JP3427273B2 - How to clean and remove contaminated concrete surfaces - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the protection of exposed surface of concrete, and the long-term and safe purification or removal of concrete contaminated with radioactivity in nuclear power plants, radioactive material handling facilities and the like. The present invention relates to a suitable method for cleaning and removing contaminated concrete surface.

[0002]

2. Description of the Related Art As a method for protecting the exposed surface of concrete, for example, 1) a method of applying a water repellent agent containing a mixture of silicon and kerosene to the concrete surface, and 2) applying an aqueous solution of sodium fluorosilicate and cement. There is a method of making fluorspar by reacting with the released calcium of 3), a method of coating and impregnating an emulsion of acrylic or EVA, and 4) a method of coating and curing transparent acrylic urethane or a fluororesin. On the other hand, as a method for treating concrete contaminated by radioactivity, there are, for example, 1) a method for removing the contaminated concrete portion, and 2) a method for coating the concrete surface with paint.

On the other hand, there are various known techniques for treating the surface of concrete. For example, JP-A-64-3
086, JP 1-275484, JP 3-16979, JP 60-44899, JP 60-174994, and JP 61-2.
The techniques disclosed in Japanese Patent Application No. 42273, Japanese Patent Application Laid-Open No. 3-112878, and Japanese Patent Application No. 5-234939 by the applicant of the present invention can be cited.

Japanese Patent Laid-Open No. Sho 64-3086 discloses a method for repairing or protecting the surface of concrete, in which a high concentration of silane or siloxane compound is applied to the surface of concrete and the surface of concrete structures deteriorated by chlorine ions. The repair and protection of Japanese Patent Laid-Open No. 1-275
The "process surface modification method" of Japanese Patent No. 484 is a method of baking a pigment on the surface of a work such as concrete to form a durable finished surface and also to form a free pattern on the surface. Further, "Ceramics-coated concrete and method for producing the same" in JP-A-3-16979 discloses a technique of coating and firing a ceramic coating layer on the surface of concrete. All of the above are related to the treatment of the concrete surface, and the melting treatment by the laser beam and the like are performed, but they are not the techniques for stabilizing and solidifying the contaminated concrete surface like the purification / removal method of the present invention. Further, the "contamination concrete removing method" of JP-A-60-44899 is a method of mechanically shaving a contaminated portion of concrete to suck and remove the powder, and the "concrete of JP-A-60-174994". The method of removing radioactively contaminated parts '' is to impregnate an aqueous solution of an inorganic salt to crush the contaminated part, further impregnate the crushed part with a metal alkoxide, and bond and solidify the crushed concrete pieces to separate them. Japanese Unexamined Patent Publication (Kokai) No. 61-242273, "Cutting Method for Reinforced Concrete Structure and Apparatus Therefor", discloses a technique for fusing and removing by laser light. Unlike the present invention, it is difficult to collect the removed substances, which have their own characteristics, and also differ in the method of cleaning the contaminated portion. Further, in Japanese Unexamined Patent Publication (Kokai) No. 3-112878, "Ceramic Coated Concrete Manufacturing Method" heats the concrete surface with a laser beam to burn a ceramic coating layer on the surface of the concrete. They are different. Further, Japanese Patent Application No. 5-23493 discloses a technique for thermal spraying treatment on the surface of concrete, which is different from the object of the present invention in that the surface is given a metallic finish.

[0005]

As described above, the methods described in 1) to 4) have heretofore been used as the surface protection method for the exposed concrete. However, in the case of these methods, there is a problem that the application of the resin causes gloss and the goodness of the exposed concrete is lost. Further, since the concrete is not uniform, the water absorption rate on the surface is different, which causes a problem that unevenness occurs. On the other hand, there are methods 1) to 2) described above as methods for treating concrete contaminated by radioactivity. These are methods for crushing or grinding the surface layer of concrete as in the known art. Also concrete powder is scattered. A dust collector is required to collect this concrete powder, and the filter and the dust collector itself become new pollutants, leading to an increase in the amount of radioactive waste. In addition, there is a danger that workers may be internally exposed to dust due to dust suction during work. Furthermore, the method of covering the concrete surface with paint is
There is a problem that the film thickness is thin, the adhesive force is weak and peeling, cracks on the film surface, film evaporation due to water evaporation force or efflorescence, and the like cause deterioration of durability. Further, as described above, there are problems in various known techniques,
It is not a suitable method for surface treatment of contaminated concrete.

[0006] The present invention solves the above problems, and cleans the contaminated part of the concrete surface and solidifies it in a durable and stable shape for storage, or removes it in a dust-free state to contaminate it. A method for cleaning and removing contaminated concrete surface, which can clean and remove the contaminated concrete, handle radioactive materials safely, and easily and safely recover the contaminated layer, and can perform unmanned operation. The purpose is to provide.

In order to achieve the above object, the present invention provides
After curing, the contaminated concrete is evaporated to dryness, the dust and efflorescence on the concrete surface are removed, and further dried by low-power laser irradiation, if necessary. Spraying or coating or impregnating a pollution purifying material, then solidifying or vitrifying the surface of the concrete by high-power laser irradiation, and if necessary, pulverizing and removing the glassy material of the contaminated concrete surface It features a purification / removal method. Further, the method is characterized in that the surface of the contaminated concrete is irradiated with a low-power laser to form spherical glass particles in which the contaminants are aggregated, and then the glass particles are removed. Further, specifically, the organic pollution control material is a polysiloxane resin, and the inorganic pollution control material is a substance containing a metal having a shielding effect against radiation. Is a substance that is exchanged into glass. Well
Also, spray a pollution control material onto the concrete surface or
After applying or impregnating the
At the same time as the concrete surface in the layer, it is solidified by laser irradiation.
In order to make glass or glass
Laser irradiation from the case where only concrete is vitrified
Therefore, a large amount of heat is required for administration, so the laser output
High output is required. Further, desirably, the output of the low-power laser is 0.1 [kw] or more and 2 [kw] or less, and the output of the high-power laser is 3 [kw] or more and 7 [kw].
It is characterized by the following. Here, the output of the laser is set within the above range because it is experimentally determined in order to prevent the bursting due to the laser irradiation and maintain the desired molten state.

[0008]

[Function] The surface of the hardened concrete is irradiated with a low-power laser to evaporate the water content in the concrete to remove dust and efflorescence and to perform a groundwork adjustment process. A high output can be obtained by spraying or coating or impregnating this substrate with an organic substance such as polysiloxane resin, a substance containing a metal having a shielding effect against radiation and an inorganic substance such as a substance having a property of being converted into glass. Laser (wavelength approx. 10 [μ
m]) is irradiated and melted to form a strong glass layer having high water repellency on the concrete surface. The surface temperature of concrete is 500 to 1500 by the irradiation of the high power laser.
The temperature rises instantaneously to about [° C]. The pollution control material is applied to the concrete surface using a spray, a roller, a brush or the like. Further, when the high-power laser is irradiated, the pollution purifying material applied is 500 to 1500 [°
C] becomes a high temperature and becomes in a molten state, and a highly radioactive pollutant is melted and fixed as a glass layer. This
Uses decontamination materials to solidify contamination more strongly
Can be stably contained in a layer or glass layer
is there. In addition, even if this contamination treatment layer is removed, the removal target
Since the solidified material is stable
The risk can be reduced.

As a substance that lowers the melting temperature than that of ordinary concrete by laser irradiation, there are alkali metal oxides and hydroxides, and specific examples thereof include oxides of lithium, sodium, potassium and the like. The hydroxide is raised. These substances react with substances such as silica and calcium silicate that absorb laser light in concrete to form an alkali silicate compound that melts at a lower temperature. Next, as a material for forming glass, silica, alumina, phosphoric acid, boric acid and their alkali metal salts such as lithium, sodium and potassium, and alkaline earth salts such as magnesium and calcium can be used. The compounds of silica and alumina, such as zeolites, feldspar, mica, such as clay minerals can be used. Furthermore, glass powder using silica, alumina, boric anhydride, etc., and glaze powder of burned material can also be used. The method of applying and permeating these substances into contaminated concrete can be carried out by making a water-soluble substance into an aqueous solution, spraying it on the concrete surface, and then permeating from the concrete surface. When water is used, relatively low power of about 0.99 [° by irradiating a laser at for its drying
C] to evaporate the water content on the surface and dry it sufficiently. Na
When laser irradiation after natural drying,
Rapid expansion of distilled water causes a rapid expansion, resulting in concrete
Since the surface layer bursts, it forms a stable surface layer that contains contamination.
I can't do it. The adhesive material used in the present invention may be any material that can adhere to and hold the glass forming material on the surface of the concrete until it is irradiated with a laser. In particular, when a substance that forms a glass that does not dissolve in water is used, a method of dispersing a glass-forming material in an adhesive material to form a paint and spraying it on a concrete surface, or a method of applying it using a roller is used. Of the types of adhesive materials used,
Inorganic materials include sodium silicate and potassium silicate. These are highly viscous substances and are used as a coating composition by dispersing a glass-forming substance.
Further, as the organic material, there are materials such as water-soluble polymers, emulsion polymers and hot-melt polymers. Specific examples of water-soluble polymer materials include polymer materials based on natural products such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, glue, agar and alginate. Examples of synthetic water-soluble polymer materials include polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, partially saponified polyvinyl acetate, and polymer materials containing acrylic acid or a salt thereof. Next, examples of the emulsion type polymer material include water dispersion type emulsions of polyvinyl acetate, ethylene / vinyl acetate resin, acrylic resin, styrene / butadiene resin and the like. When a water-soluble polymer or emulsion-type polymer is used as an adhesive material for a substance that forms glass and is applied to concrete, a laser is irradiated at a relatively low output for about 150 [for drying it]. [° C] to evaporate the water and dry it sufficiently. When the surface of the concrete to which the resin adheres is irradiated with a laser, resin or carbon may remain, but in order to avoid it, it is preferable to use a resin of thermal depolymerization.
An example of the resin that undergoes thermal depolymerization is a resin emulsion using an ester and / or salt of acrylic acid or methacrylic acid, and these resins are almost completely dissociated into monomers at about 400 [° C]. When the glass component is made into a paint using these resins and applied to the concrete surface and the substance that forms the glass is heated when irradiated with laser, the resin undergoes depolymerization and burns, leaving behind in the glass. Absent. The synthetic polymer material may be used by dispersing the above glass-forming substance in a solvent-type paint, but it is dangerous because the solvent volatilizes in the closed concrete,
It is also recommended to avoid it from the viewpoint of preventing air pollution. Furthermore,
Examples of the hot-melt type adhesive material include terpene resin, petitral resin, petroleum resin, asphalt, ethylene / vinyl acetate resin, polyester resin, polyamide resin, polyisobutylene, and polyolefin. A glass-forming substance is added to these sticky materials, the sticky materials are heated and melted, transported by a pump and a heated hose, and applied to the concrete surface using an applicator. As the pump, the heatable hose and the applicator to be used, an ordinary hot melt adhesive application device may be used.

In the present invention, a substance that forms and adheres to the surface of concrete to form glass is heated and melted by a carbon dioxide gas laser, and the concrete surface is covered with cooled and solidified glass. The carbon dioxide laser used at this time is laser oscillation. The carbon dioxide gas laser which is usually used industrially can be used for the part. However, a special lens system is attached to guide the oscillated laser light to the concrete surface. The principle is that a horizontal laser beam is applied to the concrete surface at a right angle to the wall, and a lens system or light guide tube that can scan vertically and horizontally is applied, and to the floor, the laser beam is directed vertically downward. A lens system and a light guide tube which can be vertically and horizontally scanned are used. Further, a lens system and a light guide tube which are vertically and horizontally scanned by applying a laser beam to the ceiling at a right angle are used for the ceiling. By applying the method of the present invention to the surface treatment of radioactively contaminated concrete, it is possible to vitrify the concrete surface, and therefore it is possible to provide an effective technique for storage of radioactively contaminated concrete. It will be possible.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 is an explanatory block diagram for explaining a purification method according to claim 1 of the present invention, FIG. 2 is a flowchart thereof, and FIG. 3 is a process explanatory diagram of a removal method according to claim 2.
4 is an explanatory view showing laser irradiation of the embodiment of claim 3, FIG. 5 is a schematic diagram showing a skeleton of polysiloxane resin, FIG. 6 is an explanatory view showing laser irradiation of the embodiment of claim 4, Table 1, Table 2
Shows a comparison between the effect of the embodiment of claim 5 and the prior art.

Example 1 As shown in FIGS. 1 and 2, a low-power laser beam of 0.1 [kw] or more and 2 [kw] or less was applied to the surface of concrete that had been radioactively contaminated to dry it. Step 100), evaporating water and removing dust and efflorescence (step 101). Next, a low-power laser is irradiated as needed to perform a background adjustment process (step 102). Next, the surface of the concrete is sprayed or coated with or impregnated with a pollution control material (step 10).
3). The pollution purifying material is irradiated with a laser having a high output of 3 [kw] or more and 7 [kw] or less to melt it (step 10).
4). Further, while the laser light is irradiated, the melted contaminants are cured and fixed (step 105). As described above, a hard glassy layer is formed on the surface of the concrete (step 106). This glass layer consists of a spherical body that is easy to remove and can be easily removed (step 107). The following forms radioactively contaminated concrete (step 108). In the above explanation, efflorescence is a white crystal formed on the surface of stone or concrete, and in the case of concrete, it is mainly lime hydroxide produced by hydrolysis of cement and filth that is said to be white flower, dripping, etc. Is.

(Embodiment 2) As shown in FIG. 3, when the radioactive ray-contaminated concrete 3 composed of the aggregate 1 and the cement paste 2 is irradiated with laser light, the surface temperature is about 1400.
It becomes [℃]. Radioactively contaminated cement paste 2
Is melted by the laser irradiation, and meat shaving occurs. The cement paste begins to make round spheres and the spheres melted by the air and gas inside the concrete are pressed from the inside,
The surface tension causes the spheres to aggregate to form spherical glass particles 4. The glass bulb 4 is easily peeled off and sucked by a vacuum means or the like. In addition, as shown in the figure, it is collected by a brush or the like and discarded in the drum. The contaminated cement paste is encased in the glass particles 4, so the glass particles do not become a contaminant. The above embodiment will be described more specifically. Prepare a concrete hardening body with the same mix as the concrete used for the containment vessel of a nuclear power plant.
By installing this in a radioactive material handling facility for several years, a radioactive contamination layer of about 10 [mm] was formed. In order to remove this 10 [mm] contaminated layer, the work was performed in the following order. First, a carbon dioxide gas laser was used to heat the surface of the concrete under the conditions of a laser output of 1 [kw], a beam diameter of 12 [mm], an irradiation speed of 4000 [mm / min], and an irradiation pitch of 9 [mm]. Was evaporated. Next, using a carbon dioxide gas laser, laser output 5 [kw], beam diameter 9 [mm], irradiation speed 1200
Under the irradiation conditions of [mm / min] and an irradiation pitch of 6 [mm], the concrete was melted to a depth of about 3 [mm] from the surface to generate spherical glass particles 4. Next, the glass particles 4 were removed by vacuum means or the like. At this time, concrete powder was not generated. Step 4
By repeating the operation repeatedly, the contaminated concrete layer having a thickness of 10 [mm] could be removed without generating dust.

(Embodiment 3) In this embodiment, a polysiloxane resin is used as a pollution control material. As shown in FIG. 4, the surface of the concrete 3 contaminated with radioactivity is irradiated with a laser beam 5. That is, a laser beam 5 from a laser light source (not shown) is irradiated through a focusing lens 6, a fixed mirror 7 and an oscillating mirror 8 onto a surface of concrete 3 which is radioactively contaminated by forming a focal position 9 in the middle. A permeated polysiloxane resin layer 10 is formed on the surface, and the layer 10 is melted by a laser beam 5 to form a melted 12 layer by laser irradiation. The resin skeleton of the polysiloxane resin A used in this example is shown in the schematic view of FIG.
As shown in the figure, this resin has water repellency, reactivity, heat resistance, and film forming property. The above embodiment will be described more specifically. Prepare a hardened concrete with the same mix as the concrete containment vessel of the nuclear power plant. It will be installed in a facility that handles radioactive substances for one year. One year later, the concrete surface is irradiated with a carbon dioxide laser with an output of 500 [w]. This removes dust, efflorescence, and water adhering to the concrete surface to obtain a sound concrete surface layer. In order to obtain a strong film surface, the quality of the underlying layer affects the quality. A polysiloxane resin is roller-coated on this base material to sufficiently permeate the concrete into the base material. Then, by irradiating the concrete surface with a carbon dioxide gas laser with an output of 1.6 [kw], the polysiloxane resin and the cement were melted and mixed with each other to immobilize the radioactive substance existing on the surface layer. The melting energy of the concrete surface can be calculated by the following formula by experiment. P = 4.2 × V × ρ × K × H / T P: Power required for melting polysiloxane resin and concrete [joul / sec] V: Volume of newly formed melt [cm ³ ] ρ: group Material density [g / cm ³ ] K: Specific heat of substrate [joul / g · ° C] H: Melting temperature of substrate [1300 ° C] T: Processing time [sec]

(Embodiment 4) In this embodiment, a metal having a radiation shielding effect is used as a pollution control material. In FIG. 6, the same reference numerals as those in FIG. The surface of the radioactively contaminated concrete 3 has a shielding effect on the surface of the sprayed metal 1
1 is formed, and this metal sprayed surface 11 is melted by the laser beam 5 to form a molten layer 12 by laser irradiation, and the substance contaminated by radioactivity is fixed. Next, the above embodiment will be described more specifically. Prepare a concrete hardened material in the same proportion as the concrete containment vessel of the nuclear power plant.
It will be installed in a facility that handles radioactive substances for one year. 1
After a year, the concrete surface is irradiated with a carbon dioxide laser with an output of 500 [w]. This removes dust, efflorescence, and water adhering to the concrete surface to obtain a sound concrete surface layer. In order to obtain a strong film surface, the quality of the underlying layer affects the quality. A zinc wire rod having a diameter of 1.6 [mm] is plasma-irradiated on the base. Zinc has a large specific gravity and contributes to shielding, and since it has a low melting temperature of about 400 [° C.], it has an advantage of easily adhering to the concrete of the base material, and is excellent in durability and economical efficiency.
Then, by irradiating with a carbon dioxide gas laser with an output of 1.6 [kw], zinc and cement were melted and mixed, and a substance contaminated with radioactivity existing on the surface was immobilized.

(Embodiment 5) This embodiment shows a case where a substance which is converted into glass is used as the pollution purifying material. Experiment numbers 1 to 3 in Table 1 are comparative examples of the prior art, and experiment numbers 4 to 10 are examples of the present invention.

[0017]

[Table 1]

In this embodiment, a square thickness of 30 cm is 10
A [cm] concrete test body is used, and a water-soluble glass-forming substance is adhered and penetrated into the test body, and a low-power laser is irradiated onto the concrete to heat and dry it. Then, a high-power laser was irradiated to melt and cool various glass forming substances and concrete, and the surface of the concrete was coated with glass. Also, for comparison, samples of the same size were prepared by conventional coating and metal coating. For these test bodies, a durability test by γ-rays and a deterioration test in air were performed,
The results are shown in Table 1. In this example, since it was difficult to handle the concrete contaminated with radioactivity, the durability test was conducted by irradiating the ordinary concrete covering body which is relatively easy to experiment with γ-rays. According to these results, all the methods of the present invention showed good durability in each test.

Next, Experiment Nos. 11 to 23 in Table 2 show other experiments of this embodiment.

[0020]

[Table 1]

A test substance similar to that shown in Table 1 was adhered and permeated with a substance that forms various types of glass that is insoluble in water by using an adhesive material, and then a low-power laser was applied as needed. This concrete was irradiated, heated and dried, and then irradiated with a high-power laser beam to melt and cool various glass-forming substances, and an experiment for coating the surface of the concrete with glass was performed. For these test bodies,
Similar to Example 1, a durability test deterioration test by γ-rays was performed, and the results are shown in Table 2. According to these results, all the methods of the present invention showed good durability in each test. As described above, according to the method of the present invention, it becomes possible to form concrete having a radiation-stable vitrified surface, and an effective method and safety for storage and disposal of contaminated concrete such as nuclear power facilities. It is possible to provide such a covered body, which can be said to be an industrially effective invention.

[0022]

According to the present invention, the following remarkable effects are obtained. 1) Spraying, coating, and impregnating an organic or inorganic pollution-cleaning material on the surface of activated or radioactively contaminated concrete, melting the material with a laser beam, and enclosing the contaminated part of the concrete with these molten layers. Since it can be solidified, the contaminated part of concrete can be completely purified. 2) The solidified body of the molten layer enclosing the contaminated portion is composed of spherical glass particles and can be easily removed. Therefore, the radioactive substance can be concealed and removed without generating dust. 3) Since the radioactive substance is covered with the glass layer etc., the radioactive substance can be handled safely. 4) Since the purification / removal method of the present invention does not require human power, it can be unmanned.

[Brief description of drawings]

FIG. 1 is an explanatory block diagram for explaining a purification method of an embodiment corresponding to claim 1 of the present invention.

FIG. 2 is a flowchart for explaining the operation of FIG.

FIG. 3 is a process explanatory diagram of a removing method corresponding to claim 2 of the present invention.

FIG. 4 is an explanatory diagram showing laser irradiation according to an embodiment of claim 3 of the present invention.

5 is a schematic diagram showing a skeleton of a polysiloxane resin used in the example shown in FIG.

FIG. 6 is an explanatory view showing laser irradiation according to an embodiment of claim 4 of the present invention.

[Explanation of symbols]

1 aggregate 2 Cement paste 3 Radioactive concrete 4 glass grains 5 laser beam 6 focus lens 7 Fixed mirror 8 oscillating mirror 9 Focus position 10 Infiltrated polysiloxane resin 11 Metal sprayed surface 12 Melt layer by laser irradiation

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomio Fujioka 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Within Taisei Corporation (72) Inventor Kenji Sugimoto 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo In Taisei Corporation (72) Inventor Masaaki Tateiwa 1-25-1 Nishishinjuku, Shinjuku-ku, Tokyo Inside Taisei Corporation (56) Reference JP-A-63-157778 (JP, A) JP JP 6-10517 (JP, A) JP 1-130872 (JP, A) JP 5-113041 (JP, A) JP 61-721476 (JP, A) JP 64-3087 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E04G 23/02 C04B 41/72

Claims (5)

(57) [Claims] 1. The concrete surface, which has been contaminated after hardening, is dried by evaporating water to remove dust and efflorescence on the concrete surface, and further dried by low-power laser irradiation, if necessary. Spraying or coating or impregnating with an organic or inorganic pollution-purifying material, then solidifying or vitrifying the surface of the concrete by high-power laser irradiation, and removing the glassy material by pulverizing it if necessary. A method for cleaning and removing contaminated concrete surface, characterized by: 2. A pollution characterized by irradiating a surface of a contaminated concrete with a low-power laser to form spherical glass particles in which the contaminants are aggregated, and then removing the glass particles. Method for cleaning and removing concrete surface. 3. The method for purifying / removing a contaminated concrete surface according to claim 1, wherein the organic pollution purifying material is a polysiloxane resin. 4. The method for purifying / removing a contaminated concrete surface according to claim 1, wherein the inorganic contaminant purifying material is a substance containing a metal having a shielding effect against radiation. 5. The method for purifying and removing contaminated concrete surface according to claim 1, wherein the inorganic contaminant purifying material is a substance that is exchanged with glass.