JP2015169437A - Method for decontaminating concrete body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for decontaminating a concrete body, the method being capable of easily decontaminating a surface layer portion of the concrete body contaminated with a radioactive substance.SOLUTION: The decontamination method comprises following steps which are performed in this order: a fluid supply step S1 of supplying an acid solution on a surface of the concrete body contaminated with the radioactive substance; a cement dissolution step S2 of dissolving a contaminated cement component on the surface of the concrete body with the supplied acid solution; a first contamination removal step S3 of removing the dissolved cement component from the surface of the concrete body; a second contamination removal step S4 of removing the cement component remains in cracks on the surface of the concrete body; a surface neutralization step S5 of neutralizing the surface of the concrete body, from which the dissolved cement component has been removed, by supplying a neutralizer; and a surface cleaning step S6 of cleaning the neutralized surface of the concrete body with purified water to eliminate fine contaminants and the like therefrom.

Description

  The present invention relates to a concrete body decontamination method for decontaminating a surface layer portion such as dirt concrete contaminated with a radioactive substance.

  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 a concrete body such as a building, a radioactive substance penetrates from the surface to a predetermined depth, but it is difficult to physically remove the contaminated surface layer portion without damaging the concrete body.

  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.

  Here, 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 solution is sprayed on the liquid-absorbing material. There has been proposed a technique for permeating and removing the acidic liquid by permeating the spray material containing asbestos (see, for example, 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 body, 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 body by jetting high-pressure 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 spray material containing asbestos, and cannot be utilized for decontaminating the surface layer part contaminated with the radioactive substance of the concrete body as it is.

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

  In order to solve the above-described problems, a decontamination method for a concrete body according to the present invention includes a fluid supply step of supplying an acidic fluid to the surface of a concrete body whose surface layer is contaminated with a radioactive substance, and the supplied acidity A structure dissolving step in which the cement component in the contaminated surface portion of the concrete body is dissolved with a fluid, and a first decontamination step in which the cement component dissolved from the surface of the concrete body is sucked and removed. And a second decontamination step for removing the dissolved cement component remaining inside cracks generated on the surface of the concrete body, and the surface of the concrete body from which the dissolved cement component has been removed. A surface neutralization step for neutralizing by supplying a summing agent, and a surface washing for washing the neutralized surface of the concrete body with purified water. Has a step, a.

  Therefore, in this concrete body decontamination method, in the fluid supply step, an acidic fluid is supplied to the surface of the concrete body whose surface layer portion is contaminated with a radioactive substance. Next, it is left until the cement component of the contaminated surface layer portion of the concrete body is dissolved by the supplied acidic fluid in the structure dissolving step. Next, in the first decontamination step, the dissolved cement component is removed by suction from the surface of the concrete body. Next, in the second decontamination step, the dissolved cement component remaining inside the crack generated on the surface of the concrete body is removed. Next, in the surface neutralization step, the surface of the concrete body 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 body in the contamination removal step are removed by cleaning the purified water. For this reason, it is possible to easily decontaminate a concrete body whose surface layer is contaminated with a radioactive substance.

  In the concrete body decontamination method as described above, further in the present invention, the second decontamination step supplies purified water to the surface of the concrete body at a high pressure, and the inside of the crack generated on the surface of the concrete body. The dissolved cement component remaining in the container is removed by suction.

  Therefore, in this decontamination method of the concrete body, clean water is supplied to the surface of the concrete body at a high pressure, and the dissolved cement component remaining inside the cracks generated on the surface of the concrete body is sucked and removed, so The dissolved cement component remaining inside is also reliably removed.

  In the decontamination method for a concrete body as described above, in the present invention, the second decontamination step may be performed by supplying an acidic fluid to the surface of the concrete body before supplying purified water to the surface of the concrete body at a high pressure. Includes processing to supply.

  Therefore, in this decontamination method of the concrete body, even if the precipitate remaining inside the crack is solidified by supplying an acidic fluid before supplying purified water to the surface of the concrete body at a high pressure, By re-dissolving, the cement component easily flows out to the outside, and more reliable removal is possible.

  In the concrete body decontamination method 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, in this decontamination method of concrete body, as an acidic fluid that dissolves contaminated cement components on the surface of concrete body, it easily penetrates into fine pores and cracks, etc., and has a high dissolving ability, but pH is an inorganic acid. It is possible to supply an acidic fluid which is not so low and has high safety and good reactivity.

  In the concrete body decontamination method as described above, in the present invention, the structure dissolving step further includes the depth of contamination of the concrete body, the dissolving ability of the acidic fluid, It is allowed to stand for a time corresponding to at least one of the acid dissociation constants of the acidic fluid.

  Therefore, in this concrete body decontamination method, the concrete body to which the acidic fluid has been supplied corresponds to at least one of the depth of contamination, the dissolving ability of the acidic fluid, and the acid dissociation constant of the acidic fluid. Since it is left until time, the contaminated cement component of the surface layer portion is surely dissolved.

  In the decontamination method for a concrete body as described above, in the present invention, the first decontamination step and the second decontamination step solidify the precipitate that precipitates as the cement component of the concrete body dissolves. Remove before.

  Therefore, in this decontamination method of the concrete body, a precipitate is deposited with the dissolution of the cement component of the concrete body, but this precipitate is 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.

  In addition, the concrete body referred to in the present invention is a so-called cement mixed with water or gravel, solidified, using asphalt instead of cement, so-called soil-concrete, surface-cement finished, surface mortar For example, a finished body, etc. is included. For example, in addition to an outer wall, an inner wall, a roof, a veranda, etc. of various buildings, a concrete body that does not constitute a structure, such as precast concrete, is also included.

  In the decontamination method for a concrete body described in the present invention, an acidic fluid is supplied to the surface of the concrete body whose surface layer is contaminated with a radioactive substance, and the contaminated cement component on the surface of the concrete body is supplied with the supplied acidic fluid. A concrete body from which the dissolved cement component is removed by sucking and removing the dissolved cement component from the surface of the concrete body, and further removing the dissolved cement component from the inside of the crack generated on the surface of the concrete body. The surface of the surface is neutralized by supplying a neutralizing agent, and fine contaminants are removed from the surface of the neutralized concrete body by washing with clean water. Can be decontaminated.

It is a typical flowchart which shows the decontamination method of the concrete body 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 body which will be decontaminated with the decontamination method of the concrete body 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 body decontaminated with the decontamination method of the concrete body 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 supplies the acidic fluid to the concrete body contaminated by the fluid supply step of the decontamination method of the concrete body 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 body contaminated by the fluid supply step of the decontamination method of the concrete body by the concrete decontamination system of embodiment of this invention. It is a typical vertical front view which shows the state which the acidic fluid osmose | permeated to the surface layer part which the concrete body was contaminated by the structure melt | dissolution step of the decontamination method of the concrete body by the concrete decontamination system of embodiment of this invention. It is a typical vertical front view which shows the state which has removed the contaminated surface layer part in the 1st decontamination step of the decontamination method of the concrete body by the concrete decontamination system of embodiment of this invention. . The state which is removing the contaminated cement component from the inside of the crack produced in the surface of the concrete body at the 2nd decontamination step of the decontamination method of the concrete body by the concrete decontamination system of the embodiment of the present invention is shown. It is a typical longitudinal section front view. The typical vertical front view which shows the state which wash | cleans the surface of the concrete body from which the surface layer part contaminated by the surface washing | cleaning step of the decontamination method of the concrete body by the concrete decontamination system of embodiment of this invention was removed It is. It is a typical vertical front view which shows the concrete body from which the surface layer part contaminated with the decontamination method of the concrete body 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 the concrete body decontamination method of the present embodiment, FIG. 2 is a schematic diagram showing the configuration of the concrete decontamination system of the present embodiment, and FIGS. FIG. 2 is a schematic longitudinal sectional front view showing a concrete body decontamination method by the concrete decontamination system of the present embodiment.

  As shown in FIG. 2, the concrete decontamination system 100 according to the present embodiment includes a fluid supply device 110, a first decontamination device 120, a second decontamination device 130, and a surface cleaning device 140. Have.

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

  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 first decontamination device 120 is connected to a disposal tank 121, a flexible tube 122 connected to the disposal tank 121, a fluid pump 123 through which the flexible tube 122 is inserted, and a distal end of the flexible tube 122. A suction nozzle 124.

  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 second decontamination apparatus 130 includes a water purification tank 131 and a waste water tank 132, a first flexible tube 133 and a second flexible tube 134 that are individually connected to the water purification tank 131 and the waste water tank 132, and the first The one flexible tube 133 and the second flexible tube 134 are individually connected to the pumping pump 135 and the suction pump 136 into which the flexible tube 133 and the second flexible tube 134 are inserted, respectively, and the tips of the first flexible tube 133 and the second flexible tube 134. An injection nozzle 137 and a suction nozzle 138;

  The purified water tank 131 contains purified water CW such as tap water and pure water. Further, as described above, the first flexible tube 133 is inserted through the pressure pump 135 and connects the purified water tank 131 and the first injection nozzle 137, and the purified water CW flows.

  The pumping pump 135 pumps the purified water CW from the purified water tank 131 to the injection nozzle 137 by the first flexible tube 133, and the injection nozzle 137 jets the purified water CW to be pumped.

  Further, as will be described in detail later, the waste water tank 132 accommodates purified water CW that has been cleaned from the dissolved cement component CB sucked from the pores of the surface of the concrete body CS or the inside of the crack CR. Further, the second flexible tube 134 is inserted into the suction pump 136 as described above, and connects the waste water tank 132 and the suction nozzle 138, so that the purified water CW that has washed the dissolved cement component CB flows.

  Further, the suction pump 136 pumps the purified water CW from which the dissolved cement component CB has been washed, from the suction nozzle 138 to the waste water tank 132 via the second flexible tube 134. Furthermore, the suction nozzle 138 is used for suction of the purified water CW from which the dissolved cement component CB has been washed.

  In the second decontamination apparatus 130 shown in FIGS. 2 and 9, the suction nozzle 138 and the injection nozzle 137 are integrated in parallel. However, the present invention is not limited to this. You may employ | adopt the provided structure.

  The surface cleaning device 140 includes a water purification tank 141 and a waste water tank 142, a first flexible tube 143 and a second flexible tube 144 individually connected to the water purification tank 141 and the waste water tank 142, and the first flexible tube. The pump 145 and the suction pump 146 into which the tube 143 and the second flexible tube 144 are individually inserted, and the injection nozzle 147 individually connected to the tips of the first flexible tube 143 and the second flexible tube 144 And a suction nozzle 148. That is, the surface cleaning apparatus 140 has a configuration that is roughly the same as that of the second decontamination apparatus 130 by the above configuration.

  The purified water tank 141 contains purified water CW such as tap water and pure water, as with the second decontamination device 130. Similarly, the 1st flexible tube 143 is penetrated by the pumping pump 145 as mentioned above, has connected the purified water tank 141 and the 1st injection nozzle 147, and purified water CW flows.

  Further, like the second decontamination apparatus 130, the pressure pump 145 pumps the purified water CW from the purified water tank 141 to the spray nozzle 147 by the first flexible tube 143, and the spray nozzle 147 sprays the pumped purified water CW. To do.

  Similarly, as will be described in detail later, the waste water tank 142 contains purified water CW from which the contaminant AC has been washed. Further, the second flexible tube 144 is inserted through the suction pump 146 as described above, and connects the waste water tank 142 and the suction nozzle 148, so that the purified water CW that has cleaned the contaminant AC flows.

  Furthermore, the suction pump 146 pumps the purified water CW from which the contaminant AC has been washed from the suction nozzle 148 to the waste water tank 142 through the second flexible tube 144. Further, the suction nozzle 148 is used for suction of the purified water CW that has cleaned the contaminant AC. The suction nozzle 148 and the injection nozzle 147 are integrated in parallel.

  In the above-described configuration, the concrete body CS decontamination method by the concrete decontamination system 100 of the present embodiment will be described below in order with reference to FIGS. 1 and 3 to 11.

  First, as shown in FIG. 3, when a concrete body 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, the surface layer portion SL of the concrete body CS is contaminated by the radioactive material RM.

  Therefore, in the decontamination method of the concrete body CS by the concrete decontamination system 100 of the present embodiment, first, as shown in FIGS. 1 and 5, first, as the fluid supply step S1, the surface layer portion SL 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 body CS contaminated with water.

  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 body CS contaminated by this injection, as shown in FIG. 1, the supplied acidic solution is used as a cement dissolution step S2. The contaminated cement component CB on the surface of the concrete body CS is dissolved by 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 body 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 body CS, the acid dissociation constant indicating the dissolving ability of the acid solution AL, the temperature of the concrete body CS, the temperature of the atmosphere, etc. from the supply of the acid solution AL to the concrete Leave the body 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 permeates into the contaminated surface layer portion SL of the concrete body CS, so that the surface layer portion SL is dissolved in the acidic solution AL to become a contaminated cement component CB.

  In this state, as shown in FIG. 1 and FIG. 8, as a first contamination removal step S <b> 3, the first cement removal device 120 removes the dissolved cement component CB from the surface of the concrete body CS. At this time, the first 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.

  Further, as shown in FIGS. 1 and 9, as a second contamination removal step S4, the dissolved cement component CB remaining inside the crack CR generated on the surface of the concrete body CS is removed. Specifically, in the second decontamination step S4, the purified water CW is supplied to the surface of the concrete body CS by the second decontamination device 130, and the dissolution remaining in the crack CR on the surface of the concrete body CS. The finished cement component CB is led out and removed.

  At this time, the second decontamination apparatus 130 simultaneously injects the purified water CW accommodated in the purified water tank 131 from the injection nozzle 137 to the surface of the concrete body CS with the pressure of the pressure feed pump 135 at the same time. From the inside of the crack CR on the surface of the concrete body CS, the purified water CW mixed with the dissolved cement component CB is sucked from the suction nozzle 138 with the negative pressure of the suction pump 136 and stored in the waste water tank 132.

  Alternatively, in the second decontamination step S4, first, purified water CW is sprayed from the spray nozzle 137 to the entire surface of the concrete body CS at a high pressure, and then the presence or absence of pores or cracks CR on the surface of the concrete body CS is scanned. (Visual confirmation). Thereafter, the purified water CW mixed with the dissolved cement component CB can be sucked with the suction nozzle 138 from the inside only at the positions where the pores and cracks CR are present on the surface of the concrete body CS.

  In addition, when the cement component CB of the concrete body CS is dissolved by the acidic solution AL as described above, a precipitate (not shown) is deposited. Therefore, in the first decontamination step S3 and the second decontamination step S4 described above, it is preferable to remove the cement component CB before the deposited precipitate solidifies.

  On the other hand, for example, if the time until the second decontamination step S4 is increased after the completion of the first decontamination step S3, the precipitates remaining in the crack CR on the surface of the concrete body CS solidify. There is a possibility. In such a case, in the second decontamination step S4, a process of supplying an acidic fluid to the surface of the concrete body CS before supplying the purified water CW to the surface of the concrete body CS at a high pressure in the above procedure. By including the method, the precipitate remaining inside the crack CR easily flows out to the outside together with the purified water CW, thereby enabling more reliable removal.

  Specifically, before supplying the purified water CW to the surface of the concrete body CS, the acidic solution AL is supplied to the surface of the concrete body CS using the same procedure and apparatus as the fluid supply step S1 described above. And like the above-mentioned cement melt | dissolution step S2, the deposit containing the cement component CB which remained in the inside of the crack CR is left by leaving for a predetermined time in the state where the acidic solution AL exists on the surface of the concrete body CS. Since it melt | dissolves and it becomes easy to flow out outside with the purified water CW, a more reliable removal is attained (not shown).

  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 body CS as a surface neutralization step S5. Further, in order to eliminate the uneven distribution of the sprayed neutralizing agent, the surface of the concrete body CS to which the neutralizing agent is sprayed is brushed with a deck brush or the like. And using pH test paper etc., it confirms that the surface of concrete body CS became neutral about pH 5-9, more preferably about pH 6-8 (not shown).

  When this neutralization is confirmed, basically, the decontamination work of the concrete body CS contaminated with this is completed. However, as described above, even if the dissolved cement component CB is removed from the surface of the concrete body CS with the first decontamination device 120 and the second decontamination device 130, as shown in FIGS. Fine contaminants AC may remain on the surface of the concrete body CS from which the contaminated cement component CB has been removed.

  Therefore, in the decontamination method using the concrete decontamination system 100 of the present embodiment, the cement component CB dissolved in the first decontamination step S3 and the second decontamination step S4 is removed on the surface of the concrete body CS. The remaining fine contaminant AC is removed by suction (not shown) with a general vacuum cleaner or the like.

  Furthermore, in the decontamination method of the concrete body CS by the concrete decontamination system 100 of the present embodiment, the fine pollutant AC as described above is removed by a vacuum cleaner or the like, and then FIG. 1 and FIG. As shown in FIG. 3, the surface of the concrete body CS that has been dissolved in the first decontamination step S3 and the second decontamination step S4 and has been neutralized with the neutralizing agent in the surface neutralization step S5. Is cleaned by the surface cleaning apparatus 140 as a surface cleaning step S6.

  At this time, the surface cleaning device 140 injects the purified water CW stored in the purified water tank 141 from the injection nozzle 147 to the surface of the concrete body CS with the pressure of the pressure feed pump 145, and at the same time from the surface of the concrete body CS. The purified water CW mixed with the pollutant AC is accommodated in the waste water tank 142 from the suction nozzle 148 by the negative pressure of the suction pump 146.

  Thus, as shown in FIG. 11, the concrete body 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 concrete body CS decontamination method by the concrete decontamination system 100 of the present embodiment, the concrete body 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 body CS by the first decontamination device 120 and the second decontamination device 130, the fine contaminant AC sucked by a vacuum cleaner, etc., and The purified water CW accommodated in the waste water tank 142 of the surface cleaning device 140 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 decontamination method of the concrete body CS by the concrete decontamination system 100 of the present embodiment, the contaminated cement component CB is dissolved and removed from the surface of the concrete body CS washed with the purified water CW as described above. Therefore, the surface of the concrete body CS can be decontaminated with a small amount of purified water CW.

  In particular, since the surface of the concrete body 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 does not remain on the surface of the washed concrete body CS or the surroundings.

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

  Therefore, as the acidic solution AL for dissolving the contaminated cement component CB on the surface of the concrete body CS, an acidic solution AL having a high dissolving ability but a pH not lower than that of an inorganic acid and having a high safety and a good reactivity is supplied. be able to.

  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 body CS. For this reason, the acidic solution AL can be supplied in a liquid state that penetrates well into the surface of the concrete body CS.

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

  Therefore, the cement component CB of the contaminated surface layer portion SL of the concrete body CS to which the acidic solution AL is supplied can be reliably dissolved.

  In particular, in the cement dissolving step S2, after the acidic solution AL is supplied, the concrete body CS is left for a time corresponding to the depth of contamination of the concrete body 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 body CS supplied with the acidic solution AL can be surely dissolved without excess or deficiency.

  Moreover, in the decontamination method of the concrete body CS by the concrete decontamination system 100 of the present embodiment, the dissolved cement component CB is suctioned and removed by the first decontamination device 120 in the first decontamination step S3. To do.

  Therefore, since the cement component CB dissolved from the concrete body CS is removed by suction, the contaminated and dissolved cement component CB is removed without scattering around.

  Furthermore, in the decontamination method of the concrete body CS by the concrete decontamination system 100 of the present embodiment, in the second decontamination step S4, the second decontamination apparatus 130 causes pores and cracks on the surface of the concrete body CS. The dissolved cement component CB present inside the CR is removed by suction.

  Therefore, since not only the dissolved cement component CB existing on the surface of the concrete body CS but also the dissolved cement component CB existing in the pores and cracks CR are removed by suction, they are contaminated and dissolved. The cement component CB is more reliably removed without being scattered around.

  In particular, precipitates are deposited as the cement component CB of the concrete body CS is dissolved. In the first decontamination step S3 and the second decontamination step S4, the precipitates are solidified by removing them before solidifying. It is possible to prevent the deposited precipitates from adhering to the surface of the concrete body CS.

  On the other hand, even if the deposit remaining in the crack CR on the surface of the concrete body CS is solidified, in the second decontamination step S4, before the purified water CW is supplied to the surface of the concrete body CS at a high pressure. Moreover, since the precipitate containing the cement component CB in the crack CR is dissolved by adopting a method including a process of supplying an acidic fluid to the surface of the concrete body CS, reliable removal is possible.

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

In the experiment, a concrete body was prepared by blending according to the design strength standard 27 (N / mm ² ) and standard curing at 100 mmφ × 200 mmH for 28 days. Next, an aqueous solution of 20% by mass of citric acid, an aqueous solution of 20% by mass of malic acid, an aqueous solution of 20% by mass of fermented lactic acid, and an aqueous solution of 20% by mass of tartaric acid were prepared as acidic solutions.

  And the concrete body 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 decreased by about 0.3 mm to 0.8 mm, respectively, as compared to the standard concrete body that was not immersed in the acidic solution.

  From this, it was confirmed that the surface layer of the concrete body CS can be sufficiently dissolved in a practical time by the decontamination method of the concrete body 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, the operator manually operates the fluid supply device 110, the first decontamination device 120, the second decontamination device 130, and the surface cleaning device 140 of the concrete decontamination system 100. Was assumed.

  However, in the present invention, the concrete removal connected to the robot arm from the fluid supply device 110, the first decontamination device 120, the second decontamination device 130, and the surface cleaning device 140 as described above. A dyeing system (not shown) or the like may be configured, and a concrete decontamination work may be performed by remotely operating the system.

  Further, in the above embodiment, the use of the acidic solution AL of the organic acid in the fluid supply step S1 by the fluid supply device 110 is exemplified, but an acidic solution of an inorganic acid may be used.

  Furthermore, in the above embodiment, the use of food additives such as citric acid, malic acid, fermented lactic acid, and tartaric acid is exemplified as the acidic solution AL of organic acid, but food additives such as acetic acid, formic acid, and oxalic acid Not organic acids 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 body 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, as mixing | blending of such surfactant, 0.01 mass%-10 mass% may be sufficient with respect to the acidic solution AL, and about 0.5 mass%-2 mass% are good especially.

  Moreover, in the said form, it illustrated that the acidic solution AL was sprayed and apply | coated to the surface of the concrete body 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 the concrete body 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 body CS.

  In the above embodiment, the cement component CB dissolved in the first decontamination step S3 and the second decontamination step S4 is removed, and the surface of the concrete body CS neutralized with the neutralizing agent in the surface neutralization step S5 is removed. In the surface cleaning step S6, the cleaning with the purified water CW is exemplified.

  However, the surface of the concrete body CS from which the cement component CB dissolved in the first decontamination step S3 and the second decontamination step S4 has been removed is used as a surface neutralization step and a surface cleaning step. The solution may be neutralized and washed with dissolved water (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. 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 ... 1st decontamination apparatus, 130 ... 2nd decontamination apparatus, 140 ... Surface washing apparatus, CS ... Concrete body, CR ... Crack, S1 ... Fluid supply Step, S2 ... Cement dissolution step, S3 ... First contamination removal step, S4 ... Second contamination removal step, S5 ... Surface neutralization step, S6 ... Surface cleaning step.

Claims (6)

A fluid supply step for supplying an acidic fluid to the surface of the concrete body whose surface layer is contaminated with radioactive material;
A structure dissolving step that is allowed to stand until the cement component of the contaminated surface portion of the concrete body is dissolved by the supplied acidic fluid;
A first decontamination step of sucking and removing the cement component dissolved from the surface of the concrete body;
Furthermore, a second decontamination step of removing the dissolved cement component remaining in the cracks generated on the surface of the concrete body,
A surface neutralization step of neutralizing the surface of the concrete body from which the dissolved cement component has been removed by supplying a neutralizing agent;
And a surface cleaning step of cleaning the neutralized surface of the concrete body with purified water.   The second decontamination step supplies clean water at a high pressure to the surface of the concrete body, and sucks and removes the dissolved cement component remaining inside cracks generated on the surface of the concrete body. The decontamination method of the concrete body as described in 1.   3. The concrete body according to claim 2, wherein the second decontamination step further includes a process of supplying an acidic fluid to the surface of the concrete body before supplying purified water to the surface of the concrete body at a high pressure. Decontamination method.   The said fluid supply step is a decontamination method of the concrete body as described in any one of Claims 1-3 which supplies the said acidic fluid of the organic acid which added surfactant.   The structure dissolving step is a time corresponding to at least one of the depth of contamination of the concrete body, the dissolving ability of the acidic fluid, and the acid dissociation constant of the acidic fluid after the acidic fluid is supplied. The concrete body decontamination method according to any one of claims 1 to 4, wherein the concrete body is left to stand.   The said 1st decontamination step and the said 2nd decontamination step are removed before solidifying the deposit which precipitates with melt | dissolution of the cement component of the said concrete body, The any one of Claims 1-5. The decontamination method of the concrete body as described in 4.

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