JP5800636B2 - Radioactive metal waste treatment equipment - Google Patents

Description

  The present invention relates to a radioactive metal waste processing apparatus for processing metal waste having a low radioactivity level among wastes generated by the abolition of nuclear facilities.

In addition to radioactive waste that requires special management from the viewpoint of radiation protection due to nuclear power development and use such as nuclear power generation and nuclear fuel cycle business, there is also a large amount of waste that is not radioactive waste and does not need to be treated as radioactive material Occurs.
For example, the waste generated at the Tokai Power Plant where decommissioning has been implemented is said to contain 11% of low-level radioactive waste, but otherwise it is necessary to treat it as non-radioactive waste and radioactive material. There is no waste.

Waste that is classified as radioactive waste must be properly treated and disposed of so as not to adversely affect the public and the environment, but waste that is not radioactively contaminated or treated as radioactive material Even so, it is a great waste to perform the same treatment and disposal as radioactive waste. As long as it can be reasonably achieved, it is preferable to carry out recycling such as recycling and simpler proper disposal.
Although the human body is constantly receiving natural radiation caused by natural radioactive materials and cosmic rays, an object that contains only a small amount of radioactive material that emits a dose that is sufficiently smaller than the natural radiation level is treated as radioactive material. The idea that it is not necessary is called clearance, and the level that separates items that may be excluded from the system of regulation on radiation protection is called clearance level.

For example, the clearance level of an object is evaluated by the sum of values obtained by dividing the radioactivity of each radionuclide contained in the object by the weight of the object and dividing the value by the clearance level of each nuclide. The dose for deriving the clearance level for each radionuclide is 10 μSv / year.
It is reasonable from the viewpoint of radiation protection to treat an object that emits a dose below the clearance level as a non-radioactive substance. In other words, it is easier to separate waste that can be disregarded from the risks associated with research and development and use of nuclear energy, and to use those that can be reused or recycled, and that does not consider radiation protection. It can be disposed of by the disposal method.

  Waste that is higher than the clearance level will be properly managed as radioactive waste as before, and will be handled as radioactive material using the clearance level in order to ensure a system that only clears items below the clearance level under strict safety checks. Clearance level probation is planned to ensure that the state is properly involved in the judgment of the operator that it is not necessary. In this way, only those that have been approved by public institutions are supposed to be used as clearance metals.

  Clearance level verification is performed by a public institution with regard to the results of highly reliable execution of each stage, such as prior evaluation, appropriate measurement / judgment, and subsequent storage / management. The result is confirmed.

  Patent Document 1 discloses a decontamination apparatus for decontaminating clearance objects separated from demolition waste associated with demolition and removal of nuclear facilities, and pre-clearance measurement for measuring the surface contamination density of decontaminated clearance objects. A clearance processing system is disclosed that includes an apparatus and a clearance measuring device that measures the radioactivity concentration of a clearance object that has been confirmed to have no highly contaminated sites as a result of pre-clearance measurement.

Hereinafter, a conventional low-concentration radioactive metal waste treatment apparatus will be described by taking as an example the case of dismantling waste.
FIG. 4 is a flowchart for explaining an example of a procedure for carrying out contaminated waste from a radiation control area, which has been conventionally performed.
According to the illustrated procedure, a box pallet containing demolition waste is carried from the storage location to the sorting area, opened, and transferred to the cutting area. Dismantling waste includes small parts such as pipes, flat plates, steel shapes, valves, pumps, etc., and small items such as bolts and nuts.

The demolition waste, which is selected based on the evaluation results in advance and separated from the radioactive waste by pretreatment such as decontamination and suspension as needed, is supplied in the state of being stored in the box pallet. The demolition waste is taken out from the box pallet by work and placed on the workbench (S1).
At the workbench, in order to make it easier to remove the contamination caused by radioactive materials from the dismantled waste, valves, pipes, tanks, etc. have a high degree of contamination by prior evaluation, such as by vertically dividing them with a hand saw. It shreds so that the part to be exposed may be exposed (S2).
The demolition waste is required to have a cross section of 400 mm square and a height of 40 mm or less based on the structure of the contamination monitor. Further, the protrusions are managed so as to be 100 mm or less. For this reason, the dismantled waste is shredded by a worker's manual work and adjusted to a shape and size that can be easily applied to a contamination monitor (S3).

Among these shredding operations, particularly time-consuming operations are an operation of making a thick plate a predetermined thickness, an operation of removing protrusions, and an operation of exposing a contaminated surface by vertically dividing a thick pipe. Moreover, it is necessary to divide the valve so that the inside of the valve box is exposed.
It should be noted that the chips and dross generated by cutting are difficult to apply to the contamination monitor, so in reality, they are treated as waste with a high radioactivity concentration even though the radioactivity concentration is low. Yes.
The dismantled waste whose shape has been adjusted is again stored in the box pallet and transferred to the decontamination area. In the decontamination area, the demolition waste is taken out and, for example, blast decontamination is performed by manual blasting to remove radioactive substances, surface oxides, coatings, and the like (S4) and weigh (S5).

After being weighed, the demolished waste is stored in a box pallet using a crane or the like (S6), and the contamination monitor is measured (S7). Then, appropriate disposal according to the degree of contamination is performed (S8).
As described above, in the current process, preprocessing for passing through the contamination monitor takes time and there is a request for rationalization. It should be noted that approximately 10 skilled workers are required to perform the above process on a certain amount of demolition waste.

JP 2007-248066 A

  Therefore, the problem to be solved by the present invention is to reduce the volume of radioactive metal waste and to reduce the amount of pretreatment of demolition waste applied to a contamination monitor, for example, and to make it easy to handle demolition waste after inspection. It is providing the radioactive metal waste processing apparatus which can be supplied by.

  A radioactive metal waste treatment apparatus of the present invention includes a high-frequency melting furnace for melting radioactive metal waste, a plurality of molds for forming a flat ingot, a casting apparatus for casting molten metal in the high-frequency melting furnace into a mold, a mold And a degassing device for taking out the ingot from the mold after cooling, and transporting radioactive metal waste to a flat plate It is characterized by being formed into a simple ingot and supplied.

When hanging on a contamination monitor, the ingot formed by the mold preferably has a flat plate shape capable of measuring radiation in the contamination monitor.
The radioactive metal waste treatment apparatus of the present invention may further include a blasting apparatus for blasting the extracted ingot, and a mobile storage device such as a crane for storing the ingot in a pallet adapted to the measurement site of the contamination monitor. good.
Further, the mold may be fixed to a conveyance band (for example, a conveyor belt) of the conveyance device at a predetermined interval, and cast, cooled, and released while moving together with the conveyance band.

According to the radioactive metal waste processing apparatus of the present invention, it is possible to reduce the volume of radioactive metal waste by melting an object, casting it in a predetermined mold, and forming the object into an ingot having a predetermined shape and size from the mold. it can.
Therefore, it is possible to omit the shredding work of manually adjusting the shape of each demolition waste to be put on the contamination monitor.
Also, the radioactive metal waste is thoroughly mixed in the melting furnace, so that locally contaminated parts are diluted. Even when the concentration of radioactive material on the surface of the material is regulated, shredding that exposes the contaminated surface for decontamination may be omitted.

  The shape of the ingot is preferably a simple flat plate. In the case of a flat ingot, sludge or oxide adhering to the surface of the ingot that has just been cooled is easy to peel off. There is no need to select a method and perform blast irradiation, and it is possible to mechanically remove surface impurities from the object by simply placing an ingot on the irradiated portion and placing it on a blast irradiation apparatus.

  Moreover, according to the radioactive metal waste processing apparatus of this invention, since a target object is once fuse | melted and cast in a casting_mold | template, it is fixed to the shape and dimension convenient for a post process. Therefore, for example, it can supply as a test object adapted to the shape conditions imposed in the contamination monitor. Since the shape and position of the measurement object are constant for each measurement, it is easy to detect an abnormality and the monitoring time can be shortened.

In particular, conventional dismantled waste has various shapes and dimensions, so that it is not always easy to use, such as extra cost for recycling. According to the radioactive metal waste treatment apparatus of the present invention, it is possible to supply a metal material having a shape and dimensions that are easy to use, such as a flat plate or tile of several hundred mm square by appropriately selecting a mold.
Moreover, since the metal material obtained as a casting can orderly arrange or stack the casting itself or a pallet containing a large number of castings, the storage in the storage place is rationalized.

The radioactive metal waste processing apparatus of the present invention saves labor for pre-processing such as shredding and decontamination, which requires complicated and skillful work, so that, for example, the amount of contamination that has been conventionally performed by about 10 workers can be measured. It was found that the pre-treatment can be carried out by five people, almost halved, and a high labor saving effect can be obtained.
Further, when dismantling waste is supplied as a flat ingot, it can be reused or utilized more easily in a wider application field.

It is process drawing which shows the first half part of the process in 1 Example of the radioactive metal waste processing apparatus which concerns on this invention. It is process drawing which shows the latter half part of the process in a present Example. It is a flowchart explaining the process of a present Example. It is a flowchart explaining the process in the conventional radioactive metal waste processing apparatus.

Hereinafter, the radioactive metal waste processing apparatus of this invention is demonstrated in detail using an Example.
FIG. 1 and FIG. 2 are process diagrams for explaining the steps of dismantling waste pretreatment based on the arrangement of each element device in the radioactive metal waste treatment apparatus of this embodiment, and FIG. 3 is a flowchart for explaining the steps of this embodiment. is there. A step subsequent to the step shown in FIG. 1 is shown in FIG.

The radioactive metal waste treatment apparatus of the present embodiment is an apparatus for pre-processing for carrying out measurement from a radiation control area regarding demolition waste having a low radioactivity concentration. The radioactive metal waste treatment apparatus according to the present embodiment is installed in a building in which exhaust is exhausted via a pipe attached with a dust recovery apparatus so as not to pollute the outside air.
The radioactive metal waste processing apparatus of the present embodiment can be temporarily divided into a loading area, a melt casting area, a cooling deagglomeration area, and a decontamination storage area. The demolition waste is supplied to the radioactive metal waste processing apparatus of the present embodiment in a state of being stored in a box pallet.

As shown in FIG. 1, a material supply conveyor 1, an object weighing device 2, and a loading jib crane 3 are arranged in the loading area.
As shown in FIG. 3, in the work procedure in the loading area, first, as a material supply step (S11), an operator moves the dismantled waste from the box pallet to the shooter of the material supply conveyor 1 using a crane or the like. .

Next, in the object weighing step (S12), since the charging basket 4 is placed on the object weighing device 2, the material supply conveyor 1 is advanced to drop the demolition waste into the charging basket 4. The object weighing device 2 measures the input amount together with the input basket 4. When the scale of the object weighing device 2 reaches a desired weight, the material supply conveyor 1 is stopped to stop the supply of the dismantling waste. The operation of the material supply conveyor 1 may be automatically adjusted based on the output of the object weighing device 2.
The charging basket 4 having a desired weight is moved by the charging jib crane 3 onto the melting furnace in the melt casting region.

As shown in FIG. 1 and FIG. 2, a high-frequency melting furnace 5, a casting apparatus, and a mold conveyor 6 are disposed in the melt casting region.
The work procedure in the melt casting region is as follows. First, in the furnace charging step (S13), when the bottom of the charging basket 4 brought into the furnace of the high frequency melting furnace 5 is opened by remote control, the demolition waste is melted into the melting furnace. Falls into the melt and is replenished. The replenishment amount is the amount of demolition waste that has been previously measured by the object weighing instrument 2. The empty input basket 4 is set again on the object weighing instrument 2 by the input jib crane 3 and waits for the next replenishment.

In the melting step (S14), the demolition waste set in the high-frequency melting furnace 5 by the crucible transport lifter and supplied into the crucible 7 is induction-heated and melted by the high-frequency power source. If the melt in the crucible 7 is reduced, it can be replenished at any time using the charging basket 4.
Several crucibles 7 set in the furnace of the high-frequency melting furnace 5 are prepared, so that not only when the crucible 7 is consumed but also when the type and components of the demolition waste change, impurities are not mixed. The crucible 7 in the high frequency melting furnace 5 can be exchanged.

In the melting furnace tilting step (S <b> 15), the molten demolition waste melted in the high-frequency melting furnace 5 can be poured into the mold by tilting the high-frequency melting furnace 5.
In the casting step (S 16), a mold 8 is installed on the mold conveyor 6, and the molten metal is poured into the mold 8 by tilting the high-frequency melting furnace 5.
The mold 8 is preferably formed so that a sample having a size suitable for a measurement table of an existing contamination monitor, such as a width and a depth of 500 mm and a depth of 40 mm, is formed.
When the ingot of the demolition waste has a simple tile shape by the mold 8, it is convenient not only for the convenience of measurement but also for reuse or recycling.

  As shown in FIG. 2, the cooling degassing region is provided in the cooling chamber 9, and the cooling nozzle 10, the degassing device 11, and the mold conveyor 6 are arranged. The cooling chamber 9 includes a blower 13 that sucks the internal air through the filter 12 to create a negative pressure. The exhaust of the blower 13 is completely decontaminated by a dust recovery device provided in the building of the radioactive metal waste treatment apparatus and then discharged to the outside air.

A cooling nozzle 10 is provided below the mold conveyor 6 to blow out outdoor air and promote cooling of the ingot.
In the cooling step (S17), the cooling nozzle 10 blows the outside air sucked by the negative pressure in the cooling chamber onto the mold 8 transported by the mold conveyor 6 to cool and solidify the melt. The air heated by cooling the mold 8 containing the molten metal is sucked and discharged by the blower 13 so that the temperature in the cooling chamber 9 does not rise.

In the ingot removal step (S18), the ingot 14 of the demolition waste solidified in the mold 8 is carried to the position of the deaggregating device 11 at the end of the conveyor, and the mold 8 is reversed and impact is applied from the back side using a hammer. The mold is released by a giving operation or the like and dropped onto the ingot transfer conveyor 15. A slag collection conveyor 16 is disposed under the deagglomeration device 11 and collects so that slag and oxides peeled off from the ingot 14 of demolition waste are not dissipated due to the reversal and impact of the mold 8. The ingot 14 separated from the mold 8 is carried out of the cooling chamber 9 by the ingot transfer conveyor 15 and supplied to the decontamination storage area.
When the emptied mold 8 is collected, inspected, and determined to be reusable, it is stored in a mold rack so that it cannot be used again. When next used, the surface of the mold 8 is sprayed with a release agent spray to treat the release agent, preheated, and then supplied again to the casting position.

As shown in FIG. 2, an ingot transport conveyor 15, a blast irradiation device 17, an ingot weigher 18, an alignment jib crane 19, and a pallet loading jib crane 21 are arranged in the decontamination storage area.
In the blast irradiation step (S 19), the ingot transport conveyor 15 transports the ingot to the irradiation position of the blast irradiation device 17. In accordance with an automated procedure, the blast irradiation device 17 irradiates the ingot at the irradiation position with blast and scrapes off impurities on the surface. The blast irradiation device 17 is installed in a hood so that slag that may contain a radioactive substance is scattered by blast irradiation and does not diffuse outside.

Next, in the ingot weighing step (S20), the ingot 20 from which the surface slag and the like are removed is conveyed to the measurement position of the ingot weigher 18 and the weight of each ingot 20 is measured and recorded.
In the unloading step (S21), the ingot 20 after the ingot is weighed is transported to the gripping position of the pallet-loading jib crane 21, stored in order on the pallet 22 using the pallet-loading jib crane 21, and the pallet 22 is transported to the next step.

Further, after weighing, each ingot 20 may be visually inspected to eliminate abnormal products that can be visually determined.
In addition, when it cannot process immediately at the next process, you may carry the pallet 22 which accommodated the ingot 20 to the appropriate storage place in a building until it can process, and may store it.

In the next step, contamination monitor measurement (S22) is performed to confirm that the radioactivity concentration of the target demolition waste satisfies a predetermined disposal condition.
In the contamination monitor measurement (S22), when it is determined that the demolition waste needs to be handled as a waste having a level exceeding a predetermined disposal condition, the waste is collected again and disposed as a high-level waste.

The measurement object that can be mounted on the measurement table of the contamination monitor needs to be within an area of 1000 mm in length and width and 40 mm in thickness, excluding, for example, a partial protrusion.
In the case of this apparatus, up to four items having a length and width of 500 mm or less can be simultaneously measured. Therefore, for example, the measurement efficiency can be increased by arranging four ingots of dismantling waste formed in a square plate shape and measuring them at a time.

  According to the radioactive metal waste treatment apparatus of this embodiment, by melting the demolition waste into an ingot, the thick plate is split in the thickness direction, the inner surface of the pipe is exposed, and the contaminated portion is caught. This eliminates the need for shaping processing and shredding processing, and can save labor in pretreatment for surface contamination measurement. For example, in the conventional method, two persons from the material supply step (S11) to the melting step (S14), the melting furnace tilting step, for the amount of demolition waste that is estimated to require about 10 skilled workers Two people from (S15) to the ingot weighing step (S20) and one in the unloading step (S21), a total of five workers, can be evaluated to reduce the labor by half.

In addition, since the shape and size of the metal applied to the contamination monitor are constant, the measurement time can be shortened.
Furthermore, chips generated by cutting are reduced, and the amount of waste to be handled as radioactive waste is reduced.

Furthermore, ingot-shaped dismantling waste is highly adaptable, for example, when it is recycled for other uses, for example, it is melted again and formed into an arbitrary shape.
Also, when storing, it can be arranged in close proximity with a high density within a certain area, and can be easily stacked, so that storage efficiency is also high. Also, a plurality of pallets can be stored in a suitable pallet, and the pallets can be closely arranged and stored at high density.
In addition, since an object having an appropriate shape is melted and shaped into a predetermined shape, the effect of volume reduction is great, and the efficiency in transportation and storage is improved. Furthermore, when disposing of landfills, disposal efficiency improves due to the volume reduction effect.

  In addition, even if it is the waste of the part which is evaluated in advance and is expected to be lower than the predetermined disposal condition, the concentration of radioactive material may be locally high, but if such a part is small, By melting and mixing together with a low-contamination part, a part having a high radioactive substance concentration may be dispersed and diluted throughout to satisfy predetermined disposal conditions.

  With the radioactive metal waste treatment apparatus of the present invention, it is possible to reduce the volume of metal waste at each radioactive substance concentration level and rationalize disposal costs. Further, it can be supplied in the form of a rectangular plate convenient for the subsequent process.

DESCRIPTION OF SYMBOLS 1 Material supply conveyor 2 Object weighing device 3 Jib crane 4 for input throwing basket 5 High frequency melting furnace 6 Mold conveyor 7 Crucible 8 Mold 9 Cooling chamber 10 Cooling nozzle 11 Deaggregating device 12 Filter 13 Blower 14 Ingot 15 Ingot conveyer 16 Slag collection Conveyor 17 Blast irradiation device 18 Ingot weigher 19 Jib crane for alignment 20 Ingot 21 Pallet loading jib crane 22 Pallet

Claims (3)

A high-frequency melting furnace for high-frequency melting of a metal dismantling waste to be processed generated in a radiation utilization facility, a plurality of molds forming a flat ingot suitable for a measurement table of a contamination monitoring device used for radiation measurement, and the high-frequency melting furnace A casting apparatus for casting the melt in the mold, a transport apparatus for transporting the mold, a cooling apparatus for cooling the melt cast in the mold during transport into an ingot, and the mold after cooling And a deagglomerating device for taking out the ingot from, and forming and supplying the metal demolition waste to be processed into a flat ingot suitable for the radiation measurement . The plurality of molds are fixed on a transport band of the transport device at a predetermined interval, and the molten mold can be poured into the next mold each time the transport band advances. 1 Symbol placing radioactive metal waste processing apparatus. Furthermore, a blasting apparatus for irradiating a blast on the ingot taken out, the ingot further comprising a mobile storage device for storing the compatible palette measurement site of the pollution monitoring equipment, radioactive metal waste according to claim 1 or 2, wherein Material processing equipment.

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