Decontamination system, and decontamination method

Abstract

To provide a combination that is suited to blast decontamination and a wet type dust collection for a usage of radioactive decontamination.SOLUTION: The present invention is a decontamination system for radioactive decontamination, and comprises following constituents. A blast processing unit is configured to cause a polishing particle to run into a surface of a contamination member, and grind contaminated dust including a radioactive substance from a surface layer of the contamination member. A particle recycling unit is configured to roughly separate the contaminated dust to be discharged from the surface layer, and the polishing particle thereto, in which the blast processing unit is configured to recycle the roughly separated polishing particle. A dust collection unit is configured to perform a wet type dust collection for the roughly separated contaminated dust, using a liquid mixing a dust absorbent material. A liquid recycling unit is configured to aggregate and roughly separate the dust absorbent material with respect to a waste liquid undergoing the wet type dust collection, reproduce the liquid, in which the dust collection unit is configured to recycle the post-reproduction liquid. A volume reduction unit is configured to burn the aggregated dust absorbent material to reduce a volume of contaminated waste.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a decontamination system and a decontamination method for radioactive contamination. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a decontamination process is known that reduces radioactive contamination of a contaminated member by using a blast process.

[0003] For example, Patent Document 1 discloses a decontamination technology that "comprises a process in which an abrasive is blown with gas to continuously perform dry blasting to remove radioactive contaminants adhering to the surface of the object to be decontaminated together with the base material, a process in which the used abrasive generated by the dry blasting process and the removed contaminants are collected and separated, and the abrasive is reused, and a waste gas treatment process in which the separated contaminants are stored and then disposed of."

[0004] Also, for general use, a wet dust collector is known that wet-collects dust generated during blast processing.

[0005] For example, Patent Document 2 discloses a dust collection technology of "a wet dust collection device equipped with a gas-liquid mixing chamber that mixes dust-laden air after blast processing with mist and traps dust in the mist, and a gas-liquid separation chamber that separates water droplets and air from the dust-laden air mixed with gas-liquid." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-230185 [Patent Document 2] JP 2007-000736 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the blasting process described in Patent Document 1 is combined with general wet dust collection as in Patent Document 2, problems specific to radioactive decontamination arise, such as an increase in contaminated waste such as radioactively contaminated water.

[0008] Therefore, an object of the present invention is to provide a suitable combination of blast decontamination and wet dust collection for use in radioactive decontamination. [Means for solving the problem]

[0009] The present invention provides a decontamination system for grinding a surface layer of a contaminated component whose surface layer is contaminated with a radioactive substance, and includes the following configuration.

[0010] The blasting treatment section causes abrasive particles to collide with the surface of the contaminated member, thereby grinding off the contaminated dust containing the radioactive material from the surface layer of the contaminated member.

[0011] The particle recycling section roughly separates the contaminating dust discharged from the surface layer from the abrasive particles, and reuses the roughly separated abrasive particles in the blast processing section.

[0012] The dust collecting section performs wet dust collection on the roughly separated contaminated dust using a liquid mixed with a dust adsorbent.

[0013] The liquid recycling section coagulates the dust adsorbent in the waste liquid from which the wet dust collection has been completed, roughly separates the dust adsorbent, and regenerates the liquid, and reuses the regenerated liquid in the dust collecting section.

[0014] The volume reducing section burns the aggregated dust adsorbent to reduce the volume of the contaminated waste. Effect of the Invention

[0015] According to the present invention, it is possible to provide a suitable combination of blast decontamination and wet dust collection in radioactive decontamination applications.

[0016] The details of the problems, configurations, and effects other than those described above will be described in the embodiments described later. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram illustrating a schematic configuration of a decontamination system 100. [Diagram 2] FIG. 2 is a diagram illustrating a plant configuration of the decontamination system 100. [Diagram 3] FIG. 3 is a diagram showing an example of the centrifugal projection unit 113. As shown in FIG. [Figure 4] FIG. 4 is a diagram showing an example of the arrangement of a plurality of centrifugal projection units 113. As shown in FIG. [Diagram 5] FIG. 5 is a diagram illustrating a plant facility of the decontamination system 300. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in explaining the decontamination method here, in order to clarify the subject of each action, the actions corresponding to "xx step" in the claims will be described as actions mainly consisting of "xx part." EXAMPLES

[0019] Overview of Example 1 FIG. 1 is a block diagram illustrating a schematic configuration of a decontamination system 100. In FIG. 1, the decontamination system 100 includes a blast processing section 110 , a particle recycle section 120 , a dust collection section 130 , a liquid recycle section 140 , and a volume reduction section 150 .

[0020] Among these, the blasting processing section 110 processes the contaminated member 200 whose surface layer is contaminated with radioactive substances. The blasting processing section 110 causes abrasive particles to collide with the surface of the contaminated member 200, grinding the surface layer of the contaminated member 200. By this grinding process, contaminated dust containing radioactive substances is peeled off from the surface layer of the contaminated member 200, completing surface decontamination to a degree required for post-processing of the contaminated member 200.

[0021] In addition, in the blast processing unit 110, it is preferable to increase or decrease the particle shape, size, projection speed, projection angle, projection amount, projection time, etc. of the abrasive particles depending on the material, hardness, and thickness of the contaminated surface layer.

[0022] For example, it is preferable that the abrasive particles satisfy at least one or all of the following conditions 1 to 3.

[0023] (Condition 1) The particle size of the abrasive particles is set so that the size of the contaminating dust to be ground can be adsorbed by the dust adsorbent. This condition 1 makes the dust size of the contaminating dust finer, and makes it possible to increase the adsorption rate of the contaminating dust by the dust adsorbent. For example, the particle size of such abrasive particles is preferably 250 to 500 μm.

[0024] (Condition 2) The abrasive particles must have a hardness that prevents dirt from penetrating into the particles during grinding. This condition 2 ensures that dirt does not penetrate into the inside of the abrasive particles after grinding, with dirt only adhering to the surface. As a result, when disposing of the abrasive particles, it is only necessary to clean off the dirt on the surface, making decontamination of the abrasive particles easy.

[0025] (Condition 3) The abrasive particles have a nearly spherical shape (i.e., a shape without edges that are prone to fracture) and are tough enough not to fracture during grinding. This condition 3 makes it possible to suppress fracture of the abrasive particles and increase the number of times the abrasive particles can be reused.

[0026] For example, abrasive particles that satisfy all of these conditions 1 to 3 are preferably zirconium oxide particles having a hardness of HV1100 or more, a particle size of 250 to 500 μm, a substantially spherical shape, and high toughness.

[0027] The particle recycle section 120 receives contaminating dust generated from the surface layer and abrasive particles after blasting from the blasting processing section 110. The particle recycle section 120 roughly separates the contaminating dust from the abrasive particles. The particle recycle section 120 returns the roughly separated abrasive particles to the blasting processing section 110. The blasting processing section 110 reuses the roughly separated abrasive particles in a blasting process in a circulatory manner. Meanwhile, the roughly separated contaminating dust is sent to the dust collection section 130.

[0028] The dust collector 130 generates a liquid mixed with a dust adsorbent and mixes it with the roughly separated contaminated dust. At this time, the dust adsorbent in the liquid adsorbs and captures the contaminated dust, thereby performing wet dust collection. The dust adsorbent preferably contains powdered bamboo charcoal.

[0029] The liquid recycling section 140 aggregates the dust adsorbent in the waste liquid after the wet dust collection. When an aggregating agent is used for the aggregating process, it is preferable to use an "incinerator" that can be incinerated in preparation for the combustion process in the volume reduction section 150. The dust adsorbent in the waste liquid aggregates, resulting in rough separation into the dust adsorbent that has captured the contaminated dust and the remaining liquid. The liquid that has been clarified to a certain extent after the rough separation is regenerated with a lower level of contamination. The liquid recycling section 140 circulates the regenerated liquid to the dust collection section 130. Through this circulation, the dust collection section 130 repeatedly reuses the regenerated liquid for wet dust collection.

[0030] The volume reduction section 150 combusts the dust adsorbent that has been aggregated in the liquid recycle section 140. This combustion process burns the combustible parts of the dust adsorbent, such as bamboo charcoal. As a result, the volume of the contaminated waste containing contaminated dust is reduced as unburned residue.

[0031] <<Description of the Operation of Plant Equipment in the First Embodiment>> Next, the operation of the plant facility of the first embodiment will be described. 2 to 4 are diagrams illustrating examples of plant facilities of the decontamination system 100. FIG. Here, a duplicated explanation of the parts already explained in FIG. 1 will be omitted, and the operation will be explained focusing on the specific configuration of each part.

[0032] First, the blast processing unit 110 will be described. 2 to 4, the blast processing section 110 includes a sealed blasting chamber 111, a particle supply section 112, a centrifugal projection section 113, collection sections 114a and 114b, a blast cleaning chamber 115, a transport section 116, a shape measurement section 117, and a projection adjustment section 118.

[0033] Of these, the sealed blast chamber 111 is a space maintained at a lower pressure than the outside environment, and is an isolated space installed to prevent contaminated dust from leaking and scattering into the outside environment.

[0034] The particle supplying section 112 accumulates the abrasive particles roughly separated in the particle recycling section 120, and supplies them to the centrifugal projection section 113. The inlet of this particle supplying section 112 is opened and closed in synchronization with the lifespan determination of the abrasive particles by the lifespan management section 122, which will be described later, to replenish or completely replace the abrasive particles with new ones.

[0035] The centrifugal projection unit 113 centrifugally projects the abrasive particles onto the surface of the contaminated member 200 . As shown in FIG. 3, the centrifugal projection section 113 includes a transport pipe 113A for transporting abrasive particles from the particle supply section 112, an input port 113B for receiving the abrasive particles at any time, a rotating wheel 113C for accelerating the input abrasive particles and projecting them onto the surface layer of the contaminated member 200, and a drive section 113D for rotating the rotating wheel 113C.

[0036] The collecting section 114a collects the contaminated dust that is ground and discharged from the surface layer of the contaminated member 200, together with the used abrasive particles.

[0037] The blast cleaning chamber 115 is an isolated space for brushing or air treating the contaminated member 200 after the blasting process to remove contaminated dust and abrasive particles adhering to the contaminated member 200. The blast cleaning chamber 115 is a space maintained at a lower pressure than the outside environment, and is installed so that contaminated dust and the like do not leak and scatter into the outside environment. The sealed blast chamber 111 and the blast cleaning chamber 115 may be combined into one compartment.

[0038] FIG. 4 is a diagram showing an example of the arrangement of a plurality of centrifugal projection units 113. As shown in FIG. In Fig. 4, the transport unit 116 transports the contaminated member 200. The multiple centrifugal projection units 113 are arranged so that no shadow is cast on the projection range of the abrasive particles over the entire surface of the contaminated member 200. Since the projection ranges of the centrifugal projection units 113 cannot overlap at the same time, the multiple centrifugal projection units 113 perform centrifugal projection on the contaminated member 200 at spatial (or temporal) intervals, as illustrated in Fig. 4.

[0039] As shown in FIG. 4, the blast processing unit 110 further includes a shape measuring unit 117 and a projection adjusting unit 118.

[0040] The shape measuring unit 117 measures the 3D shape (or the cross-sectional shape perpendicular to the conveying direction) of the surface of the contaminated member 200 using a stereoscopic imaging camera or the like.

[0041] The projection adjustment unit 118 automatically adjusts the position and orientation of each of the multiple centrifugal projection units 113 so that the projection range of the abrasive particles covers the entire surface of the contaminated member 200, depending on the dimensions and uneven shape of the contaminated member 200 measured by the shape measurement unit 117.

[0042] Next, the particle recycling section 120 will be described. In FIG. 2, particle recycling unit 120 includes a sorting unit 121, a lifetime management unit 122, a particle cleaning unit 123, and a separation management unit .

[0043] Among these, the sorting unit 121 roughly separates contaminated dust discharged from the surface layer of the contaminated member 200 from used abrasive particles. For the rough separation here, for example, sieve sorting based on differences in particle size, cyclone sorting based on differences in weight or specific gravity, etc. are used.

[0044] The lifespan management unit 122 performs a lifespan judgment as to whether the abrasive particles can be reused. If the lifespan management unit 122 judges that the abrasive particles can be reused, the abrasive particles are circulated to the particle supply unit 112 for reuse. On the other hand, if the lifespan management unit 122 judges that the abrasive particles cannot be reused, the abrasive particles are discharged to the particle cleaning unit 123.

[0045] For example, the following determination method can be used for lifetime management by the lifetime management unit 122 here.

[0046] (1) Determining the life span based on the weight of abrasive particles As the abrasive particles are repeatedly reused, the particle surface wears away and the particle size gradually becomes smaller. As wear progresses, the toughness decreases and the abrasive particles begin to break down. Therefore, the life management unit 122 detects the weight of all or part of the abrasive particles after use using a sensor or the like, and when the weight reaches a predetermined percentage (e.g., 90%) of the initial weight, performs a lifespan determination that the abrasive particles cannot be reused, with a margin of error relative to the limit at which the abrasive particles break down (experimental values, simulation values, etc.).

[0047] (2) Lifespan determination based on the bulk volume of abrasive particles As the abrasive particles wear down, their particle size decreases. Therefore, the lifespan management unit 122 detects the bulk volume of the whole or part of the abrasive particles after use using a sensor or the like, and when the bulk volume reaches a predetermined ratio (e.g., 90%) of the initial state, performs a lifespan determination that the abrasive particles cannot be reused, with a margin of error relative to the limit at which the abrasive particles break (experimental value, simulation value, etc.).

[0048] (3) Lifespan determination based on number of times abrasive particles are reused As the abrasive particles are repeatedly reused, the abrasive particles wear out. Therefore, the life management unit 122 counts the number of times the abrasive particles are reused, and performs a lifespan determination that the abrasive particles cannot be reused, with a margin of error with respect to the limit at which the abrasive particles break (experimental value, simulation value, etc.).

[0049] The particle cleaning unit 123 cleans the dirt on the particle surface of the abrasive particles that have been determined to be unreusable with a gas-liquid mixture containing tiny bubbles (such as microbubbles and nanobubbles). Due to the hardness of condition 2 above, dirt such as contaminant dust does not bite into the inside of the abrasive particles. Therefore, it is possible to proceed with decontamination of the abrasive particles by cleaning only the surfaces of the abrasive particles to the required extent.

[0050] The separation management unit 124 manages the abrasive particles with reduced dirt on the particle surface as waste. The separation management unit 124 may detect radiation from the abrasive particle waste it manages, and automatically increase or decrease the cleaning time, number of cleanings, amount of cleaning water, etc., of the particle cleaning unit 123 so that the detected radiation value meets the standard for general waste.

[0051] Next, the dust collecting section 130 will be described. As shown in FIG. 2, the dust collecting section 130 includes a cyclone separator 131, a wet scrubber dust collector 132, and a HEPA filter 133.

[0052] Of these, the cyclone separator 131 separates larger contaminated dust that is not adsorbed to the dust adsorbent from the contaminated dust roughly separated in the particle recycle section 120. The larger contaminated dust separated here is sent to other decontamination processes such as melting decontamination. The cyclone separator 131 sends the contaminated dust that can be wet-collected to the wet scrubber dust collector 132.

[0053] If larger contaminated dust particles can be coagulated and removed from the waste liquid after wet dust collection, the cyclone separator 131 may be omitted and the contaminated dust may be sent directly to the wet scrubber dust collector 132.

[0054] The wet scrubber dust collector 132 drops contaminated dust and a dust adsorbent (e.g., powdered bamboo charcoal) into a liquid (e.g., water) in a tank and stirs them. The stirred contaminated dust is adsorbed and captured by the dust adsorbent, thereby performing wet dust collection.

[0055] The gas generated during stirring in the tank is filtered by the HEPA filter 133 and discharged as clean gas.

[0056] The liquid recycling section 140 collects the waste liquid from the wet scrubber dust collector 132. The liquid recycling section 140 coagulates and roughly separates the dust adsorbent by, for example, mixing a coagulant with the collected waste liquid. At this time, the supernatant liquid is clarified and regenerated. The regenerated liquid returns to the tank of the wet scrubber dust collector 132 and is repeatedly reused for wet dust collection. Meanwhile, the coagulated dust adsorbent (including contaminated dust) is deliquified, if necessary, by compression, centrifugation, drying, or the like, and then discharged from the liquid recycling section 140 to the volume reduction section 150.

[0057] The volume reduction section 150 includes a combustion section 151 and a HEPA filter 152. The combustion section 151 burns the aggregated dust adsorbent (including contaminated dust). The gas generated during combustion is filtered by the HEPA filter 152 and discharged as clean gas. This combustion process burns down the combustible dust adsorbent such as bamboo charcoal, and further causes the contaminated dust to cluster together (or adhere or fuse), thereby reducing the volume of the contaminated waste.

[0058] In the above-mentioned series of plant processes, the blast decontamination of the surface layer of the contaminated component 200 and the wet collection of the contaminated dust generated by the blast decontamination are completed.

[0059] Effects of Example 1 The effects achieved by the first embodiment will be described below.

[0060] (1) When contaminated dust generated by blast decontamination is treated by wet dust collection, a problem occurs in that a large amount of radioactively contaminated waste liquid is generated. Therefore, in Example 1, wet dust collection is performed using a liquid mixed with a dust adsorbent. As a result, it is possible to reduce radioactive contamination of the waste liquid by agglomerating and removing the dust adsorbent (including contaminated dust) from the waste liquid of wet dust collection. Therefore, Example 1 is superior in that it can reduce radioactive contamination of the waste liquid of wet dust collection.

[0061] (2) In Example 1, the waste liquid in which radioactive contamination has been reduced by the coagulation and removal of the dust adsorbent is circulated again to the wet dust collection as regenerated liquid. Therefore, Example 1 is superior in that the amount of waste liquid generated can be significantly reduced even if the wet dust collection is repeated, since only a small amount of new liquid is added to the wet dust collection each time (just enough to make up for the loss of the regenerated liquid).

[0062] (3) The contaminated dust generated by blast decontamination is powdery and bulky, and is prone to scattering in the air as radioactive contaminants, making it difficult to handle. However, in Example 1, the contaminated dust is adsorbed to a dust adsorbent in liquid by wet dust collection. The contaminated dust adsorbed to the dust adsorbent is unlikely to scatter in the air, making it easy to handle as radioactive contaminants. Therefore, Example 1 is superior in that the contaminated dust generated by blast decontamination is adsorbed to a dust adsorbent, reducing the possibility of scattering in the air and making it easy to handle radioactive contaminants.

[0063] (4) In Example 1, the contaminated dust is packed (or adhered or melted) together by the combustion treatment of the dust adsorbent. Therefore, Example 1 is superior in that the possibility of scattering into the air is reduced by packing (or adhering or melting) the contaminated dust by the combustion treatment of the dust adsorbent, making it easier to handle radioactive contaminated materials.

[0064] (5) Furthermore, Example 1 is superior in that the burnable parts of the dust adsorbent are burned by the combustion treatment, thereby reducing the volume of contaminated waste.

[0065] (6) In the conventional technology (Patent Document 1), a blasting process is carried out by spraying an abrasive with gas pressure. Therefore, the sprayed gas tends to cause contaminated dust to fly up, making it difficult to collect the contaminated dust. In addition, because gas is sprayed, it is difficult to maintain the air pressure in the blasting space lower than the ambient air pressure, making it difficult to reduce the possibility of contaminated dust leaking to the outside.

[0066] However, in Example 1, the abrasive particles are centrifugally projected by the rotating wheel 113C onto the surface of the contaminated member 200. Therefore, Example 1 is superior in that the amount of air blown is not so great that the floating up of contaminated dust and leakage to the outside are reduced, and the contaminated dust can be easily collected.

[0067] (7) The abrasive particles of Example 1 include particles that are finely divided so that the dust size of the contaminant dust to be ground can be adsorbed by the dust adsorbent as condition 1. For example, abrasive particles with a particle size of 250 to 500 μm are used as such abrasive particles. In this case, the dust size of the contaminant dust generated during the collision of the abrasive particles rarely exceeds 250 to 500 μm. As a result, the contaminant dust is adsorbed by the dust adsorbent as fine contaminant dust. Therefore, Example 1 is superior in that the particle size of the abrasive particles is adjusted and controlled to meet condition 1, thereby improving the dust collection efficiency of the contaminant dust by wet dust collection.

[0068] (8) The abrasive particles of Example 1 include particles having a hardness that prevents dirt from penetrating into the inside of the particles during grinding as condition 2. This condition 2 makes it difficult for dirt to penetrate into the inside of the abrasive particles after grinding, and radioactive dirt is only attached to the surface. Therefore, it is possible to remove most of the radioactive contamination by simply washing the dirt off the surface when disposing of the abrasive particles. Therefore, Example 1 is superior in that the use of abrasive particles that satisfy condition 2 makes it relatively easy to decontaminate the abrasive particles to be disposed of.

[0069] (9) The abrasive particles of Example 1 are those having a nearly spherical particle shape with reduced corners and having the toughness to prevent fracture during grinding as condition 3. This condition 3 can suppress fracture, such as the loss of part of the abrasive particles. Therefore, Example 1 is superior in that by using abrasive particles that satisfy condition 3, fracture of the abrasive particles can be prevented as much as possible, thereby increasing the number of times the abrasive particles can be reused.

[0070] (10) In Example 1, powdered bamboo charcoal is used as all or part of the dust adsorbent. Powdered bamboo charcoal has a large surface area due to the numerous holes unique to charcoal, and can efficiently adsorb contaminated dust. Furthermore, bamboo charcoal is known to have surface substances and surface structures that strongly bind with some radioactive elements. Therefore, radioactive elements are less likely to be released back into the liquid from the bamboo charcoal that has adsorbed the contaminated dust. Therefore, Example 1 is superior in that it can efficiently collect radioactive contamination in a wet dust collection by using powdered bamboo charcoal as the dust adsorbent.

[0071] (11) Furthermore, most of the bamboo charcoal used in Example 1 is burned away by the combustion process in the volume reduction section 150. Therefore, Example 1 is superior in that it can reduce the volume of contaminated waste by using powdered bamboo charcoal as a dust adsorbent and performing combustion treatment.

[0072] (12) However, abrasive particles wear down as they are repeatedly reused, and their toughness gradually decreases. Therefore, when the decrease in toughness exceeds a certain limit, the abrasive particles break down during blasting. In this regard, in Example 1, a lifespan determination is performed at which the abrasive particles become unreusable, and the reuse of the abrasive particles is stopped before they break down. Therefore, Example 1 is superior in that the lifespan determination of the abrasive particles can prevent situations such as the abrasive particles breaking down. EXAMPLES

[0073] <<Structural Features of the Second Embodiment>> FIG. 5 is a diagram illustrating a plant facility of the decontamination system 300. As shown in FIG. In FIG. 5, the configuration of the second embodiment is characterized in that piping and pumps are provided for transporting liquid or waste liquid so that the liquid or waste liquid is circulated from the liquid recycling section 140A through the particle cleaning section 123A and the wet scrubber dust collector 132A in this order, and then back to the liquid recycling section 140A.

[0074] The other configurations are the same as those in the first embodiment, so a duplicated description will be omitted here.

[0075] Operational Features of the Second Embodiment The operational features of the second embodiment will be described below with reference to FIG.

[0076] (1) The liquid recycling unit 140A regenerates the liquid after wet dust collection by separating the coagulated dust adsorbent. The liquid recycling unit 140A sends the regenerated liquid to the particle cleaning unit 123A.

[0077] (2) The particle cleaning unit 123A reuses the liquid regenerated by the liquid recycling unit 140A to clean the abrasive particles to be discarded. The particle cleaning unit 123A separates the cleaned abrasive particles from the waste liquid containing the liberated contaminants. The particle cleaning unit 123A sends the waste liquid containing the contaminants to the wet scrubber dust collector 132A.

[0078] (3) The wet scrubber dust collector 132A (dust collection section 130) mixes the waste liquid containing abrasive particle contamination with a dust adsorbent and reuses it for wet dust collection of contaminated dust. As a result, the wet scrubber dust collector 132A performs wet dust collection of "contaminated dust" and "abrasive particle contamination." The waste liquid from the wet scrubber dust collector 132 is sent to the liquid recycling section 140A.

[0079] Other operations are the same as those in the first embodiment, so a duplicated description will be omitted here.

[0080] Effects of Example 2 In addition to the effects described in the first embodiment, the second embodiment has the following effects.

[0081] (1) In the second embodiment, the contamination (radioactive contamination) of the wastewater from the particle cleaning unit 123A can also be collected by the wet scrubber dust collector 132A. Therefore, the second embodiment is superior in that it does not require a separate wastewater treatment device dedicated to the wastewater treatment of the particle cleaning unit 123A.

[0082] (2) Furthermore, in Example 2, the dust adsorbent that adsorbs the "contaminated dust from blast decontamination" and the "dirt from abrasive particles to be disposed of" is burned to reduce the volume of contaminated waste. Therefore, Example 2 is superior in that it can reduce the volume of the "contaminated dust from blast decontamination" and the "dirt from abrasive particles to be disposed of" together and centralize them as contaminated waste.

[0083] (3) In Example 2, the waste liquid in which radioactive contamination has been reduced by the coagulation and removal of the dust adsorbent in the liquid recycling section 140A is circulated as regenerated liquid to the particle cleaning section 123A and the wet scrubber dust collector 132A. Therefore, Example 2 is superior in that the amount of new liquid added each time for wet dust collection or cleaning of abrasive particles is small (just enough to make up for the loss of the regenerated liquid), and therefore the amount of waste liquid generated can be significantly reduced even if wet dust collection or cleaning of abrasive particles is repeated.

[0084] (4) In Example 2, contaminated dust is generated every time blasting is performed. On the other hand, since abrasive particles are repeatedly reused for blasting, abrasive particles to be discarded are generated once every several blasting processes. Therefore, in Example 2, liquid is circulated every time contaminated dust is wet-collected, so that liquid circulates even when the particle cleaning unit 123A is empty, and dirt adhering to the tank and piping of the particle cleaning unit 123A is washed away. Therefore, Example 2 is superior in that dirt accumulated around the tank and piping of the particle cleaning unit 123A can be washed away at any time due to the difference in the generation timing between "contaminated dust" and "abrasive particles to be discarded."

[0085] Other supplementary information The decontamination systems 100 and 300 of the present embodiment may decontaminate radioactive contamination to a safety standard, or may decontaminate to a certain extent and then entrust decontamination to another decontamination process to meet the safety standard. Examples of such other decontamination processes include a chemical method that dissolves contaminated parts using chemical agents, an electrochemical method that dissolves contaminated parts by electrolysis, and a melting decontamination method that melts and separates contaminated parts by applying heat.

[0086] In the present embodiment, the blast treatment of the contaminated member 200 is performed in only one stage. However, the present invention is not limited to this. The blast treatment unit 110 may be configured to perform the blast treatment multiple times in stages.

[0087] Furthermore, in the present embodiment, an example in which the wet dust collection of the contaminated dust is performed in only one stage has been described. However, the present invention is not limited to this. The dust collection unit 130 may be configured to perform the wet dust collection multiple times in stages.

[0088] In the present embodiment, the cleaning process of the abrasive particles to be discarded is performed in only one stage. However, the present invention is not limited to this. The particle recycling unit 120, 120A may be configured to perform particle cleaning multiple times in stages.

[0089] In the second embodiment, an example in which only one set of circulation paths for the wet scrubber 132A, the liquid recycle unit 140A, and the particle cleaning unit 123A is provided has been described. However, the present invention is not limited to this. By providing multiple sets of these circulation paths, wet dust collection and particle cleaning may be performed multiple times in stages.

[0090] The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0091] For example, the above-described embodiment has been described in detail in its entirety in order to clearly explain the present invention, and the present invention is not necessarily limited to having all of the configurations and steps described.

[0092] Also, individual elements of the embodiments may be combined as appropriate. Furthermore, other configurations and other steps may be added or substituted to the embodiments. Also, some configurations and some steps may be deleted from the embodiments. [Explanation of symbols]

[0093] 100...decontamination system, 110...blast processing section, 111...sealed blast chamber, 112...particle supply section, 113...centrifugal projection section, 113A...transport pipe, 113B...feed port, 113C...rotating wheel, 113D...drive section, 114a...collection section, 114b...collection section, 115...blast cleaning chamber, 116...transport section, 117...shape measurement section, 118...projection adjustment section, 120...particle recycling section, 121...sorting section, 122 ...lifetime management section, 123...particle cleaning section, 123A...particle cleaning section, 124...separation management section, 130...dust collection section, 131...cyclone separator, 132...wet scrubber dust collector, 132A...wet scrubber dust collector, 133...HEPA filter, 140...liquid recycling section, 140A...liquid recycling section, 150...volume reduction section, 151...combustion section, 152...HEPA filter, 200...contaminated parts, 300...decontamination system

Claims

1. A decontamination system for grinding a surface layer of a contaminated member having a surface layer contaminated with a radioactive substance, comprising: a blasting treatment section that collides abrasive particles with a surface of the contaminated member to grind off contaminated dust containing the radioactive material from the surface layer of the contaminated member; a particle recycling section that roughly separates the contaminant dust discharged from the surface layer from the abrasive particles, and reuses the roughly separated abrasive particles in the blast processing section; a dust collection section that performs wet dust collection on the roughly separated contaminated dust using a liquid mixed with a dust adsorbent; a liquid recycling section that performs coagulation of the dust adsorbent in the waste liquid after the wet dust collection, roughly separates the dust adsorbent, and regenerates the liquid, and reuses the regenerated liquid in the dust collection section; A volume reduction unit that burns the aggregated dust adsorbent to reduce the volume of contaminated waste; A decontamination system comprising:

2. 2. The decontamination system of claim 1, The blasting treatment section includes: a centrifugal projection unit that centrifugally projects the abrasive particles onto the surface of the contaminated member using a rotating wheel; a collecting section for collecting the abrasive particles and the contaminant dust discharged from the surface layer; A decontamination system comprising:

3. 2. The decontamination system of claim 1, The abrasive particles include particles that satisfy all of the following conditions 1 to 3: (Condition 1) The particles have a particle size such that the dust size of the contaminant dust to be ground can be adsorbed by the dust adsorbent, (Condition 2) The particles have a hardness such that dirt does not bite into the inside of the particles after grinding, (Condition 3) The particles have a substantially spherical shape and are tough enough not to be crushed during grinding. A decontamination system comprising:

4. 2. The decontamination system of claim 1, The dust-absorbing material contains powdered bamboo charcoal. A decontamination system comprising:

5. 2. The decontamination system of claim 1, The particle recycling unit includes: a sorting unit that roughly separates the contaminating dust discharged from the surface layer from the abrasive particles; a lifespan management unit that determines when the abrasive particles reach a point at which they can no longer be reused; a particle cleaning unit that cleans dirt from the abrasive particles that have been determined to be unreusable by the life management unit; A decontamination system comprising:

6. 6. The decontamination system of claim 5, the liquid recycling section sends the liquid regenerated by crude separation of the coagulated dust adsorbent to the particle cleaning section; the particle cleaning unit reuses the liquid regenerated in the liquid recycling unit for cleaning the abrasive particles, and sends the waste liquid after cleaning the dirt from the abrasive particles to the dust collecting unit; The dust collecting unit mixes the dust adsorbent with the waste liquid containing the dirt of the abrasive particles, and reuses the waste liquid in the wet dust collection of the contaminated dust, so that the dust collecting unit performs the wet dust collection by combining "the contaminated dust" and "the dirt of the abrasive particles". A decontamination system comprising:

7. A decontamination method for grinding a surface layer of a contaminated member having a surface layer contaminated with a radioactive substance, comprising: a blasting step of grinding contaminated dust containing the radioactive material from the surface layer of the contaminated member by colliding abrasive particles against the surface of the contaminated member; a particle recycling step of roughly separating the contaminant dust discharged from the surface layer from the abrasive particles, and reusing the roughly separated abrasive particles in the blasting step; a dust collection step of performing wet dust collection on the roughly separated contaminated dust using a liquid mixed with a dust adsorbent; a liquid recycling step of coagulating the dust adsorbent in the waste liquid after the wet dust collection, roughly separating the dust adsorbent, and regenerating the liquid, and reusing the regenerated liquid in the dust collection step; A volume reduction step of burning the aggregated dust adsorbent to reduce the volume of contaminated waste; A decontamination method comprising:

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