JP4063750B2 - Radioactive waste sorting system - Google Patents

Description

  The present invention relates to a radioactive waste sorting system that separates and collects radioactive waste mixed with iron, austenitic stainless steel, non-ferrous metal, graphite and the like for each material.

A large amount of graphite is used as a neutron moderator in gas-cooled reactors and research facilities. The graphite waste generated by the operation of a gas cooling furnace or the like has been stored in the facility after being crushed. Moreover, when the nuclear reactor is dismantled, a large amount of radioactive waste containing metal and graphite is generated from, for example, nuclear fuel elements.
Graphite waste is radioactive and needs to be solidified with mortar and buried. The graphite waste generated when the nuclear fuel element is disassembled may be mixed with metal parts such as austenitic stainless steel, zirconium alloy, and magnesium alloy having different radioactivity concentrations, and may exhibit high radioactivity.

  Disposal standards such as burial depth and necessity of concrete pits differ depending on the radioactivity of the waste, and the cost of disposal varies greatly. The disposal method for waste is determined based on the highest radioactivity it exhibits, and the radioactivity of waste mixed with different substances is determined by the radioactivity and composition ratio of each substance. Therefore, stricter standards are applied to graphite waste mixed with foreign substances, even if the radioactivity of the graphite itself is low, and even if a very high amount of high activity metal such as austenitic stainless steel is included, the disposal cost increases. .

Conventionally, graphite waste mixed with radioactive metal has been buried without being sorted or stored in a facility for temporary storage. However, it is desirable to dispose of graphite waste mixed with radioactive metal by sorting out graphite and metal, and since the radioactivity is determined by the type of metal, it is also necessary to separate and dispose of the metal separately. It is clear that this is preferable for reducing.
Therefore, with regard to graphite waste mixed with radioactive metals, it is possible to separate graphite and metal, incinerate the graphite and reduce the volume of incinerated ash and metal separately by solidification with mortar etc. System development is desired.

However, at present, a system for discriminating substances mixed in graphite waste has not been realized.
In the sorting and collection of cans, which are general industrial waste, as shown in Fig. 7, the residue is separated by wind sorting, magnetic materials by magnetic sorting, foreign matter by visual sorting, and aluminum by aluminum sorting, and then recycled. There is a method of extracting the components that can be converted and packing them and supplying them as a classification standard conforming product. However, since this method is manually sorted to increase the separation accuracy, when it is applied to the sorting of radioactive waste, it is necessary to install strict shielding and protective devices and further perform sorting operations by remote operation. Is large and expensive, and a large amount of processing cannot be performed.

Also, in the non-ferrous metal sorting process of general industrial waste, as shown in FIG. 8, a method of separating and discriminating non-ferrous metals such as aluminum with a magnetic separator and an eddy current sorter and removing residues is used. Yes.
However, if this method is applied to radioactive waste, an eddy current sorter that sorts non-ferrous metals such as aluminum cannot discriminate foil-like metals, and it cannot discriminate metals of different materials. In other words, substances with different levels of radioactivity are mixed in the selected substances, resulting in inefficient treatment.

Note that if graphite is pulverized during the sorting process, it becomes dusty, which not only increases the load on the dust collector, but also requires more stringent measures against static electricity and explosion protection, resulting in higher costs. Further, when graphite is finely divided or dusted, solidification for incineration or burying treatment becomes difficult.
In addition, the shape of the metal parts contained in the graphite waste generated in the gas cooling furnace and the research facility therefor is a functional part, so it is constant for each part. It is possible. However, if there is a pulverization process, the metal waste is shredded and deformed, and sorting based on the shape becomes difficult.

  In Patent Document 1, radioactive waste is crushed with a biaxial shear crusher and a high-speed rotary crusher, dried with a dryer, a magnetic separator, a rotary particle size separator, a specific gravity difference separator, and aluminum. A sorting system that separates each component with a waste sorting apparatus combined with a sorter is disclosed. In this disclosed apparatus, magnetic ferrous metals and non-ferrous metals, paper, cloth, etc. are separated by a magnetic separator, and a rotary particle size sorter, in short, using a sieve, removes non-ferrous metals and other fine powder components. And coarse powder component and larger combustible material flame retardant, fine powder is combined with wind-powered vibration specific gravity difference sorter to classify combustible material flame retardant contained in incombustible material, and coarse powder component is permanent magnet drum Use a rotary aluminum sorter to remove combustible and incombustible materials contained in non-ferrous metal wastes, and fill them into drums etc. in a state where they are separated.

In the apparatus disclosed in Patent Document 1, since radioactive waste is pulverized at the initial stage, the sorting system may be filled with difficult-to-handle fine powder components, which may impair separation performance. For example, since wind force is used to separate components other than the magnetic material from the magnetic drum in the magnetic separator, an increase in the size of the apparatus for processing the fine powder accompanying the wind becomes a problem. In addition, since all the fine particle components separated by the particle size sorter are put into the specific gravity difference sorter, the enlargement of facilities such as a cyclone for removing fine powder from the circulating airflow is also a problem here.
Moreover, since the separation for each component of the non-ferrous metal is not sufficient, classification according to the activation intensity is difficult.
JP-A-11-14797

  Therefore, the problem to be solved by the present invention is to dispose of radioactive waste mixed with non-metals and metals, such as those generated in gas-cooled reactors and research facilities therefor. It is to supply an automatic sorting system that separates and classifies these metals and stores them. Furthermore, it is to provide a sorting system that removes the remaining highly radioactive material.

  A radioactive waste sorting system according to the present invention includes a transporter that transports radioactive waste, a turning machine that aligns the posture of the supplied radioactive waste, an eddy current sorter that generates an alternating magnetic field, and a plurality of collection containers. The radioactive waste transported from upstream by the transporter is supplied to the eddy current sorter in the desired posture by the turning machine, and is separately collected in the collection container according to the repulsive force against the AC magnetic field by the eddy current sorter. Features.

  Further, a magnetic sorter may be provided, and radioactive waste before or after separation may be separated by magnetic force. Further, a sieve sorter may be provided, and the separation may be performed according to the particle size of the radioactive waste at any stage of the separation of the radioactive waste. In addition, it is possible to sort by the difference in the transportability with respect to the wind at any stage of sorting by providing a wind sorter.

  The radioactive waste sorting system of the present invention includes, for example, a turning machine including a rotating belt and a drop chute. The rotating belt is disposed at a position sandwiching a gap from the downstream end of the transporter, and rotates in a direction perpendicular to the transport direction. The falling chute is disposed below the gap. When the rod-shaped radioactive waste is conveyed from upstream in a posture parallel to the conveyance direction, one end crosses the gap and contacts the rotating belt and moves with the rotating belt in the vertical and lateral direction in the conveying direction. The posture of the object is corrected so as to be along the rotating belt, and the posture is aligned so that the longitudinal direction is perpendicular to the conveying direction, and dropped from the gap onto the drop chute. Needless to say, the turning machine may be of another type.

Further, as another aspect of the radioactive waste sorting system of the present invention, a radioactive waste comprising an iron component, a large non-ferrous metal component, a small non-ferrous metal component, a thin-film component, a fine granular material, and a coarse granular non-metallic component is used. There are systems that can be separated.
The system includes a magnetic sorter, a turning machine, an eddy current sorter, and a first sieve sorter that further sorts radioactive waste bearing eddy currents sorted by the eddy current sorter based on size. A second sieve sorter that further sorts radioactive waste that does not carry eddy currents based on size, and a wind sorter that applies particles having a large particle size to be sorted by the second sieve sorter. A plurality of collection outlets for distributing the components are provided. Collection containers can be arranged at the collection outlets to store the radioactive waste after classification.

  In this system, radioactive waste mixed with metal is applied to a magnetic separator to receive the iron component in the recovery container of the first recovery outlet, and the rest is adjusted by a turning machine and then applied to the eddy current separator to repel it. The components to be separated are further separated into a predetermined size by a first sieve sorter, separated into small non-ferrous metal components and large non-ferrous metal components, and received in the collection containers of the second and third collection outlets, respectively. The remainder is passed through the second sieve separator and the fine granular non-metallic components are sieved and received in the collection container of the fourth recovery outlet. The remaining large components are further passed through the wind power sorter and the thin-film components and coarse granular non-metallic components are collected. By separating the components and receiving them in the recovery containers of the fifth and sixth recovery outlets respectively, the radioactive waste is an iron component, a large non-ferrous metal component, a small non-ferrous metal component, a fine non-metallic component, a thin film Component and coarse granular non-metallic component It can be to the reservoir.

  In addition, a conveyor device having a conveyor belt for conveying the separated waste is provided, and a radiation detector and an exclusion arm are provided on the conveyor belt to detect radiation while the sorted radioactive waste is conveyed to the conveyor device. When the high radioactive substance is detected by the vessel, when the detected high radioactive substance reaches the position of the exclusion arm, the exclusion arm is driven to remove the portion containing the high radioactive substance from the conveyor belt and remove it. A mechanism may be provided. When the high radioactive substance is a metal, a metal detector may be provided instead of the radiation detector.

  In the radioactive waste sorting system of the present invention, for example, the large non-ferrous metal component is a pipe-like zirconium alloy, the small non-ferrous metal component is a rivet-like magnesium alloy, the non-metal component is graphite, and the thin-film component Can be conveniently used also when is austenitic stainless steel.

  Radioactive waste generated in gas-cooled reactors and research facilities for that purpose includes non-metallic materials such as low-radiation graphite, iron, rivet-like magnesium alloys, pipe-like zirconium alloys, and thin-film austenitic stainless steels. A small amount of radioactive metal member is contained. Therefore, the radioactive waste sorting system of the present invention includes an eddy current sorter, and sorts members in the radioactive waste according to the material depending on the difference in repulsive force against overcurrent.

The eddy current sorter uses a phenomenon in which when an eddy current is induced inside a good conductor in an alternating magnetic field, it reacts with the alternating magnetic field to generate a repulsive force, and the good conductor jumps out of the magnetic field. Theoretically, the repulsive force generated by the good conductor particles is proportional to the volume of the particles, the electric conductivity, and the change rate of the magnetic field, and further proportional to the square of the magnetic flux density of the magnetic field.
Using the difference in repulsive force, it should be possible to sort out different types of non-ferrous metals, but in industrial sorting, the structure of the eddy current generator, the shape, posture, and supply method of the object are sorted. In order to affect the performance, it was actually limited to sorting aluminum cans from PET bottles that are insulators.

  The inventors paid attention to the fact that the metallic substances contained in the radioactive waste retain an almost constant shape, and as a result of repeatedly examining the actual machine model experiment taking into account the shape factor, the inventors have selected the actual radioactive waste. It was confirmed that the eddy current sorter is effective in a certain range.

That is, when non-ferrous metals such as aluminum alloy, magnesium alloy, zirconium alloy, etc. contained in radioactive waste are contained in the form of particulates or lumps, the repulsive force due to eddy current is more than 15 times that of graphite grains, which is easy It was proved that it can be selected from non-metals such as graphite.
However, since the repulsive force of a rod-like object or the like varies greatly depending on the posture supplied to the AC magnetic field, accurate separation is difficult. Therefore, by making the posture supplied to the eddy current sorter by the turning machine substantially constant, the variation in the repulsive force of the same member can be reduced and the members can be separated efficiently.

Thereby, if adjustment of the distribution plate having the function of setting a threshold value for the repulsive force of the object is appropriate, for example, a rivet-like magnesium alloy and a pipe-like zirconium alloy can be separated with a probability of almost 100%. .
On the other hand, a thin plate or foil-like metal has a volume which is insufficient, and therefore has only a repulsive force comparable to that of a nonmetal, and is discriminated in the same place as the nonmetal.

  In this way, by using an eddy current sorter, metals and nonmetals with very small volumes such as thin plates and foils, and nonferrous metals such as pipes and rivets with large volumes of magnesium alloys, aluminum alloys, zirconium alloys, etc. Can be sorted with high accuracy.

  Furthermore, in the case of a device equipped with a magnetic sorter, magnetic materials such as iron contained at the start of processing are separated and then applied to the eddy current sorter, so that the magnetic material adheres to the eddy current generating rotary magnet of the eddy current sorter. It is possible to prevent accidents that generate heat by eddy currents and damage magnet covers made of fiber-reinforced plastic.

In addition, in a device equipped with a sieve sorter, for example, a non-ferrous metal separated by an eddy current sorter, a non-metal that has passed through an eddy current sorter, and a metal having a small volume can be further sorted by a difference in particle size. If necessary, preliminary sorting by particle size may be performed before applying to the eddy current sorter.
A device equipped with a wind sorter can be conveniently used for separating a thin plate-like or foil-like metal from a non-metal.

  As an example, radioactive waste containing coarse and fine graphite in small amounts of highly radioactive metal members such as iron, rivet-like magnesium alloy, pipe-like zirconium alloy, thin-film austenitic stainless steel, etc. for each material. In the case of sorting, the radioactive waste sorting system including a magnetic sorter, an eddy current sorter, a sieve sorter, and a wind sorter in that order may be used.

  The radioactive waste is first subjected to a magnetic sorter to receive the iron component in a first recovery container, and the rest is subjected to an eddy current sorter to further separate the repulsive component into a predetermined size by a first sieve to form a rivet-like magnesium alloy And the pipe-shaped zirconium alloy separated into the second and third recovery containers, respectively, and the rest is passed through the second sieve and the fine graphite is screened and received in the fourth recovery container. By separating it into thin film austenitic stainless steel and coarse granular graphite through a sorter and receiving them in the fifth and sixth recovery containers, respectively, radioactive waste can be separated and stored by component.

  If adjustment of the distribution plate of the eddy current sorter is appropriate, the rivet-like magnesium alloy and the pipe-like zirconium alloy can be separated almost certainly. In other cases, it is only necessary to distinguish between those that repel the AC magnetic field and those that do not repel. Of course, the rivet-like magnesium alloy and the pipe-like zirconium alloy can be separated by an eddy current sorter and separately stored in the second and third recovery containers, respectively.

In this case, the components separated by natural fall without being repelled by the eddy current sorter include graphite grains and a thin plate-shaped austenitic stainless steel foil.
When the fine particle component of graphite is separated by sieving and then the foil is separated using a wind power sorter, it can be distinguished with a probability of almost 100%. Fine graphite particles are blown by the wind with a wind sorter and mixed and scattered on the foil side, making it difficult to handle, but in this separation system, the fine particle components are separated by sieving before being applied to the wind sorter. There is no difficulty.

In this way, non-metals can be separated from the metal and removed, so that non-metallic components generated in large quantities are disposed of economically using a simple method according to the characteristics of the non-metal itself, which is inherently weakly activated. be able to.
Furthermore, since the metal is separated and recovered for each component, it is possible to perform a disposal process at a level determined according to the radioactivity different for each metal. Therefore, the amount of components to which an advanced disposal method has to be applied is reduced, and a comprehensive economical disposal can be performed.

The sorting system of the present invention further includes a conveyor device including a conveyor belt for transporting the sorted non-metallic waste, and further includes a radiation detector and an exclusion arm on the conveyor belt, and is sorted by the conveyor device. When high radioactive material is detected by the radiation detector while the non-metal is transported later, when the detected high radioactive material comes to the position of the exclusion arm, the high activity material is driven from the conveyor belt by driving the exclusion arm. A portion including the above may be dropped from the conveyor belt and removed.
When a radiation detector is provided, even if there are high-activity components that cannot be sufficiently separated even by the above-mentioned sorting sequence, the radioactive material is detected and eliminated by actually measuring the radiation intensity. Disposal is even more secure and secure.
Note that a metal detector may be used in place of the radiation detector to detect and eliminate metal mixed in graphite or the like.

Hereinafter, the radioactive waste sorting system of the present invention will be described in detail using embodiments.
FIG. 1 is a block diagram of the sorting system of the present embodiment, FIG. 2 is a perspective view conceptually showing the arrangement of the components, FIG. 3 is a side view conceptually showing the turning machine, and FIG. 4 is conceptually showing the turning machine. FIG. 5 is a conceptual diagram showing the principle of the radiation detector of the sorting system of this embodiment, and FIG. 6 is a perspective view of the apparatus of FIG.

The radioactive waste carried from the waste storage facility or gas cooling furnace or the dismantling site of the research facility is put into the supply hopper 1, and the supply amount is increased and decreased while the radioactive waste is leveled by the vibratory feeder 2 to increase the magnetic force. Supplied to the sorter 3.
The magnetic separator 3 has a pulley magnet 5 on the downstream shaft of a non-magnetic belt conveyor 4. Of the radioactive waste supplied upstream of the belt conveyor 4, non-magnetic materials such as graphite and non-ferrous metals fall as they are from the lower end of the belt conveyor 4, but magnetic materials such as iron contained in the waste are pulley magnets 5. And is rotated together with the belt conveyor 4.

  When the radioactive waste stuck on the belt conveyor 4 passes through the magnet region, the magnetic force disappears, so that the adsorbed magnetic material is peeled off and dropped. When the magnetic body recovery container 21 is installed immediately below, the dropped magnetic body passes through the drop chute 31 as it is, and when the magnetic body recovery container is installed at a remote location, it can be removed by a belt conveyor or the like. It is carried and stored in the magnetic material collection container.

On the other hand, non-magnetic materials such as graphite and non-ferrous metal fall on the vibrating conveyor 6, are oriented by the turning machine 37, and are supplied to the supply chute 32 of the eddy current sorter 7 by a certain amount.
The eddy current sorter 7 has a magnet cover 8 made of a non-magnetic material such as FRP (fiber reinforced plastic), and a rotating magnet 9 attached so that a large number of magnets alternately alternate magnetic poles on the outer periphery. By rotating, an alternating magnetic field is formed.
The supply chute 32 is narrower than the effective magnetic field width of the rotating magnet 9 so that the radioactive waste surely falls into the alternating magnetic field.

  When the conductive material enters the alternating magnetic field, an eddy current is generated and a repulsive force is generated, which causes it to jump off. The non-ferrous metal jumped out of the magnetic field slides along the surface of the sorting plate 10 beyond the upper end of the sorting plate 10 and falls on the metal sorting screen 11. On the other hand, a substance such as graphite that has insufficient repulsive force does not reach the upper end of the sorting plate 10, and falls as it is and is supplied to the non-metallic sorting sieve 12.

  In this way, the eddy current sorter 7 can sort based on the strength of the repulsive force by sorting according to whether or not the top of the sorting plate 10 is exceeded. Since the eddy current is larger as the electric resistance of the material is smaller and the repulsive force is proportional to the eddy current, the eddy current sorter sets the sorting conditions such as the magnet strength and the rotation speed of the rotating magnet, and the end point position and height of the sorting plate 10. By precisely setting the value, it is possible to sort the types of target substances.

However, in the usage mode of the present embodiment, it is only necessary to be able to sort out conductors such as metals and non-conductors such as graphite. Therefore, by distinguishing materials that do not exceed the appropriately set sorting plate 10 from those that do not exceed Can fully achieve the purpose.
However, as described above, the metal in the form of a thin film or foil cannot be sorted by the eddy current sorter 7, and is later sorted by the wind sorter.

The position and height of the sorting plate 10 determine the substance that is the boundary for sorting. Since the repulsive force of the metal varies depending on the state of the rotating magnet or the like, it is preferable that the actual configuration can be adjusted based on the actual results.
Since waste is radioactive and cannot be handled directly, the sorting plate 10 has a structure that can be remotely adjusted using an actuator such as a ball screw.

  When the waste is solidified and supplied to the eddy current sorter 7, graphite and the like are also spun off together with the metal, so the sorting performance is lowered. Therefore, the waste is supplied after being sufficiently dispersed by the vibrating conveyor 6. The supply amount of the vibrating conveyor 6 is determined so as to match the processing capability of the sorter.

  In addition, when supplying a pipe-shaped nonferrous metal to the eddy current sorter 7, the influence of a magnetic field changes greatly with the attitude | position of the component at the time of passing an alternating current magnetic field. For example, if the rod enters the magnetic field in a posture close to the rotation axis of the rotating magnet 9, the influence of the magnetic field increases and the repulsive force increases. Conversely, if the rod enters a posture close to vertical, the repulsive force decreases. Therefore, in order to reliably distinguish the pipe-like non-ferrous metal, a turning device 37 is installed downstream of the vibrating conveyor 6, and even when a long bar-shaped waste part flows, the eddy current separator 7 is kept in a constant posture. To be supplied.

FIG. 3 and FIG. 4 show a mechanism diagram of the turning machine 37.
A protruding belt 61 that moves to the right with respect to the traveling direction of the vibrating conveyor 6 is installed at a predetermined distance from the lower end of the vibrating conveyor 6. Coarse grain or rivet-like small waste conveyed by the vibration conveyor 6 and rod-like waste conveyed in a posture in which the longitudinal direction is perpendicular to the traveling direction are supplied from the groove 62 without touching the protruding belt 61. It falls to the chute 32 and is supplied to the eddy current sorting device 7 as it is.

  However, the rod-like waste 63 conveyed in parallel with the traveling direction is pushed out to the vibration conveyor 6 and the tip thereof straddles the groove 62 and comes into contact with the belt 61 with the protrusions. Since the belt 61 with protrusions is driven rightward with respect to the traveling direction of the vibration conveyor 6, the tip of the rod-like waste 63 is caught by the protrusions and is moved to the right together with the protrusions so that the posture is perpendicular to the vibration conveyor 6. I will change. When the posture of the rod-like waste 63 becomes vertical for a certain level or more, the rod-like waste 63 is pushed out of the vibrating conveyor 6 and falls into the groove 62 and is guided to the supply chute 32 to the eddy current sorting device 7 in the same posture. Supplied.

  In this embodiment, the rod is supplied to the eddy current sorter 7 perpendicularly to the traveling direction so as to receive the maximum repulsive force from the magnetic field. The posture to be supplied to the sorter 7 may be appropriately adjusted so that the separation can be efficiently performed in consideration of the repulsive force of other waste.

For example, in order to reduce the repulsive force, the rod body is supplied to the eddy current sorter 7 horizontally with respect to the traveling direction, so that the traveling direction of the vibrating conveyor 6 and the traveling direction of the supply chute 32 are perpendicular to each other. The machine 37 may be arranged. In this case, the rod-shaped waste 63 whose posture is changed perpendicularly to the traveling direction of the vibrating conveyor 6 by the protruding belt 61 falls in the groove 62 in that posture and is disposed perpendicularly to the vibrating conveyor 6. Then, it is guided by the supply chute 32 and supplied to the eddy current sorter 7 in the longitudinal direction.
The diverter 37 may be one in which a sawtooth wave vibrating plate is installed vertically to align the posture of the abutted bar-shaped waste in a certain direction, instead of the rotating belt system with protrusions. . Needless to say, not only these but also various lateral movement mechanisms can be used.

By the way, when a magnetic material is supplied to the eddy current sorter 7, the magnetic material is attracted to the rotating magnet 9 and does not leave the magnet cover 8, and generates heat by induction heating. Since the magnet cover 8 is formed of FRP or the like, it may be damaged by heat.
However, in the sorting system of the present embodiment, the magnetic material is removed by the magnetic sorter 3 before being supplied to the eddy current sorter 7, so that the risk of breakage of the magnet cover 8 is small.

The metal screening sieve 11 does not pass a large non-ferrous metal such as a pipe-shaped zirconium alloy member, but passes a small non-ferrous metal such as a rivet-shaped member made of magnesium alloy, for example, having a size of about 30 mm. The metal waste that has been held, slightly tilted and vibrated, slid down on the sorting plate 10 and received on the sieving surface is sieved according to the size.
The material remaining on the sieve is recovered in the large metal recovery container 22, and the material that has passed through the sieve is recovered in the small metal recovery container 23. Since the metal waste in the radioactive waste is closely related in material and part shape, for example, a zirconium alloy is recovered in the large metal recovery container 22, and a magnesium alloy is recovered in the small metal recovery container 23, for example.

In addition, when selecting a plurality according to the size of the metal, a plurality of sieves may be used. For example, when it is desired to classify into three, it is possible to sort using two stages of sieves.
Also, when it is necessary to further sort different metals sorted into the same size, sorting can be performed by using an eddy current sorter again using the difference in electrical conductivity depending on the material.

  The non-metal screening sieve 12 is a belt-like conveyor having a mesh of an appropriate size such as 10 mm, for example, and sifts out fine non-metals such as fine graphite particles and graphite dust that fall freely from the eddy current sorter 7 and moves downward. It collects in the installed fine-grained nonmetal recovery container 24. In addition, the substance which did not reach the upper end of the sorting plate 10 due to insufficient repulsive force given by the eddy current sorter 7 is guided to the skirt 33 provided on the back of the sorting plate 10 and the non-metal sorting sieve 12 Drops on top and sifts.

On the conveyor of the graphite sorting screen 12, non-metals such as graphite grains larger than the mesh and thin film components such as foil-like austenitic stainless steel foil that could not be distinguished by the eddy current sorter 7 remain.
The non-metal sorting sieve 12 carries these substances into the separation box 34 of the wind sorter 13. The wind generated by the circulation blower 14 is supplied from a duct connected to the bottom of the separation box 34, and the wind is blown from the bottom of the conveyor to lift a light material such as a foil from the bottom of the conveyor. Is carried to the stagnation box 35 through the duct.
Since the wind sorter 13 handles radioactive materials, it is preferable to handle the wind in a closed space as much as possible. Therefore, the air flow passes through the filter 36 and is guided to the duct, returns to the circulation blower 14, is pressurized, and is blown again into the separation box 34. In addition, a curtain or the like is provided at the opening through which the conveyor passes so that the effective opening area is as small as possible.

Note that the waste supplied to the wind sorter 13 has been removed from the fine non-metal such as graphite fine particles and graphite dust by the non-metal sorting sieve 12 in advance, so that the wind sorter 13 is exposed to the wind. Since such fine components do not exist, they are not bothered by dust, and are collected and collected with high accuracy without mixing non-metallic particles into thin plate or foil austenitic stainless steel.
The wind speed of the wind sorter must be such that it can accompany the foil-like material to be collected, but can be reliably sorted at a wind speed of about 15 m / sec. In addition, when there is only one type of foil-like substance to be selected, it is possible to select a vertical-type wind power selection that is simple in structure and compact. However, when each of a plurality of substances is selected, it is preferable to provide a plurality of vertical wind power sorters or employ a horizontal wind power sorter.

In the stagnation box 35, the conveyed foil or the like is collected in the foil collection container 26 placed below.
In addition, substances such as large graphite remaining on the conveyor pass through the separation box 34 and are dropped from the end of the conveyor and collected in the coarse-grained non-metallic recovery container 25.

In addition, the non-metal sorting sieve 12 may be configured such that instead of a conveyor, a sieve screen that is inclined is screened by vibration and an object placed thereon is moved to one side.
Further, the wind power sorter may be provided at the end of a conveyor or a vibrating screen, and may have a mechanism that separates the foil material that blows up by applying wind to the falling waste.

By utilizing the physical properties and shape of the target substance by the radioactive waste sorting system of the present embodiment, austenitic stainless steel having a very small volume in the shape of non-metal, thin plate or foil such as graphite coarse particles, fine graphite particles, etc. Thin non-ferrous metals such as steel and the like, large non-ferrous metals such as pipe-shaped zirconium alloy members, and small non-ferrous metals such as rivet-shaped magnesium alloy members and aluminum alloy members can be accurately selected for each material.
While these wastes are used in nuclear facilities, etc., there is a difference in radioactivity based on the position of each material and the activation capacity of substances, so appropriate disposal methods should be used for each selected material. select.

In addition, when there are few kinds of components contained in the radioactive waste made into object, several sorters can be selected and a sorting system can be built. For example, when radioactive waste is composed of three components: iron, one non-ferrous metal, and non-metal, the magnetic separator separates iron by using a magnetic separator and an eddy current separator. The remainder can be separated into non-ferrous metal and non-metal by an eddy current sorter and stored for each component.
Similarly, when sorting radioactive waste made of rivet-like magnesium alloy members, coarse granular graphite, fine granular graphite, foil-like austenitic stainless steel, use an eddy current sorter, sieve sorter, wind sorter, etc. A sorter may be appropriately selected and used.

However, even with the sorting system of the present embodiment, it is unavoidable that a small amount of impurities is mixed into each sorted material.
When such impurities are high-dose materials such as austenitic stainless steel, the handling standards also change, which hinders on-site transportation and solidification processing performed in the next process.
Since the radioactivity for each type of waste is known in advance, there are known collection containers that are likely to be contaminated with high radioactivity components. It is preferable to perform additional sorting on the contents of the collection container having such a concern to ensure sorting accuracy.
Additional sorting can be done by re-applying the sorting system. In addition, it is possible to perform a sorting process through a similar process before collecting in a collecting container. However, more directly, the radiation intensity of the selected component may be measured to remove a portion showing an abnormal value.

FIGS. 5 and 6 are a principle view and a perspective view, respectively, of a radiation detection and removal unit that can be used for such purposes.
A radiation detector 41 is provided above the conveyor 44 for feeding the measurement object 45 little by little, and a pusher 43 is provided downstream of the radiation detector 41. The radiation detector 41 is placed at the center of the collimator 42, and the detector visual field is adjusted to a certain size so that the radiation outside the detection visual field is blocked and the radioactive substance can be detected accurately.
It is preferable that the detection field of view is made narrow enough to contain one or a small number of objects 45 and the number of parts to be eliminated is reduced, because the amount of costly high-level disposal must be reduced. However, if the detection field of view is too small, it takes a long time to detect, so it goes without saying that there is an appropriate harmony point.

When sorting based on the radiation intensity is performed, the sorting target is charged into the supply hopper 46, and is fed onto the conveyor 44 by an appropriate amount by the quantitative feeder 47 provided under the hopper. When the object to be sorted is powder, the object 54 is placed on the conveyor while being stretched so as to have an appropriate width and thickness in order to appropriately measure the radiation.
The conveyor 44 sends the object 54 to the measuring device 48 in which the radiation detector 41 shown in FIG. If the measurement results indicate abnormal radiation intensity, the drive cylinder 49 is driven to activate the pusher 43 at the time when the high radioactivity portion reaches the position of the pusher 43, and the high radioactivity material is moved out of the conveyor. Extrude.

A discharge chute 50 and a highly radioactive substance container 52 are provided at a position corresponding to the pusher 43, and the substance removed by the pusher 43 falls into the highly radioactive substance container 52.
A protective chute 51 and an inspected product collection container 53 are disposed at the end of the conveyor 44, and a portion where no high-radioactive material is detected is conveyed to the end of the conveyor 44 as it is, and the protective chute 51 is provided. And then dropped into the inspected product collection container 53 and collected.

The remaining part from which the high-radioactivity part has been removed in this way contains only low-radioactive substances, and therefore may be disposed of in accordance with a low standard.
On the other hand, the substance stored in the highly radioactive substance container 52 needs to be disposed of at a high level. However, since the part that actually exhibits high radioactivity is selected and limited by measurement, it is limited to the minimum necessary. There is no waste because we dispose of the amount.

The high radioactive material on the conveyor is removed by the pusher, but a switching plate is provided at the conveyor outlet, and this switching plate is operated based on the detection signal to be selected. Also good.
In addition, in the above method, while detecting the radioactivity and eliminating the high radioactivity substance while being transported by the belt conveyor, for example, it is transported using a bucket conveyor and the contents are removed by overturning the bucket according to the radiation detection signal. Also good.

  Although the radiation detector was used in the above method, when the substance having the highest radioactivity is limited to a specific metal component such as iron and austenitic stainless steel, it is sensitive to changes in the magnetic field instead of the radiation detector. Then, a metal detector that detects iron, austenitic stainless steel, or the like may be used. In the case of using a metal detector, a cheaper metal detector may be incorporated in the measurement device 48 of the radiation detection and removal unit shown in FIG. 6 instead of the radiation detector.

As explained above, the radioactive waste sorting system according to the present invention allows radioactive waste mixed with radioactive metals such as iron, austenitic stainless steel, and non-ferrous metals to be further crushed or manually sorted by remote operation. , Magnetic separators, eddy current separators, sieves, wind separators are used for precise sorting, and non-metals such as graphite and metals that are not mixed with non-metallic components are collected for each material. Therefore, it is possible to dispose of the entire waste at an appropriate cost.
Further, by detecting and removing more highly radioactive substances from the sorted or classified and collected waste, it is possible to prevent any obstacles to on-site transportation and solidification treatment.

It is a block diagram explaining the structure of one Example of the radioactive waste selection system of this invention. It is a perspective view which shows notionally the arrangement | positioning of the component apparatus of a present Example. It is a side view which shows notionally the turning machine of a present Example. It is a top view which shows notionally the turning machine of a present Example. It is a conceptual diagram which shows the principle of the radiation detection removal part of the selection system of a present Example. It is a perspective view which shows the example of the apparatus of FIG. It is a block diagram which shows the example of the conventional waste sorting system. It is a block diagram which shows another example of the conventional waste sorting system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supply hopper 2 Vibrating feeder 3 Magnetic sorter 4 Belt conveyor 5 Pulley magnet 6 Vibrating conveyor 7 Eddy current sorter 8 Magnet cover 9 Rotating magnet 10 Sorting plate 11 Metal sorting sieve 12 Non-metal sorting sieve 13 Wind sorter 14 Circulation Blower 21 Magnetic material recovery container 22 Large metal recovery container 23 Small metal recovery container 24 Fine-grain non-metal recovery container 25 Coarse-grain non-metal recovery container 26 Foil recovery container 31 Falling chute 32 Supply chute 33 Skirt 34 Separation box 35 Lagging box 36 Filter 37 Turning machine 41 Radiation detector 42 Collimator 43 Pusher 44 Conveyor 45 Measurement object 46 Supply hopper 47 Metering feeder 48 Measuring device 49 Drive cylinder 50 Discharge chute 51 Protective chute 52 High radioactive material container 53 Inspected Goods collection container 54 Object 61 Belt with protrusion 62 Groove 63 Stick-shaped waste

Claims (6)

A radioactive waste sorting system for separating radioactive waste mixed with iron, austenitic stainless steel, non-ferrous metal, graphite, etc. according to shape and material, comprising a magnetic sorting machine and a magnetic material recovery outlet, The magnetic material is separated from the radioactive waste by the magnetic sorter, distributed to the magnetic material recovery outlet, and supplied to a transporter that transports the remaining radioactive waste distributed to the magnetic material recovery outlet. A turning device for aligning the posture of the remaining radioactive waste, an eddy current sorter for generating an alternating magnetic field, and a plurality of non-ferrous metal recovery outlets, and the turning device feeds pipe-shaped material to the eddy current sorter. The remaining radioactive waste is prepared while aligning the pipe-shaped nonferrous metal material conveyed from the magnetic sorter by the conveyor to the desired attitude by the turning machine. The non-ferrous metal material supplied to the eddy current sorter and separated according to the repulsive force against the AC magnetic field by the eddy current sorter is distributed to the non-ferrous metal recovery outlet, and a sieve sorter and a fine graphite recovery outlet, A coarse graphite recovery outlet is provided, and the remaining radioactive waste distributed to the nonferrous metal recovery outlet is sorted according to particle size and assigned to the fine graphite recovery outlet or the coarse graphite recovery outlet. A sorting system that distributes the austenitic stainless steel having a small weight per area according to the wind speed and distributes it to the assigned foil collection container. The remaining waste that received the components at the magnetic material recovery outlet is applied to an eddy current sorter, and the remaining waste from which the repelling components are separated is passed through a sieve sorter to obtain fine graphite particles and graphite dust. The fine non-metallic components of sieving are collected at the outlet for collecting fine-grained graphite, and the rest is separated into thin austenitic stainless steel with a small weight per area according to the wind speed by a wind separator. A radioactive waste sorting system, in which non-metallic components such as large graphite are distributed to a coarse graphite recovery outlet, and thin austenitic stainless steel is distributed to a foil recovery container. The turning machine is composed of a rotating belt and a chute, and the rotating belt is arranged at a position sandwiching a gap from the downstream end of the transfer machine, and rotates in a direction perpendicular to the transfer direction. When one end of the radioactive material transported from upstream with the longitudinal direction horizontal to the transport direction is in contact with the rotating belt across the gap, the one end together with the rotating belt. Drive vertically and laterally in the conveying direction to correct the attitude of the radioactive waste along the rotating belt, align the attitude so that the longitudinal direction is perpendicular to the conveying direction, and drop from the gap onto the chute The radioactive waste sorting system according to claim 1, wherein: A magnetic sorter, an eddy current sorter, a first sieve sorter that sorts radioactive waste sorted by generating eddy currents in the eddy current sorter based on size, and an eddy current A second sieve sorter that further sorts radioactive waste that does not occur based on size, and a wind sorter that separates thin-film-like material from particles having a large particle size sorted by the second sieve sorter. A sorting system comprising a plurality of recovery outlets for allocating the respective components, wherein the radioactive waste mixed with metal is applied to the magnetic sorter and the iron components are fed to the first recovery outlet. The rest is subjected to the eddy current sorter after adjusting the posture by the turning machine, and the repulsive component is further separated into a small non-ferrous metal component and a large non-ferrous metal component by the first sieve sorter, respectively. Second and third recovery Receiving at the discharge port, the rest is passed through the second sieve sorter to screen out the fine non-metallic component and received at the fourth recovery discharge port, and the remaining large component is further passed through the wind power sorter to form the thin film component and The radioactive waste is separated into coarse non-metallic components and received in the fifth and sixth recovery outlets, respectively, so that the radioactive waste is an iron component, a large non-ferrous metal component, a small non-ferrous metal component, and a fine granular non-metal. A radioactive waste sorting system, which is separated into components, thin film components, and coarse non-metallic components and discharged. Wherein a large size of the non-ferrous metal component is a pipe-shaped zirconium alloy, wherein a small size of non-ferrous metal components are rivet-like magnesium alloy, according to claim 3, wherein said non-metallic component is graphite Radioactive waste sorting system. Furthermore, a conveyor device including a conveyor belt that conveys waste after separation from a collection container in which high-radioactivity components may be mixed is provided, and a radiation detector and an exclusion arm are provided on the conveyor belt, When the radioactive substance is detected by the radiation detector while the sorted waste is conveyed to the conveyor device, the exclusion arm is moved when the detected high radioactive substance reaches the position of the exclusion arm. The radioactive waste sorting system according to any one of claims 1 to 4 , wherein the system is driven to remove a portion containing the high-activity material from the conveyor belt. Further, a conveyor device comprising a conveyor belt for conveying the non-metallic components separated and collected to the fine graphite recovery outlet or the coarse graphite recovery outlet is provided, and a metal detector and an exclusion arm are provided on the conveyor belt. When the metal detector detects the metal while the non-metallic component after sorting is conveyed to the conveyor device, the exclusion arm is driven when the detected metal reaches the position of the exclusion arm. sorting system of radioactive waste according to any one of claims 1 to 5, the portion including the metal from the conveyor belt, characterized in that to eliminate dropped from the conveyor belt Te.

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