JP2004163415A - System for screening radioactive waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic screening system for disposing of radioactive waste by separating mixed metals from nonmetal and also classifying and discharging the metals by type. <P>SOLUTION: The system for screening radioactive waste is provided with a transfer machine (oscillating conveyer 6) for supplying radioactive waste; a turning machine 37 for aligning the attitude of the supplied radioactive waste; eddy current screening machines 7, 8, 9 for generating an AC magnetic field; and a plurality of recovery containers 22-26. The radioactive waste transferred from upstream by the transferring machine is aligned into a target attitude by the turning machine and supplied for the eddy current screening machine and separately collected to the recovery containers according to repulsion to the AC magnetic field by the eddy current screening machine. <P>COPYRIGHT: (C)2004,JPO

Description

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

Large amounts of graphite are used as neutron moderators in gas-cooled reactors and their research facilities. Graphite waste generated by the operation of a gas-cooled furnace has been processed by crushing and stored in a facility. Further, when the dismantling of the nuclear reactor is started, a large amount of radioactive waste containing metal and graphite is generated from, for example, a nuclear fuel element.
Graphite waste is radioactive and must be solidified with mortar or the like for disposal. Graphite waste generated when dismantling a nuclear fuel element may show high radioactivity by mixing metal parts such as austenitic stainless steel, zirconium alloy, and magnesium alloy having different radioactivity concentrations.

  Disposal standards, such as the depth of burial and the necessity of concrete pits, differ depending on the radioactivity of waste, and the cost of disposal varies greatly. The disposal method of waste is determined based on the highest radioactivity indicated, and the radioactivity of waste mixed with foreign substances is determined by the radioactivity and composition ratio of each substance. Therefore, graphite waste mixed with foreign substances, even if the radioactivity of graphite itself is low, if even a very small amount of highly radioactive metals such as austenitic stainless steel is included, stricter standards will be applied and disposal costs will increase. .

Conventionally, graphite waste mixed with radioactive metals has been buried without sorting, or temporarily stored in a facility. However, it is desirable to dispose of graphite waste mixed with radioactive metals by separating graphite and metal, and since radioactivity is determined by the type of metal, it is wasteful to separate and dispose of each metal. It is clear that it is preferable to reduce the
Therefore, for graphite waste mixed with radioactive metals, it is possible to separate graphite and metal, and to separate incinerated ash and metal that have been incinerated and reduced in volume by mortar, etc., and separate them into burial disposal. System development is desired.

However, at present, a system for discriminating substances mixed in graphite waste has not been realized.
In the sorting and recovery of bottles, which are general industrial waste, as shown in Fig. 7, the residue is separated by wind separation, the magnetic substance is separated by magnetic force, the foreign matter is separated by visual separation, and the aluminum is separated by sorting aluminum. There is a method in which components that can be converted are extracted, packed, and supplied as products conforming to the classification standards. However, since this method performs manual sorting to increase the separation accuracy, when applying radioactive waste sorting, it is necessary to introduce strict shielding and protective equipment and further perform sorting work by remote control. However, the cost is large and expensive, and a large amount of processing cannot be performed.

In the non-ferrous metal sorting treatment of general industrial waste, as shown in FIG. 8, a method of separating and discriminating iron by a magnetic separator and non-ferrous metal such as aluminum by an eddy current separator to remove residues is used. I have.
However, when applying this method to radioactive waste, an eddy current sorter that sorts non-ferrous metals such as aluminum cannot discriminate foil-like metals and cannot discriminate metals of different materials. In addition, substances having different radioactivity levels are mixed in the selected substances, resulting in inefficient treatment.

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 strict measures against static electricity and explosion-proofing, resulting in an increase in cost. Further, when the graphite is finely divided or dusted, it becomes difficult to solidify it for incineration or burying.
The shape of metal parts contained in graphite waste generated in gas-cooled reactors and research facilities therefor is constant for each part because it is a functional part. It is possible. However, if there is a pulverizing process, the metal waste is fragmented or deformed, so that sorting based on the shape becomes difficult.

  Also, Patent Document 1 discloses that radioactive waste is crushed by a twin-shaft shear crusher and a high-speed rotary crusher, dried by a dryer, and then subjected to magnetic force sorting, a rotary particle size sorter, a specific gravity difference sorter, and aluminum. A sorting system that separates each component with a waste sorting device that combines a sorting machine is disclosed. In this disclosed device, a ferrous metal having magnetic properties and a non-ferrous metal or paper or cloth are separated by a magnetic force sorter, and a rotary type particle sizer, in short, a non-ferrous metal or the like is finely divided into fine powder components using a sieve. And coarse powder components and larger combustible flame-retardant materials, and the fine powder is separated by a vibrating gravity specific gravity separator with wind power to separate the combustible and flame-retardant materials contained in incombustible materials, and the coarse powder components are permanently magnetized drums The combustible and flame retardant contained in the non-ferrous metal waste is removed by a rotary aluminum sorter, and each is separated and filled in a drum or the like.

In the apparatus disclosed in Patent Document 1, since radioactive waste is pulverized in the initial stage, the sorting system may be filled with difficult-to-handle fine powder components, which may impair the separation performance. For example, since a wind force is used to separate components other than a magnetic material from a magnetic drum in a magnetic separator, an increase in the size of an apparatus for processing fine powder accompanying the wind is a problem. In addition, since all the fine particles separated by the particle size separator are fed into the specific gravity difference separator, a large-sized facility such as a cyclone for removing fine powder from the circulating airflow also poses a problem.
In addition, since the separation of 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 in which non-metals and metals are mixed such as those generated in gas-cooled reactors and research facilities therefor, so that the mixed metals are converted from non-metals. The purpose is to provide an automatic sorting system that separates and classifies and stores these metals. Another object is to provide a sorting system that removes the remaining highly radioactive materials.

  The radioactive waste sorting system of the present invention includes a transporter that transports radioactive waste, a turning machine that aligns the attitude of the supplied radioactive waste, an eddy current sorter that generates an AC magnetic field, and a plurality of collection containers. The radioactive waste conveyed from the upstream by the transporter is supplied to the eddy current sorter with the turning machine aligned in the target position, and separated and collected in the collection container according to the repulsive force against the AC magnetic field by the eddy current sorter. Features.

  Furthermore, a magnetic separator 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 radioactive waste may be separated at any stage of the separation according to the particle size of the radioactive waste. In addition, it is also possible to provide a wind separator, and to separate at any stage of the separation by the difference in transportability to the wind.

  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 the gap from the downstream end of the transporter and rotates in a direction perpendicular to the transport direction. The drop chute is arranged below the gap. When the rod-shaped radioactive waste is transported from the upstream in a posture parallel to the transport direction, one end contacts the rotating belt across the gap and moves with the rotating belt in the vertical and horizontal direction in the transport 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 the object is dropped from the gap onto the dropping chute. Needless to say, the turning machine may be of another type.

Further, as another embodiment of the radioactive waste sorting system of the present invention, a radioactive waste composed of 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-metal component. 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 eddy current-bearing radioactive waste 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 sieve that applies large-sized particles that are sorted by the second sieve sorter. It is provided with a plurality of recovery outlets for distributing the components. A collection container can be arranged at each of the collection outlets to store the classified radioactive waste.

  In this system, the radioactive waste mixed with metal is passed through a magnetic separator, the iron component is received in a recovery container at the first recovery outlet, the rest is adjusted in posture by a turning machine, and then passed through an eddy current separator to repel. The components to be separated are further separated by a first sieve sorter into a predetermined size, separated into a small non-ferrous metal component and a large non-ferrous metal component, and received in second and third collecting outlets respectively. The remainder is passed through a second sieve separator to screen the fine-grained non-metallic components, received in a collecting container at a fourth recovery outlet, and the remaining large components are further passed through a wind separator to be formed into thin-film components and coarse-grained non-metallic components. The radioactive waste is separated into iron components, large non-ferrous metal components, small non-ferrous metal components, fine non-metal components, and thin films by being separated into components and received in the collection containers at the fifth and sixth discharge outlets for collection, respectively. Component and coarse-grained nonmetallic component It can be to the reservoir.

  In addition, a conveyor device equipped with a conveyor belt that transports the separated waste is provided, and a radiation detector and an exclusion arm are provided on the conveyor belt, and radiation detection is performed while the conveyor device transports the sorted radioactive waste. When the high-radioactive substance is detected by the detector, 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-activity substance from the conveyor belt and drop it from the conveyor belt. A mechanism may be provided. When the highly 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-shaped zirconium alloy, the small non-ferrous metal component is a rivet-shaped magnesium alloy, the non-metal component is graphite, and the thin film component is Can be conveniently used when is austenitic stainless steel.

  Radioactive waste, such as that generated in gas-cooled reactors and research facilities therefor, can be deposited on non-metallic materials such as graphite with low radioactivity and high-grade materials such as iron, rivet-like magnesium alloys, pipe-like zirconium alloys, and thin-film austenitic stainless steel. Radioactive metal members are included in small amounts. Therefore, the radioactive waste sorting system of the present invention is provided with an eddy current sorter, and sorts the members in the radioactive waste for each material by a difference in repulsive force against overcurrent.

The eddy current sorter utilizes a phenomenon that when an eddy current is induced inside a good conductor in an alternating magnetic field, the eddy current acts on 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 particle volume, the electrical conductivity, and the rate of change of the magnetic field, and is proportional to the square of the magnetic flux density of the magnetic field.
It should be possible to sort different types of non-ferrous metals by using the difference in repulsive force.However, in industrial sorting, the structure of the eddy current generator, the shape, attitude, and supply method of the object are further sorted. In order to affect the performance, it is actually limited to the case where aluminum cans are selected from PET bottles, which are insulators.

  The inventors have paid attention to the fact that the metallic substance contained in radioactive waste retains a substantially constant shape, and as a result of repeatedly examining actual model experiments taking into account the shape factor, the actual radioactive waste sorting It was confirmed that the eddy current sorter was effective within a certain range.

That is, when non-ferrous metals such as aluminum alloys, magnesium alloys, and zirconium alloys contained in radioactive waste are contained as granules or lumps, the repulsive force due to eddy current is at least 15 times that of graphite particles, and is easy to use. It was found that it could be separated from non-metals such as graphite.
However, accurate recognizing is difficult because the repulsive force of a rod-shaped object or the like greatly differs depending on the attitude of being supplied to the AC magnetic field. Therefore, by making the posture supplied to the eddy current sorter by the turning machine almost constant, the variation of the repulsive force of the same member can be reduced, and the member can be separated efficiently.

Accordingly, if the distribution plate having a function of setting a threshold value for the repulsive force of the object is appropriately adjusted, for example, the rivet-shaped magnesium alloy and the pipe-shaped zirconium alloy can be separated with a probability of almost 100%. .
On the other hand, a thin plate or foil metal has a shortage in volume and therefore has only the same repulsive force as a nonmetal, and is discriminated in the same place as the nonmetal.

  In this way, by using an eddy current sorter, metals and non-metals having extremely small volumes such as thin plates and foils and non-ferrous metals such as magnesium alloys, aluminum alloys, and zirconium alloys having large volumes such as pipes and rivets are obtained. Sorting can be performed with high accuracy.

  In the case of a machine equipped with a magnetic separator, the magnetic material such as iron contained at the start of processing is separated and then applied to the eddy current separator, so the magnetic material adheres to the eddy current generating rotating magnet of the eddy current separator. In addition, it is possible to prevent an accident such as heat generated by eddy current and damage to a magnet cover made of fiber reinforced plastic or the like.

Further, in the apparatus provided with a sieve sorter, for example, non-ferrous metals separated by an eddy current sorter and metals having a small volume from non-metals passed through an eddy current sorter can be further separated by a difference in particle size. If necessary, pre-sorting by particle size may be performed before applying to the eddy current sorter.
A device equipped with a wind separator can be conveniently used for separating thin or foil-like metals from nonmetals.

  As an example, radioactive wastes containing a small amount of highly radioactive metal members such as iron, rivet-like magnesium alloy, pipe-like zirconium alloy, and thin-film austenitic stainless steel in coarse and fine-grained graphite are classified by material. In the case of sorting, a radioactive waste sorting system having a magnetic sorter, an eddy current sorter, a sieve sorter, and a wind sorter in this order may be used.

  The radioactive waste is first passed through a magnetic separator, the iron component is received in a first recovery container, and the rest is passed through an eddy current separator, and the repelling component is further separated by a first sieve into a predetermined size to form a rivet-shaped magnesium alloy. And a pipe-shaped zirconium alloy, respectively, and received in the second and third recovery containers. The remainder is sieved through a second sieve to filter fine-grained graphite and received in the fourth recovery container. By separating into thin-film austenitic stainless steel and coarse-grained graphite by a separator and receiving them in fifth and sixth recovery containers, respectively, radioactive waste can be separated and stored for each component.

  If the distribution plate of the eddy current sorter is properly adjusted, the rivet-shaped magnesium alloy and the pipe-shaped zirconium alloy can be almost certainly separated, but, for example, when the separation can be easily performed by sieving. For example, in the case where sorting can be performed more easily by another method, it is only necessary to sort those that repel the AC magnetic field and those that do not. Of course, the rivet-shaped magnesium alloy and the pipe-shaped zirconium alloy can be separated by an eddy current sorter and separated and stored in the second and third recovery containers, respectively.

In this case, the components separated by natural fall without receiving a repulsive force by the eddy current sorter include graphite grains and a thin austenitic stainless steel foil.
After sieving the fine particle components of graphite, the foil can be separated using a wind separator, so that it can be discriminated with almost 100% probability. Fine graphite particles are blown by the wind with a wind separator and mixed into the foil side or scattered, making it difficult to handle.However, this separation system separates the fine particle components by sieving before passing through the wind separator, There is no difficulty.

In this way, the non-metal can be separated and taken out of the metal, so that the non-metal component generated in large quantities is economically disposed of using a simple method according to the characteristics of the non-metal itself, which is relatively weak in activation. be able to.
Furthermore, since the metal is separated and recovered for each component, a predetermined level of disposal can be performed according to the radioactivity different for each metal. Therefore, the amount of the component to which the advanced disposal method has to be applied is reduced, and comprehensive and economical disposal can be performed.

Further, the sorting system of the present invention further includes a conveyor device provided with a conveyor belt for transporting the sorted non-metallic waste, and a radiation detector and an exclusion arm are provided on the conveyor belt, and the sorting device performs sorting. If a high-activity substance is detected by the radiation detector while transporting the non-metal later, when the detected high-activity substance comes to the position of the exclusion arm, the exclusion arm is driven to drive the high-activity substance from the conveyor belt. May be dropped from the conveyor belt and removed.
In the case where a radiation detector is provided, even if there is a high-radioactive component that cannot be sufficiently separated even in the above-mentioned sorting sequence, high-radioactive foreign substances are detected and eliminated by actually measuring the radiation intensity, so waste The disposal will be more secure.
Note that a metal detector may be used instead of the radiation detector to detect and exclude metal mixed with graphite or the like.

Hereinafter, the radioactive waste sorting system of the present invention will be described in detail using examples.
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 a turning machine, and FIG. FIG. 5 is a conceptual diagram showing the principle of the radiation detection unit of the selection system of the present embodiment, and FIG. 6 is a perspective view of the apparatus shown in FIG.

Radioactive waste brought in from a waste storage facility or a gas-cooled reactor or a dismantling site of a research facility therefor is introduced into a supply hopper 1 and a vibratory feeder 2 flattens the radioactive waste to reduce or increase the supply amount to produce a magnetic force. It is supplied to the sorting machine 3.
The magnetic separator 3 has a pulley magnet 5 at the downstream shaft of the 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 from the lower end of the belt conveyor 4 as they are, while magnetic materials such as iron contained in the waste are produced by a pulley magnet 5 And rotates together with the belt conveyor 4.

  When the radioactive waste stuck to the belt conveyor 4 passes through the magnet area, the magnetic force is lost, so that the magnetic material adsorbed is separated and falls. When the magnetic material collection container 21 is installed immediately below, the dropped magnetic material passes through the drop chute 31 as it is, and when the magnetic material collection container is installed at a distant place, a belt conveyor or the like is used. It is carried and stored in a magnetic material collection container.

On the other hand, a non-magnetic material such as graphite or non-ferrous metal falls on the vibrating conveyor 6, is oriented by the turning machine 37, and is supplied to the supply chute 32 of the eddy current sorter 7 by a fixed amount.
The eddy current sorter 7 has a high-speed rotating magnet 9 in a magnet cover 8 made of a non-magnetic material such as FRP (fiber reinforced plastic) and having a large number of magnets mounted on the outer peripheral portion so that the magnetic poles alternate alternately. 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 can be surely dropped into the AC magnetic field.

  When a conductive substance enters an alternating magnetic field, an eddy current is generated, and a repulsive force is generated and the electric substance is bounced off. The non-ferrous metal bounced out of the magnetic field slides along the surface of the distribution plate 10 beyond the upper end of the distribution plate 10 and falls on the metal sorting sieve 11. On the other hand, a substance such as graphite having a low repulsive force does not reach the upper end of the distribution plate 10, but falls freely and is supplied to the nonmetal sorting sieve 12.

  As described above, the eddy current sorter 7 can perform sorting based on the strength of the repulsive force by classifying the eddy currents according to whether the eddy currents exceed or cannot exceed the distribution plate 10. The eddy current increases as the electrical resistance of the material decreases, and the repulsive force is proportional to the eddy current. Therefore, in the eddy current selector, the setting of the sorting conditions such as the strength of the magnet and the rotation speed of the rotating magnet, the position of the end point and the height of the distribution plate 10 are performed. By precisely setting, the type of the target substance can be separated.

However, in the usage mode of the present embodiment, it is only necessary to be able to select a conductor such as a metal and graphite and other non-conductors. , 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 subsequently sorted by the wind sorter.

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

  If the waste is supplied to the eddy current separator 7 in a solidified state, graphite and the like are also bounced off together with the metal, so that the sorting performance is reduced. 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 capacity of the sorting machine.

  When the pipe-shaped non-ferrous metal is supplied to the eddy current sorter 7, the influence of the magnetic field greatly changes depending on the posture of the component when passing the AC magnetic field. For example, when the rod enters the magnetic field in a posture close to being parallel to the rotation axis of the rotating magnet 9, the influence of the magnetic field increases and the repulsive force increases. Conversely, when the rod enters the posture close to perpendicular, the repulsive force decreases. Therefore, the turning machine 37 is installed downstream of the vibrating conveyor 6 so that the pipe-shaped non-ferrous metal can be reliably distinguished. To be supplied.

3 and 4 show the mechanism diagrams of the turning machine 37. FIG.
A belt 61 with a protrusion that moves rightward with respect to the traveling direction of the vibrating conveyor 6 is provided at a position separated from the lower end of the vibrating conveyor 6 by a predetermined distance. Small-sized waste such as coarse-grained and rivet-shaped waste conveyed by the vibrating conveyor 6 and rod-shaped 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 belt 61 with projections. It falls to the chute 32 and is supplied to the eddy current selection device 7 as it is.

  However, the bar-shaped waste 63 conveyed in parallel with the traveling direction is pushed out by the vibrating conveyor 6 and the leading end thereof straddles the groove 62 and contacts the belt 61 with projections. Since the belt 61 with the protrusion is driven rightward with respect to the traveling direction of the vibrating conveyor 6, the tip of the bar-shaped waste 63 is caught by the protrusion and moved to the right together with the protrusion to take a posture perpendicular to the vibrating conveyor 6. Change. When the posture of the bar-shaped waste 63 is vertical to a certain degree or more, the bar-shaped waste 63 is extruded from the vibrating conveyor 6 and falls into the groove 62, and is guided by the supply chute 32 to the eddy current sorter 7 in the same posture. Supplied.

  In this embodiment, the rod is supplied to the eddy current separator 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 sorting machine 7 may be appropriately adjusted in consideration of the repulsive force of other waste so as to efficiently separate the waste.

For example, when the rod is supplied to the eddy current selector 7 horizontally with respect to the traveling direction in order to reduce the repulsive force, the rod is turned so that the traveling direction of the vibrating conveyor 6 and the traveling direction of the supply chute 32 are perpendicular to each other. Machine 37 may be arranged. In this case, the rod-shaped waste 63 whose posture has been changed in the direction perpendicular to the traveling direction of the vibrating conveyor 6 by the protruding belt 61 falls in the groove 62 in that posture, and is arranged perpendicular to the vibrating conveyor 6. It is guided to the supply chute 32 and supplied to the eddy current sorter 7 in the longitudinal direction.
In addition, the turning machine 37 may be one in which a saw-tooth wave vibration plate is installed vertically so that the posture of the rod-shaped waste that abuts is aligned in a certain direction, instead of the above-mentioned rotating belt system with projections. . Further, it is needless to say that not only these but also various lateral movement mechanisms can be used.

By the way, when the magnetic material is supplied to the eddy current sorter 7, the magnetic material is attracted by the rotating magnet 9 and stays attached to the magnet cover 8 and does not separate, and generates heat by induction heating. Since the magnet cover 8 is formed of FRP or the like, there is a possibility that the magnet cover 8 will be damaged by heat.
However, in the sorting system of the present embodiment, the magnetic material is removed by the magnetic force sorter 3 before the magnetic material is supplied to the eddy current sorter 7, so that the risk of damaging the magnet cover 8 is small.

The metal screening sieve 11 is a sieve having a size of, for example, about 30 mm, which does not allow a large non-ferrous metal such as a pipe-shaped zirconium alloy member to pass therethrough but allows a small non-ferrous metal such as a magnesium alloy rivet-shaped member to pass therethrough. The metal waste is held down, slightly tilted and vibrated, and slid down on the distribution plate 10 and sieved according to the size.
The material remaining on the sieve is collected in a large metal collection container 22, and the material that has passed through the sieve is collected in a small metal collection container 23. Since the material and the component shape of the metal waste in the radioactive waste are closely linked, 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.

When a plurality of screens are selected according to the size of the metal, a plurality of sieves may be used. For example, when it is desired to classify into three, the sieve can be selected using two stages.
Further, when it is necessary to further sort different metals sorted into the same size, sorting can be performed by using the difference in electrical conductivity depending on the material and again using the eddy current sorter.

  The nonmetal sorting sieve 12 is, for example, a belt-shaped conveyor having a mesh of an appropriate size such as 10 mm, and sieves small nonmetals such as graphite fine particles and graphite dust which fall freely from the eddy current sorter 7 and moves downward. It is collected in the installed fine-grain non-metal collection container 24. In addition, the material which did not reach the upper end of the distribution plate 10 due to the insufficient repulsive force given by the eddy current separator 7 is guided by the skirt 33 provided on the back of the distribution plate 10 to pass through the nonmetal sorting sieve 12. Drops on top and is sieved.

Non-metals such as graphite grains larger than the mesh and thin-film components such as foil-like austenitic stainless steel foil which could not be discriminated by the eddy current sorter 7 remain on the conveyor of the graphite sorting sieve 12.
The nonmetal sorting sieve 12 carries these substances into the separation box 34 of the wind separator 13. The air generated by the circulation blower 14 is supplied from a duct connected to the bottom of the separation box 34, and the air is blown up from under the conveyor. And transported to the stagnant box 35 through the duct.
Since the wind separator 13 handles radioactive materials, it is preferable to handle wind in a closed space as much as possible. For this reason, the air flow is guided to the duct through the filter 36, returns to the circulation blower 14, is pressurized, and is blown into the separation box 34 again. Further, a curtain or the like is provided in 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 separator 13 is firstly blown by the wind in the wind separator 13 because fine nonmetals such as graphite fine particles and graphite dust have been removed by the nonmetal sorting sieve 12. Since such fine components do not exist, there is no problem with dust, and nonmetallic particles are not mixed into thin or foil-like austenitic stainless steel.
The sorting wind speed of the wind sorting machine must be a wind speed capable of entraining the foil-like substance to be collected, but can be reliably sorted at a wind speed of about 15 m / sec. When only one kind of foil material is selected, it is possible to select a vertical type wind separation which has a simple structure and is compact. However, when each of a plurality of substances is to be sorted, it is preferable to provide a plurality of vertical wind sorters or adopt a horizontal wind sorter.

In the accumulation box 35, the transported foil and the like are collected in the foil collection container 26 installed below.
In addition, substances such as large-grain graphite remaining on the conveyor pass through the separation box 34, are dropped from the end of the conveyor, and are collected in the coarse-grain nonmetal recovery container 25.

In addition, the nonmetal sorting sieve 12 may be configured such that an inclined sieve net is used for sieving by vibration and moving the material placed on the upper side to one side instead of the conveyor.
Further, the wind separator may be provided at the end of a conveyor or a vibrating sieve, and may have a mechanism of applying a wind to the falling waste to separate the blowing-up foil-like substance.

By the radioactive waste sorting system of this embodiment, austenitic stainless steel having a very small volume in the form of a non-metal such as graphite coarse particles and graphite fine particles, a thin plate or foil, utilizing the physical properties and shape of the target substance. A thin film component such as steel, a large non-ferrous metal such as a pipe-shaped zirconium alloy member, and a small non-ferrous metal such as a rivet-shaped magnesium alloy member or an aluminum alloy member 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 location of each material and the difference in the activation capability of each substance. select.

When the types of components contained in the target radioactive waste are small, some sorters can be selected to form a sorting system. For example, when radioactive waste is composed of iron, one type of non-ferrous metal, and three types of non-metallic components, using a magnetic separator and an eddy current separator, iron is separated by a magnetic separator. The remainder can be separated into non-ferrous metals and non-metals by an eddy current sorter and stored for each component.
Similarly, when sorting radioactive waste composed of rivet-shaped magnesium alloy members, coarse-grained graphite, fine-grained graphite, and foil-like austenitic stainless steel, using an eddy current sorter, a sieve sorter, a wind sorter, etc. A sorter may be appropriately selected and used.

However, even with the sorting system of the present embodiment, it is inevitable that a small amount of impurities is mixed into each of the sorted materials.
When such impurities are high-dose substances such as austenitic stainless steel, the handling standards are changed, and this becomes an obstacle to the on-site transportation and solidification treatment performed in the next step.
Since the radioactivity of each type of waste is known in advance, there is known a collection container in which high radioactive components may be mixed. It is preferable to additionally sort the contents of the collection container having such a concern to secure the sorting accuracy.
Additional sorting can be performed by re-running the sorting system. In addition, sorting can be performed through a similar process before collecting in a collection container. However, more directly, the radiation intensity of the selected component may be measured to remove a portion showing an abnormal value.

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 a purpose.
The radiation detector 41 is provided above the conveyor 44 for feeding the measurement object 45 little by little, and the pusher 43 is provided downstream of the radiation detector 41. The radiation detector 41 is installed at the center of the collimator 42, and adjusts the detector field of view to a certain size so that radiation outside the detection field of view is blocked and radioactive substances can be accurately detected.
It is preferable that the detection field of view is made narrow enough to accommodate one or a small number of objects 45 and the number of parts to be eliminated is reduced, because the amount of expensive high-level disposal must be suppressed. However, if the detection field of view is too small, it takes too much detection time, and it goes without saying that there is an appropriate harmony point.

When performing sorting based on the radiation intensity, the sorting target is charged into a supply hopper 46, and is supplied onto the conveyor 44 in an appropriate amount by a quantitative feeder 47 provided below 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 perform radiation measurement.
The conveyor 44 sends the object 54 to a measuring device 48 in which the radiation detector 41 shown in FIG. 5 is installed. If the result of the measurement indicates an abnormal radiation intensity, the drive cylinder 49 is driven to operate the pusher 43 at a 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 material container 52 are provided at positions corresponding to the pushers 43, and the material removed by the pusher 43 falls into the highly radioactive material container 52.
At the end of the conveyor 44, a protection chute 51 and an inspected product collection container 53 are provided. The portion where the high radioactive substance is not detected is transported to the end of the conveyor 44 as it is, and the protection chute 51 is provided. Fall into the inspected product collection container 53 and accumulate.

The remaining portion from which the high-activity portion has been removed in this way contains only low-activity materials, and may be disposed of according to low standards.
On the other hand, it is necessary to dispose of the substance contained in the highly radioactive substance container 52 at a high level. However, since the part exhibiting the high radioactivity is actually selected and limited by measurement, it is limited to the minimum necessary. There is no waste because the disposed amount is disposed.

In addition, the high radioactive material on the conveyor is removed by a pusher, but a switching plate is provided at the outlet of the conveyor, and the switching plate is operated based on the detection signal to sort. Is also good.
In addition, in the above method, radioactivity detection and removal of highly radioactive materials are carried out while being conveyed by a belt conveyor, but, for example, the contents are eliminated by carrying over using a bucket conveyor and overturning the bucket according to the radiation detection signal, for example. Is also good.

  In the above method, a radiation detector was used.However, when the substance having the highest radioactivity is limited to iron and specific metal components such as 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. When a metal detector is used, an inexpensive metal detector may be incorporated in the measuring device 48 of the radiation detection and removal unit shown in FIG. 6 instead of the radiation detector.

As described above, the radioactive waste sorting system of the present invention enables the radioactive waste mixed with radioactive metals such as iron, austenitic stainless steel and non-ferrous metals to be further pulverized or manually sorted by remote control without being manually selected. , Using a magnetic separator, an eddy current separator, a sieve, and a wind separator to accurately sort, and collect non-metals such as graphite and metals in which non-metal components are not mixed for each material. By performing the appropriate level of waste treatment, the entire waste can be disposed of at an appropriate cost.
Further, by detecting and removing the highly radioactive substance from the waste which has been further sorted or sorted and collected, it is possible to prevent the transportation in the premises and the solidification treatment from being an obstacle.

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

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Supply hopper 2 Vibration feeder 3 Magnetic force sorter 4 Belt conveyor 5 Pulley magnet 6 Vibration conveyor 7 Eddy current sorter 8 Magnet cover 9 Rotating magnet 10 Distributing plate 11 Metal sorting sieve 12 Nonmetal sorting sieve 13 Wind separator 14 Circulation Blower 21 Magnetic 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 Dropping chute 32 Supply chute 33 Skirt 34 Separation box 35 Flowing box 36 Filter 37 Turning machine 41 Radiation detector 42 Collimator 43 Pusher 44 Conveyor 45 Object to be measured 46 Supply hopper 47 Quantitative feeder 48 Measuring device 49 Driving cylinder 50 Discharge chute 51 Protection chute 52 Highly radioactive material container 53 Tested Product collection container 54 Object 61 Belt with projection 62 Groove 63 Rod-shaped waste

Claims (10)

A radioactive waste sorting system for separating radioactive waste according to shape and material, comprising a transporter for transporting the radioactive waste, a turning machine for aligning the attitude of the supplied radioactive waste, and a vortex for generating an alternating magnetic field. A current separator and a plurality of recovery outlets are provided, and the radioactive waste transported from the upstream by the transporter is supplied to the eddy current selector by aligning the radioactive waste in a desired posture by the turning machine, and A radioactive waste sorting system, wherein the waste separated according to the repulsive force against an alternating magnetic field is distributed to the recovery outlet. Further provided with a magnetic separator and a magnetic material recovery outlet, the magnetic separator separates the magnetic material members from the radioactive waste, distributes the magnetic material members to the magnetic material recovery outlet, and supplies other members to the turning machine. The radioactive waste sorting system according to claim 1, wherein: The radioactive waste sorting system according to claim 1 or 2, further comprising a sieve sorter, wherein the radioactive waste is sorted according to particle size and distributed to the allocated discharge outlet. The radioactive waste according to any one of claims 1 to 3, further comprising a wind separator, wherein a small one having a small weight per area according to the wind speed is sorted and allocated to the allocated collection outlet. Sorting system. The turning machine includes a rotating belt and a shooter, and the rotating belt is disposed at a position sandwiching a gap from a downstream end of the transporter and rotates in a direction perpendicular to a transport direction, and the chute is disposed in the gap. When one end of the radioactive substance conveyed from the upstream in a posture in which the longitudinal direction is horizontal in the conveyance direction and contacts the rotating belt across the gap, the one end is placed together with the rotating belt. The radioactive waste is driven in the horizontal direction perpendicular to the transport direction to correct the attitude of the radioactive waste along the rotating belt, and the attitude is aligned so that the longitudinal direction is perpendicular to the transport direction, and the radioactive waste falls from the gap onto the chute. The radioactive waste sorting system according to any one of claims 1 to 4, wherein: A magnetic sieve, an eddy current sorter, a first sieve sorter that further sorts the radioactive waste sorted by generating the eddy current in the eddy current sorter based on the size, A second sieve sorter that further sorts the radioactive waste that is not generated based on the size, a wind sorter that applies particles having a large particle size to be sorted by the second sieve sorter, and a separated component. A sorting system comprising a plurality of collecting outlets to be distributed, wherein the radioactive waste mixed with metal is passed through the magnetic separator to receive an iron component at a first collecting outlet, and the rest is collected. After adjusting the posture by the turning machine, the eddy current is applied to the eddy current sorter, and the repelling component is further separated into a predetermined size by the first sieve sorter into a small non-ferrous metal component and a large non-ferrous metal component. Separate second and third respectively Received at the recovery outlet, the remainder is passed through the second sieve separator to screen fine non-metallic components, received at the fourth recovery outlet, and the remaining large components are further passed through the wind separator to remove the thin film. The radioactive waste is separated into an iron component, a large non-ferrous metal component, a small non-ferrous metal component, a fine A radioactive waste sorting system, which separates and discharges a granular nonmetallic component, a thin film component, and a coarse nonmetallic component. A diverter comprising a rotating belt and a chute is provided on the inlet side of the eddy current sorter, and the rotating belt is disposed at a position sandwiching a gap from the downstream end of the transporter, and is disposed in a lateral direction perpendicular to the transport direction. The chute is disposed below the gap, and one end of the radioactive substance conveyed from the upstream in a posture in which the longitudinal direction is horizontal in the conveying direction is rotated over the gap. Upon contact with the belt, the one end is driven with the rotating belt in a lateral direction perpendicular to the transport direction to correct the posture of the radioactive waste so as to be along the rotating belt so that the longitudinal direction becomes perpendicular to the transport direction. 7. The radioactive waste sorting system according to claim 6, wherein the radioactive waste is dropped from the gap to the chute in such a posture. Further, a conveyor device having a conveyor belt for transporting the separated waste is provided, and a radiation detector and an exclusion arm are provided on the conveyor belt, and the conveyor device transports the radioactive waste after sorting. When the radioactive substance is detected by the radiation detector, when the detected high radioactive substance comes to the position of the exclusion arm, the exclusion arm is driven to include the high radioactivity substance from the conveyor belt. 8. The radioactive waste sorting system according to claim 6, wherein a part of the radioactive waste is removed from the conveyor belt. Further, a conveyor device having a conveyor belt for conveying the separated non-metal components is provided, and a metal detector and a rejection arm are provided on the conveyor belt, and the conveyor device conveys the sorted non-metal components. When the metal is detected by the metal detector in between, when the detected metal comes to the position of the exclusion arm, the exclusion arm is driven to drop a portion including the metal from the conveyor belt from the conveyor belt. The radioactive waste sorting system according to any one of claims 6 to 8, wherein the system is excluded. 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 is austenitic stainless steel. The radioactive waste sorting system according to any one of claims 6 to 9, wherein:

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