JP2003139891A - Formation method for photocatalyst film of reactor structure material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce corrosion during reactor operation by uniformly forming photocatalyst film corresponding to water quality standard and a control target value of reactor cooling water on reactor structure material surfaces. SOLUTION: Particle diameter and concentration of photocatalyst contained in solution, the concentration of photocatalyst assistant, fractions of dispersing agent and binder, the concentration of impurity are controlled. The photocatalyst is TiO2 and only the thickness of the film is controlled in 0.3 μm to 2 μm. If it is over 2 μm the electron and positive hole excited by photocatalytic reaction in titanium oxide are recombined and the electric potential of the material gradually rises. If it is below 0.3 μm, grain boundary stress corrosion cracking prevention is suppressed, which is not desirable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a photocatalyst coating on a nuclear reactor structural material for forming a photocatalytic coating on the surface of the nuclear reactor structural material in order to suppress corrosion of the primary reactor material of a nuclear power plant.

[0002]

In a boiling water nuclear power (BWR) power plant, oxygen produced by radiolysis of water in a radiation field,
Hydrogen peroxide etc. exists in the reactor water. It is known that stainless steel and nickel-based metals, which are reactor structural materials, cause stress corrosion cracking in the presence of oxygen and hydrogen peroxide in a high temperature environment such as a nuclear reactor.

As a countermeasure for this, a hydrogen injection technique for injecting hydrogen from feed water to reduce oxygen and hydrogen peroxide in the reactor water has been carried out in several nuclear plants in Japan and overseas. The effect of reducing oxygen and hydrogen peroxide appears in the corrosion potential of the material, and the corrosion potential decreases. The occurrence of stress corrosion cracking and the progress of crack cracking depend on this corrosion potential, and the lower the potential, the more the occurrence of cracking and the progress of cracking are suppressed.

Hydrogen injection is carried out against such a background, but the harmful effect is an increase in the dose rate of the turbine system. This is because N-16 produced in the nuclear reaction reacts with hydrogen to become volatile ammonia and easily transfer to the vapor system. Further, also in hydrogen injection, various equipments such as oxygen injection and recombination of off-gas excess hydrogen generated by the injected hydrogen are required.

In order to reduce this adverse effect as much as possible and to lower the corrosion potential of the structural material, in recent years, a method of adding a noble metal to reactor water, adhering the noble metal to the structural material and injecting a small amount of hydrogen to lower the corrosion potential. Is proposed. This is because noble metals such as platinum utilize the property of selectively capturing the reversible reaction of hydrogen, which has a low potential. By attaching a noble metal to a structural material, a small amount of hydrogen is injected to lower the corrosion potential. .

However, when this method is carried out in an actual plant, it has been found that the oxidation and hydrogenation of the fuel material are increased because they are also deposited on the zirconium oxide film of the fuel. In addition, there are problems such as an increase in the dose rate due to the increased migration of N-16 to the turbine system. There is also a problem of affecting the soundness of the fuel material due to deterioration of water quality due to the high concentration of the precious metal chemical containing impurities.

These effects, that is, the conventional noble metal injection technique has a negative effect on water quality conservation, reduction of radioactivity transfer and high burnup of fuel, so that the injection amount of noble metal is reduced and the cost is high. It is important to reduce the amount of precious metals used or to develop substances that replace precious metals.

As a method for reducing the corrosion potential, the use of photocatalytic reaction has recently attracted attention. It is known that when a photocatalyst is placed on the surface of a material and light having a wavelength near the ultraviolet ray is irradiated on the surface, the corrosion potential is reduced by the action of electrons activated by the photoexcitation reaction. This reaction efficiently proceeds due to the presence of the noble metal near the photocatalyst, and the corrosion potential decreases.

By utilizing this reaction, a photocatalyst or a highly functional photocatalyst having a noble metal previously attached is attached to the surface of the structural material, and the light of Cherenkov light generated in the core is used to reduce the corrosion potential during operation. be able to.

The inventors of the present invention, as a method for inhibiting corrosion of a water-cooled reactor primary system material, are conventional techniques such as hydrogen injection, a method of attaching noble metal colloidal particles to the material surface and performing hydrogen injection, and insulation such as ZrO _2. A photocatalytic method, which replaces the method of forming a film on the surface of a material, has been filed and published as Japanese Patent Laid-Open No. 2001-4789.

[0011]

When a photocatalyst is applied to or sprayed on a reactor structural material or is injected into reactor water to form a photocatalyst film on the reactor structural material, the corrosion potential depends on the thickness of the formed film. The issue will be how it affects.

The present invention has been made to solve the above problems, and is a method of forming a photocatalyst film so that a sufficient effect of the photocatalyst can be expected in the reactor. It is to provide a method for forming a photocatalyst film on a reactor structural material that can uniformly form a photocatalyst film on the surface of the reactor structural material by controlling the impurity concentration that satisfies the water quality standard set from the viewpoint. .

[0013]

The invention according to claim 1 is
In a method of forming a photocatalyst film on the nuclear reactor structural material by injecting components constituting a photocatalyst into the nuclear reactor structural material, the particle size of the injected photocatalyst, a dispersant contained in the photocatalytic agent, a binder, and It defines the proportion of impurities and controls the concentration of the photocatalyst in the reactor water in the case of injection into the reactor water, or it is applied in the case of injection by the spraying method or the photocatalyst in the spray solution. It is characterized by controlling the concentration of.

According to the first aspect of the present invention, there is no influence on the water quality standard of the reactor water set from the viewpoint of the soundness of the reactor, that is, the water quality standard of the reactor cooling water and the control target value, and the surface material of the reactor structural material is not affected. It is possible to uniformly form a film of a high-performance photocatalyst having photoexcitation characteristics in which a current flows by irradiation of light or radiation existing in a nuclear reactor.

This photocatalyst film can prevent corrosion such as stress corrosion cracking of the nuclear reactor structural material.
The life of the nuclear reactor plant can be extended and stable operation can be achieved.

According to a second aspect of the present invention, in the first aspect, the photocatalyst is TiO ₂ (titanium oxide), and the film thickness of the TiO ₂ is controlled from 0.1 μm to 10 μm.

In the invention of claim 2, by selecting the film thickness of TiO ₂ as a photocatalyst from 0.1 μm to 10 μm, the potential of the material for suppressing the prevention of intergranular stress corrosion cracking is sufficiently satisfied with −230 mV or less. it can. Film thickness is 0.1μ
If it is less than m, the potential of the material of -230 mV for suppressing the prevention of intergranular stress corrosion cracking cannot be satisfied. On the other hand, if the film thickness exceeds 10 µm, the potential of the material cannot be satisfied, which is not preferable. In addition, preferably 0.3μm to 2μ
control to m.

The invention according to claim 3 is the invention according to claim 1 or 2.
In, the particle size of the photocatalyst is 20 nm or less (however,
Is not included). In the invention of claim 3, the particle size of TiO ₂ as a photocatalyst is 50n.
The reason for limiting to m or less is that when the grain size exceeds 50 nm, the potential of the material for suppressing the intergranular stress corrosion cracking prevention is −230 m.
This is not preferable because it does not satisfy V or less. In addition, when the thickness is preferably selected from 5 nm to 30 nm, the result satisfying the photocatalytic performance is obtained.

According to a fourth aspect of the present invention, in the first aspect, at least one photocatalytic auxiliary agent of Pt, Rh, Ru, or Pd is attached to the surface of the photocatalyst by 0.05% to 3%. .

According to the invention of claim 4, a photocatalyst auxiliary agent such as Pt or Rh is attached to the surface of TiO ₂ as a photocatalyst in an amount of 0.05% to 3%. If the content is less than 3%, the photocatalytic reaction is reduced due to the decrease in the amount of ultraviolet rays irradiated to titanium oxide, and the effect of suppressing the intergranular stress corrosion cracking becomes less, which cannot be expected.

According to a fifth aspect of the present invention, in the first aspect, the concentration of the photocatalyst is controlled to 10% or less (not including 0). In the invention of claim 5, the reason why the TiO ₂ concentration as the photocatalyst is limited to 10% or less is that when the concentration exceeds 10%, the potential of the material for suppressing the intergranular stress corrosion cracking prevention is −230 mV or less. Will not do. A stable potential can be obtained by controlling the concentration to preferably 5% or less.

The invention according to claim 6 is the method according to claim 1, wherein when the photocatalyst-containing solution is injected into the reactor water, it is 500 ppb when continuously injecting during the steady operation of the reactor.
The following is characterized in that the concentration of the photocatalyst is controlled to 10 ppb or less when injecting at the time of transient at the time of starting and stopping.

In the sixth aspect of the present invention, when injecting the component constituting TiO ₂ as a photocatalyst into the reactor water, the amount is 500 ppb or less when continuously injecting in a steady operation.
Control to 10ppm or less during transients when starting and stopping. The reason for limiting the TiO ₂ concentration at the time of steady operation injection to 500 ppb or less is as follows.

[0024] limited by water quality standards, chloride and sulfate ion impurities of the TiO ₂ solution that are commercially available TiO ₂
Is about 1/100. Therefore, the maximum concentration of TiO _{2 in} the reactor water is 500 ppb.

If it exceeds 500 ppb, the effect of forming a TiO ₂ film cannot be expected. On the other hand, the reason for controlling to 10ppm or less is that the impurity ion standard is 20
Doubles, because the conductivity is 10 times, respectively TiO ₂
The effect on the standard is based on 10ppm. Ti
If the O ₂ concentration exceeds 10 ppm, it becomes difficult to form an optimum film.

According to a seventh aspect of the present invention, in the first aspect, the dispersant that suppresses aggregation of the photocatalyst is ammonia and carboxylic acid, and the concentration of the dispersant is 3.4% or less with respect to the photocatalyst (however, It is characterized by controlling to 0).

In the invention of claim 7, the photocatalyst TiO 2
_The reason for limiting the concentration of the dispersant to 3.4% or less relative to TiO ₂ when ammonia or carboxylic acid is used as a dispersant for suppressing the aggregation of ₂ is the ion exchange resin for removing impurities in the primary reactor system. In consideration of the cleanup effect of the cleanup, it is possible to maintain a good condition without causing stress corrosion cracking, but if it exceeds 3.4%, the effect of maintaining a good condition cannot be expected, which is not preferable. It is preferably controlled to 1% or less.

The invention according to claim 8 is the same as in claim 1, wherein a binder for mechanically forming a film of the photocatalyst and for promoting the film formation is added to the photocatalyst.
It is characterized by controlling from 5% to 0.02%.

In the invention of claim 8, the photocatalyst TiO 2
_{2 The} reason for controlling the binder for promoting film formation from 2.5% to 0.01% with respect to TiO _{2 is} that if it is less than 0.01%, the adhesiveness for forming a film becomes poor, making it difficult to form a uniform film. The potential of the material for suppressing the prevention of intergranular stress corrosion cracking does not satisfy −230 mV or less. on the other hand,
If it exceeds 2.5%, the electric conductivity will increase and the potential of the material for suppressing the prevention of intergranular stress corrosion cracking will not be satisfied. In addition, it is preferably controlled to 0.02% or more.

The invention according to claim 9 is the method for forming a film according to claim 6, wherein 1 pp of the binder according to claim 8 is added.
It is characterized by controlling to m or less. In the invention of claim 9, the reason why the binder of claim 8 is controlled to 1 ppm or less in reactor water is that the amount of TiO ₂ deposited increases as the binder concentration increases, but the corrosion potential decreases. I am An optimum film can be efficiently formed by controlling the TiO ₂ concentration and the binder concentration in the reactor water, but if it exceeds 1 ppm, the potential of the material rises, which is not preferable.

According to a tenth aspect of the present invention, in the first aspect, the photocatalyst, the dispersant, and the binder are contained in the reactor water during operation of the reactor as harmful impurities such as Cl ⁻ or S.
It is characterized in that O ₄ ²⁻ is controlled to 0.05 ppb or less and controlled to the reference value or less during the normal operation of the reactor.

In the invention of claim 10, the photocatalyst TiO 2
₂ , a dispersant for suppressing the agglomeration of TiO, a binder for promoting the film formation of TiO ₂ , and an impurity concentration of Cl ⁻ or SO ₄ ²⁻ which is a typical harmful impurity in the reactor water during the operation of the reactor. Is 0.05 ppb or less, and the reason for controlling it so that it is below the standard during normal reactor operation is to solve the problem that affects the water quality of the reactor water. That is, when the ratio of chlorine and sulfuric acid to TiO ₂ exceeds 0.022%, the water quality control target value of reactor water exceeds 5 ppb. Therefore, the above problems can be solved by controlling the chlorine and sulfuric acid concentrations in the TiO ₂ solution when applying the TiO ₂ coating to the reactor structural material to 0.5 ppb with respect to TiO ₂ .

The invention according to claim 11 is the control according to any one of claims 2 to 10 so that the electrical conductivity of the reactor water during the operation of the reactor is 0.1 μS / cm, which is the reference value during the normal operation of the reactor. It is characterized by doing.

According to the eleventh aspect of the present invention, the TiO ₂ film can be formed on the reactor structural material without impairing the soundness of the nuclear reactor. Further, the reason for controlling the electric conductivity in the reactor water during the reactor operation to be 0.1 μS / cm, which is the standard during the normal reactor operation, is because of the water quality of the reactor when the TiO ₂ film is formed on the reactor structural material. By not exceeding the standard.

According to the twelfth aspect of the present invention, the photocatalyst is adhered during the period of start-up, intermediate stop, and final stop when the water quality of the reactor in claim 6 is excluded from the standard defined as normal operation. It is characterized by

According to the twelfth aspect of the invention, it is possible to inject in a short period of time in accordance with the criteria of conductivity of 10 μS / cm, chlorine and sulfuric acid concentrations of 100 ppb or less. That is,
If the water quality of the reactor is excluded from the standard set for normal operation, the standard will be applied if it is injected during the period of start-up, intermediate stop, and stop. Infusion can also be done if the total period is less than the specified time. When injecting, the injection concentration and operation mode are controlled. In addition, the water quality during injection is monitored and its value is controlled.

According to a thirteenth aspect of the present invention, in the twelfth aspect, C which is an impurity in the reactor water during the operation of the reactor is used.
It is characterized in that the concentrations of l ⁻ and SO ₄ ²⁻ are controlled to 5 ppb or less and the conductivity is controlled to 1 μS / cm or less.

The water quality standard of the reactor water, which is determined from the viewpoint of the soundness of the material of the nuclear reactor, is a conductivity of 1 μS / cm, chlorine and sulfuric acid concentration is 100 ppb or less, but the conductivity is 1 μm during the operation period.
S / cm, chlorine and sulfuric acid concentrations should be 5 ppb or less each. According to the thirteenth aspect of the present invention, the injection can be performed in accordance with this.

According to a fourteenth aspect of the invention, in the sixth aspect, the concentration of the photocatalyst and impurities in the reactor water, the conductivity,
It is characterized by having a measuring system for measuring pH and feeding back the data of the measuring system to the control system of the injection system, temperature, flow rate, flow path, and purification system flow rate.

According to the invention of claim 14, a TiO ₂ film can be formed on a reactor structural material without impairing the soundness of the reactor. Further, TiO ₂ concentration, infusion pump while monitoring the electrical conductivity by controlling the reactor coolant cleanup system pump, TiO ₂ without departing from water quality regulations
Can be injected into the reactor.

According to a fifteenth aspect of the present invention, in the sixth aspect, the adhesion amount of the photocatalyst to the structural material immersed in the reactor water is fed back to the control system having the injection system, temperature, flow rate and flow path. Characterize.

According to the invention of claim 15, the TiO of the test piece
_{(2) The} optimum TiO ₂ film can be formed on the surface of the structural material of the reactor by controlling the flow rate of the injection pump while considering the deposition amount and deposition time. In addition, TiO ₂ attached to the test piece
The deposition thickness can be controlled to a target value by depositing TiO ₂ on the reactor structural material while monitoring the deposition thickness of No.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION The water quality standard value set from the viewpoint of reactor soundness is set under various operating conditions, but the conductivity is approximately 1 μS / cm, and the concentration of chlorine, sulfuric acid, and silica oxide is approximately. The standard value and management target value are set as shown in Table 1.

On the other hand, as a method for producing titanium oxide, when extracting titanium from a mineral, there are roughly a titanium chloride method using hydrochloric acid and a titanium sulfate method using sulfuric acid. Change to Japanese
After that, titanium oxide is obtained. Titanium oxide sol manufactured for general industry does not have restrictions on chlorine, sulfuric acid, etc. and is mixed in the solution in the order of several%, and it becomes chlorine, and sulfuric acid is generally mixed as an impurity. The current situation.

Therefore, the increase in the amount of titanium oxide film is caused by chlorine,
In addition to causing an increase in the amount of sulfuric acid, exceeding the reactor water quality standard value causes a shutdown of the reactor.
Similarly, in order to chemically and mechanically stabilize titanium oxide on the material surface, it is necessary to use titanium oxide, which is difficult to dissolve in water, as small particles in suspension. For this reason,
It must be stably dispersed in a liquid before use.

About 2% to 10% of the dispersant is mixed in the titanium oxide sol produced for general industry, and the chemicals involved in this dispersion have conductivity which is the standard of reactor water quality depending on the type and concentration. To raise. Ammonia, carboxylic acid, etc. are used as these agents, and in order to ensure conductivity of 1 μS / cm, the concentration in reactor water is
If it is not controlled below 80 ppb, the reference conductivity may increase and the reactor may be shut down.

Further, it is necessary to use a binder for the purpose of improving the adhesion of the titanium oxide film. About 20% of the binder in titanium oxide sol manufactured for general industry is mixed with titanium oxide, and like the dispersant, the type and concentration of the binder, and the agent that stabilizes the binder in the solution, Increase the electrical conductivity, which is the standard for reactor water quality.

The binders of these agents include inorganic silica oxide and polyorganosiloxane. Regarding silica oxide, it does not elute into the reactor water as ions so it does not increase the conductivity, but ethanol or the like is used to stabilize the binder, and its concentration may reach 40%.

When these alcohols are decomposed and dissolved as carbonate ions in the reactor water, the concentration in the reactor water must be controlled to 1000 ppb or less in order to ensure a conductivity of 1 μS / cm, or the reference conductivity increases. It can be a factor in shutting down the reactor.

Table 1 shows the standard values (reactor structural material area and reactor water amount are plant design parameters) and management target values set from the viewpoint of the material integrity of the reactor shown above, and they are commercially available. Table 2 shows the properties of titanium oxide, which is one of the photocatalysts used.

[0051]

[Table 1]

[0052]

[Table 2]

As a method of forming a photocatalytic coating on the surface of the structural material of a nuclear reactor, there are a mechanical method such as coating and spraying, and a method of chemically injecting a photocatalyst into reactor water to form a film. There is. In the mechanical way,
Since it is applied or sprayed on a necessary part, it can be performed without affecting the plant.

However, in the case where it is applied over a wide area or where it is difficult to reach by hand or machine, the method of injecting the photocatalyst into the reactor water can form a film on all the wetted parts at once. . Therefore, it is most appropriate to adopt an injection method as a method for forming a photocatalyst film over the entire reactor in an existing plant, and a mechanical film formation method for adapting to a limited site such as a welded part. .

The present invention is to remove impurities mixed in from titanium oxide, a dispersant, a binder, etc., and to optimize the dispersant or binder. First, regarding the removal of impurities mixed in from titanium oxide, a dispersant, a binder, etc., the concentration of chlorine (Cl ⁻ ) and sulfuric acid (SO ₄ ²⁻ ) in a titanium oxide solution for photocatalyst commercially available in general industry is 1
Although the content is ~ 10%, the impurities in the chemicals used in the titanium chloride method or titanium sulfate method for extracting titanium from minerals in the titanium oxide manufacturing method are controlled.

After that, when changing to a hydrate such as titanium hydroxide, the water used is pure water containing as few impurities as possible. After that, when oxidizing the titanium oxide, the environmental atmosphere is controlled, and as a result, the chlorine and sulfuric acid concentrations in the titanium oxide solution can be reduced to about 1 ppm.

Next, regarding the optimization of the dispersant, it is generally said that about 1% is optimal with respect to titanium oxide as described above, but it is necessary to control the dispersant according to the purpose of use. is there. It is considered that the above amount is necessary to prevent the aggregation of titanium oxide for a long period of time, but when the storage period and the use period are limited, such a large amount of dispersant is not necessary.

Therefore, when the ratio of the dispersant to titanium oxide and the dispersion state of titanium oxide were tested, the ratio of the dispersant to titanium oxide was required to be about 1% in order to prevent the aggregation of titanium oxide for one month or longer. However, for the purpose of preventing the aggregation of titanium oxide for about 2 weeks, it was recognized that the dispersant should be present at 0.4% with respect to titanium oxide.

Regarding the optimization of the binder for increasing the adhesion of titanium oxide, the binder in the titanium oxide sol produced for general industry contains about 20% of the titanium oxide. The concentration should also be controlled according to the purpose of use.

Therefore, when a film was formed by changing the binder ratio with respect to titanium oxide, and the film strength was tested under reactor temperature and pressure conditions, it was used in general industry although there were some differences depending on the type of binder. It was confirmed that there was no tendency for the coating to peel under reactor temperature and pressure conditions from 1/200 to 1/20000 relative to the amount of binder used.

When the photocatalytic film is formed by coating, spraying or injecting into the reactor structural material, a uniform photocatalytic film is formed without adversely affecting the water quality of the reactor by totally controlling the following means. can do.

The potential of the material for suppressing the intergranular stress corrosion cracking prevention with respect to the thickness of the titanium oxide film formed on the nuclear reactor structural material is determined, and the thickness of the titanium oxide film that sufficiently exhibits the photocatalytic performance is controlled.

The corrosion potential with respect to the particle size of titanium oxide itself when forming the titanium oxide film is determined to control the particle size of titanium oxide at which the photocatalytic performance is sufficiently exhibited. The corrosion potential with respect to the titanium oxide concentration at the time of forming the titanium oxide film is determined to control the titanium oxide concentration at which the photocatalytic performance is sufficiently exhibited.

The corrosion potential was calculated with respect to the ratio of the dispersant that suppresses the aggregation of titanium oxide when forming the titanium oxide film, and the photocatalytic performance was determined from the influence of the reactor water conductivity on the ratio of titanium oxide and the dispersant. The dispersant that prevents the aggregation of titanium oxide is controlled for the purpose of keeping the water quality below the water quality standard set sufficiently from the viewpoint of material integrity.

A reactor in which the corrosion potential with respect to the ratio of the binder for promoting the film formation when forming the titanium oxide film was determined, and the ratio of the titanium oxide and the binder and the stabilizer used for the binder were added. Due to the influence of water conductivity, the binder is controlled so that the photocatalytic performance is sufficiently exerted and the water quality is maintained below the water quality standard set from the viewpoint of material integrity.

When forming a titanium oxide film, titanium oxide itself, a dispersant that suppresses the aggregation of titanium oxide, a binder for promoting film formation, a stabilizer for the binder, and the like are all of the material integrity. Since the water quality standard set from the viewpoint is affected, the concentration of these impurities is controlled.

The water quality standard defined from the viewpoint of the soundness of the material of the nuclear reactor is approximately 10 μS / cm of conductivity, chlorine,
It is necessary to keep the sulfuric acid concentration below 100 ppb each. However, even during the operation period, stricter water quality standards are recommended, and their values are conductivity 1 μS / cm, chlorine and sulfuric acid concentrations of 5 ppb or less each.

In order to constantly inject titanium oxide into the reactor, it is necessary to satisfy this standard, and it is necessary to reduce the concentration of titanium oxide, the concentration of dispersant and binder, and the concentration of impurities. On the other hand, for a short period of time, it is possible to inject with conductivity of 10 μS / cm and chlorine and sulfuric acid concentrations of 100 ppb or less.

These standards are currently applied at the time of start-up, intermediate stop, and stop, and if injected during these periods, these standards will be applied. Moreover, even if it is not these periods, if the total period is less than the specified time, it is possible to inject.

When injecting, it is necessary to control the injection concentration and the operation mode so as to satisfy the above conditions. Most nuclear reactors are equipped with a conductivity meter and a pH meter, and the concentration of various ions in the reactor water can be measured by a water quality measuring instrument such as ion chromatography. In addition to these, a device that can measure the concentration of titanium oxide will be added to monitor the water quality during injection, and the value will be fed back to the injection system and reactor operation system for control.

According to the present embodiment, by controlling the film thickness, particle size, concentration, dispersant, binder, and impurities of the photocatalyst, which has an anticorrosive effect when irradiated with light, it is possible to meet the water quality standard of the reactor. The high-performance photocatalyst layer thus formed can form a uniform film on the surface of the reactor structural material, and can reduce corrosion during operation.

Next, specific examples of the method for forming a photocatalyst for a nuclear reactor structural material according to the present invention will be described with reference to FIGS. 1 to 13. (Example 1) In Example 1, a photocatalyst is applied to a reactor structural material, sprayed, or injected into reactor water to form a film on the structural material, and how the corrosion potential affects the thickness of the formed film. It is an example of an experiment investigating whether or not. As is clear from FIG. 1, the thickness of the titanium oxide film is 0.1 μm to 10 μm.
It can be seen that, in the range of, the potential of the material for suppressing the prevention of intergranular stress corrosion cracking is sufficiently below −230 mV.

In the range of 0.3 μm to 2 μm, the potential of the material is maintained at −300 mV. However, when the thickness of the titanium oxide film becomes 2 μm or more, the potential of the material for suppressing the prevention of intergranular stress corrosion cracking gradually increases due to the reaction of recombination of electrons and holes excited by the photocatalytic reaction in titanium oxide. It is rising.

If the thickness of the titanium oxide film is less than 0.1 μm, the material potential of −230 mV for suppressing the prevention of intergranular stress corrosion cracking cannot be satisfied. Therefore, the photocatalytic performance is satisfied when the thickness of the titanium oxide film on the reactor structural material is 0.1 μm to 10 μm, but preferably 0.3 μm to 2 μm.
It is important to control to m.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG.
Will be explained. Example 2 is an experimental example in which how the corrosion potential is affected by the particle size of titanium oxide itself when the titanium oxide film is formed on the reactor structural material. FIG. 2 shows the case where the thickness of the titanium oxide film is 0.3 μm. When the titanium oxide particle size is 50 nm or less, the potential of the material for suppressing the intergranular stress corrosion cracking prevention is sufficiently below −230 mV. You can see that

However, when the particle size of titanium oxide is 30 nm or more, the potential of the material for suppressing the prevention of intergranular stress corrosion cracking is increased by the reaction of recombination of electrons and holes excited by the photocatalytic reaction in titanium oxide. It is gradually rising.

When the thickness of the titanium oxide film is reduced, the specific surface area per unit volume decreases in inverse proportion to the grain size, and the potential of the material for suppressing the intergranular stress corrosion cracking is -230 mV. The following is no longer satisfied. Therefore, when the titanium oxide film is applied to the reactor structural material, the particle size of titanium oxide satisfies the photocatalytic performance at 50 nm or less, but it is important to control it to 5 nm to 30 nm.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG.
Will be explained. Example 3 investigates how the corrosion potential is affected by the concentration of platinum or rhodium, which is a photocatalyst aid for promptly promoting the movement of potential when forming a titanium oxide film on a reactor structural material. It is an experimental example. As shown in FIG. 3,
When 0.3 μm, the ratio of platinum to titanium oxide is
In the range of 0.05 to 3%, the potential of the material for suppressing the intergranular stress corrosion cracking prevention is the potential of only titanium oxide-
It can be seen that it is higher than 300 mV.

Further, the ratio of platinum to titanium oxide is 0.
When it is about 1%, the potential of the material is greatly improved to −330 mV. However, when the proportion of the photocatalyst auxiliary agent is 3% or more, the photocatalytic reaction is reduced due to the decrease in the amount of ultraviolet rays irradiated to titanium oxide, and the potential of the material for suppressing the intergranular stress corrosion cracking gradually increases, Titanium oxide only potential-300 mV
Below.

When the proportion of the photocatalyst aid is less than 0.05%, the effect as the photocatalyst aid is weakened, and the potential of the material for suppressing the prevention of intergranular stress corrosion cracking is -O.
300mV cannot be satisfied. Therefore, when a titanium oxide film is formed on the reactor structural material, platinum or rhodium in the film satisfies the performance as a photocatalyst auxiliary agent in the range of 0.05 to 3%, but it is preferably controlled to about 0.1%. Is essential.

(Embodiment 4) Embodiment 4 of the present invention will be described with reference to FIG.
Will be explained. Example 4 is an experimental example in which how the corrosion potential affects the titanium oxide concentration when forming the titanium oxide film on the reactor structural material. In the method of applying and spraying titanium oxide on the target material, as shown in Fig. 4, when the titanium oxide concentration is 10% or less, the material potential of -230 mV or less for suppressing the intergranular stress corrosion cracking prevention is sufficient. You can see that you are satisfied.

However, as shown in the figure, when the titanium oxide concentration exceeds 5%, the film formation by coating and spraying deteriorates, and a uniform film is lacking or desorption due to lack of adhesion occurs. The potential of the material for suppressing the prevention of intergranular stress corrosion cracking in the state film gradually rises, and when the titanium oxide concentration exceeds 10%, it does not satisfy −230 mV or less.

Accordingly, when the titanium oxide film is applied to the reactor structural material by spraying or spraying, the titanium oxide concentration satisfies the photocatalytic performance at 10% or less, but it is important to control it to 5% or less. .

(Fifth Embodiment) Referring to FIG. 5, a fifth embodiment of the present invention will be described.
Will be explained. When the method of forming a film on the reactor structural material by injecting titanium oxide into the reactor is used, it is injected for a long time during steady operation of the reactor or at start-up /
Transients, such as at rest, can be injected briefly, or a combination of both.

The temperature of the reactor water is 280 in the injection during the steady operation.
It is ~ 288 ° C, giving an infusion time of about 10,000 hours. During transient, the temperature can be arbitrarily selected from 100 to 288 ° C, and the injection time is considered to be maximum 48 hours.

The titanium oxide concentration at the time of steady operation injection is limited by the water quality standard shown in Table 1. The titanium oxide solution currently on the market contains less chlorine and sulfate ion impurities, which is about 1/100 that of titanium oxide. Therefore, the maximum concentration of titanium oxide in the reactor water is 500 ppb.

It is the dispersant that affects the conductivity, and 0.4% of the injection liquid is necessary for dispersion. 1 μS / cm of reactor water corresponds to 80 ppb in dispersant concentration.
Considering that the concentration of titanium oxide in the injection liquid is about 5% from the soundness of the injection pump, the concentration of titanium oxide in the reactor water is limited to 1 ppm.

These are the ratios of titanium oxide and impurities at the time of injection. In an actual machine, titanium oxide adheres to the structural material and the fuel assembly, and both titanium oxide and impurities are removed by the purification system. Therefore, it is considered that the limit value of titanium oxide in the reactor water becomes lower than the above value when continuous injection is performed.

At the time of transient implantation, the standard of impurity ions is 20 times and the conductivity is 10 times. Therefore, the effect of titanium oxide on the standard is 10 ppm. FIG. 5 shows the dependence of corrosion potential upon light irradiation on the titanium oxide concentration when stainless steel was immersed in a titanium oxide solution kept at 285 ° C. and 150 ° C. for 24 hours. 10ppm at 285 ℃
A film of titanium oxide having a thickness of 0.69 μm and a thickness of 0.21 μm is formed at 150 ° C.

As shown in FIG. 5, under the condition of immersion for 24 hours, the grain boundary stress corrosion cracking of the line at 285 ° C. indicated by the thick line does not occur at the concentration of 1.5 ppm in the reactor water. ℃
Therefore, a concentration of 5 ppm is required. In this way, by controlling the concentration of titanium oxide in the reactor water by controlling the reactor water temperature and the injection time, it is possible to form an optimum film.

(Sixth Embodiment) A sixth embodiment of the present invention will be described with reference to FIGS. 6 and 7. Example 6 is set from the viewpoint of the influence of the corrosion potential by the dispersant that suppresses the aggregation of titanium oxide when the titanium oxide film is formed on the reactor structural material, or the reactor soundness depending on the amount of the dispersant mixed in. This is an experimental example that examined how it affects the existing water quality standards.

As shown in FIG. 6, when the ratio of the dispersant to titanium oxide is 0.4% or more, the potential of the material for suppressing the prevention of intergranular stress corrosion cracking should be sufficiently below −230 mV. Recognize.

The ratio of the dispersant to titanium oxide is 0.4%
In the case of the following, it becomes difficult to form a uniform film by agglomeration before forming a film, the potential of the material for suppressing the intergranular stress corrosion cracking rises, and the ratio of the dispersant to titanium oxide is 0.3%. Below the value, the material potential of −230 mV or less cannot be satisfied.

However, when stress corrosion cracking of the material was confirmed by a test piece added with 1% of ammonia and carboxylic acid as a dispersant, no stress corrosion cracking of the test piece material was observed for a long period of time. Therefore, it has been confirmed that stress corrosion cracking does not occur when about 1% of ammonia or carboxylic acid is added to titanium oxide as a dispersant.

Further, when ammonia is used as the dispersant as shown in FIG. 7, when the ratio of the dispersant to titanium oxide is increased, the conductivity of the reactor water is also increased, and the ratio of the dispersant to titanium oxide is increased. If it exceeds 0.34%, the electrical conductivity of the reactor water quality standard will exceed 1 μS / cm.

Therefore, the ratio of the dispersant to titanium oxide when the titanium oxide film is applied to the reactor structural material must be 0.4% or more relative to titanium oxide from the potential of the material for suppressing the prevention of intergranular stress corrosion cracking. However, considering that the electrical conductivity of 1 μS / cm of the reactor water quality standard is ensured, the ratio of the dispersant to titanium oxide needs to be controlled to 0.34% or less.

However, the conductivity of 1 μS / cm as the standard value of reactor water quality does not mean that the reactor is stopped immediately when it exceeds this value, and it is 14 days / 12
Even if the conductivity is increased due to the presence of a dispersant for a period of time, there is no problem if impurities can be removed in a short time by the cleanup system shown below.

That is, in the reactor primary system, a cleanup system for removing cation and anion components is installed from the viewpoint of removing impurities, and the removal performance for the dispersant component is 1 / Since it has a performance of about 10 or more, even if the ratio of the dispersant to titanium oxide exceeds 0.34%, it can be purified by the cleanup system in a short time, so that the reactor water conductivity can be guaranteed at 1 μS / cm. Is.

Further, as described above, it has been confirmed that stress corrosion cracking does not occur when about 1% of ammonia or carboxylic acid is added as a dispersant to titanium oxide. Therefore, the ratio of the dispersant to titanium oxide is 3.
About 4% can be mixed, but it is important to control the concentration of the dispersant that does not cause stress corrosion cracking of the material to 1% or less.

However, the above dispersant concentration is the result of obtaining the concentration necessary to form a film on all 5000 m ^{2 of the} reactor structural material, and the film formation is limited to the welded part where stress corrosion of the material is likely to occur. In this case, the amount of titanium oxide to be used can be reduced because the film forming area is reduced, so that it is possible to increase the dispersant concentration in consideration of the reactor water quality standard and the management target. In the above, when converting the ratio of the dispersant to titanium oxide into reactor water, Table 3 is used.

[0101]

[Table 3]

(Embodiment 7) Referring to FIG. 8, Embodiment 7 of the present invention will be described.
Will be explained. This is an experimental example in which the influence of the corrosion potential of the binder for promoting the film formation when forming the titanium oxide film on the reactor structural material and the influence of the amount of the mixed binder on the water quality standard of the reactor water are examined.

As shown in FIG. 8, it was found that the potential of the material for suppressing the prevention of intergranular stress corrosion cracking was sufficiently below −230 mV when the ratio of the binder to titanium oxide was 0.01% or more. . However, when the ratio of the binder to titanium oxide is 0.01% or less, the adhesiveness for forming a film becomes poor, making it difficult to form a uniform film and suppressing the intergranular stress corrosion cracking material. The potential of -230 mV or less is no longer satisfied.

Inorganic silica, polyorganosiloxane and the like are used as the binder for promoting the formation of the titanium oxide film, both of which are based on silica oxide, and the silica oxide is dissolved as ions in the reactor water. As shown in Table 1, the control target value for silica oxide is 1 in reactor water.
Must be below ppm. Therefore, it is necessary to control the ratio of silica oxide to titanium oxide to be 2.5% or less.

Therefore, if the ratio of the binder to titanium oxide is 2.5% or less when converted from the control target value, it is possible to mix it, but from the potential of the material for suppressing the intergranular stress corrosion cracking prevention, the binder concentration is 0.02%. It is important to control to about% or more.

However, the above-mentioned binder concentration is the result of obtaining the concentration necessary to form a film on all 5000 m ^{2 of the} reactor structural material, and the film formation is limited to the welded portion where stress corrosion of the material is likely to occur. If you do
Since the amount of titanium oxide used can be reduced because the film formation area is reduced, it is possible to increase the binder concentration in consideration of the reactor water quality standards and management targets. In the above, when converting the ratio of the binder to titanium oxide into reactor water, Table 3 is used.

(Embodiment 8) Referring to FIG. 9, an embodiment 8 of the present invention will be described.
Will be explained. When using the method of forming a film on the reactor structural material by injecting titanium oxide into the reactor, the film is formed with a lower concentration of titanium oxide by adding a binder that improves the adhesion of titanium oxide. .

As shown in FIG. 9, at 285 ° C. for 24 hours, 1 p
When stainless steel is exposed to pm titanium oxide, the amount of titanium oxide attached increases as the concentration of the binder increases, and the corrosion potential decreases. When the titanium oxide concentration is further increased, the binder can be decreased, and conversely, when the binder concentration is increased, the titanium oxide concentration can be decreased.

As described above, it is possible to form an optimum film by controlling the titanium oxide concentration and the binder concentration in the reactor water. The target value of silicon oxide (SiO ₂ ) is 1 ppm as shown in Table 1 during steady operation.
Therefore, the titanium oxide can be efficiently attached by controlling the binder concentration to be as high as 1 ppm or less during injection.

(Ninth Embodiment) A ninth embodiment of the present invention will be described with reference to FIG.
Will be explained. In Example 9, when forming a titanium oxide film on a reactor structural material, titanium oxide itself, a dispersant that suppresses the aggregation of titanium oxide, and the inclusion of impurities by a binder to accelerate the film formation affect the water quality of the reactor water. It is an example of an experiment which investigated.

As described above, the conductivity of the reactor water is guaranteed to be 1 μS / cm or less, but the chlorine and sulfuric acid concentrations are controlled similarly to the conductivity. As is clear from FIG. 10, when the chlorine and sulfuric acid concentration ratios of titanium oxide exceed 0.022%, the reactor water quality management target value of 5 ppb is recognized to be exceeded.

Therefore, as described above, when controlling impurities of the chemicals used in the titanium chloride method or the titanium sulfate method for extracting titanium from minerals in the production method of titanium oxide, and then changing to a hydrate such as titanium hydroxide, Use pure water with no impurities as much as possible.

Further, when oxidizing the titanium oxide, the concentration of chlorine and sulfuric acid in the titanium oxide solution can be reduced to about 0.002% with respect to the titanium oxide by controlling the environmental atmosphere. Therefore, it is important to control the concentration of chlorine and sulfuric acid in the titanium oxide solution when applying the titanium oxide film to the reactor structural material to 0.02% or less of titanium oxide.

However, the above-mentioned chlorine and sulfuric acid concentrations are the results of obtaining the concentrations necessary to form a film for all 5000 m ^{2 of the} reactor structural material, and a film that limits the welded portion where stress corrosion of the material is likely to occur. When forming,
Since the amount of titanium oxide used can be reduced because the film formation area is reduced, it is possible to increase the concentration of chlorine and sulfuric acid in consideration of reactor water quality standards and management targets. In the above, when converting the impurity concentration with respect to titanium oxide into reactor water, Table 3 is used.

(Tenth Embodiment) A tenth embodiment of the present invention will be described with reference to FIGS. 11 and 12. When a titanium oxide film is formed on the reactor structural material by injecting titanium oxide into the reactor 1, the titanium oxide is injected from any or all of the injection points 2a, 2b and 2c. , The water supply line 16 and the PLR (reactor recirculation system) line 3 and the CUW (reactor coolant purification system) line 5 adhere to the surface of the material in contact with the liquid.

Most of the injected titanium oxide, the dispersant, the binder, and the impurities contained therein are
It is removed from the reactor water by the filter demineralizer of the purification system 7 installed in the CUW line 5. Therefore, it is considered that their concentration is determined by the adhesion to the material surface and the balance between injection and purification, and the injection pump 12 and CUW are used for concentration control.
This is possible by controlling the flow rate of the pump 6.

Most of the nuclear reactors have a water quality measuring system 11 capable of measuring conductivity, pH and impurity ion concentration for confirmation of soundness. This normal measuring system 11
A system that can measure the concentration of titanium oxide is added to the system, and the data is fed back to the injection control system 14 and the operation system of the reactor.

A value lower than the limit values of conductivity and impurity concentration, for example, 90% is set as a target value. When the titanium oxide concentration and the impurity concentration exceed the target values, the flow rate of the injection pump 12 is decreased and the flow rate of the CUW pump 6 is increased. If only the titanium oxide concentration exceeds the target value,
Only the flow rate of infusion pump 12 is reduced.

Although the titanium oxide concentration is low, there is no increasing tendency, and when the impurity concentration is lower than the target value, the flow rate of the injection pump 6 is increased, and when it is higher than the target value, the injection pump 12, CUW. Both the pump 6 and the pump 6 increase the flow rate. By performing such an operation, it is possible to form a titanium oxide film without impairing the soundness of the nuclear reactor.

FIG. 12 shows an example of changes over time in the TiO ₂ concentration and the conductivity at the start of injection. When the implantation is started, both the TiO ₂ concentration and the electric conductivity increase. The TiO ₂ concentration increases while subtracting the injected amount, the amount adhering to the structural material or the fuel rod surface, and the amount removed by the purification system.

On the other hand, the conductivity, which is considered to represent the amount of impurities, also increases in concentration depending on the amount injected and the amount removed by the purification system. When TiO ₂ reaches the target concentration, the flow rate of the injection pump is reduced so that the TiO ₂ reaches the target concentration. CUW when the conductivity reaches 90% of the limit concentration
Increase the flow rate of the pump and improve the purification power.

Then, the electric conductivity is lowered and the TiO ₂ concentration is also lowered. When the conductivity decreases and falls below 85%, for example, the flow rate of the injection pump is increased to increase the TiO ₂ concentration. In this way, by controlling the injection pump and the CUW pump while monitoring the TiO ₂ concentration and conductivity,
Injection can be done without departing from water quality regulations.

(Embodiment 11) Embodiment 11 of the present invention will be described with reference to FIGS. 13 and 14. 13, the same parts as those in FIG. 11 are designated by the same reference numerals. When the method of forming a film on the reactor structural material by injecting titanium oxide into the reactor 1, the titanium oxide is injected from any or all of the injection points 2, and the reactor 1 and the PLR line 3 , Adheres to the surface of the material in contact with the CUW line 5.

The adhesion to the material surface depends on the temperature of the reactor water, the concentration of titanium oxide and the concentration of the binder. The control of these concentrations is increased by increasing the flow rate of the injection pump 12, and conversely is decreased by increasing the flow rate of the CUW pump 6. Although the reactor water temperature does not change during steady-state reactor operation, it changes during start-up / shutdown transients and can be controlled.

For example, at the time of stoppage, the temperature can be lowered by increasing the flow rate of the residual heat removing system or opening the isolation valve of the main steam system. The test piece 18 is immersed in the reactor water sampled to optimize the amount of titanium oxide deposited, and the amount of deposit is measured appropriately.
Measure by 17. The data of the adhesion amount is fed back to the injection control system 14 and the reactor operation system.

When the adhesion amount of the test piece 18 is lower than the target value considering the adhesion time until then, the flow rate of the injection pump 12 is increased, and when the water quality is close to the limit value, the temperature is increased. Let If it exceeds the target value, the flow rate of the injection pump 12 is decreased and the flow rate of the CUW pump 6 is increased. It is possible to control the flow rate of the injection pump 12 and form an optimum titanium oxide film on the surface of the reactor material.

FIG. 14 shows an example of changes over time in the TiO ₂ concentration and the TiO ₂ film thickness at the start of implantation. This is an example of injecting to a target thickness in 24 hours. Adhesion test pieces shall be taken out and analyzed every 2 hours after the start of injection. At the start of injection, the injection is performed at 1/3 of the provisional target value of concentration.

If the adhesion thickness after 2 hours was 2% of the target, the target could not be reached even if it was 36 times (1/3 in concentration, 1/12 in time). Therefore, it is judged that this does not occur, and the injection is started at a temporary concentration. afterwards,
After another 2 hours, the adhesion test piece is taken out and the adhesion thickness is analyzed. If the amount of increase in the adhesion thickness during 2 hours was 8% of the target, the adhesion thickness is not reached in the remaining time, so the implantation is performed at 120% of the provisional value.

Thereafter, the adhered amount was measured every 2 hours, and when the adhered thickness reached 90% of the target, injection was performed at 1 / of the provisional value.
Set to 3 and make fine adjustments. As described above, by performing the adhesion while monitoring the adhesion thickness in the adhesion test piece, the adhesion thickness can be controlled to the target value.

[0130]

According to the present invention, the film thickness, particle size, concentration, dispersant of a photocatalyst having an anticorrosion effect when irradiated with light,
By controlling the binder and impurities, a high-performance photocatalyst layer corresponding to the water quality standard of the reactor cooling water can be formed into a uniform film on the surface of the reactor structural material, and corrosion during the reactor operation can be reduced.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a titanium oxide film thickness and a material potential for explaining a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the titanium oxide particle size and the potential of the material for explaining the second embodiment of the present invention.

FIG. 3 is a characteristic diagram illustrating a relationship between a potential of a material and a ratio of platinum added to titanium oxide for explaining a third embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the titanium oxide concentration and the potential of the material for explaining Example 4 of the present invention.

FIG. 5 is a characteristic diagram showing the relationship between the concentration in reactor water and the potential of the material for explaining the fifth embodiment of the present invention.

FIG. 6 is a characteristic diagram showing the relationship between the potential of the material and the proportion of the dispersant added to titanium oxide, for explaining Example 6 of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between reactor water conductivity and the ratio of titanium oxide to which a dispersant has been added, as in FIG.

FIG. 8 is a characteristic diagram illustrating the relationship between the potential of a material and the proportion of a binder added to titanium oxide for explaining Example 7 of the present invention.

FIG. 9 is a characteristic diagram showing the relationship between the concentration in the reactor water and the potential of the material for explaining the eighth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing the relationship between chlorine and sulfuric acid concentrations in reactor water with respect to the proportion of impurities added to titanium oxide, for explaining Example 9 of the present invention.

FIG. 11 is a piping system diagram of a nuclear reactor and its periphery for explaining a tenth embodiment of the present invention.

FIG. 12 is a characteristic diagram showing changes over time in TiO ₂ concentration and conductivity at the start of injection in FIG.

FIG. 13 is a piping system diagram of a nuclear reactor and its surroundings for explaining an eleventh embodiment of the present invention.

FIG. 14 is a characteristic diagram showing changes over time in TiO ₂ concentration and film thickness at the start of implantation in FIG.

[Explanation of symbols]

1 ... Reactor, 2 (2a, 2b, 2c) ... Injection point, 3, 4
… PLR lines, 5, 6… CUW lines, 7… Purification system, 8, 9
… RHR line, 10… Sampling line, 10a, 10b…
Sampling point, 11 ... Measuring system, 12 ... Infusion pump,
13 ... injection line, 14 ... injection control system, 15 ... signal line, 16 ... water supply line, 17 ... adhesion amount measuring system, 18 ... adhesion test piece.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 37/02 301 B01J 37/02 301Z C23F 11/18 C23F 11/18 15/00 15/00 G21D 1 / 00 G21D 1/00 X (72) Inventor Nagaka Ichikawa 2-1, Ukishimacho, Kawasaki-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Hamakawasaki Factory (72) Inventor Yukio Hemi 2 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 Incorporated company Toshiba Hamakawasaki Plant (72) Inventor Junichi Takagi 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Incorporated Toshiba Corporation Yokohama Works (72) Inventor Yotsuyanagi Hata, 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Address Incorporated company Toshiba Yokohama Works (72) Inventor Masato Okamura 2-1, Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa F-star inside Toshiba Hamakawasaki factory (Reference) 4G069 AA02 AA03 BA02A BA02B BA04A BA04B BA21C BA48A BB01C BB02A BB02B BC70A BC71A BC71B BC72A BC75A BC75B BD01C BD06C BE08C CD10 EA07 EB15X EB15Y FA03 FA04 FB06 FB23 FB24 FB77 FC04 FC08 4K062 AA01 AA03 BA14 BA20 BB04 BB06 BB12 BC16 CA02 CA05 DA05 FA20

Claims (15)

[Claims] 1. A method of forming a photocatalyst film on the reactor structural material by injecting a component constituting the photocatalyst into the reactor structural material, the particle size of the injected photocatalyst, and the chemical content of the photocatalyst. Defining the proportions of dispersant, binder and impurities, controlling the concentration of photocatalyst in the reactor water in the case of injection into the reactor water, or coating,
A method for forming a photocatalyst film of a reactor structural material, characterized in that in the case of injection by a spray method, the concentration of the photocatalyst in a spray solution is applied. 2. The photocatalyst is TiO _2.
The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 1, wherein the O ₂ film thickness is controlled to 0.1 μm to 10 μm. 3. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 1, wherein the particle diameter of the photocatalyst is controlled to 20 nm or less (however, not including 0). 4. A photocatalyst auxiliary agent of at least one of Pt, Rh, Ru, and Pd is 0.05% to 3% on the surface of the photocatalyst.
The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 1, wherein the photocatalyst film is attached. 5. The concentration of the photocatalyst is 10% or less (however,
The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 1, wherein the photocatalyst film is controlled to a value not including 0). 6. When injecting the photocatalyst-containing solution into the reactor water, it is 500 ppb or less when continuously injecting during steady operation of the reactor, and 10 ppb or less when injecting at transients at startup and shutdown. The method for forming a photocatalyst film of a reactor structural material according to claim 1, wherein the concentration of the photocatalyst is controlled. 7. The dispersant for suppressing aggregation of the photocatalyst is composed of ammonia or carboxylic acid, and the concentration of the dispersant is controlled to be 3.4% or less (not including 0) with respect to the photocatalyst. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 1. 8. The method for forming a photocatalyst film of a reactor structural material according to claim 1, wherein the binder for promoting the film formation of the photocatalyst is controlled to 2.5% to 0.01% with respect to the photocatalyst. 9. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 6, wherein the binder according to claim 8 is controlled to 1 ppm or less. 10. The photocatalyst, the dispersant, and the binder, which are harmful impurities C in the reactor water during the operation of the reactor.
2. The method for forming a photocatalyst film of a structural material for a reactor according to claim 1, wherein l ⁻ or SO ₄ ²⁻ is controlled to be 0.05 ppb or less and controlled to be equal to or lower than a reference value during the normal operation of the reactor. 11. The method according to claim 2, wherein the electric conductivity of the reactor water during the operation of the reactor is controlled to be 0.1 μS / cm which is the reference value during the normal operation of the reactor. A method for forming a photocatalytic film on a nuclear reactor structural material as described in (1). 12. At startup, the water quality of the reactor according to claim 6 is excluded from the standard established as normal operation,
7. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 6, wherein the photocatalyst is attached during the intermediate stop and the final stop. 13. When forming a photocatalyst film by the method according to claim 6 during the period according to claim 12, C which is a harmful impurity in the reactor water during the operation of the reactor.
13. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 12, wherein the concentrations of l ⁻ and SO ₄ ²⁻ are controlled to 5 ppb or less and the conductivity is controlled to 1 μS / cm or less. 14. A measuring system for measuring the concentration, conductivity, and pH of the photocatalyst and impurities in the reactor water is provided in order to meet the criteria of claims 11 to 13 by the method according to claim 6. The method for forming a photocatalyst film of a reactor structural material according to claim 6, wherein the data of the measurement system is fed back to the control system of the injection system, temperature, flow rate, flow path, and purification system flow rate. 15. The reactor water according to claim 6, wherein the reactor water is sampled, a test piece is immersed in the sampled reactor water, and the adhering amount of the photocatalyst on the test piece is measured by an injection system, a temperature, a flow rate, and a flow path. The method for forming a photocatalyst film of a nuclear reactor structural material according to claim 6, which is fed back to a control system having the above.