JP2012247322A - Method for forming platinum film on plant component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently forming a platinum film on a nuclear reactor component and a ferrite film surface in succession with chemical decontamination.SOLUTION: A feature of this invention is to bring film formation solution containing a platinum ion and a reducer into contact with the surface of a plant component after stopping the operation of the plant having the component and before start of the operation of the plant, so that a platinum film is formed on the surface of the plant component.

Description

  The present invention relates to a method for forming a platinum film on a plant component, and more particularly to a method for forming a platinum film on a plant component suitable for application to a boiling water nuclear power plant.

  As power plants, for example, boiling water nuclear power plants (hereinafter referred to as BWR plants) and pressurized water nuclear power plants (hereinafter referred to as PWR plants) are known. For example, a BWR plant has a nuclear reactor with a core built in a reactor pressure vessel (referred to as RPV). Cooling water supplied to the core by the recirculation pump (or internal pump) is heated by heat generated by nuclear fission of nuclear fuel material in the fuel assembly loaded in the core, and a part thereof becomes steam. This steam is led from the nuclear reactor to the turbine and rotates the turbine. The steam exhausted from the turbine is condensed in a condenser to become water. This water is supplied to the reactor as feed water. In order to suppress the generation of radioactive corrosion products in the nuclear reactor, metal impurities are mainly removed by a filtration and desalination apparatus provided in the water supply pipe.

  In a power plant such as a BWR plant and a PWR plant, a main component such as a reactor pressure vessel uses stainless steel, a nickel-based alloy, or the like for a water contact portion in contact with water in order to suppress corrosion. In addition, components such as the reactor coolant purification system, residual heat removal system, reactor isolation cooling system, core spray system, feed water system and condensate system are used from the viewpoint of reducing the cost required for manufacturing the plant, Carbon steel members are mainly used from the viewpoint of avoiding stress corrosion cracking of stainless steel caused by high-temperature water flowing in the water system.

  In addition, since corrosion products that are the source of radioactive corrosion products are also generated from water contact parts such as RPV and recirculation piping, the primary primary components are made of stainless steel and nickel bases with low corrosion. Stainless steel such as alloy is used. In addition, the low alloy steel RPV has a stainless steel overlay on the inner surface, preventing the low alloy steel from coming into direct contact with the reactor water (cooling water present in the RPV). Reactor water is cooling water present in the nuclear reactor. Furthermore, a part of the reactor water is purified by a filter demineralizer of the reactor purification system, and metal impurities that are slightly present in the reactor water are positively removed.

  Even if the above-mentioned corrosion countermeasures are taken, it is inevitable that very few metal impurities remain in the reactor water, so some metal impurities adhere to the surface of the fuel rods included in the fuel assembly as metal oxides. To do. Metal impurities (for example, metal elements) adhering to the fuel rod surface cause a nuclear reaction by irradiation of neutrons generated by fission of nuclear fuel material in the fuel rod, and radioactive materials such as cobalt 60, cobalt 58, chromium 51, manganese 54, etc. Become a nuclide. Most of these radionuclides remain attached to the fuel rod surface in the form of oxides, but some radionuclides elute as ions in the reactor water depending on the solubility of the incorporated oxides. Or re-released into the reactor water as an insoluble solid called clad. The radioactive material contained in the reactor water is removed by the reactor purification system. However, the radioactive material that has not been removed accumulates on the surface of the constituent members of the BWR plant that come into contact with the reactor water while circulating in the recirculation system together with the reactor water. As a result, radiation is radiated from the surface of the component member, which causes radiation exposure of workers during regular inspection work. The exposure dose of the employee is managed so that it does not exceed the prescribed value for each person. In recent years, this regulation value has been lowered, and it has become necessary to make the exposure dose of each person as low as economically possible.

  Thus, various methods for reducing the adhesion of radionuclides to piping and methods for reducing the concentration of radionuclides in the reactor water have been studied. For example, by injecting metal ions such as zinc into the reactor water, and forming a dense oxide film containing zinc on the inner surface of the recirculation piping that contacts the reactor water, cobalt 60 and cobalt 58 in the oxide film, etc. Has been proposed (see Japanese Patent Laid-Open No. 58-79196).

  Moreover, after chemical decontamination, by forming a magnetite film as a ferrite film on the surface of a component of a nuclear power plant, a method for suppressing the attachment of radionuclides to the surface of the component after the operation of the plant is disclosed in Japanese Patent Application Laid-Open No. 2006-2006. -38483 and Japanese Patent Application Laid-Open No. 2007-192745. In this method, a formic acid aqueous solution containing iron (II) ions, hydrogen peroxide and hydrazine, and a treatment liquid heated to a temperature ranging from room temperature to 100 ° C. are brought into contact with the surface of the component member to form a ferrite film on the surface. To form. Furthermore, a method has been proposed in which a nickel ferrite film or zinc ferrite film, which is more stable than a magnetite film, is formed on the surface of a component of a nuclear power plant and the radionuclide is further prevented from adhering to the surface of the component after the operation of the plant. ing.

In order to suppress stress corrosion cracking of components of nuclear power plants, zinc containing chromite (ZnCr ₂ O ₄ ) and chromium oxide (Cr ₂ O ₃ ) is mixed on the surface of the component that contacts the cooling water The formation of a complex oxide layer of chromium is described in Japanese Patent Application Laid-Open No. 2001-91688.

Japanese Patent Laid-Open No. 2000-352597 describes stabilizing Cr contained in a component of a nuclear power plant. This stabilization of Cr alleviates the stress corrosion cracking susceptibility of the component, We are trying to suppress corrosion. The suppression of corrosion can reduce the exposure dose during periodic inspection. The Cr stabilization proposes to form a compound in the form of MCr ₂ O ₄ (M is a mixture of one or more of Zn, Ni, Fe and Co) on the surface of the component. . As a method for forming MCr ₂ O ₄ , for example, FeCr ₂ O _{4 on} the surface of the constituent member, one or more of plating, painting, lining, pardon, plating, prefilming, and polishing surface treatment are used.

At the nuclear power plant, a technique of injecting platinum into the nuclear reactor is applied to suppress the development of stress corrosion cracking. In this platinum injection technology, platinum is injected into the cooling water in the nuclear reactor to maintain the surface of the nuclear plant components that are in contact with the cooling water in a strongly reducing environment, and to promote the development of stress corrosion cracking in the components. Suppress. However, the hydrogen injection technique can suppress the development of stress corrosion cracking in the component by keeping the surface of the component in a strong reducing environment, but the surface of the component has an oxide film that easily incorporates ⁶⁰ Co. It has been reported that it is easily formed. For this reason, there is a risk of an increase in the radiation dose of periodic inspection workers.

JP 58-79196 A JP 2006-38483 A JP 2007-182604 A JP 2007-192745 A JP 2001-91688 A JP 2000-352597 A

proceedings of water chemistry 2004, p1054-1059.

As a method of forming platinum on the pipe surface of a nuclear power plant, a method of injecting a platinum complex from a water supply pipe after starting a nuclear reactor has been implemented (Non-Patent Document 1). In addition, by maintaining the surface of the nuclear reactor component in a strongly reducing environment with platinum, the development of stress corrosion cracking in the component can be suppressed, but an oxide film that easily incorporates ⁶⁰ Co is formed on the surface of the component. It has been reported that it becomes easier. For this reason, there is a risk of an increase in the radiation dose of periodic inspection workers.

It is described in JP 2006-38483 A, JP 2007-182604 A, and JP 2007-192745 A, in which a dense ferrite film is formed on the surface of a nuclear plant component to suppress the amount of ⁶⁰ Co adhesion. The method for forming a ferrite film is to form iron film (II), which is a film forming liquid that is brought into contact with the surface of a constituent member of a nuclear power plant when forming a ferrite film on the surface of the constituent member of a nuclear power plant. including solution, and addition of an oxidizing agent and a pH adjusting agent in turn, further describes that forming the platinum ferrite film surface by introducing an agent comprising a platinum ion, ⁶⁰ Co with reducing stress corrosion cracking of the piping It is described that the amount of adhesion is suppressed.

  The inventors have studied in detail a method of forming platinum suitable for application to a component of a nuclear power plant and the surface of a ferrite film. As a result, it was discovered that a platinum film can be formed efficiently if a platinum film is formed in succession to chemical decontamination of the reactor components and the ferrite film surface during the plant shutdown period.

  An object of the present invention is to provide a method for efficiently forming a platinum coating on the surface of a nuclear reactor component and a ferrite coating continuously following chemical decontamination.

  The feature of the present invention that achieves the above-described object is that the film forming liquid containing platinum ions and a reducing agent is brought into contact with the surface of the plant component after the plant having the plant component is stopped and before the operation of the plant is started. And forming a platinum film on the surface of the plant component.

  ADVANTAGE OF THE INVENTION According to this invention, the method of forming a platinum membrane | film | coat efficiently on a reactor structural member and a ferrite membrane | film | coat surface can be provided continuously following chemical decontamination.

It is a flowchart which shows the procedure of the ferrite film formation method to the plant structural member of Example 1 applied to the recirculation system piping of a BWR plant which is one suitable Example of this invention. It is explanatory drawing which shows the state which connected the film forming apparatus used when implementing the platinum film forming method to the plant structural member shown in FIG. 1 to the recirculation system piping of a BWR plant. It is a detailed block diagram of the film forming apparatus shown in FIG. It is the cross-sectional image of a film | membrane at the time of forming a platinum film | membrane on the stainless steel member surface, and the result of a composition analysis. It is the result of the cross-sectional image and composition analysis of the test piece which formed the platinum film on the stainless steel surface in which the ferrite film was formed. It is a relative comparison of the platinum film formation amount by the conventional method and this invention. It is explanatory drawing which shows the adhesion state of the radionuclide to the test piece which formed the platinum membrane | film | coat on the untreated and the test piece which formed the platinum membrane | film | coat on the stainless steel surface which formed the platinum membrane | film | coat in the stainless steel surface. It is a flowchart which shows the procedure of the ferrite film formation method to the plant structural member of Example 2 applied to a BWR plant which is another Example of this invention. It is a flowchart which shows the procedure of the ferrite film formation method to the plant structural member of Example 3 applied to a BWR plant which is another Example of this invention. It is a detailed block diagram of the membrane | film | coat formation apparatus used for the ferrite membrane | film formation method to the plant structural member shown in FIG.

  The inventors have made a detailed examination of the platinum formation mechanism at 280 ° C. in the conventional noble metal injection for forming platinum on the surface of the component of the nuclear power plant. As a result, it was found that platinum ions were reduced on the reactor constituent member and the ferrite film surface to form platinum. Thus, as a result of various studies on methods for reducing platinum ions even at a low temperature of 100 ° C. or lower, the inventors have found that platinum can be obtained by bringing a chemical containing platinum ions and a reducing agent into contact with the surface of a nuclear plant component at the same time. I understood that it can be formed. It has also been found that platinum can be formed into a dense film by reducing platinum ions more efficiently than before. Therefore, the above-described nuclear reactor constituent members and platinum film formation methods on the ferrite film surface were studied.

  The inventors considered that platinum can be formed based on the reaction of formula (1) by bringing a first agent containing platinum ions and a second agent containing a reducing agent into contact with the surface of the nuclear reactor component.

Pt ²⁺ + 2e ^2- → Pt …… (1)
Accordingly, the inventors have used a film-forming solution containing a first agent containing platinum ions and a second agent containing a reducing agent as a test piece made of stainless steel simulating stainless steel components of a nuclear power plant. An experiment was made to form a platinum film on the surface and the stainless steel surface on which the ferrite film was formed.

The inventors have made a film-forming solution produced by adding a first drug containing platinum ions and a second drug containing a reducing agent to water, and made of stainless steel simulating stainless steel components of a nuclear power plant. The test piece was brought into contact with the surface, and a platinum film was formed on this surface. The inventors performed electron microscope observation and composition analysis of the platinum film formed on the surface of the test piece after the film formation (FIG. 4). As a result, it was confirmed that platinum was formed into a dense film. In addition, a ferrite film was formed on the surface of a stainless steel specimen simulating a stainless steel component of a nuclear power plant, and an electron microscope observation and composition analysis of the specimen formed with a platinum film on the surface of this ferrite film Performed (FIG. 5). It was confirmed that a dense ferrite film and a platinum film were formed simultaneously. As described above, formation of a dense platinum film could be confirmed by adding a film-forming solution containing platinum and a reducing agent. FIG. 6 shows the relative value of the platinum film formation amount according to the conventional method and the present invention. The present invention has made it possible to form a film about 9 times as much as the conventional method. Furthermore, the inventors confirmed the effect of inhibiting the adhesion of radioactivity on the stainless steel test piece on which stainless steel and a ferrite film were formed by experiments. The obtained corrosion inhibition effect will be described with reference to FIG. The vertical axis in FIG. 7 shows the relative value of the amount of ⁶⁰ Co deposited. The adhesion of radioactivity to both the untreated test piece and the stainless steel test piece formed with a platinum film on the surface of the ferrite film is suppressed. That is, by forming platinum in a film shape, it was possible to suppress not only the stainless steel test piece on which the ferrite film was formed but also the amount of ⁶⁰ Co attached to the stainless steel test piece.

  A method for forming a platinum film on a plant component of Example 1 applied to a recirculation system piping of a BWR plant, which is a preferred embodiment of the present invention, will be described with reference to FIGS. Here, the platinum film is formed continuously after chemical decontamination and ferrite film formation.

  As shown in FIG. 2, the BWR plant, which is a nuclear power plant, includes a reactor 1, a turbine 3, a condenser 4, a recirculation system, a reactor purification system, a water supply system, and the like. The nuclear reactor 1 has a nuclear reactor pressure vessel (hereinafter referred to as RPV) 12 in which a core 13 is built, and a jet pump 14 is installed in the RPV 12. The core 13 is loaded with a large number of fuel assemblies (not shown). The fuel assembly includes a plurality of fuel rods filled with a plurality of fuel pellets made of nuclear fuel material. The recirculation system includes a stainless steel recirculation pipe 22 and a recirculation pump 21 installed in the recirculation pipe 22. The water supply system includes a condensate pump 5, a condensate purification device (for example, a condensate demineralizer) 6, a low-pressure feed water heater 8, a feed water pump 7, and a high-pressure feed water in a feed water pipe 10 that connects the condenser 4 and the RPV 12. The heater 9 is installed from the condenser 4 toward the RPV 12 in this order. In the reactor purification system, a purification system pipe 24 that connects the recirculation system pipe 22 and the feed water pipe 10 is connected to a purification system pump 24, a regenerative heat exchanger 25, a non-regenerative heat exchanger 26, and a reactor water purification device 27 in this order. It is installed. The purification system pipe 20 is connected to the recirculation system pipe 22 upstream of the recirculation pump 21. The nuclear reactor 1 is installed in a nuclear reactor containment vessel 11 arranged in a nuclear reactor building (not shown).

  The cooling water in the RPV 12 is boosted by the recirculation pump 21, and jetted into the jet pump 14 through the recirculation system pipe 22. Cooling water existing around the nozzles of the jet pump 14 is also sucked into the jet pump 14 and supplied to the core 13. The cooling water supplied to the core 13 is heated by the heat generated by the nuclear fission of the nuclear fuel material in the fuel rod, and a part of the heated cooling water becomes steam. This steam is guided to the turbine 3 from the RPV 12 through the main steam pipe 2 after moisture is removed by a steam separator (not shown) and a steam dryer (not shown) provided in the RPV 12. The turbine 3 is rotated. A generator (not shown) connected to the turbine 3 rotates to generate electric power.

  The steam discharged from the turbine 3 is condensed by the condenser 4 to become water. This water is supplied into the RPV 12 through the water supply pipe 10 as water supply. The feed water flowing through the feed water pipe 10 is boosted by the condensate pump 5, impurities are removed by the condensate purification device 6, and further boosted by the feed water pump 7. The feed water is heated by the low pressure feed water heater 8 and the high pressure feed water heater 9 and guided into the RPV 12. Extracted steam extracted from the turbine 3 through the extracted piping is supplied to the low-pressure feed water heater 8 and the high-pressure feed water heater 9, respectively, and serves as a heating source for the feed water.

  A part of the cooling water flowing in the recirculation system pipe 22 flows into the purification system pipe 20 of the reactor purification system by driving the purification system pump 24 and is cooled by the regenerative heat exchanger 25 and the non-regenerative heat exchanger 26. Then, the water is purified by the reactor water purification device 27. The purified cooling water is heated by the regenerative heat exchanger 25 and returned to the RPV 12 through the purification system pipe 20 and the water supply pipe 10.

  Within the operation stop period of the BWR plant after the operation of the BWR plant is stopped, both ends of the circulation pipes (film forming liquid pipes) 35 of the film forming apparatus 30 which is temporary equipment are made of stainless steel recirculation pipes 22. Connected to. The operation of connecting the circulation pipe 35 to the recirculation system pipe 22 will be specifically described. After the operation of the BWR plant is stopped, for example, the bonnet of the valve 23 installed in the purification system pipe 20 connected to the recirculation system pipe 22 is opened to block the purification system pump 24 side. One end of the circulation pipe 35 of the film forming apparatus 30 is connected to the flange of the valve 23. Thus, one end of the circulation pipe 35 is connected to the recirculation system pipe 22 upstream of the recirculation system pump 21. On the other hand, a branch pipe such as a drain pipe or an instrumentation pipe connected to the recirculation system pipe 22 on the downstream side of the recirculation pump 21 is cut off, and in addition to the circulation pipe 35 of the film forming apparatus 30, the branch pipe is cut off. Connect the ends. By connecting both ends of the circulation pipe 35 to the recirculation pipe 22, a closed loop including the recirculation pipe 22 and the circulation pipe 35 is formed. Each opening in the RPV 12 at both ends of the recirculation system pipe 22 is sealed with a plug (not shown) so that the film forming liquid does not flow into the RPV 12. The film forming apparatus 30 has a ferrite and platinum film formed on the inner surface of the recirculation piping 22, and after the processing of the film forming liquid used for forming these films is completed and within the operation stop period of the BWR plant, It is removed from the recirculation piping 22. Thereafter, the operation of the BWR plant is started.

  The film forming apparatus 30 is used for both the formation of a platinum and ferrite film on the inner surface of the recirculation pipe 22 and the treatment of the film forming liquid used for forming this film. Furthermore, the film forming apparatus 30 is also used when chemical decontamination of the inner surface of the recirculation system pipe 22 is performed. The film forming apparatus 30 connected to the recirculation piping 22 is disposed in the reactor containment vessel 11 which is a radiation management area in the BWR plant.

  In this embodiment, the recirculation system pipe 22 is a film formation target. However, when each pipe of the water supply system, the coolant purification system, and the auxiliary machine cooling water system is a film formation target, the corresponding film formation is performed. A circulation pipe 35 is connected to the piping system of the object.

  A detailed configuration of the film forming apparatus 30 will be described with reference to FIG. The film forming apparatus 30 includes a surge tank 31, a circulation pipe 35, an iron (II) ion implanter 88, an oxidant implanter 86, a pH adjuster implanter 87, a platinum ion implanter 85, a filter 51, a heater 53, and a decomposition. An apparatus 64 and a cation exchange resin tower 60 are provided.

  The on-off valve 47, the circulation pump 48, the valve 49, the heater 53, the valves 55, 56 and 57, the surge tank 31, the circulation pump 32, the valve 33 and the on-off valve 34 are provided in the circulation pipe 35 in this order from the upstream. . A valve 50 and a filter 51 are installed in a pipe 71 that bypasses the valve 49 and is connected to the circulation pipe 35. A pipe 66 that bypasses the heater 53 and the valve 55 is connected to the circulation pipe 35, and a cooler 58 and a valve 59 are installed in the pipe 66. A cation exchange resin tower 60 and a valve 61 are installed in a pipe 67 having both ends connected to the circulation pipe 35 and bypassing the valve 56. A mixed bed resin tower 62 and a valve 63 are installed in a pipe 68 having both ends connected to the pipe 67 and bypassing the cation exchange resin tower 60 and the valve 61.

  A pipe 69 in which the valve 65 and the decomposition device 64 are installed bypasses the valve 57 and is connected to the circulation pipe 35. The decomposition apparatus 64 is filled with, for example, an activated carbon catalyst in which ruthenium is impregnated on the surface of the activated carbon. A surge tank 31 is installed in the circulation pipe 35 between the valve 57 and the circulation pump 32. A pipe 70 provided with the valve 36 and the ejector 37 is connected to the circulation pipe 35 between the valve 33 and the circulation pump 32, and further connected to the surge tank 31. Potassium permanganate (oxidative decontamination agent) used to oxidize and dissolve contaminants on the inner surface of the recirculation system pipe 22, and oxalic acid used to reduce and dissolve contaminants on the inner surface of the recirculation system pipe 22 ( A hopper (not shown) for supplying a reductive decontamination agent) into the surge tank 31 is provided in the ejector 37.

  The iron (II) ion implanter 88 includes a chemical tank 45, an injection pump 43, and an injection pipe 72. The chemical tank 45 is connected to the circulation pipe 35 by an injection pipe 72 having an injection pump 43 and a valve 41. The chemical solution tank 45 is filled with a drug (fourth drug) containing divalent iron (II) ions prepared by dissolving iron with formic acid. This drug contains formic acid. In addition, as a chemical | medical agent which dissolves iron, the carboxylic acid or carbonic acid which becomes a counter anion of iron (II) ion can be used not only formic acid. As a carboxylic acid other than formic acid that dissolves iron, oxalic acid or malonic acid may be used.

  The oxidant injector 86 includes a chemical tank 46, an injection pump 44, and an injection pipe 73. The chemical tank 46 is connected to the circulation pipe 35 by an injection pipe 73 having an injection pump 44 and a valve 42. The chemical tank 46 is filled with hydrogen peroxide which is an oxidizing agent (third chemical).

  The pH adjusting agent injection device 87 has a chemical tank 40, an injection pump 39 and an injection pipe 74. The chemical tank 40 is connected to the circulation pipe 35 by an injection pipe 74 having an injection pump 39 and a valve 38. The chemical tank 40 is filled with hydrazine which is a pH adjuster (second drug).

  The platinum ion implantation apparatus 85 includes a chemical tank 80, an injection pump 81, and an injection pipe 83. The chemical tank 80 is connected to the circulation pipe 35 by an injection pipe 83 having an injection pump 81 and a valve 82. The chemical tank 80 is filled with a drug (first drug) containing platinum ions prepared by dissolving a platinum complex in water.

  In the present embodiment, the first connection point (connection point between the injection pipe 83 and the circulation pipe 35) 84 to the circulation pipe 35 of the platinum ion implantation apparatus 85 and the second connection point to the circulation pipe 35 of the iron (II) ion implantation apparatus 88. A connection point (connection point between the injection pipe 72 and the circulation pipe 35) 78, a third connection point (connection point between the injection pipe 73 and the circulation pipe 35) 79 to the circulation pipe 35 of the oxidant injection device 86, and pH adjusting agent injection Of the fourth connection points (connection points between the injection pipe 74 and the circulation pipe 35) 77 to the circulation pipe 35 of the device 87, it is preferable that the fourth connection point 77 is arranged at a position as close as possible to the film formation target.

  The decomposition apparatus 64 can decompose carboxylic acid (for example, formic acid) used as a counter anion of iron (II) ions and hydrazine as a pH adjusting agent. That is, as the counter anion of the iron (II) ion, carboxylic acid that can be decomposed into water and carbon dioxide in consideration of reduction of the amount of waste, or carbonic acid that can be released as a gas and does not increase waste is used.

  The platinum film formation method in a present Example is demonstrated in detail using FIG. Since the platinum film is continuously formed after the chemical decontamination and the formation of the ferrite film, the procedure shown in FIG. 1 is not only the formation of the platinum film, but also the film formation used for the chemical decontamination and the film formation. It also includes a procedure for treating a liquid (for example, a film-forming aqueous solution). First, the film forming apparatus 30 is connected to the piping system to be coated (Step S1). That is, in the BWR plant operation stop period after the operation of the BWR plant is stopped for the periodic inspection of the BWR plant, as described above, the recirculation system pipe in which the circulation pipe 35 is the pipe system of the film formation target. (Nuclear plant component) 22.

  Chemical decontamination is performed on the film formation target portion (step S2). In the BWR plant that has undergone operation, an oxide film is formed on the inner surface of the recirculation piping 22 that is in contact with cooling water (hereinafter referred to as reactor water) in the RPV 12. In the BWR plant, this oxide film contains a radionuclide. An example of step S2 is a process of removing the oxide film from the inner surface of the recirculation system pipe 22 that is a film formation target by a chemical process. The formation of platinum and ferrite films on the piping system of the film formation target is intended to suppress the adhesion of radionuclides and the stress corrosion cracks on the inner surface of the recirculation system piping. It is preferable to carry out chemical decontamination on the inner surface of the circulation system pipe 22 in advance.

  The chemical decontamination applied in step S2 is a known method (see Japanese Patent Laid-Open No. 2000-105295), but will be briefly described. First, the valves 34, 33, 57, 56, 55, 49 and 47 are opened, and the circulation pumps 32 and 48 are driven with the other valves closed. Thereby, the water in the surge tank 31 is circulated in the closed loop of the circulation pipe 35 and the recirculation system pipe 22. The circulating water is heated by the heater 53, and the valve 36 is opened when the temperature of the water reaches 90 ° C. A necessary amount of potassium permanganate supplied from a hopper connected to the ejector 37 is guided into the surge tank 31 by water flowing in the pipe 70. Potassium permanganate is dissolved in water in the surge tank 31, and an oxidative decontamination solution (potassium permanganate aqueous solution) is generated. The oxidative decontamination liquid is supplied from the surge tank 31 through the circulation pipe 35 into the recirculation system pipe 22 by driving the circulation pump 32. The oxidative decontamination solution oxidizes and dissolves contaminants such as an oxide film formed on the inner surface of the recirculation pipe 22.

  After the oxidative decontamination is completed, oxalic acid is injected into the surge tank 31 from the hopper. This oxalic acid decomposes potassium permanganate contained in the oxidative decontamination solution. Thereafter, the reductive decontamination liquid (oxalic acid aqueous solution) generated in the surge tank 31 and adjusted in pH is supplied into the recirculation system pipe 22 by the circulation pump 32 and exists on the inner surface of the recirculation system pipe 22. Reduces and dissolves corrosion products. The pH of the reductive decontamination liquid is adjusted by hydrazine supplied from the chemical liquid tank 40 into the circulation pipe 35. A part of the reductive decontamination liquid discharged from the recirculation system pipe 22 and returned to the circulation pipe 35 is guided to the cation exchange resin tower 60 by a necessary valve operation in order to remove metal cations.

  After completion of the reductive decontamination, the valve 65 is opened to adjust the opening degree of the valve 57, and a part of the reductive decontamination liquid flowing in the circulation pipe 35 is supplied to the decomposition device 64. Oxalic acid and hydrazine contained in the reductive decontamination solution are decomposed by the action of hydrogen peroxide introduced from the chemical solution tank 46 to the decomposition device 64 through the pipe 75 and the activated carbon catalyst in the decomposition device 64. After decomposition of oxalic acid and hydrazine, the valve 55 is closed to stop the heating by the heater 53, and at the same time, the valve 59 is opened to cool the decontamination solution by the cooler 58. The cooled decontamination liquid (for example, 60 ° C.) is supplied to the mixed bed resin tower 62 in order to remove impurities.

  After the chemical decontamination of the recirculation system pipe 22 which is a constituent member of the nuclear power plant is completed, a ferrite film forming process is executed.

  After the decontamination of the film forming target is completed, the temperature of the film forming liquid is adjusted (step S3). After the decontamination of the film forming object, that is, after the final purification operation by the film forming apparatus 30 is completed, the following valve operation is performed. The valve 50 is opened, the valve 49 is closed, and water flow to the filter 51 is started. By opening the valve 56 and closing the valve 63, water flow to the mixed bed resin tower 62 is stopped. Further, the valve 55 is opened and the water in the circulation pipe 35 is heated to a predetermined temperature by the heater 53. Valves 47, 57, 33 and 34 are open and valves 36, 59, 61, 65, 38, 41, 42 and 82 are closed. Circulation pumps 32 and 48 are rotating. The flow of water through the filter 51 is to remove fine solids remaining in the water, and to prevent the use of chemicals due to the formation of a ferrite film on the surface of the solids. In addition, when the film forming solution is supplied to the filter 51 during chemical cleaning, the pressure loss of the filter may be increased due to hydroxide caused by high-concentration iron generated by dissolution. Absent.

  In the present embodiment, the temperature of the film forming liquid is adjusted to 75 ° C. by the heater 53 and maintained at this temperature while the film is formed on the inner surface of the recirculation pipe 22. However, the temperature of the film forming liquid is not limited to that temperature. In short, it is only necessary that the ferrite film can be formed and the film structure such as crystals of the film can be densely formed to such an extent that corrosion of the recirculation piping 22 which is a constituent member during the operation of the nuclear reactor can be suppressed. Therefore, the temperature of the film-forming solution is preferably 100 ° C. or lower, and the lower limit may be 20 ° C., but 60 ° C. or higher is preferable because the ferrite film formation rate is within the practical range. Therefore, it is desirable to adjust the temperature of the film forming solution in the film forming process to a temperature within the range of 60 ° C. to 100 ° C. by controlling the heater 53.

  After each chemical decontamination is completed and before each of the chemicals described below is injected into the circulation pipe 35, the liquid supplied from the circulation pipe 35 to the recirculation system pipe 22 is water that becomes a film-forming liquid by the injection of each chemical. is there.

  In order not to oxidize iron (II) ions contained in the fourth agent to produce ferric hydroxide, it is necessary to remove dissolved oxygen in the film forming solution. For this reason, it is preferable to perform bubbling of inert gas or vacuum deaeration in the surge tank 31 and the chemical solution tank 45. The formation of the ferrite film in step 4 is also a known method, but will be briefly described.

  A chemical solution (fourth drug) containing iron (II) ions is injected into the film-forming solution. The valve 41 is opened to drive the injection pump 43, and the chemical liquid (fourth chemical) containing iron (II) ions and formic acid flows from the chemical liquid tank 45 through the injection pipe 72 and through the circulation pipe 35. Injected into the forming solution. The fourth drug to be injected here contains, for example, iron (II) ions prepared by dissolving iron with formic acid and this formic acid. Part of the injected iron (II) ions becomes ferrous hydroxide in the film forming solution.

  An oxidizing agent (third agent) is injected into the film forming solution. The valve 42 is opened to drive the injection pump 44, and the hydrogen peroxide as the oxidant is supplied from the chemical tank 46 through the injection pipe 73 to the iron (II) ions and ferrous hydroxide flowing in the circulation pipe 35. Inject into the film forming solution. As the oxidizing agent, in addition to hydrogen peroxide, a chemical in which ozone or oxygen is dissolved may be used.

  A pH adjuster (second drug) is injected into the film forming solution. By opening the valve 38 and driving the injection pump 39, a pH adjusting agent (for example, hydrazine) is injected from the chemical liquid tank 40 into the film forming liquid flowing through the circulation pipe 35 through the injection pipe 74. The pH meter 76 measures the pH of the film forming liquid flowing through the circulation pipe 35. A control device (not shown) controls the rotational speed of the injection pump 39 (or the opening degree of the valve 38) based on the measured pH value to adjust the injection amount of hydrazine, thereby adjusting the pH of the film forming solution to 5. Within the range greater than 0.5 and less than 9.0, for example, it is adjusted to 7.0. That is, the pH of the film-forming solution which is an aqueous solution containing hydrazine, iron (II) ions, ferrous hydroxide, formic acid and hydrogen peroxide is adjusted to 7.0.

  A film forming liquid containing iron (II) ions, ferrous hydroxide and hydrogen peroxide whose pH is adjusted to 7.0 with hydrazine and the temperature is 90 ° C. flows through the recirculation system pipe 22 and is recirculated. Since it contacts the inner surface of the system pipe 22, the iron (II) ions and ferrous hydroxide contained in the film forming liquid are adsorbed on the inner surface of the recirculation system pipe 22 which is a component of the nuclear power plant, Ferrite is formed by the action of hydrogen oxide. As a result, a ferrite film is formed on the inner surface of the recirculation pipe 22. Hydrogen peroxide contained in the film forming liquid causes a reaction to oxidize and ferritize iron (II) ions and ferrous hydroxide adsorbed on the inner surface of the recirculation system pipe 22. Since the pH of the film-forming solution is adjusted to 7.0 that causes the ferrite film formation reaction to proceed with hydrazine, a ferrite film is formed on the inner surface of the recirculation system pipe 22 as described above.

  Since the circulation pumps 32 and 48 are driven, the film forming liquid containing hydrazine, iron (II) ions, ferrous hydroxide and hydrogen peroxide is recirculated through the open / close valve 34 by the circulation pipe 35. It is supplied into the pipe 22. This film forming liquid flows through the recirculation pipe 22 and is returned to the valve 47 side of the circulation pipe 35. When a film-forming liquid (for example, a film-forming aqueous solution) comes into contact with the inner surface of the recirculation system pipe 22, iron (II) ions and ferrous hydroxide are adsorbed on the inner surface of the recirculation system pipe 22 that is a member. Since the adsorbed iron (II) ion and ferrous hydroxide are ferritized by hydrogen peroxide and the pH is 7.0 due to the action of hydrazine, a ferrite film is formed on the inner surface of the recirculation pipe 22. It is formed on the inner surface of the recirculation pipe 22.

  By carrying out this step, a chemical solution containing iron (II) ions, hydrogen peroxide and hydrazine are injected into the film forming solution. The injection of each drug is preferably performed continuously.

  After the formation of the ferrite film is completed, the formation of the Pt film is started as step 5. Specifically, an aqueous solution containing platinum ions is injected from an injection point 84 by starting an injection pump 81 and opening a valve 82 from a chemical tank 80 containing platinum ions obtained by dissolving a platinum complex with water. Thereafter, as step 6, hydrazine, which is a pH adjusting agent contained in the chemical tank 40, is added to the film forming liquid by opening the valve 38 and starting the injection pump 39, thereby forming a Pt film. Here, since hydrazine, which is a pH adjusting agent, is also known as a reducing agent, the pH adjusting agent used in decontamination and film formation can also be used as a reducing agent. Thereafter, the formation of ferrite and pt film is determined (step S7). This determination is made based on the elapsed time from the start of the ferrite film formation process to the end of the pt film process. Until this elapsed time reaches the time required to form the ferrite film and the platinum film having a predetermined thickness on the inner surface of the recirculation pipe 22, the determination in step S7 is "NO". Steps S4 to S6 are repeated. When the determination in step S7 is “YES”, the control device (not shown) stops the infusion pumps 39, 43, 44, and 81 (or closes the valves 38, 41, 42, and 82). The injection into the circulating film forming solution is stopped. Thus, the platinum and ferrite film forming work on the inner surface of the recirculation pipe 22 is completed. A ferrite and platinum film having a predetermined thickness is formed over the entire inner surface of the recirculation pipe 22 in contact with the film forming liquid.

  Thereafter, the medicine contained in the film forming liquid is decomposed (step S8). The film forming liquid used for forming the ferrite film containing chromium on the inner surface of the recirculation pipe 22 contains hydrazine and formic acid which is an organic acid even after the formation of the ferrite film containing chromium is completed. . Hydrazine and formic acid, which are drugs contained in the film-forming solution, are decomposed by the decomposition device 64 in the same manner as oxalic acid, which is a reducing decontamination agent. In the decomposition treatment of each drug contained in the film forming liquid, the opening degree of the valves 57 and 65 is adjusted, and a part of the film forming liquid in the circulation pipe 35 is supplied to the decomposition apparatus 64. By opening the valve 54, hydrogen peroxide is supplied from the chemical tank 46 through the pipe 75 to the decomposition device 64. Hydrazine and formic acid are decomposed in the decomposition apparatus 64 by the action of hydrogen peroxide and activated carbon catalyst. Hydrazine decomposes into nitrogen and water, and formic acid decomposes into carbon dioxide and water. After the decomposition of each chemical contained in the film forming liquid is completed, the circulation pipe 35 is removed from the recirculation system pipe 22, and the valve 28 and the like are restored to their original positions. Thereby, the operation of the BWR plant can be started.

  An ultraviolet irradiation device can be used instead of the decomposition device 64 using a catalyst. An ultraviolet irradiation device can also decompose hydrazine, formic acid and oxalic acid in the presence of an oxidizing agent.

  A method for forming a platinum film on a plant constituent member of Example 2 applied to a recirculation piping of a BWR plant which is another example of the present invention will be described with reference to FIGS. This example differs from Example 1 in that it includes a step of collecting ferrite particles floating in the film forming liquid after chemical decontamination and forming a ferrite film. In Example 1, fine particles of ferrite that did not become a film are floating in the film forming liquid after the film is formed. If Pt ions and a reducing agent are added to the film forming solution in this state, Pt is formed not only on the pipe surface but also on the surface of floating ferrite grains, and the use efficiency of Pt decreases. Therefore, the ferrite particles are collected using a filter before adding Pt ions to the film forming solution. Specifically, the film-forming liquid after film formation is opened through valve 50 and passed through filter 51 to remove floating ferrite particles, and then Pt ions and a reducing agent are added.

  A method for forming a Pt film on the recirculation piping of a BWR plant, which is another embodiment of the present invention, will be described with reference to FIGS.

  The method for forming a Pt film on a plant component according to this example differs from the other examples in that a Pt film is formed continuously after chemical decontamination. A film forming apparatus 30B shown in FIG. 10 is used. In the film forming apparatus 30B, the iron (II) ion implantation apparatus 88 is removed from the constituent elements of the film forming apparatus 30 used in the first embodiment.

  A method for forming a ferrite film on a plant constituent member of the present embodiment using the film forming apparatus 30B will be described based on the procedure shown in FIG. In step S1, the circulation pipe 35 of the film forming apparatus 30B is connected to the recirculation system pipe. At this time, the piping connection is at the same position as in the first embodiment. Thereafter, chemical decontamination in step S2 and temperature adjustment of the film forming liquid (or water) in step S3 are performed. In the chemical solution, first, Pt ions are implanted (step S4). A chemical solution containing a reducing agent is injected into the film forming solution (step S5).

  A film forming liquid containing platinum ions and hydrazine is introduced into the recirculation pipe through the circulation pipe 35 and a platinum film is formed on the inner surface of the pipe in contact with the film forming liquid.

  The platinum and ferrite film forming method on the plant constituent members of this embodiment is different from the above-described embodiments in that platinum and ferrite films are formed on the inner surface of the piping system of the newly installed BWR plant. In the present embodiment, any of the procedures except for the film forming apparatus used in Embodiment 1 and the chemical decontamination in Step S2 can be applied. The film forming apparatus 30 used in Example 1 and the film forming method of this example to which each procedure shown in FIG. 1 is applied will be described below.

  In the present embodiment, before the construction of the new BWR plant is completed and the trial operation of this BWR plant is started, the procedure shown in FIG. 1 (except step S2) is performed, for example, on the inner surface of the recirculation pipe 22. Form a platinum film.

  First, in the step S1, before the installation of the plant constituent member that is a film formation target in the newly installed BWR plant, for example, the recirculation system piping 22 that is a piping system is finished, and the trial operation of this BWR plant is started, Similar to the first embodiment, both ends of the circulation pipe 35 of the film forming apparatus 30 are connected to the recirculation system pipe 22 of the BWR plant. In the new BWR plant, since no radioactive substance is attached to the inner surface of the recirculation system pipe 22, it is not necessary to perform chemical decontamination on the recirculation system pipe 22. For this reason, this example does not carry out the chemical decontamination of step S2 of the procedure shown in FIG. 1, but heats the water (or film-forming liquid) in the circulation pipe 35 of step S3, thereby water (or film-forming liquid). ) Is adjusted to a temperature within the range of 60 ° C to 100 ° C.

  After the temperature increase in step S3 is completed, steps S4 to S5 are performed, and a drug containing platinum ions and hydrazine are sequentially injected into the circulation pipe 35. A film forming liquid containing platinum ions and hydrazine is supplied to the recirculation system pipe 22 and contacts the inner surface of the recirculation system pipe 22. When the film forming liquid comes into contact with the inner surface of the recirculation system pipe 22, a platinum film is formed on the inner surface of the recirculation system pipe 22. When the thickness of the platinum film formed on the inner surface of the recirculation system pipe 22 reaches a predetermined thickness, the determination in step S7 becomes “YES”, and the operation of forming the platinum film on the inner surface of the recirculation system pipe 22 is completed. To do. Thereafter, in step S8, formic acid and hydrazine contained in the film forming solution are decomposed by the decomposition device 64.

  In the present embodiment, each effect produced in the first embodiment can be obtained.

  The present embodiment can also be applied to a newly installed PWR plant and thermal power plant.

  The present invention can be applied to a nuclear power plant and a thermal power plant.

DESCRIPTION OF SYMBOLS 1 Reactor 3 Turbine 4 Condenser 10 Feed water piping 12 Reactor pressure vessel 20 Purification system piping 22 Recirculation system piping 30, 30A, 30B Film formation apparatus 31 Surge tank 32, 48 Circulation pump 35 Circulation piping 37 Ejectors 39, 43 , 44, 81, 91 Injection pump 40, 45, 46, 80 Chemical liquid tank 51 Filter 53 Heater 58 Cooler 60 Cation exchange resin tower 62 Mixed bed resin tower 64 Decomposition apparatus 72, 73, 74, 83 Injection pipe 76 pH meter 85 Platinum ion implanter 86 Oxidant implanter 87 pH adjuster injector 88 Iron (II) ion implanter

Claims (10)

  After the operation of the plant having the plant component is stopped and before the operation of the plant is started, a film forming liquid containing platinum ions and a reducing agent is brought into contact with the surface of the plant component, and platinum is applied to the surface of the plant component. A method for forming a platinum film on a plant component, comprising forming a film.   The method for forming a platinum film on a plant component according to claim 1, wherein the reducing agent contained in the film forming liquid is hydrazine.   A method for forming a platinum film on a plant constituent member, comprising forming a platinum film on the surface of the constituent member of the plant after chemical decontamination after the operation of the plant having the plant constituent member is stopped and before starting the operation of the plant. .   After the operation of the plant having the plant component is stopped and before the operation of the plant is started, a ferrite film is formed on the surface of the plant component after chemical decontamination, and a platinum film is formed thereon. A method for forming a platinum film on a plant component.   The temperature of the said film formation liquid which contacts the said surface of the said plant structural member is adjusted in the range of 60 to 100 degreeC, The platinum membrane | film | coat to the plant structural member of any one of Claim 1 thru | or 4 Forming method.   The method for forming a platinum film on a plant constituent member according to claim 1, wherein the contact of the film forming liquid with the surface of the plant constituent member is performed after chemical decontamination of the surface of the plant constituent member.   Before the first trial operation of the plant is started after the installation of the plant having the plant component that is the film formation target is completed, a film forming solution containing platinum ions and a reducing agent is applied to the surface of the plant component. A method for forming a platinum film on a plant constituent member, comprising: contacting the surface and forming a platinum film on the surface of the plant constituent member. After shutting down the plant having plant components and before starting the plant,
Connect the piping with the heating device to the piping system, which is a plant component,
A film forming liquid containing platinum ions and a reducing agent is supplied into the piping system through the piping,
A method for forming a platinum film on a plant component, wherein the film forming liquid is brought into contact with an inner surface of the piping system, and a platinum film is formed on the inner surface.   The method for forming a platinum film on a plant component according to claim 8, wherein a closed loop is formed by the piping system and the piping, and the film forming liquid circulates in the closed loop.   The said piping system which forms the said platinum membrane | film | coat is either a stainless steel piping system or a carbon steel piping system, The platinum membrane formation to the plant structural member of any one of Claim 8 thru | or 9 Method.