JP5667029B2 - Radioactive material decontamination and recovery method and apparatus therefor - Google Patents

Description

  The present invention cleans (decontaminates) substances contaminated with radioactive substances resulting from accidents at nuclear power plants, etc., and removes radioactive substances mixed in the washed liquid (also called drainage or contaminated water). The present invention relates to a method and apparatus for separating and recovering from a liquid.

  An unexpected accident at a nuclear power plant (called a nuclear power plant) occurred, and radioactive materials were scattered over a wide area. In such an unprecedented situation, we are trying to gather the wisdom of Japan and collect accidents.

Due to the accident, a wide area centered on the nuclear power plant is contaminated by the diffusion of radioactive materials from the nuclear power plant. To make matters worse, in such contaminated areas within the prescribed range from the coast, the tsunami of a large earthquake that occurred immediately before the accident destroyed structures such as buildings and industrial products such as automobiles and home appliances. In the state of scrap (rubble), it is contaminated with radioactive materials.
Therefore, the scraped structure or the like cannot be simply scrapped as it is like ordinary scrap.

  By the way, it has been known that, as a decontamination method in the case of being contaminated with a radioactive substance, it is effective to wash away the radioactive substance attached to the surface by washing with water.

  In addition, a method for decontaminating the radioactive material deposited on the primary cooling water pipe wall is also provided (see Patent Document 1).

Unexamined-Japanese-Patent No. 2011-153855.

  However, naturally, the discharged radioactive material used for cleaning (referred to as contaminated water) contains the removed radioactive substances. Therefore, from the viewpoint of preventing environmental pollution, the contaminated water used for such cleaning is also used. Radioactive material must be effectively recovered.

  However, recovering the radioactive substance dissolved in the contaminated water from the liquid requires a large and expensive apparatus and a large running cost.

  The present invention has been made in view of such circumstances, and a method for effectively decontaminating a substance contaminated with a radioactive substance and effectively recovering the radioactive substance in the contaminated water used for the cleaning, and for the same An object is to provide an apparatus.

The method for decontamination and recovery of a radioactive substance according to the present invention is a method of cleaning an object to be cleaned contaminated with a radioactive substance.
Using a cleaning liquid obtained by diluting a drug having polyoxyalkylene alkyl ether, dioctyl sodium sulfosuccinate and glycerin as components to a concentration of about 25 ppm to about 1000 ppm and adding an insolubilizing agent to the diluted liquid Decontamination by washing
After that, after collecting the liquid after washing (also called contaminated water), the pH is adjusted to be weakly alkaline,
After that, by adding polyaluminum chloride (PAC) to agglomerate solids in the liquid,
The radioactive material is configured to be separated from the liquid.

Thus, according to the radioactive substance decontamination and recovery method according to the present invention configured as described above, the radioactive substance adhering to the surface of the object to be cleaned is removed and the decontamination is performed by the cleaning liquid. At that time, due to the components of the cleaning liquid, the cleaning liquid penetrates into fine gaps, so that a high cleaning action is obtained and the decontamination action is promoted. In addition, since an insolubilizing agent is added to the cleaning liquid, water-soluble cesium and strontium in the radioactive substance are insolubilized.
And pH adjustment is performed about the contaminated water after washing | cleaning containing the said radioactive substance, Then, addition of a polyaluminum chloride is performed.
As a result, the radioactive substance containing cesium or strontium adheres to the aggregate, and the radioactive substance can be separated from the contaminated water. Such separation may be performed by separation using a filter, separation by a solid-liquid separation device such as a centrifugal separator (dehydrator), separation by precipitation, or a combination of these separation methods, or all separation methods. May be performed in sequence.

  In addition, in the method for decontamination and collection of radioactive material, if the liquid after separating the radioactive material (also referred to as treated water) is recycled again as a cleaning liquid, the absolute amount of waste liquid generated can be reduced. it can.

  Further, in the method for decontamination and recovery of radioactive substances, the cleaning liquid further contains about 100 ppm to about 100 ppm of a drug having acrylamide / acrylic acid / 2-acryloylamino-2-methylpropane sulfonic acid copolymer sodium salt as a component. When it is added so as to have a concentration of 10,000 ppm, the action of capturing radioactive substances is improved.

  In the method for decontamination and recovery of radioactive material, the insolubilizing agent is a chelating agent, and the amount added is about 0.01 to about 10.0 percent by weight with respect to the solid content contained. Therefore, it is preferable because it is a relatively inexpensive drug and can be effectively used.

An apparatus according to the present invention is an apparatus for carrying out the decontamination and recovery method of the radioactive substance,
A first container for containing an object to be cleaned;
Means for spraying or stirring the cleaning liquid on the object to be cleaned in the first container;
A second container that collects and stores the jetted or stirred cleaning liquid (contaminated water), adjusts the pH, and adds and aggregates polyaluminum chloride;
A solid-liquid separation device for solid-liquid separation of the substance aggregated in the second container;
A flow path for returning the liquid component (treated water) separated by the solid-liquid separator as the cleaning liquid;
It is characterized by having.

  In this specification and claims, the “container” means a container that can collect and store the liquid (contaminated water, treated water) after washing, such as a pool, or simply a concave. It is used in a broad concept including a sheet with a waterproof function in place.

  Thus, according to the apparatus according to the present invention configured as described above, a method for decontaminating and collecting the radioactive substance without leaking the washed liquid (contaminated water) containing the radioactive substance to the outside, Can be implemented. Further, since the treated water separated into solid and liquid can be recycled as a cleaning liquid, the amount of uselessly contaminated liquid (liquid related to decontamination) is not increased. For this reason, it is possible to implement a processing method that is environmentally friendly and has low processing costs.

  In the above apparatus, when the apparatus includes a conveying device such as a conveyor as an apparatus for carrying in and out the object to be cleaned in the first container, an apparatus having a high processing capacity can be realized.

  According to the radioactive substance decontamination and recovery method and the apparatus therefor according to the present invention, the substance contaminated with the radioactive substance is effectively decontaminated and the radioactive substance in the effluent used for the cleaning is effectively recovered. be able to.

It is a figure which shows the process of one Example of the method concerning this invention. It is the figure which represented notionally the structure of 1 Example of the apparatus for enforcing the method shown in FIG. It is a table | surface figure which shows the effect regarding removal of a radioactive substance.

Hereinafter, an apparatus according to an embodiment of the present invention and a method for decontaminating a radioactive substance and a method for recovering the radioactive substance using the apparatus will be described.
(Example)
As shown in FIG. 2, the apparatus A that performs the radioactive material decontamination and recovery method according to the present embodiment is a product to be cleaned (for example, a product such as an automobile or household appliance in a scrap (rubble) state) or a building. ) It has the 1st container 1 which accommodates S.
The first container 1 may be, for example, a pool (pit) -like structure that does not leak into the basement or the surroundings, or a vinyl sheet that has a bottom and side portions so as to prevent leakage of harmful substances by digging a hole in the ground. It may be a simple pool-shaped container covered with a sheet having a sealing function such as.

  Then, as described above, the cleaning liquid is sprayed from above and from the side toward the object S to be cleaned, which is accommodated in the first container 1 and to which the radioactive substance is attached. First Embodiment) The object to be cleaned S is cleaned by spraying in the form of a shower using 4.

As the cleaning liquid, in this embodiment, water such as tap water and well water,
(1). A drug having polyoxyalkylene alkyl ether, dioctyl sodium sulfosuccinate and glycerin as components (for example, trade name “EB-Eco Dash BB” (Eco Bond Co., Ltd. (head office: 164-19, Tojocho Kawato, Shobara, Hiroshima)) And about 25 ppm to about 1000 ppm (generally about 100 ppm to about 500 ppm, basically about 300 PPM),
(2). A drug containing acrylamide, acrylic acid, 2-acryloylamino-2-methylpropane sulfonic acid copolymer sodium salt as a component (for example, “EB-2000WJ” (Ecobond Co., Ltd. (Head office: Kawato, Tojo-machi, Shobara-shi, Hiroshima)) 164-19) sales) to a concentration of about 100 ppm to about 10,000 ppm (generally about 500 ppm to about 1500 ppm, basically about 1000 PPM),
Furthermore, (3). As an insolubilizer, a chelating agent is added to about 0.01 weight percent to about 10.0 weight percent based on the solids contained in the water. In addition, when processing incineration ash, it is added so that it may become about 1.0 weight percent-about 5.0 weight percent with respect to the quantity of ash.
The “EB-Eco Dash BB” has an action of increasing the permeability of the cleaning liquid, and the “EB-2000WJ” has an action of improving the scavenging ability of the cleaning liquid.
Further, the insolubilizing agent is not limited to the chelating agent, and it goes without saying that other insolubilizing agents may be used.

When the cleaning liquid is sprayed toward the object S to be cleaned, the radioactive material adhering to the object S to be cleaned is cleaned, and the water (contaminated water) after the cleaning becomes a water-insoluble radioactive substance. Needless to say, the water-soluble radioactive substance is also contained without being dissolved.
Further, due to the configuration of the cleaning liquid, the cleaning liquid can penetrate into a very small gap of the object to be cleaned, and the radioactive substance adhering to the gap can be effectively cleaned. Further, due to the configuration of the cleaning liquid, radioactive substances are effectively captured.
In addition, as described above, the cleaning device S is sprayed by the spraying device 4 to clean the cleaning target S, and the cleaning target S is immersed in the cleaning solution in the first container 1 and the cleaning liquid is sprayed by the jet flow device. If it is configured such that it is jetted in the liquid in the container and stirred and washed with a jet, it is preferable in that a higher cleaning effect can be obtained.

Then, the object to be cleaned S after being cleaned is removed from the first container 1 after the attached radioactive material is removed.
Further, as shown in FIG. 2, the drainage liquid containing the radioactive substance is sent from the first container 1 whose bottom surface is inclined to the second container 2 through the flow path 11, and the second In the container 2. In this apparatus A, since the contaminated water is in a batch processing format, when being sent to the second container 2 as described above, the openable / closable valve 24 is opened from the closed state to the downstream side. The arranged valve 25 is closed. Next, the valve 24 is closed again.

  Next, pH adjustment is performed so that the contaminated water stored in the second container 2 becomes weakly alkaline. In this embodiment, the adjustment is made to achieve about pH 7 to about 8.5, more preferably about pH 7.5 to about 8.

Next, PAC (polyaluminum chloride) has a concentration of about 20 ppm to about 3000 ppm (generally about 30 ppm to about 1000 ppm, basically about 50 ppm to 500 PPM) in the contaminated water whose pH has been adjusted. ) To be added. As a result, aggregation occurs in the drainage. Here, “PAC” is used because it is a basic salt, so that the consumption of alkalinity is small and an alkali agent is unnecessary or a small amount may be used. Furthermore, since “PAC” has a wide pH range that exhibits a coagulation effect, it can cope with changes in the pH value of the drainage to be treated. In addition, “PAC” has a feature that the coagulation effect does not decrease even when the contaminated water is at a low temperature.
And the radioactive substance in contaminated water adheres to an aggregate by the said aggregation.

  Next, the valve 25 is opened, and the contaminated water in which the aggregation has occurred is sent from the second container 2 to the solid-liquid separator 5 through the flow path 12. Here, the solid substance containing the radioactive substance is separated from the liquid from which the radioactive substance has been removed (treated water).

  Then, the liquid component (treated water) from which the radioactive substance has been separated is transferred to a third container (tank or the like) 3 disposed on the downstream side as a solid liquid if necessary in relation to the flow path 13 (in terms of height difference). It is sent via a pump provided in the separation device 5 and recycled as a cleaning liquid. In addition, it is sent from the third container 3 to the injection device 4 provided in the first container 1 via the pump 6 and the flow path 14.

  On the other hand, the solid matter containing the separated radioactive substance is recovered from the solid-liquid separation device 5 and processed by a conventional method, for example, packed in a container as radioactive waste containing the radioactive substance. .

  When the method and apparatus according to the embodiment of the present invention are used, the above-described operational effects can be obtained. However, the contaminated water, treated water, and slime (the separated radioactive material is used for cleaning the scrap to which the actual radioactive material is attached). As a result, the effect as shown in FIG. 3 was obtained. That is, per 1 kg of contaminated water, cesium 134 was about 240 becquerels, cesium 137 was about 320 becquerels, and iodine 131 was about 13 becquerels or less. In the treated water, cesium 134 was reduced to about 8.4 becquerel or less, cesium 137 was reduced to about 7.1 becquerel, and iodine 131 was reduced to about 6.7 becquerel or less per 1 kg of treated water. On the other hand, cesium 134 was about 7300 becquerels, cesium 137 was about 8900 becquerels, and iodine 131 was about 48 becquerels or less per 1 kg of agglomerated solids. From these results, the excellent effect of the present invention can be seen.

In the case of the apparatus according to this embodiment, the valves 24 and 25 are disposed in the flow paths 11 and 12, respectively, and the valves 24 and 25 and the pump 6 are connected to control lines L1 to L3. And is configured to be controllable by the control device C.
Therefore, the operator can perform the series of processes only by giving an instruction to the control device C by remote operation.
In addition, when a sensor or the like is added to a necessary part of the device, it is possible to automatically operate while ensuring good processing.

Further, the object S to be washed into and out of the first container 1 can be remotely operated or automatically operated by an unmanned transfer device (for example, a crane, a loader, or a conveyor). It is desirable to keep it.
In particular, a conveyor such as a slat conveyor or a trolley conveyor is provided as a transport device, and the object to be cleaned is carried into the first container 1, and the cleaning is performed while the object to be cleaned is placed on the conveyor, and then is carried out. Such a configuration is preferable for dramatically increasing the processing amount per unit time.

  If the remote control or automatic operation is performed as described above while checking with the camera and the monitor, even if the radioactive level of the radioactive material is high, the worker S can be safely cleaned without being exposed to the explosion. It becomes possible to process.

  In addition, as for the object S to be cleaned, decontamination and collection of radioactive materials can be carried out through the above-mentioned steps for contaminated soil, crushed stone, and the like, as in the case of the automobiles and electrical products.

  In addition, when a radioactive substance remains in the liquid to be recycled (treated water), an adsorption tank filled with zeolite, activated carbon or the like is provided in front of the third container 3, and this adsorption tank Therefore, it is desirable to configure so as to remove the remaining radioactive material.

  The various embodiments described above are merely examples of the present invention, and the present invention is not limited to the above-described embodiments, and can be implemented in various forms within the scope based on the technical idea of the present invention. It goes without saying that it is possible.

  The radioactive substance decontamination and recovery method and apparatus therefor according to the present invention can be used to safely and effectively decontaminate scraps and the like contaminated with radioactive substances.

DESCRIPTION OF SYMBOLS A ... Apparatus 1 ... 1st container 2 ... 2nd container 4 ... Injection apparatus 5 ... Solid-liquid separation apparatus

Claims (6)

The object to be cleaned whose surface has been contaminated by radioactive material attached to the surface ,
A drug having polyoxyalkylene alkyl ether, dioctyl sodium sulfosuccinate and glycerin as components is diluted to a concentration of 25 ppm to 1000 ppm and washed with a washing solution obtained by adding an insolubilizing agent to the diluted solution. By decontamination and
After that, collect the liquid after washing, adjust the pH to be weakly alkaline,
After that, by adding polyaluminum chloride to agglomerate solids in the liquid,
A method for decontaminating and collecting a radioactive substance, characterized in that the radioactive substance is separated from the liquid.   2. The method for decontaminating and collecting a radioactive substance according to claim 1, wherein the liquid after separating the radioactive substance is recycled again as a part of the cleaning liquid.   The cleaning liquid further comprises a chemical agent containing acrylamide / acrylic acid / 2-acryloylamino-2-methylpropane sulfonic acid copolymer sodium salt as a component so as to be 100 ppm to 10,000 ppm in the cleaning liquid. The method for decontaminating and collecting a radioactive substance according to claim 1 or 2.   The said insolubilizing agent is a chelating agent, and the addition amount is 0.01 weight percent-10.0 weight percent with respect to the solid content contained, The statement of any one of Claims 1-3 characterized by the above-mentioned. A method for decontamination and recovery of the radioactive material described. An apparatus for carrying out the method for decontaminating and collecting a radioactive substance according to any one of claims 1 to 4,
A first container for containing an object to be cleaned;
Means for spraying or stirring the cleaning liquid on the object to be cleaned in the container;
A second container for collecting and containing the jetted or stirred cleaning liquid, adjusting the pH, and adding and aggregating polyaluminum chloride;
A solid-liquid separation device for solid-liquid separation of the substance aggregated in the second container;
A flow path for returning the liquid component separated by the solid-liquid separator as the cleaning liquid;
A device characterized by comprising:   6. The apparatus according to claim 5, further comprising a conveying device as an apparatus for carrying in and carrying out the object to be cleaned in the first container.

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