the present invention, an example in which the containers H, M, and L are arranged in the removed matter storage yard 12 by laying and stacking a plurality of containers H, M, and L is shown. , M, and L may be disposed with the containers H, M, and L in contact with each other, or may be disposed with a gap therebetween. Further, a partition wall formed of concrete or the like may be provided between the medium concentration removed matter storage region 30 and the low concentration removed matter storage region 28.

  Moreover, in the embodiment of the present invention, the example in which the container H packed with the high-concentration removed material 46 is arranged in the container 52 formed of reinforced concrete is shown. However, the removal arranged in the container 52 is shown. The container 52 may be formed of any material as long as the radiation emitted from the object can be shielded. For example, the container 52 may be formed of iron, lead, tungsten, or the like. Further, the container L arranged in the low concentration removed matter storage area 28 and the container M arranged in the medium concentration removed article storage area 30 are arranged in a container having the same configuration as the container 52. Alternatively, the side wall and the upper side of the low-concentration removed material storage region 28 and the medium-concentration removed material storage region 30 may be surrounded by a wall formed of the same radiation shielding material as the container 52. .

  In the embodiment of the present invention, the medium-concentration removal object 48 is disposed above the high-concentration removal object 46 and the low-concentration removal object 50 is disposed above the medium-concentration removal object 48 in a front view and a side view. Although an example is shown, if the scattered radiation (sky shine) emitted from the high-concentration removal object 46 or the medium-concentration removal object 48 does not leak outside the storage facility 10, the medium-concentration removal is performed above the high-concentration removal object 46. The object 48 may not be arranged, or the low concentration removal product 50 may not be arranged above the medium concentration removal product 48.

  When it is considered that scattered radiation (sky shine) emitted from the high concentration removal object 46 or the medium concentration removal object 48 leaks outside the storage facility 10, the medium concentration removal object is located above the high concentration removal object 46. For example, a method as shown in FIGS. 6 and 7 may be used in addition to the arrangement of 48 and the arrangement of the low concentration removal product 50 above the medium concentration removal product 48.

  In the front sectional view of FIG. 6, non-contaminated soil 74 (soil not contaminated by radiation) is formed on the upper surface of the removed matter 72 packed in the containers H, M, and L so as to cover the removed matter. ). Thereby, a plurality of substantially horizontal shielding layers are formed by the non-contaminated soil 74.

  In the front cross-sectional view of FIG. 7, a radiation shielding plate 76 made of an iron plate, a lead plate, or the like is disposed on the upper surface of the containers H, M, and L packed with the removal object 72. The containers H, M, and L are placed. Thereby, a plurality of substantially horizontal shielding layers by the radiation shielding plate 76 are formed.

  Moreover, the upper surface of the water-impervious sheet 62 (see FIG. 2) constituting the roof is covered with non-contaminated soil 74 (soil not contaminated with radiation), or the roof surface is covered with lead, iron, tungsten, concrete ( In particular, if it is made of light weight concrete), it is possible to improve the shielding property of the scattered radiation (sky shine) emitted from the high concentration removed material 46 and the medium concentration removed material 48.

  In the embodiment of the present invention, an example in which the peripheral wall 14 is configured by laying and stacking a plurality of containers N packed with soil that is not contaminated with radiation has been shown. The peripheral wall 14 is an outer side of the peripheral wall 14. As long as radiation can be prevented from leaking, any material may be used. If the excavated soil of the ground 34 is used, the excavated soil can be effectively used.

  Further, the peripheral wall 14 may not be provided as long as radiation does not leak outside the storage facility 10 from the low-concentration removal objects 50 packed in the containers L arranged in the low-concentration removal object storage region 28. For example, if a distance sufficient to prevent radiation radiation from leaking to the outside of the storage facility 10 due to weakening of the radiation energy can be secured between the outer periphery of the low concentration removed material storage region 28 and the outer periphery of the storage facility 10, the peripheral wall 14 May not be provided.

  Further, in the embodiment of the present invention, as shown in FIG. 2, an example in which the floor slab 40 is provided on the excavated ground surface 36 obtained by excavating the surface layer of the ground 34 via the zeolite layer 38 is shown. 9, the ground 34 may be deeply excavated and the floor slab 40 may be provided on the excavated ground surfaces 78 and 80 via the zeolite layer 38. In this way, the ground 34 can be used as a radiation shielding wall. In FIG. 9, the high concentration removed matter storage region 32 is arranged at a deeper position of the ground 34, and the medium concentration removed matter storage region 30 in which the medium concentration removed matter 48 having a lower radiation concentration than the high concentration removed matter 46 is arranged. Is disposed at a position shallower than the high-concentration removed material storage area 32, and the low-concentration removal material storage area 28 in which the low-concentration removal material 50 having a lower radiation concentration than the medium-concentration removal material 48 is disposed is stored in the medium-concentration removal material. By arranging it at a position shallower than the region 30, the excavation amount of the ground 34 can be made smaller than that in FIG.

  Further, in the embodiment of the present invention, an example in which the floor slab 40 is directly based has been shown. However, the floor slab 40 may be supported by a support pile, or the ground 34 is subjected to ground improvement, and the ground improvement is performed. You may make it arrange | position a removal thing on the ground to which was given. If the ground 34 is improved, it is possible to impart water-imperviousness to the ground, so that leakage of radioactive materials from the ground can be expected.

  In addition, the radioactive contaminant storage method shown in the embodiment of the present invention has a low-concentration removal product storage region 28, a medium-concentration removal product storage region 30, and a high-concentration removal product storage region 32 according to the required specifications. By appropriately setting the thickness and the like, it can be applied to an intermediate storage facility.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in a various aspect.

(Example)

  In this embodiment, the radiation shielding effect evaluated by numerical simulation will be described.

FIG. 10 shows a model 82 for evaluating the shielding effect of a straight line that is a part of radiation. In model 82, low concentration removal was 86 8000Bq / kg on the upper surface of the flat ground 84 is arranged, by a non-contaminated soil (radiation between the measuring point 90 at a distance _{d 1} from the low concentration of removal 86 A radiation shielding wall 88 formed by uncontaminated soil) is erected. The heights of the low concentration removed substance 86 and the radiation shielding wall 88 are the same.

As a result of performing a numerical simulation on the model 82, the air dose at the measurement point 90 is 1 mSv / year or less when the thickness t ₁ of the radiation shielding wall 88 is 30 cm or more and the distance d ₁ is 10 m or more. Therefore, it was found that the influence of the straight line at the measurement point 90 is small.

  FIG. 11 shows a model 92 for evaluating the shielding effect of scattered rays (sky shine) that is a part of radiation. In the model 92, a low-concentration removal product 86 of 8000 Bq / kg, a medium-concentration removal product 94,000 Bq / kg, and a high-concentration removal product 104,000,000 Bq / kg are arranged on the flat ground 84 and arranged on the left side. A radiation shielding wall 88 formed by non-contaminated soil (soil not contaminated by radiation) is erected at a position away from the end of the low-concentration removed material 86. The upper surface of the intermediate concentration removal product 94 is covered with a shielding lid 96 having radiation shielding properties, and the heights of the intermediate concentration removal product 94 and the radiation shielding wall 88 are the same. Further, the upper surface of the high concentration removed substance 104 is covered with a lid member 54.

FIG. 12 is a graph of the result of numerical simulation performed on the model 92 (radiation from the medium concentration removal product 94 with respect to the distance d ₂ (horizontal axis) from the end of the low concentration radiation removal product 86 arranged on the left side. The scattered radiation dose (vertical axis) is shown. A value 98 indicates a value when the shielding lid 96 is soil having a thickness t ₂ of 20 cm, and a value 100 indicates a value when the shielding lid 96 is an iron plate having a thickness t ₂ of 2 cm. Indicates values when the shielding lid 96 is not provided.

As can be seen from FIG. 12, when the shielding lid 96 has a value 98 when the thickness t ₂ is 20 cm of soil, the scattered radiation dose is 1 mSv / year or less at the measurement point 90 where the distance d ₂ is 30 m or more. In the case where the shielding lid 96 is an iron plate having a thickness t ₂ of 2 cm, the scattered radiation dose can be 1 mSv / year or less at the measurement point 90 where the distance d ₂ is 50 m or more. .

14 Perimeter wall (radiation shield)
46 High-concentration removal material (first radiation contaminant)
48 Medium-concentration removed substances (first and second radiation contaminants)
50 Low-concentration removal product (second radiation contaminant)
56 Non-contaminated soil (soil not contaminated with radiation)
H, M, L, N container

Claims (4)

  A method for storing radiation contaminants, wherein the outside of the first radiation contaminant is surrounded by a second radiation contaminant having a radiation concentration lower than that of the first radiation contaminant.   The storage method of the radiation contaminant of Claim 1 which covers the upper part of the said 1st radiation contaminant with the said 2nd radiation contaminant.   The storage method of the radiation contaminant of Claim 2 which surrounds the outer periphery of the said 2nd radiation contaminant with a radiation shield. The first radiation contaminant and the second radiation contaminant are packed and stacked in a container, and the radiation shield is configured by stacking a container packed with soil not contaminated with radiation. Item 4. A method for storing radioactive contaminants according to Item 3.

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