JP5557475B2 - Method and apparatus for forming ferrite film on members constituting nuclear power plant - Google Patents

Description

  The present invention relates to a method for forming a ferrite film containing zinc on a member constituting a nuclear power plant and a film forming apparatus therefor, and more particularly, a member suitable for application to a boiling water nuclear power plant and a pressurized water nuclear power plant. The present invention relates to a method for forming a ferrite film containing zinc and a film forming apparatus therefor.

  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 boiling water nuclear power plant (hereinafter abbreviated as a BWR plant) has a nuclear reactor with a reactor core built in a reactor pressure vessel (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, main components such as a reactor pressure vessel use 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 or low alloy steel is 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 to positively remove metal impurities that are slightly present in the reactor water.

  However, even if the above-described corrosion countermeasures are taken, the presence of very few metal impurities in the reactor water is inevitable, so some metal impurities are converted into metal oxides to the fuel rods contained in the fuel assembly. Adhere to the surface. Metal impurities (for example, metal elements) adhering to the surface of the fuel rod cause a nuclear reaction when irradiated with neutrons emitted from the nuclear fuel in the fuel rod, and become radioactive nuclides such as cobalt 60, cobalt 58, chromium 51, manganese 54, and the like. Become. 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. Radioactive material 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 component that contacts 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 worker 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).

  Further, a method for suppressing the attachment of radionuclides to the surface of a constituent member after the operation of the plant by forming a magnetite film as a ferrite film on the surface of the constituent member of the nuclear power plant after chemical decontamination is disclosed in Japanese Patent Application Laid-Open No. 2006-2006. No. 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. Further, there is a method for further suppressing the deposition of radionuclides on the surface of a constituent member after the operation of the plant by forming a nickel ferrite film that is more stable than the magnetite film or a ferrite film containing zinc on the surface of the nuclear plant constituent member. It is proposed in Japanese Patent Application Laid-Open No. 2008-304381.

JP 58-79196 A JP 2006-38483 A JP 2008-304381 A

  A zinc ferrite film forming method described in Japanese Patent Application Laid-Open No. 2008-304381 that forms a dense zinc ferrite film on the surface of a nuclear plant component member includes a first drug containing iron ions and zinc ions in an aqueous solution for film formation. The addition of the second drug, the third drug that oxidizes a part of iron ions to trivalent, and the fourth drug that controls the pH of the film forming solution to 5.5-9.0. The third drug and the fourth drug are performed in this order.

  The inventors have examined the formation of a zinc ferrite film on the surface of a nuclear plant component described in JP 2008-304381, and found that it takes time to form the zinc ferrite film.

  An object of the present invention is to provide a method for forming a ferrite film containing zinc on the surface of a nuclear power plant component that can further reduce the time required for forming a ferrite film containing zinc on the surface of the surface of the nuclear power plant component, and to form the film To provide an apparatus.

A feature of the present invention that achieves the above-described object is that a first agent containing iron (II) ions and an acid, a second agent containing zinc ions, and a second agent that oxidizes iron (II) ions to iron (IIIII) ions. Forming a film for forming a ferrite film containing zinc by adding a fourth drug for adjusting the pH of the film 3 and the film-forming solution to 5.5 or more and 9.0 or less after mixing in advance It is to produce a liquid.

  ADVANTAGE OF THE INVENTION According to this invention, the time which formation of the ferrite membrane | film | coat containing zinc on the surface of the nuclear power plant structural member which comprises a plant can further be shortened.

It is a flowchart which shows the procedure of the ferrite membrane | film | coat formation method containing the zinc to the nuclear power 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 a figure explaining the time-dependent change of the iron and zinc ion density | concentration at the time of the ferrite membrane | film | coat containing zinc. It is explanatory drawing which shows the difference in the ferrite film quantity containing zinc formed in the ferrite film formation method containing each zinc from which the injection | pouring order of a chemical | medical agent differs. It is a figure explaining the composition of the membrane | film | coat produced using the thin film X-ray diffraction method. It is a block diagram of the BWR plant which connected the film formation apparatus used for the ferrite film formation method containing the zinc to the nuclear power plant structural member shown in FIG. It is a detailed block diagram of the film formation apparatus shown in FIG. It is a block diagram of the membrane | film | coat formation apparatus used for the ferrite membrane | film | coat formation method containing the zinc to the nuclear power plant structural member of Example 2 applied to the feed water piping of a BWR plant which is another Example of this invention. It is a flowchart of the membrane | film | coat formation method of Example 3 which applies the crystal resonator microbalance method shown in Example 3 which is another Example of this invention. The detailed block diagram of the membrane | film | coat formation apparatus used for the formation method of the ferrite membrane | film | coat containing the zinc to the surface of the nuclear power plant structural member of Example 3 applied to the recirculation system piping of a BWR plant which is another Example of this invention. It is. The detailed block diagram of the membrane | film | coat formation apparatus used for the formation method of the ferrite membrane | film | coat containing the zinc to the surface of the nuclear power plant structural member of Example 4 applied to the recirculation system piping of a BWR plant which is another Example of this invention. It is. It is the schematic of the Co adhesion suppression method at the time of using together the injection method of the ferrite film formation method and zinc injection containing zinc which are other Examples of this invention. It is a system | strain block diagram at the time of using together the injection method of the ferrite film formation method and zinc injection containing zinc which are other Examples of this invention. It is a flowchart at the time of using together the injection method of the ferrite film formation method containing zinc which is another Example of this invention, and injection | pouring of a bivalent metal.

  The inventors of the present invention described in Japanese Patent Application Laid-Open No. 2008-304381 in detail, in order to ascertain the cause of the time required for forming the coating in the method of forming a ferrite coating containing zinc on the surface of the nuclear plant component. And experiments were performed. Hereinafter, the method described in Japanese Patent Application Laid-Open No. 2008-304381 will be referred to as Method A. FIG. 2 shows temporal changes in the iron ion and zinc ion concentrations in the film-forming solution when a film is formed by adding the chemicals in the order of addition in Method A. The concentrations of iron ions and zinc ions added at this time are 300 and 100 ppm, respectively. As shown in FIG. 2, the concentration of zinc ions added to the film forming solution decreased below the detection limit in about 10 minutes after the film formation. This result indicates that a large amount of floating zinc ferrite particles that did not form a film in the solution were deposited within 10 minutes after the addition of the drug. That is, in method A, a large amount of zinc ferrite formed is precipitated in the liquid, and the amount of zinc ferrite that contributes to film formation is small, so the growth rate of the ferrite film containing zinc is slow.

The inventors have devised a method that can suppress the precipitation of ferrite containing zinc in the film forming liquid and further reduce the time required for forming the nuclear plant component. The Gibbs free energy (-1064 KJ / mol) of ferrite containing zinc is smaller than the Gibbs free energy (-1015 KJ / mol) of magnetite. That is, ferrite containing zinc is easier to crystallize than magnetite. That is, in the conventional method A, it is considered that all the zinc ions crystallize and precipitate in the liquid as soon as the four types of chemicals are added. Therefore, all the chemicals are mixed to form a hydroxide (ZnFe ₂ (OH) ₈ ) containing iron and zinc ions, which are crystallized by the hydroxide dehydration reaction shown in chemical formula (1). It was thought that the crystallization speed could be reduced.

ZnFe ₂ (OH) ₈ → ZnFe ₂ O ₄ + 4H ₂ O Formula (1)
As a result of the examination described above, the inventors have previously prepared the first chemical, the second chemical, the third chemical, and the fourth chemical in water when forming the ferrite film containing zinc on the nuclear plant component. It has been newly found that it is sufficient to add after mixing. This method is hereinafter referred to as method B.

The inventors conducted an experiment to compare the amount of film (thickness of the film) formed by each of Method A and Method B. The amount of film formed by method A and method B is shown in FIG. As shown in FIG. 3, the amount of film formed by Method B was greater than the film formed by Method A. FIG. 4 shows the results of thin film X-ray diffraction of the film formed. Here, the vertical lines in FIG. 4 indicate the standard positions of ZnFe ₂ O ₄ and the base material. Since the standard position and the peak of the measurement result coincided, it was confirmed that the formed film was ZnFe ₂ O ₄ .

  The film forming apparatus for a ferrite film containing zinc according to the present invention includes a film forming liquid supply pipe for supplying the film forming liquid to a piping system to be formed, and iron injected into the film forming liquid in the film forming liquid supply pipe ( II) A first chemical tank for storing ions, a second chemical tank for storing a drug containing zinc ions to be injected into the film forming liquid of the film forming liquid supply pipe, and a film forming liquid for the film forming liquid supply pipe A third chemical tank for storing an oxidant to be injected into the film, a fourth chemical tank for storing a pH adjusting agent for adjusting the film forming liquid of the film forming liquid supply pipe to pH 5.5 to 9.0, The first medicine, the second medicine, the third medicine and the fourth medicine are mixed, a storage tank for storing the mixed liquid, a circulation pump for sucking the liquid mixture in the storage tank, and the mixing Temperature adjustment to adjust the temperature of the liquid to the range of 0 ℃ to 50 ℃ An apparatus and a heating means for heating the temperature of the film forming liquid to 60 ° C. to 100 ° C. are provided.

  An example of a method for forming a ferrite film on a suitable member constituting the power plant of the present invention reflecting the above-described examination results will be described with reference to the drawings.

  A method for forming a ferrite film containing zinc on a nuclear plant component of Example 1 applied to a water supply pipe of a BWR plant, which is a preferred embodiment of the present invention, will be described below with reference to FIGS. Explained.

  A 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. The recirculation system includes a recirculation system pipe 22 and a recirculation pump 21 installed in the recirculation system pipe 22. In the water supply system, a condensate pump 5, a condensate purification device 6, a feed water pump 7, a low-pressure feed water heater 8, and a high-pressure feed water heater 9 are installed in a feed water pipe 10 that connects the condenser 4 and the RPV 12. In the reactor purification system 20, a purification system pump 24, a regenerative heat exchanger 25, a non-regenerative heat exchanger 26, and a reactor water purification device 27 are installed in a purification system pipe 23 that connects the recirculation system pipe 22 and the water supply pipe 10. doing. The purification system pipe 23 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 fission of each fuel material in the fuel rod, and a part thereof becomes steam. This steam is guided from the RPV 12 through the main steam pipe 2 to the turbine 3 to rotate the turbine 3. 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, further boosted by the feed water pump 7, and heated by the low pressure feed water heater 8 and the high pressure feed water heater 9. . Extracted steam extracted from the main steam pipe 2 and the turbine 3 in the extracted pipe 15 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 23 by the drive of the purification system pump 24 and is purified by the reactor water purification device 27. The purified cooling water is returned into the RPV 12 through the purification system pipe 23 and the water supply pipe 10.

  After the operation of the BWR plant is stopped, the circulation pipe 35 of the film forming apparatus 30 is connected to the recirculation system pipe 22 and the purification system pipe 20. The film forming apparatus 30 is a temporary facility, and is removed from the recirculation system pipe 22 and the purification system pipe 20 after the processing of the solution used for forming the ferrite film is completed. The film forming apparatus 30 is used for both the formation of a ferrite film on the inner surface of the recirculation pipe 22 and the treatment of the solution (waste liquid) used for forming this film. Furthermore, the film forming apparatus 30 is also used when performing chemical decontamination in the recirculation piping 22.

  The 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 (film forming liquid supply pipe) 35, chemical liquid tanks 40, 43, 46, 74, a filter 51, a decomposition apparatus 64, an ion exchange resin tower 60, and a control apparatus (not shown). ). The on-off valve 47, the circulation pump 48, the valve 49, the heater 53, the valves 55, 56, 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. A cooler 58 and a valve 59 are installed in the pipe 66. An ion 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 ion exchange resin tower 60 and the valve 61. A pipe 69 in which the valve 65 and the disassembling device 64 are installed is connected to the circulation pipe 35 by bypassing the valve 57. 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 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 pipes subject to chemical decontamination (for example, the recirculation system pipe 22), and further reduce and dissolve contaminants in the pipes. The ejector 37 is provided with a hopper (not shown) for supplying oxalic acid (reductive decontamination agent) used for the purpose to the surge tank 31.

  The iron (II) ion implantation apparatus includes a chemical liquid tank 40, an injection pump 39, and an injection pipe 76. The chemical tank 40 is connected to a pipe 79 by an injection pipe 76 having an injection pump 39 and a valve 38. The chemical tank 40 is filled with a drug (first 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 organic acid or carbonic acid which becomes a counter anion of iron (II) ion can be used not only formic acid. The oxidant injection device has a chemical tank 46, an injection pump 45, and an injection pipe 78. The chemical tank 46 is connected to a pipe 79 by an injection pipe 78 in which an injection pump 45 and a valve 44 are installed. The chemical tank 46 is filled with hydrogen peroxide which is an oxidizing agent (third chemical). The pH adjuster injection device has a chemical tank 43, an injection pump 42, and an injection pipe 77. The chemical tank 43 is connected to a pipe 79 by an injection pipe 77 in which an injection pump 42 and a valve 41 are installed. The chemical tank 43 is filled with hydrazine which is a pH adjuster (fourth drug). The zinc ion implantation apparatus has a chemical tank 74, an injection pump 73, and an injection pipe 75. The chemical tank 74 is connected to a pipe 79 by an injection pipe 75 having an injection pump 73 and a valve 72. The chemical liquid tank 74 is filled with a drug (second drug) containing divalent zinc ions prepared by dissolving zinc with formic acid. This drug contains formic acid. In addition, as a chemical | medical agent which dissolves zinc, what melt | dissolved zinc formate with water and what melt | dissolved zinc formate with the solution containing formic acid can be used. The control device is connected to the infusion pumps 39, 45, 42 and 73, respectively, and controls these infusion pumps to control the infusion amount of the medicine filled in the medicinal solution tanks 40, 46, 43 and 74. The control device is also connected to the valves 38, 41, 44, and 72, respectively, and controls the opening and closing of these valves, whereby the first medicine, the second medicine, the third medicine, and the fourth medicine. Controls injection and stoppage.

  A pipe 79 connects the pipe 75, the pipe 76, the pipe 77 and the pipe 78. A pipe 79 is connected to an agitation tank 80 for agitating the first chemical, the second chemical, the third chemical, and the fourth chemical. A pipe 82 having a stirring tank 80 and a valve 81 is connected to the circulation pipe 35. The control device controls the opening and closing of the valve 81.

  The agitation tank 80 is connected to a temperature adjusting device that adjusts the temperature of the medicine inside. Specifically, the temperature adjusting device includes a measuring unit that measures the temperature of the drug inside, a heater that heats the drug, and a control unit that controls the heater so that the temperature of the drug is 0 ° C. or higher and 50 ° C. or lower. Have The control unit controls the heater based on the measurement result of the measurement unit.

  The surge tank 31 is initially filled with water used for processing. An inert gas injection device (not shown) for bubbling an inert gas such as nitrogen or argon is connected to the chemical liquid tank 40 and the surge tank 31 in order to remove oxygen contained in the solution existing in each of them. It is preferable to do.

  The decomposition device 64 can decompose an organic acid (for example, formic acid) used as a counter anion of iron (II) ions and a hydrazine as a pH adjusting agent. That is, as the counter anion of the iron (II) ion, an organic acid that can be decomposed into water or 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.

  A method for suppressing the attachment of radionuclides to the nuclear plant components of this embodiment, in which a ferrite film is formed in the recirculation piping 22 using the film forming apparatus 30, will be described in detail with reference to FIG. The radionuclide adhesion suppression method of the present embodiment is performed within a period of periodic inspection (maintenance inspection) of the BWR plant in which the operation of the BWR plant is stopped. First, the film forming apparatus 30 is connected to the piping system to be coated (Step S1). That is, after the operation of the BWR plant is stopped for the periodic inspection of the BWR plant, the circulation pipe 35 is connected to the recirculation system pipe 22 and the purification system pipe 20 as described above. The piping system to be coated is, for example, the recirculation piping 22. A valve 23 is provided in the purification system pipe 20. The bonnet of the valve 23 is opened to close the reactor water purification device 27 side of the purification system pipe 20. One end of the circulation pipe 35 is connected to the flange of the valve 23. The other end of the circulation pipe 35 is connected to a recirculation system pipe 22 downstream of the recirculation pump 21, for example, a branch pipe connected to the recirculation system pipe 22 (a branch pipe from which a drain pipe or an instrumentation pipe is separated). Connected. In this way, the film forming apparatus 30 is connected to the recirculation piping 22. It should be noted that both ends of the recirculation system pipe 22 are sealed with plugs so that the decontamination solution and the film-forming aqueous solution supplied into the recirculation system pipe 22 do not flow into the RPV 12.

  Chemical decontamination is performed on the film formation target portion (step S2). On the inner surface of the recirculation system pipe 22 that comes into contact with the cooling water, an oxide film (contaminant) incorporating the radionuclide is formed. An example of step S2 is a process of removing the oxide film that has taken in the radionuclide by a chemical process from the inner surface of the recirculation pipe 22 that is a film formation target location. The formation of a ferrite film on the piping system to be coated is intended to suppress the attachment of radionuclides to the piping system. It is preferable to carry out. Since it is sufficient that the surface of the metal member to be coated is exposed before the ferrite film is formed, mechanical decontamination treatment can be applied instead of chemical decontamination.

  The chemical decontamination applied in step S2 is a known method (see Japanese Patent Application Laid-Open No. 2000-105295). By repeating the oxidative dissolution, oxidant decomposition, reductive dissolution, reducing agent decomposition, and purification operation from the temperature rise, for example, about 2 or 3 times, the metal member (the constituent member of the recirculation piping 22) at the decontamination target location The contaminants including the oxide film formed on the surface in contact with the reactor water can be dissolved and removed. After removing contaminants including the oxide film on the metal member and decomposing oxalic acid and hydrazine contained in the reductive decontamination solution, a ferrite film is formed.

  In this way, after removing the corrosion products including the oxide film of the member suitable for application to a nuclear power plant, the process is switched to the ferrite film production process according to the present invention. First, after completion of the purification operation in the decontamination step, the valve 50 is opened and the valve 49 is closed, whereby the film forming liquid is caused to flow through the filter 51. Further, the film forming liquid that has passed through the filter 51 is adjusted to a predetermined temperature by the heater 53 (step S3). The film 51 is allowed to flow through the filter 51 because if fine solids remain in the film forming liquid, film formation also occurs on the surface of the solid material during the formation of the ferrite film. This is to prevent this because it will be used. Further, if the film 51 is allowed to flow through the filter 51 during chemical decontamination, it is not appropriate because the pressure loss of the filter may increase due to the hydroxide caused by the high concentration of dissolved iron. . Further, by opening the valve 56 and closing the valve 63, water flow to the mixed bed resin tower 62 used in the purification operation is stopped.

  The temperature of the film forming solution here is preferably 60 ° C. or higher and 200 ° C. or lower. The temperature of the film-forming solution may be such that a ferrite film having a dense film structure such as crystals can be formed to such an extent that corrosion of a member suitable for application to a nuclear power plant during in-service operation of a nuclear reactor can be suppressed. Accordingly, a temperature condition of not more than the maximum use temperature of the recirculation system and at least 200 ° C. is preferable. The lower limit may be normal temperature, but a temperature condition of 60 ° C. or higher is preferable so that the film formation rate is in a practical range. If the temperature condition is 100 ° C. or higher, the pressurization for suppressing the boiling of the film-forming solution is required. As a result, the equipment cost is increased, for example, the pressure resistance of the temporary equipment against the pressurization is required. Therefore, it is preferable that the temperature condition of the film forming process (temperature of the film forming liquid) is further adjusted to a range of 60 ° C. or higher and 100 ° C. or lower. In addition, about 75 degreeC is more preferable. Here, in order not to oxidize the iron in the medicine, it is necessary to remove the dissolved oxygen in the film forming liquid. For this reason, it is preferable to perform bubbling of inert gas or vacuum deaeration.

  When the temperature of the film forming liquid reaches a predetermined temperature in this way, the control device opens the valves 38, 41, 44, 72 and activates the infusion pumps 39, 42, 45, 73. Thereby, each chemical | medical agent is inject | poured into the stirring tank 80 from the chemical | medical solution tank 40,43,46,74. When the control device opens the valve 81, the liquid mixture mixed in the stirring tank 80 is injected into the circulation pipe 35 through the pipe 82 (step S4). Here, the liquid mixture in the agitation tank 80 is adjusted by a temperature adjusting device so as to have a temperature of 0 ° C. or higher and 50 ° C. or lower. In order to remove oxygen contained in the solution, it is preferable to connect an inert gas injection device (not shown) for bubbling an inert gas such as nitrogen or argon. The pH adjuster here is, for example, hydrazine. Through the processing in step 4, the control device controls the injection amount of the pH adjusting agent by controlling the injection pump 42 of the pH adjusting agent, and the film forming solution is adjusted to pH 5.5 to 9.0 which is the reaction start condition. The As a result, the formation reaction of the ferrite film proceeds, and an oxide film (hereinafter referred to as a ferrite film containing zinc) of a ferrite film containing zinc-containing ferrite as a main component is formed on the surface of the water contact portion of the member. The amount of film (thickness of the film) on the target member forming the film is measured by an electrochemical measurement method (for example, impedance method). When the film reaches the required thickness (predetermined film amount), the control device immediately closes the valve 81 to stop the injection of the film forming liquid into the circulation pipe 35 and moves to the next step. On the other hand, if the coating treatment is not completed, the control device returns to step 4 from step 5 and continues supplying the mixed solution to the coating forming solution that has made a round, so that the ferrite containing zinc of the required thickness is obtained. Create a film.

  Formic acid and hydrazine remain in the film-forming solution that contributed to the formation of the ferrite film containing zinc even after the treatment. When draining this film forming liquid, it is necessary to carry out the waste liquid treatment in Step 6 to remove these impurities. However, if the residue in the film-forming liquid is treated by the ion exchange resin tower 60, the waste of the ion exchange resin tower 60 increases. Therefore, in the waste liquid treatment in Step 8, the decomposition device 64 in the decontamination system decomposes formic acid in the film forming liquid into carbon dioxide and water, and decomposes hydrazine in the film forming liquid into nitrogen and water. preferable. Thereby, the load of the ion exchange resin tower 60 can be reduced, and the waste amount of the ion exchange resin tower 60 can be reduced. Further, it is preferable to allow the filter 51 to pass through to the outlet side of the circulation pump 48 during the waste liquid treatment process.

  The decomposition treatment is performed by adjusting the opening degree of the valve 65 of the decomposition apparatus 64 and adjusting the opening degree of the valve 57 that bypasses the decomposition apparatus 64 in the same manner as the decomposition of oxalic acid. Part is allowed to flow into the disassembly device 64. And hydrogen peroxide is inject | poured in the film formation liquid which flows into the decomposition | disassembly apparatus 64, and the formic acid and hydrazine in a film formation liquid are decomposed | disassembled.

  It is another Example of this invention. In this example, a drug containing zinc ions and iron (II) ions, an oxidizing agent and a pH adjusting agent were mixed in advance at a temperature of 0 ° C. or higher and 50 ° C. or lower and then added to a film forming solution at 90 ° C. Different from the first embodiment.

  A film forming apparatus 30A used in the method for forming a ferrite film containing zinc according to the present embodiment shown in FIG. 7 is the same as that in the film forming apparatus 30 used in the first embodiment, with chemical liquid tanks 40, 43, 74, valves 38, 41, 72. , Injection pumps 42, 39, 73 injection pipes 75, 76, 77 are deleted and chemical solution tank 83, injection pump 84, valve 85 and injection pipe 86 are newly provided. Here, the chemical solution tank 83 has a bubbling device for nitrogen gas or an inert gas or a device for exhausting the chemical solution tank in order to prevent oxidation of the drug. Other configurations of the film forming apparatus 30A are the same as those of the film forming apparatus 30. The chemical tank 83 is connected to a circulation pipe (film forming liquid supply pipe) 35 downstream of the valve 33 by an injection pipe 86. An injection pump 84 and a valve 85 are installed in the injection pipe 86.

  In this embodiment, in a non-radiation control area (for example, a factory) outside the radiation control area, the first drug, the second drug, the third drug, and the fourth drug are mixed in advance to generate a film-forming aqueous solution. The film-forming aqueous solution is stored in a transport container. By this work, the work in the management area can be shortened and simplified, so that the exposure dose of workers during the work can be reduced. The method of forming a ferrite film containing zinc according to the present embodiment differs from that according to the first embodiment in that the chemical agent according to the first embodiment is mixed in advance at a factory or the like. That is, in step S4, the control device opens the valve 85 and drives the infusion pump 84, so that the chemical containing the zinc ion, iron (II) ion, oxidizing agent, and pH adjusting agent in the chemical liquid tank 83 becomes the film forming liquid. Addition to form a ferrite film containing zinc. Subsequent steps are the same as those in Example 1. According to the present embodiment, the film forming procedure and the film growing apparatus can be simplified as compared with the first embodiment.

  It is another Example of this invention. The first embodiment is different from the first embodiment in that the crystal formation microbalance method is used in the first embodiment, and the film formation amount is continuously measured, and the completion of the construction is suitably determined.

  The film forming method of this embodiment will be described with reference to FIGS. In Example 1, the test piece immersed in the system in step S5 was taken out, and the film formation amount was determined from the change in weight. In this case, once the system is stopped and the test piece is taken out to determine whether or not the film can be formed, if the film generation is not completed, the system operation is started again and Step S4 is performed. For this reason, time may be required for film formation. Therefore, if this embodiment is used, it is confirmed that the film amount has reached the set amount by continuously measuring the film formation amount using the quartz crystal microbalance method as shown in FIG. Can move on. That is, it is possible to determine on the spot whether or not the film can be formed without stopping the system.

  The film forming apparatus 30B used in the method for forming a ferrite film containing zinc according to the present embodiment shown in FIG. 9 is the crystal resonator microbalance for continuously measuring the film formation amount in the film forming apparatus 30 used in the first embodiment. And an apparatus (arithmetic unit) 89 for converting a signal obtained from the electrode into a film amount. The arithmetic unit 89 may include a memory that stores a predetermined required film amount and a display unit that displays an injection stop when the obtained film amount reaches the required film amount. In addition, you may provide the alarm apparatus which transmits sounds, such as an alarm, instead of a display part. Other configurations of the film forming apparatus 30B are the same as those of the film forming apparatus 30. The crystal resonator microbalance electrode 88 is installed downstream of the valve 47 and upstream of the circulation pump 48 by the valve 87.

  It is another Example of this invention. In Example 2, the crystal oscillator microbalance method is used to continuously measure the amount of film formation. When the film formation rate is slow, the controller controls the rate of film formation by controlling the addition rate of the pump to which the drug is added. It differs from the second embodiment in that it is controlled.

  The film forming method of this embodiment will be described with reference to FIG. In Example 2, the test piece immersed in the system in step S5 was taken out, and the film formation amount was determined from the change in weight. In this case, once the system is stopped and the test piece is taken out to determine whether or not the film can be formed, if the film generation is not completed, the system operation is started again and Step S4 is performed. For this reason, time may be required for film formation. Therefore, as shown in FIG. 10, when the film formation amount is continuously measured using the quartz crystal microbalance method, and the film growth rate is different from the preset rate, the control device 90 controls the infusion pump 84. The number of drug additions is controlled by controlling the number of revolutions, and the film growth rate is matched with the set value. If this embodiment is used, it is possible not only to judge the completion of film formation without taking out the test piece, but also to reliably form the film within a set predetermined time.

  The film forming apparatus 30C used in the method for forming a ferrite film containing zinc according to the present embodiment shown in FIG. 10 is the same as the film forming apparatus 30A used in the second embodiment. And a control device 90 including a valve 87 for attaching the electrode 88 and a control device 90. The control device 90 includes a calculation unit for obtaining a film amount (or film formation speed) based on a signal obtained from the electrode 88, a memory for storing a predetermined required film amount (or film formation speed), and a calculation. When the film amount (film growth rate) obtained in the section is slower than the preset speed, the number of revolutions of the infusion pump 84 for injecting the drug is controlled to match the film growth rate with the set value. Part. When the obtained coating amount reaches the required coating amount stored in the memory, the control device 90 stops the injection pump 84 and stops the injection of the mixed liquid into the circulation pipe 35. Other configurations of the film forming apparatus 30C are the same as those of the film forming apparatus 30A. The crystal resonator microbalance electrode 88 is installed downstream of the valve 47 and upstream of the circulation pump 48 by the valve 87.

  According to the present embodiment, the ferrite film containing zinc is formed on the surface of the processing target site. Thereby, the corrosion of the object site | part during a normal nuclear reactor service driving | operation can be suppressed. Further, since chemicals such as chlorine are not used in the film formation process, the soundness (for example, corrosion resistance) of the reactor constituent members is not impaired.

  The method for forming a ferrite film on the surface of each plant component in Examples 1, 2, 3 and 4 is as follows: a carbon steel feed pipe for a BWR plant, a carbon steel feed pipe for a PWR plant, and a carbon steel for a thermal power plant It can be applied to the water supply piping made of stainless steel and the primary coolant piping made of stainless steel of the PWR plant. The primary coolant piping of the PWR plant supplies the high-temperature cooling water generated in the reactor pressure vessel to the steam generator, and returns the cooling water discharged from the steam generator to the reactor pressure vessel when the temperature drops. It has a function.

  When forming a ferrite film on the inner surface of the water supply pipe 10 made of carbon steel in the BWR plant that is in contact with the water supply, as shown in FIG. 4 of Japanese Patent Application Laid-Open No. 2007-182604, film forming apparatuses 30, 30A, 30B, What is necessary is just to connect the both ends of 30 C of any circulation piping (film formation liquid supply piping) 35 to the water supply piping 10, respectively. Further, when a ferrite film is formed on the inner surface of the water supply pipe of the PWR plant that is in contact with the water supply, any of the film forming apparatuses 30, 30A, 30B, and 30C as shown in FIG. 8 of Japanese Patent Application Laid-Open No. 2007-182604. What is necessary is just to connect the both ends of the circulation piping 35 to the water supply piping, respectively. In the case of forming a ferrite film on the inner surface of the water supply pipe of the thermal power plant that contacts the water supply, as shown in FIG. 9 of Japanese Patent Application Laid-Open No. 2007-182604, any one of the film forming apparatuses 30, 30A, 30B, 30C What is necessary is just to connect the both ends of the circulation piping 35 to the water supply piping, respectively. When forming a ferrite film on the inner surface of the PWR plant that contacts the cooling water of the primary coolant pipe, the isolation valve provided in the vicinity of the reactor pressure vessel of the primary coolant pipe is closed and the film-forming aqueous solution becomes the reactor pressure. What is necessary is just to supply film formation aqueous solution in the primary coolant piping using either of the film formation apparatus 30,30A, 30B, 30C so that it may not flow into the container.

  In the present embodiment, a ferrite film containing zinc is formed after the cleaning and before the operation of the reactor, and thereafter metal ions such as zinc are injected into the reactor water to thereby add cobalt 60 into the oxide film on the inner surface of the recirculation system pipe and This is a method of suppressing the uptake of a radionuclide such as cobalt 58. If this method is used, the amount of metal ions such as zinc injected into the reactor water can be reduced as compared with the method described in JP-A-58-79196.

  The film forming method of the present embodiment will be described with reference to FIGS. 11A in FIG. 11 shows an outline of the incorporation of radionuclides such as cobalt 60 and cobalt 58 when an oxide film is formed on a recirculation pipe not subjected to treatment, and 91B shows Japanese Patent Laid-Open No. 58-79196. No. 91C shows a method of suppressing the incorporation of radionuclides such as cobalt 60 and cobalt 58 into the oxide film by the method described in the publication No. 91C. Cobalt 60 and cobalt 58 into the oxide film when the present invention is used. It is a method of suppressing the uptake of radionuclides such as.

  In the method described in JP-A-58-79196, when an oxide film is formed on the pipe surface, zinc added to the furnace water is taken into the oxide film, whereby cobalt 60 and Radionuclide such as cobalt 58 is suppressed. Therefore, divalent ions such as zinc are stored in the tank 102 shown in FIG. 12, and the concentration of divalent ions in the reactor water is 10 ppb from the value of the conductivity meter 101 installed downstream of the reactor purification system pump. As described above, the opening of the valve 103 is adjusted using the control device 104 to add divalent ions to the reactor water. At this time, it is described that the connection position of the valve 103 is downstream of the demineralization tower of the reactor purification system and upstream of the water supply pipe 10.

  The amount of zinc added to the reactor water can be reduced by forming the ferrite film containing zinc formed in the present invention on the pipe surface after the pipe decontamination and before the reactor operation. The mechanism will be described with reference to 91C in FIG. By forming a ferrite film containing zinc on the pipe surface, it plays the role of an anticorrosion film, so that corrosion of the pipe can be suppressed and incorporation of radionuclides such as cobalt 60 and cobalt 58 can be suppressed. For this reason, the addition amount of zinc can be reduced. In addition, when the plant is operated for a long period of time, a small amount of oxygen and ions in the reactor water diffuse in the ferrite film containing zinc, and the radionuclide such as cobalt 60 and cobalt 58 is gradually interposed between the ferrite film containing zinc and the base material. An oxide film of the inner layer incorporating the is formed. Since the ferrite film containing zinc of the present invention can supply zinc more efficiently than adding zinc to the inner layer oxide film in the reactor water, it is in the inner layer oxide film of radionuclide ions such as cobalt 60 and cobalt 58. Incorporation into can be suppressed. Zinc is eluted from the ferrite film containing zinc not only in the inner oxide film but also in the reactor water. In order to reduce the dissolution, it is necessary to inject zinc into the reactor water. It is much less than the method described in Japanese Kokai 58-79196. In order to implement the fifth embodiment, first, as shown in the system diagram shown in FIG. 12, the film forming apparatus and the metal ion implantation tank are connected to the system. At this time, the connection position of the metal ion implantation tank to the system is raised downstream of the desalination tower of the reactor purification system or downstream of the feed water heater. That is, if it inject | pours in the reactor pressure vessel 12 via a water supply system piping downstream of the ascites purification apparatus 6, you may connect to any position. The procedure will be described according to the flowchart shown in FIG. First, after connecting the pipes, the chemical decontamination, film generation, and film forming liquid processes in steps S2 to S6 are performed in the same manner as in Example 1. Thereafter, divalent ions are added to the system while monitoring the conductivity of the reactor water. At this time, since the zinc ferrite film is formed on the pipe surface, the concentration of the added iron ions is lower than that in the method described in JP-A-58-79196.

  In Examples 1 to 5, a film forming method for forming a ferrite film after performing chemical decontamination processing on an existing nuclear plant structural member has been described. However, the example is also applied to a newly installed nuclear plant structural member. It is also possible to apply 1 to 5 ferrite film forming methods. When a ferrite film is formed on such a new nuclear plant structural member, the chemical decontamination process is not performed (steps S1 and S2 are not performed), and the temperature of the circulating process liquid is adjusted (step S3). Start.

DESCRIPTION OF SYMBOLS 1 Reactor 3 Turbine 4 Condenser 10 Water supply piping 12 Reactor pressure vessel 30, 30A, 30B Film formation apparatus 31 Surge tank 32, 48 Circulation pump 35 Circulation piping 37 Ejector 39, 42, 45, 73 Injection pump 40 Chemical solution tank (Iron (II) ion)
43 Chemical tank (pH adjuster)
46 Chemical tank (oxidizer)
51 Filter 53 Heater 58 Cooler 60 Ion Exchange Resin Tower 62 Mixed Bed Resin Tower 64 Decomposition Device 74 Chemical Tank (Zinc Ion)
80 Mixing tank 88 Electrode

Claims (9)

A method for forming a ferrite film in which a component film of a nuclear power plant is in contact with cooling water, and a film forming liquid is contacted to form a ferrite film containing zinc on the surface,
At the time before the film-forming liquid contacts the component of the nuclear power plant, the first agent containing iron (II) ions, the second agent containing zinc ions, and the iron (II) ions are converted into iron (III) A third agent that is oxidized to ions and a fourth agent that adjusts the pH of the film-forming solution to 5.5 or more and 9.0 or less are mixed in a temperature range of 0 ° C. or more and 50 ° C. or less to produce a mixed solution. And
The liquid mixture is added to cooling water at 60 ° C. or higher and 200 ° C. or lower to produce a film forming liquid,
A method of forming a ferrite film on a component of a nuclear power plant, wherein the film forming liquid is brought into contact with a surface of a structural member of the nuclear power plant to form a ferrite film containing zinc on the surface. Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
2. The method of forming a ferrite film on a component of a nuclear power plant according to claim 1, wherein the end of formation of the ferrite film is determined based on the measured formation amount of the ferrite film. Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
Based on the formation of the measured the ferrite film, method for forming a ferrite film to the configuration members of the nuclear power plant according to claim 1, characterized in that stopping the injection into the cooling water of the mixed solution. Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
Based on the measured formation amount of the ferrite film, a first agent containing the iron (II) ions, a second agent containing zinc ions, and a second agent that oxidizes the iron (II) ions to iron (III) ions. 3 of the mixing of the drug is stopped, the first agent, the second agent and a nuclear power plant according to claim 1, characterized in that addition is stopped to the cooling water of the third agent A method for forming a ferrite film on a component. Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
Based on the measured formation amount of the ferrite film, the mixing of the fourth agent for adjusting the pH to 5.5 or more and 9.0 or less is stopped to stop the addition to the cooling water. The method for forming a ferrite film on a component of a nuclear power plant according to claim 4 . Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
Based on the measured formation amount of the ferrite film, the first chemical solution containing the iron (II) ions, the second chemical solution containing zinc ions, and the second chemical solution that oxidizes the iron (II) ions to iron (III) ions. The method for forming a ferrite film on a component of a nuclear power plant according to claim 1 , wherein the injection amount of the mixture of the three chemicals is controlled. Measure the formation amount of ferrite film containing zinc formed on the surface of the component of the nuclear power plant,
Based on the measured formation amount of the ferrite film, find the film formation speed,
The first chemical solution containing the iron (II) ions, the second chemical solution containing zinc ions, and the iron (II) ions are converted into iron (III) so that the film formation rate becomes a preset set rate. 4. The method for forming a ferrite film on a plant component according to claim 3 , wherein an injection amount of a mixed liquid containing a third chemical agent oxidized to ions is injected into the film forming liquid. The surface of the structural member in contact with the film forming liquid is subjected to chemical decontamination before the contact,
The period before the chemical removal even after dyeing reactor operation, using the method of forming a ferrite film according to any one of 1 to 7, the ferrite film is formed on the surface of the structural member,
A method for suppressing radionuclide adhesion, wherein re-adhesion of radionuclides is suppressed by adding ions such as zinc during the nuclear reactor operation of the nuclear power plant. A first drug tank for storing a first drug containing iron (II) ions;
A second drug tank for storing a second drug containing zinc ions;
A third drug tank that stores a third drug that oxidizes the iron (II) ions to iron (III) ions;
A fourth drug tank for storing a fourth drug for adjusting the pH of the film-forming solution to 5.5 or more and 9.0 or less;
The first medicine tank, the second medicine tank, the third medicine tank, and the fourth medicine tank that are connected to the first medicine tank, the second medicine tank, and the fourth medicine tank, and are sucked from each medicine tank. A storage tank that mixes the four drugs and stores the mixed liquid;
A temperature adjusting device for adjusting the temperature of the mixed solution to a range of 0 ° C. or higher and 50 ° C. or lower;
A film forming liquid supply pipe for supplying the mixed liquid in the storage tank to a pipe system for film formation in a nuclear power plant;
Heating means for heating the film-forming liquid;
A film forming apparatus comprising: a heating adjusting device that controls the second heating unit and adjusts the temperature of the film forming liquid in a range of 60 ° C. to 200 ° C.

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