JP2014041100A - Surface layer decontamination method for concrete structure - Google Patents

Abstract

A surface layer decontamination method for a concrete structure that can easily decontaminate a surface layer portion of a concrete structure contaminated with a radioactive substance.
In a fluid supply step (S1), an acidic solution is supplied to the surface of a concrete structure contaminated with a radioactive substance. Next, in the cement dissolution step S2, the contaminated cement component on the surface of the concrete structure is dissolved with the supplied acidic solution. Next, in the contamination removal step S3, the dissolved cement component is removed from the surface of the concrete structure. Next, in the surface neutralization step S4, the surface of the concrete structure from which the dissolved cement component has been removed is neutralized by supplying a neutralizing agent. In the surface cleaning step S5, fine contaminants that could not be removed in the contamination removal step S3 from the surface of the neutralized concrete structure are removed by cleaning the purified water.
[Selection] Figure 1

Description

  The present invention relates to a surface layer decontamination method for a concrete structure that decontaminates a surface layer portion such as soil concrete contaminated with radioactive substances.

  For example, when an accident occurs at a nuclear power plant or the like, radioactivity may leak out and the surrounding area may be contaminated with radioactive materials.

  There are various types of contamination nuclides in such accidents, but the main contamination nuclides that become a problem in the medium to long term after the initial stage are radioactive cesium (Cs-134, Cs-137) as fission products.

  In particular, Cs-137 has a long half-life of about 30 years. For this reason, the area contaminated with Cs-137 cannot be used unless it is actively decontaminated. For example, since radioactive materials have permeated from the surface to a predetermined depth in the soil and the like, it can be decontaminated by physically removing the surface layer portion.

  However, even in concrete structures such as buildings, radioactive materials penetrate from the surface to a predetermined depth, but it is difficult to physically eliminate the contaminated surface layer without damaging the concrete structure. .

  For example, as a method for cleaning the surface of a building, cleaning using tap water or the like as clean water is common. For example, in cleaning with a high pressure washer, several tens of liters of purified water per minute is used at a pressure of several MPa.

  In addition, as a method of removing the spray material containing asbestos, a liquid-absorbing material that permeates the acidic liquid is placed on the surface of the spray material containing asbestos, and the liquid is sprayed on the liquid-absorbent material to penetrate. A technique for removing the acidic liquid by infiltrating the spray material containing asbestos has been proposed (for example, see Patent Document 1).

JP 2012-17592 A

  However, in the area contaminated with radioactive substances as described above, since tap water is also contaminated in the first place, it is necessary to carry in a large volume of purified water from the outside. Moreover, since the purified water used for cleaning is contaminated, it is necessary to collect a huge volume of contaminated purified water.

  Furthermore, when purified water is sprayed at a high pressure on the surface of a contaminated concrete structure, a large amount of splashes and dusts containing radioactive substances are generated and scattered. For this reason, secondary contamination occurs due to the splashes and dusts scattered and scattered. In such work, it is difficult to prevent the worker from being exposed to the radiation.

  In the first place, it is difficult to remove the surface of a high-strength concrete structure by jetting high-pressure purified water. In order to realize this, it is necessary to inject purified water at an extremely high pressure. However, if it does so, while the capacity | capacitance of the required purified water will become enormous, the capacity | capacitance of the contaminated purified water to collect | recover will also become enormous, and the splash and dust which will be scattered and scattered will also be enormous.

  In addition, the technique of patent document 1 is specialized in the removal of the spraying material containing asbestos, and cannot be utilized for decontaminating the surface layer part contaminated with the radioactive substance of the concrete structure as it is.

  The present invention has been made in view of the problems as described above, and provides a surface decontamination method for a concrete structure capable of easily decontaminating a surface layer portion of a concrete structure contaminated with a radioactive substance. Is.

  In order to solve the above-described problems, the surface decontamination method for a concrete structure according to the present invention includes a fluid supply step for supplying an acidic fluid to the surface of the concrete structure whose surface layer is contaminated with a radioactive substance, A structure dissolving step in which the cement component in the surface layer portion of the concrete structure contaminated with the acidic fluid is dissolved, and the cement component dissolved from the surface of the concrete structure is removed by suction. A decontamination step, a surface neutralization step of neutralizing the surface of the concrete structure from which the dissolved cement component has been removed by supplying a neutralizing agent, and washing the neutralized surface of the concrete structure with purified water A surface cleaning step.

  Therefore, in the surface decontamination method for a concrete structure, an acidic fluid is supplied to the surface of the concrete structure whose surface layer is contaminated with a radioactive substance in the fluid supply step. Next, it is allowed to stand until the cement component of the contaminated surface layer portion of the concrete structure is dissolved by the supplied acidic fluid in the structure dissolving step. Next, in the decontamination step, the dissolved cement component is removed by suction from the surface of the concrete structure. Next, in the surface neutralization step, the surface of the concrete structure from which the dissolved cement component has been removed is neutralized by supplying a neutralizing agent. Then, in the surface cleaning step, fine contaminants that could not be removed from the surface of the neutralized concrete structure by the contamination removal step are removed by cleaning the purified water. For this reason, it is possible to easily decontaminate a concrete structure whose surface layer is contaminated with a radioactive substance.

  In the surface layer decontamination method for a concrete structure as described above, in the present invention, the fluid supply step supplies the acidic fluid of an organic acid to which a surfactant is added.

  Therefore, this surface decontamination method of a concrete structure easily penetrates into fine pores and cracks as an acidic fluid that dissolves contaminated cement components on the surface of the concrete structure, and has a high dissolving ability, but has a high pH. Can supply an acidic fluid that is not as low as an inorganic acid and has high safety and good reactivity.

  In the method for surface layer decontamination of a concrete structure as described above, in the present invention, the structure dissolving step further includes a depth of contamination of the concrete structure and dissolution of the acidic fluid after the acidic fluid is supplied. Leave for a time corresponding to at least one of the capacity and the acid dissociation constant of the acidic fluid.

  Therefore, in the surface layer decontamination method for a concrete structure, the concrete structure to which the acidic fluid is supplied to the surface has at least one of the depth of contamination, the dissolving ability of the acidic fluid, and the acid dissociation constant of the acidic fluid. Therefore, the contaminated cement component of the surface layer portion is surely dissolved.

  In the surface layer decontamination method for a concrete structure as described above, in the present invention, the contamination removing step removes the precipitate that precipitates along with the dissolution of the cement component of the concrete structure before solidifying.

  Therefore, in this surface layer decontamination method of the concrete structure, precipitates are deposited as the cement components of the concrete structure are dissolved, but these precipitates are removed before solidifying.

  The various components of the present invention do not necessarily have to be independent of each other. A plurality of components are formed as a single member, and a single component is formed of a plurality of members. It may be that a certain component is a part of another component, a part of a certain component overlaps with a part of another component, or the like.

  The concrete structure referred to in the present invention means a structure formed of concrete. The concrete includes so-called cement mixed with water and gravel, etc., solidified with asphalt instead of cement, so-called soil concrete, surface with cement finish, surface with mortar finish, etc. Enclose.

  In the surface decontamination method for a concrete structure according to the present invention, an acidic fluid is supplied to the surface of the concrete structure whose surface layer is contaminated with a radioactive substance, and the surface of the concrete structure is contaminated with the supplied acidic fluid. The dissolved cement component is dissolved and sucked away from the surface of the concrete structure, and the surface of the concrete structure from which the dissolved cement component has been removed is neutralized by supplying a neutralizing agent. Since fine pollutants and the like are removed from the surface of the concrete structure by cleaning with purified water, it is possible to easily decontaminate a concrete structure whose surface layer is contaminated with radioactive substances.

It is a typical flowchart which shows the surface layer decontamination method of the concrete structure of embodiment of this invention. It is a schematic diagram which shows the structure of the concrete decontamination system of embodiment of this invention. It is a typical vertical front view which shows the concrete structure which will be decontaminated with the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention. It is a typical vertical front view which shows the state in which the concrete structure decontaminated with the surface layer decontamination method by the concrete decontamination system of embodiment of this invention is contaminated with a radioactive substance. It is a typical vertical front view which shows the state which is supplying the acidic fluid to the concrete structure contaminated by the fluid supply step of the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention. . It is a typical vertical front view which shows the state by which the acidic fluid was supplied to the concrete structure contaminated by the fluid supply step of the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention. Schematic longitudinal front view showing a state in which an acidic fluid has permeated into a contaminated surface layer portion of a concrete structure in a structure dissolving step of a surface decontamination method for a concrete structure by a concrete decontamination system according to an embodiment of the present invention. It is. It is a typical vertical front view which shows the state which has removed the contaminated surface layer part of the concrete structure in the decontamination step of the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention. . Schematic which shows the state which is wash | cleaning the surface of the concrete structure from which the surface layer part contaminated by the surface washing | cleaning step of the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention was removed. It is a vertical front view. It is a typical vertical front view which shows the concrete structure from which the surface layer part contaminated with the surface layer decontamination method of the concrete structure by the concrete decontamination system of embodiment of this invention was removed.

  Next, an embodiment of the present invention will be described below with reference to the drawings. 1 is a schematic flowchart showing a surface layer decontamination method for a concrete structure according to the present embodiment, FIG. 2 is a schematic diagram showing a configuration of a concrete decontamination system according to the present embodiment, and FIGS. 10 is a schematic longitudinal front view showing a surface layer decontamination method of a concrete structure by the concrete decontamination system of the present embodiment.

  The concrete decontamination system 100 of this Embodiment has the fluid supply apparatus 110, the decontamination apparatus 120, and the surface washing | cleaning apparatus 130, as shown in FIG.

  The fluid supply device 110 includes a solution tank 111, a flexible tube 112 connected to the solution tank 111, a fluid pump 113 through which the flexible tube 112 is inserted, and an injection nozzle 114 connected to the tip of the flexible tube 112. And having.

  The solution tank 111 contains an acidic solution AL that is an acidic fluid. The acidic solution AL is composed of an organic acid solution that has a dissolution ability as compared with an inorganic acid but does not have a low pH and a high acid dissociation constant. The organic acid of the acidic solution AL is a simple substance or a mixture of food additives such as citric acid, malic acid, fermented lactic acid and tartaric acid.

  As the acidic solution AL, a high-concentration solution may be used, but it is preferable to dilute with water or the like in consideration of the affinity with a concrete structure CS such as soil concrete. The organic acid concentration of the acidic solution AL may be 0.1 wt% to 100 wt%, and particularly about 10 wt% to 20 wt%.

  The flexible tube 112 is inserted into the fluid pump 113 as described above, and connects the solution tank 111 and the injection nozzle 114, and the acidic solution AL flows. The fluid pump 113 pumps the acidic solution AL from the solution tank 111 to the injection nozzle 114 through the flexible tube 112. The injection nozzle 114 injects the acidic solution AL to be pumped.

  The decontamination device 120 includes a waste tank 121, a flexible tube 122 connected to the waste tank 121, a fluid pump 123 through which the flexible tube 122 is inserted, and a suction nozzle 124 connected to the tip of the flexible tube 122. And having.

  As will be described later in detail, the waste tank 121 stores the cement component CB that has been dissolved and sucked. The flexible tube 122 is inserted through the fluid pump 123 as described above, and connects the waste tank 121 and the suction nozzle 124, and the dissolved cement component CB flows.

  The fluid pump 123 pumps the melted cement component CB from the suction nozzle 124 to the waste tank 121 through the flexible tube 122. The suction nozzle 124 is used to suck the dissolved cement component CB.

  The surface cleaning device 130 includes a water purification tank 131 and a waste water tank 132, a first flexible tube 133 and a second flexible tube 134 individually connected to the water purification tank 131 and the waste water tank 132, and the first flexible tube. The pump 133 and the suction pump 136 into which the tube 133 and the second flexible tube 134 are individually inserted, and the injection nozzle 137 individually connected to the tips of the first flexible tube 133 and the second flexible tube 134. And a suction nozzle 138.

  The purified water tank 131 contains purified water CW such as tap water and pure water. The first flexible tube 133 is inserted through the pressure pump 135 as described above, and connects the water purification tank 131 and the first injection nozzle 134, and the water purification CW flows.

  The pumping pump 135 pumps the purified water CW from the purified water tank 131 to the injection nozzle 137 through the flexible tube 133. The injection nozzle 137 injects the purified water CW to be pumped.

  As will be described in detail later, the waste water tank 132 stores the purified water CW from which the contaminant AC has been washed. The second flexible tube 134 is inserted through the fluid pump 136 as described above, and connects the fluid tank 132 and the suction nozzle 138, and the purified water CW that has cleaned the contaminant AC flows.

  The suction pump 136 pumps the purified water CW from which the contaminant AC has been washed from the suction nozzle 138 to the fluid tank 132 through the flexible tube 134. The suction nozzle 138 is used for suction of the purified water CW from which the contaminant AC has been washed. The suction nozzle 138 and the injection nozzle 137 are integrated in parallel.

  In the configuration as described above, the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment will be described below in order with reference to FIGS. 1 and 3 to 10.

  First, as shown in FIG. 3, when the concrete structure CS such as soil concrete not contaminated with the radioactive material RM is constructed, for example, when the radioactive material RM is scattered due to an accident at a nuclear power plant or the like, FIG. As shown in FIG. 5, the surface layer portion SL of the concrete structure CS is contaminated by the radioactive material RM.

  Therefore, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, as shown in FIGS. 1 and 5, first, as the fluid supply step S1, the surface layer portion is formed with the radioactive material RM. The acidic solution AL is supplied by the fluid supply device 110 to the surface of the concrete structure CS contaminated with SL.

  At this time, the fluid supply device 110 injects the organic acid acidic solution AL composed of the food additive from the solution nozzle 111 from the injection nozzle 114 by the pressure of the fluid pump 113 as described above.

  As shown in FIG. 6, when the acidic solution AL is evenly applied to the entire surface of the concrete structure CS contaminated by this injection, as shown in FIG. The contaminated cement component CB on the surface of the concrete structure CS is dissolved with the solution AL.

  In this cement dissolving step S2, as shown in FIG. 7, the cement component CB of the surface layer portion SL contaminated with the concrete structure CS is left to dissolve with the supplied acidic solution AL.

  For this reason, until the time corresponding to the depth of contamination of the concrete structure CS, the acid dissociation constant indicating the dissolving ability of the acidic solution AL, the temperature of the concrete structure CS, the temperature of the atmosphere, etc. after the acidic solution AL is supplied. Leave the concrete structure CS.

  As described above, the standing time is adjusted according to a plurality of conditions as described above, and is, for example, 1 to 60 minutes, more preferably 5 to 60 minutes. Then, the acidic solution AL penetrates into the contaminated surface layer portion SL of the concrete structure CS, so that the surface layer portion SL is dissolved in the acidic solution AL to become a contaminated cement component CB.

  In such a state, as shown in FIG. 1 and FIG. 8, as a contamination removal step S3, the decontaminated apparatus 120 removes the dissolved cement component CB from the surface of the concrete structure CS. At this time, the decontamination apparatus 120 sucks the cement component CB from the suction nozzle 124 by the negative pressure generated by the fluid pump 123 and stores it in the waste tank 121.

  In addition, when the cement component CB of the concrete structure CS is dissolved by the acidic solution AL as described above, a precipitate (not shown) is deposited. Therefore, in the contamination removal step S3 described above, the cement component CB is removed before the deposited precipitate is solidified.

  When the removal of the cement component CB is completed, a neutralizing agent such as baking soda is sprayed on the surface of the concrete structure CS as a surface neutralization step S4. Further, in order to eliminate the uneven distribution of the sprayed neutralizing agent, the surface of the concrete structure CS to which the neutralizing agent is sprayed is brushed with a deck brush or the like. Then, using a pH test paper or the like, it is confirmed that the surface of the concrete structure CS is neutral at about pH 5-9, more preferably about pH 6-8 (not shown).

  When this neutralization is confirmed, basically, the decontamination work of the concrete structure CS contaminated with this is completed. However, even if the cement component CB dissolved by the decontamination apparatus 120 is removed from the surface of the concrete structure CS as described above, the concrete structure from which the contaminated cement component CB is removed as shown in FIG. Fine contaminants AC may remain on the surface of the CS.

  Therefore, in the surface layer decontamination method using the concrete decontamination system 100 of the present embodiment, the fine contaminant AC remaining on the surface of the concrete structure CS from which the cement component CB dissolved in the contamination removal step S3 has been removed is generally used. Aspirated by a typical vacuum cleaner or the like (not shown).

  Furthermore, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, the fine contaminant AC as described above is eliminated by a vacuum cleaner, etc. As shown in FIG. 9, the surface of the concrete structure CS, in which the cement component CB dissolved in the decontamination step S3 is removed and neutralized with the neutralizing agent in the surface neutralization step S4, is subjected to surface cleaning as a surface cleaning step S5. Wash with device 130.

  At this time, the surface cleaning device 130 injects the purified water CW accommodated in the purified water tank 131 from the injection nozzle 137 onto the surface of the concrete structure CS with the pressure of the pressure feed pump 135 and simultaneously from the surface of the concrete structure CS. The purified water CW mixed with the pollutant AC is accommodated in the waste water tank 132 from the suction nozzle 138 by the negative pressure of the suction pump 134.

  Thus, as shown in FIG. 10, the concrete structure CS is in a state where the surface layer portion SL contaminated with the radioactive material RM is removed and the remaining fine contaminant AC is also cleaned. Thus, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, the concrete structure CS contaminated with the radioactive substance RM can be easily decontaminated.

  As described above, the cement component CB removed from the surface of the concrete structure CS by the decontamination device 120, the fine contaminant AC sucked by a vacuum cleaner, etc., and the waste water tank 132 of the surface cleaning device 130 were accommodated. The purified water CW is temporarily stored in a drum or the like (not shown) as a temporary storage step.

  Then, the drum can thus containing the contaminant AC or the like is transported to a dedicated water treatment plant as a transport processing step, and the contaminant AC or the like is decontaminated as a water treatment step by this water treatment plant (FIG. Not shown).

  In particular, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, the contaminated cement component CB is dissolved on the surface of the concrete structure CS to be cleaned with the purified water CW as described above. Since it is removed, the surface of the concrete structure CS can be decontaminated with a small amount of purified water CW.

  In particular, since the surface of the concrete structure CS is washed with the purified water CW and at the same time the purified water CW mixed with the contaminant AC is sucked in, the contaminant AC may remain on the surface of the cleaned concrete structure CS and the surroundings. Absent.

  In addition, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, the acidic solution AL of the organic acid is supplied to the concrete structure CS by the fluid supply device 110 in the fluid supply step S1.

  Therefore, as an acidic solution AL for dissolving the contaminated cement component CB on the surface of the concrete structure CS, an acidic solution AL having a high dissolving ability but a pH that is not as low as that of an inorganic acid and having high safety and good reactivity is supplied. can do.

  In particular, since the organic acid acidic solution AL made of food additives is supplied, the acidic solution AL that has been confirmed to be harmless to the human body can be supplied. Moreover, the liquid acidic solution AL is supplied to the surface of the concrete structure CS. For this reason, the acidic solution AL can be supplied in a liquid state that penetrates well into the surface of the concrete structure CS.

  Furthermore, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 according to the present embodiment, the cement of the surface layer portion SL contaminated with the supplied acidic solution AL with the supplied acidic solution AL is used as the cement dissolution step S2. Leave until component CB is dissolved.

  Therefore, the cement component CB of the contaminated surface layer portion SL of the concrete structure CS supplied with the acidic solution AL can be reliably dissolved.

  In particular, in the cement dissolving step S2, after the acidic solution AL is supplied, the concrete structure CS is left for a time corresponding to the depth of contamination of the concrete structure CS and the acid dissociation constant indicating the dissolving ability of the acidic solution AL.

  Therefore, the cement component CB of the contaminated surface layer portion SL of the concrete structure CS supplied with the acidic solution AL can be surely dissolved without excess or deficiency.

  Moreover, in the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment, the cement component CB dissolved by the decontamination device 120 is removed by suction in the decontamination step S3.

  Accordingly, since the dissolved cement component CB is removed from the concrete structure CS by suction, the contaminated cement component CB is removed without being scattered around.

  In particular, a precipitate is deposited with the dissolution of the cement component CB of the concrete structure CS. However, in the contamination removal step S3, the precipitate is removed before solidifying, so the solidified precipitate is deposited on the surface of the concrete structure CS. It can prevent sticking.

  In addition, in order to verify the effect | action of the surface layer decontamination method of concrete structure CS by said concrete decontamination system 100, this inventor actually conducted experiment which dissolves a concrete structure with an acidic solution.

  In the experiment, a concrete structure was prepared by blending according to the design strength standard 27 and standard curing at 100 mmφ × 200 mmH for 28 days. Next, an aqueous solution of 20 wt% citric acid, an aqueous solution of 20 wt% malic acid, an aqueous solution of 20 wt% fermented lactic acid, and an aqueous solution of 20 wt% tartaric acid were prepared as acidic solutions.

  And the concrete structure was immersed in these various acidic solutions for 1 hour, and the change of the diameter was measured. Then, as shown in Table 1 below, it was found that the diameters were reduced by about 0.3 mm to 0.8 mm, respectively, as compared to the standard concrete structure that was not immersed in the acidic solution.

  From this, it was confirmed that the surface layer of the concrete structure CS can be sufficiently dissolved in a practical time by the surface layer decontamination method of the concrete structure CS by the concrete decontamination system 100 of the present embodiment.

  The present invention is not limited to the present embodiment, and various modifications are allowed without departing from the scope of the present invention. For example, in the above embodiment, it is assumed that the operator manually operates the fluid supply device 110, the decontamination device 120, and the surface cleaning device 130 of the concrete decontamination system 100.

  However, a concrete decontamination system (not shown) in which the fluid supply device 110, the decontamination device 120, and the surface cleaning device 130 are connected to a robot arm is manufactured, and this is remotely operated to decontaminate the concrete. Work may be performed.

  Moreover, in the said form, using the acidic solution AL of an organic acid was illustrated in fluid supply step S1 by the fluid supply apparatus 110. FIG. However, an acidic solution of an inorganic acid may be used.

  Furthermore, in the said form, using as food acidic additives AL, such as a citric acid, malic acid, fermented lactic acid, tartaric acid, was illustrated. However, organic acids that are not food additives such as acetic acid, formic acid, and oxalic acid may be used.

  Moreover, in the said form, it illustrated using the acidic solution AL of an organic acid as it is. However, a surfactant may be added to such an acidic solution AL. In this case, the acidic solution AL can be easily infiltrated into fine pores or cracks on the surface of the concrete structure CS.

  As described above, the surfactant added to the acidic solution AL may be any surfactant that can ensure stability with an acid, and anionic, cationic, nonionic, or other surfactants can be used.

  In addition, the blending of such a surface active material may be 0.01 wt% to 10 wt% with respect to the acidic solution AL, and particularly preferably about 0.5 wt% to 2 wt%.

  Moreover, in the said form, it illustrated spraying and apply | coating acidic solution AL on the surface of concrete structure CS by the fluid supply apparatus 110 by fluid supply step S1. However, it may be applied with a brush or a roller.

  Furthermore, in the said form, supplying the acidic solution AL of a liquid state to the surface of concrete structure CS by the fluid supply apparatus 110 by fluid supply step S1 was illustrated. However, the acidic solution AL in a vapor state may be supplied and liquefied on the surface of the concrete structure CS.

  In the above embodiment, the cement component CB dissolved in the decontamination step S3 is removed, and the surface of the concrete structure CS neutralized with the neutralizing agent in the surface neutralization step S4 is washed with the purified water CW in the surface washing step S5. Exemplified what to do.

  However, while neutralizing the surface of the concrete structure CS from which the cement component CB dissolved in the decontamination step S3 has been removed, as a surface neutralization step and a surface cleaning step, the water is neutralized with purified water in which a neutralizing agent is mixed or dissolved. You may wash | clean (not shown).

  Needless to say, the above-described embodiment and a plurality of modifications can be combined within a range in which the contents do not conflict with each other. Further, in the above-described embodiments and modifications, the structure of each part has been specifically described, but the structure and the like can be changed in various ways within a range that satisfies the present invention.

DESCRIPTION OF SYMBOLS 100 Concrete decontamination system 110 Fluid supply apparatus 120 Decontamination apparatus 130 Surface cleaning apparatus CS Concrete structure S1 Fluid supply step S2 Cement dissolution step S3 Decontamination step S4 Surface cleaning step

Claims (4)

A fluid supply step for supplying an acidic fluid to the surface of the concrete structure whose surface layer is contaminated with radioactive material;
A structure dissolving step of allowing the supplied acidic fluid to stand until the cement component of the contaminated surface portion of the concrete structure is dissolved;
A decontamination step of sucking and removing the cement component dissolved from the surface of the concrete structure;
A surface neutralization step of neutralizing the surface of the concrete structure from which the dissolved cement component has been removed by supplying a neutralizing agent;
A surface washing step of washing the neutralized surface of the concrete structure with purified water;
Surface decontamination method for concrete structures having The fluid supply step supplies the acidic fluid of an organic acid to which a surfactant is added.
The surface layer decontamination method of the concrete structure of Claim 1. The structure dissolving step corresponds to at least one of the depth of contamination of the concrete structure, the dissolving ability of the acidic fluid, and the acid dissociation constant of the acidic fluid after the acidic fluid is supplied. Leave until time,
The surface layer decontamination method of the concrete structure of Claim 1 or 2. The decontamination step removes the precipitate that precipitates with the dissolution of the cement component of the concrete structure before solidifying;
The surface layer decontamination method of the concrete structure as described in any one of Claim 1 thru | or 3.

Images