JP2013130565A - Component of nuclear power plant, method for suppressing adhesion of radioactive nuclide to component of nuclear power plant, and film forming device for component of nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feasible component of a nuclear reactor to which adhesion of a radioactive nuclide is suppressed, a method for suppressing adhesion of a radioactive nuclide to a component of a nuclear power plant, and a film forming device for the component of the nuclear power plant.SOLUTION: Chemical decontamination performed after shutdown of a nuclear reactor allows the surface in contact with furnace water of the nuclear reactor to be decontaminated and exposed. Particles or a film containing cerium is then formed on the surface of the component of a nuclear power plant in contact with water. The adhesion of a radioactive nuclide to the component of the nuclear power plant is thus suppressed.

Description

  The present invention relates to a component of a nuclear power plant such as a piping of a boiling water nuclear power plant in which adhesion of a radionuclide is suppressed, a method for suppressing the attachment of a radionuclide to a component of a nuclear power plant, and a film forming apparatus for a component of a nuclear power plant About.

  As a power plant, for example, a boiling water nuclear power plant and a pressurized water nuclear power plant are known. Among these, for example, a boiling water nuclear power plant is configured as follows.

  A boiling water nuclear power plant has a nuclear reactor in which a reactor core is built in a reactor pressure vessel. Cooling water is supplied to the core by a recirculation pump (or an internal pump). The cooling water is heated by the heat generated by the nuclear fission of the 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 the case of a pressurized water nuclear power plant, a heat exchanger is provided, a pressurized water system (primary system) that circulates between the reactor and the heat exchanger, and water that circulates between the turbine and the heat exchanger. It consists of a steam system (secondary system).

  As described above, the boiling water nuclear power plant and the pressurized water nuclear power plant have different plant configurations, but the problems related to radioactivity countermeasures are common in many cases regardless of the plant configuration. For example, in order to suppress the generation of radioactive corrosion products in the nuclear reactor, the metal impurities are mainly removed by a filtration and desalination apparatus provided in the water supply pipe.

  In power plants such as a boiling water nuclear power plant and a pressurized water nuclear power plant, stainless steel and nickel-based alloys such as stainless steel and carbon steel members are selectively used depending on the parts constituting the plant.

  For example, main components such as a reactor pressure vessel use stainless steel, such as stainless steel and nickel-base alloy, in a water contact portion in contact with water in order to suppress corrosion. In addition, corrosion products that are the source of radioactive corrosion products are also generated from water contact parts such as reactor pressure vessels and recirculation piping. Stainless steel such as nickel-base alloys is used.

  On the other hand, the 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 in view of reducing the manufacturing cost of the plant, or the feed water system. Carbon steel members are mainly used from the viewpoint of avoiding stress corrosion cracking of stainless steel caused by high-temperature water flowing through the condensate system.

  Thus, from the viewpoint of corrosion prevention and cost reduction, an optimal member is selected for each part constituting the plant, and further, the following measures are taken from the viewpoint of corrosion prevention. For example, the reactor pressure vessel is made of low alloy steel, and the inner surface of the reactor pressure vessel is made of stainless steel to prevent the low alloy steel from coming into direct contact with the reactor water. 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 V15, etc. 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.

  Normally, 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 attachment of radionuclides to piping and methods for reducing the concentration of radionuclides in the reactor water have been studied.

  For example, in Japanese Patent Application Laid-Open No. 58-79196, an oxide film is formed by injecting metal ions such as zinc into the reactor water to form a dense oxide film containing zinc on the inner surface of the recirculation piping that contacts the reactor water. A method for suppressing the incorporation of radionuclides such as cobalt 60 and cobalt 58 therein has been proposed.

  Further, in JP 2006-38483 A and JP 2007-192745 A, a surface of a component after the operation of the plant is formed by forming a magnetite film as a ferrite film on the surface of the nuclear plant component after chemical decontamination. A method has been proposed for suppressing the attachment of radionuclides.

  The methods described in Japanese Patent Application Laid-Open Nos. 2006-38483 and 2007-192745 include a formic acid aqueous solution containing iron (II) ions, hydrogen peroxide, and hydrazine, which were heated in a range from room temperature to 100 ° C. The treatment liquid is brought into contact with the surface of the constituent member to form a ferrite film on the surface. 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 nuclear plant component and the radionuclide is further prevented from adhering to the component surface after the plant is operated. ing.

  In addition, about the adhesion method of the particle | grains containing a cerium, there exists the method reported to academic literature paper journal "Corrosion Science" 46, 2004 pages 75-89. Moreover, there exists a method reported by Unexamined-Japanese-Patent No. 2000-105295 about an example of chemical decontamination. The chemical decontamination method disclosed in JP 2000-105295 A can be applied to the present invention.

JP 58-79196 A JP 2006-38483 A JP 2007-192745 A JP 2000-105295 A

Journal paper “Corrosion Science” No. 46, 2004, pp. 75-89

  A technology for injecting hydrogen gas is applied to nuclear power plants in order to suppress stress corrosion cracking. By injecting hydrogen gas into the furnace, the surface of the equipment is kept in a strong reducing environment and the development of stress corrosion cracking is suppressed. According to this method, although it is possible to suppress the development of stress corrosion cracking by keeping the inside of the reactor in a strong reducing environment, it has been reported that an oxide film that easily incorporates cobalt 60 is easily formed on the surface of the reactor member. ing. For this reason, there is a risk of an increase in the radiation dose of periodic inspection workers.

  However, in the method of injecting metal ions such as zinc described in JP-A-58-79196 into the reactor water, in addition to the problem that zinc ions must be continuously injected during operation, There is a problem that isotope-separated zinc must be used to avoid radioactivation.

  Further, by forming a magnetite film as a ferrite film on the surface of a nuclear plant constituent member after chemical decontamination described in JP 2006-38483 A and JP 2007-192745 A, after the operation of the plant, The method for suppressing the attachment of the radionuclide to the surface of the constituent member has a problem that it takes a long time to form the magnetite film.

  According to the documents described above, the surface of a member such as a pipe in contact with the reactor water inside the reactor pressure vessel and the reactor water in the reactor pressure vessel (hereinafter collectively referred to as a component of the nuclear power plant). A method for suppressing the attachment of radionuclides is described. However, these methods have many implementation problems.

  An object of the present invention is to provide a nuclear plant constituent member that is highly feasible and that suppresses radionuclide deposition, a method for suppressing radionuclide adhesion to a nuclear plant component member, and a film forming apparatus for a nuclear plant component member. There is.

  A feature of the present invention that achieves the above-described object is that a particle or film containing cerium is formed on the surface of the nuclear plant component that comes into contact with water after chemical decontamination and before the start-up of the nuclear reactor. It is in the place of suppressing the attachment of nuclides. More specifically, it is as follows.

  First, the component of the nuclear power plant of the present invention is a component of the nuclear power plant whose surface is in contact with the reactor water of the nuclear reactor, and after the surface in contact with the reactor water of the nuclear reactor after being shut down is decontaminated and exposed, It is a component of a nuclear power plant on which particles and a film containing cerium are formed.

  In the method for suppressing attachment of radionuclide to a component of a nuclear power plant according to the present invention, the surface of a nuclear plant component whose surface is in contact with the reactor water of the nuclear reactor is decontaminated with respect to the component of the nuclear power plant after the reactor is shut down. After being exposed, particles and a film containing cerium are formed.

  Specifically, in order to form particles and a film containing cerium, a first agent containing cerium ions on the surface, a second agent having oxidation ability, and a third agent which is an acidic solution are added to water. It is good to add and contact.

  Furthermore, in the nuclear power plant constituent member film forming apparatus of the present invention, the nuclear power source is in contact with the reactor water after the reactor is shut down to form a film on the surface of the reactor constituent member whose surface is in contact with the reactor water. Decontamination means for decontaminating and exposing the surface of plant components, and film forming means for forming cerium-containing particles and coatings on the surfaces of nuclear plant components after being processed by the decontamination means Including.

  Specifically, the chemical decontamination means includes a first means for supplying an oxidative decontamination liquid to the surface, a second means for supplying a reductive decontamination liquid after the first means, and a reduction after the second means. It is preferable to provide a third means for collecting and decomposing the decontamination solution.

  More specifically, the film forming means includes a first agent containing cerium ions on the surface of a component of the nuclear power plant and a second agent having oxidation ability in order to form particles and films containing cerium. The third chemical agent that is an acidic solution is preferably added to water and supplied to the components of the nuclear power plant.

  ADVANTAGE OF THE INVENTION According to this invention, the cobalt 60 adhesion amount to the surface which contacts the water of the structural member of a nuclear power plant can be reduced. Furthermore, the amount of corrosion of the components of the nuclear power plant can be suppressed.

Explanatory drawing which shows the procedure of the radionuclide adhesion suppression method to the structural member of the nuclear power plant of Example 1 which is one suitable Example of this invention, Comprising: The particle | grains containing cerium and the film formation method to the structural member of a nuclear power plant It is. It is explanatory drawing which shows the state which connected the film-forming apparatus to the recirculation system piping of a boiling water nuclear power plant in order to implement the procedure shown in FIG. It is a detailed block diagram of the film-forming apparatus of FIG. It is explanatory drawing which shows the relationship between the corrosion amount of a stainless steel member, and radionuclide adhesion amount. It is explanatory drawing which shows the magnetite and the cobalt adhesion experiment result of the test piece containing cerium. It is explanatory drawing which shows the result of having compared the construction time of a magnetite and a cerium film. It is explanatory drawing which shows the result of having compared the construction time of the cerium film when using an oxidizing agent and an acidic solution, and the construction time of the cerium film when using a pH adjuster. Explanatory drawing which shows the state which connected the film-forming apparatus to the water supply piping of a boiling water nuclear power plant in implementation of the radionuclide adhesion suppression method to the structural member of the nuclear power plant of Example 2 which is another Example of this invention. It is. Explanation of a state in which a film forming apparatus is connected to the purification system piping of a boiling water nuclear power plant in the implementation of the method for suppressing attachment of radionuclide to structural members of the nuclear power plant of Example 3 which is another example of the present invention. FIG. It is explanatory drawing which shows the detailed process of the chemical decontamination shown in FIG. It is explanatory drawing which shows the procedure of the radionuclide adhesion suppression method to the structural member of the nuclear power plant of Example 4 which is another Example of this invention. It is explanatory drawing which shows the state which connected the film-forming apparatus to the water supply piping of a boiling water nuclear power plant in order to implement the procedure shown in FIG. It is a detailed block diagram of the film-forming apparatus of FIG. It is explanatory drawing which shows the procedure of the radionuclide adhesion suppression method to the structural member of the nuclear power plant of Example 5 which is another Example of this invention. Explanation of a state in which a film forming apparatus is connected to a purification system piping of a boiling water nuclear power plant in the implementation of the method for suppressing radionuclide adhesion to structural members of a nuclear power plant according to embodiment 6 which is another embodiment of the present invention. FIG.

  The inventors of the present invention have made various studies in order to suppress the attachment of radionuclides to the water-contacting surfaces of the components of the nuclear power plant. It was found that the amount of oxide film formed increases and the amount of radionuclide attached to the base material also increases.

  FIG. 4 shows the relationship between the corrosion amount (horizontal axis) of the stainless steel base material and the cobalt 60 adhesion amount (vertical axis). The amount of oxide film (base material) formed on the surface of the base material. The amount of attachment of radionuclide (for example, cobalt 60) increases to the right. From this, it was considered that the amount of radionuclide adhering to the base material can be reduced by suppressing the corrosion amount of the base material. Based on this consideration, a method for suppressing radionuclide adhesion of stainless steel under reactor operating conditions was investigated.

  As a result, it was confirmed that the deposition of radionuclides can be suppressed more than when a magnetite film is formed when particles and films containing cerium are formed on the stainless steel surface and then exposed to the reactor operating conditions. FIG. 5 shows the result of an adhesion test of cobalt 60, which is a radionuclide, using a test piece to which cerium particles are adhered.

  As is apparent from FIG. 5, when the cobalt 60 adhesion amount of the magnetite film test piece is 1.0, the cobalt 60 adhesion amount of the test piece to which particles containing cerium are attached is about 0.7. It can be seen that the amount of cobalt 60 is greatly reduced. In addition, although the cobalt 60 adhesion amount of the test piece when not performing a film | membrane process is also shown in figure, this is about 2.0.

  In addition, as a method for attaching particles containing cerium, for example, there is a method reported in the journal paper “Corrosion Science” No. 46, pages 75-89, 2004. However, since the report uses sulfuric acid for the drug, the method of the report cannot be used as it is from the viewpoint of maintaining the soundness of the component devices. The report also requires that the stainless steel surface be in contact with the drug. In other words, since the oxide film generated by corrosion is formed on the surface of the reactor constituent equipment after in-service operation, the same report cannot be used as it is.

  Therefore, the inventors have thought that the treatment should be performed after the chemical decontamination generally performed in a nuclear power plant because the treatment should be performed before the oxide film is formed. More specifically, it is desirable to be performed between the end stage of the decontamination process and the start of the reactor.

  Here, chemical decontamination is a treatment method that dissolves and removes the oxide film formed on the surface of components (piping, equipment, etc.) of the nuclear power plant and the radionuclide adhering to the surface of the component. Therefore, the radionuclide adhesion suppression method of the present invention is applied in a state where the metal surfaces of the components of the nuclear power plant are exposed by chemical decontamination. As a result, particles or a film containing cerium is formed on the surface of the component of the nuclear power plant that comes into contact with water according to the present invention, and adhesion of the radionuclide can be suitably suppressed.

  FIG. 6 shows a comparison of the construction time of the particles containing cerium and the film and the construction time of the magnetite film when formic acid is used instead of sulfuric acid in succession to the chemical decontamination treatment. The construction time in the case of a magnetite film is about 25 when the construction time in the case of a cerium film (cerium oxide film) is 1. As apparent from FIG. 6, the construction time was 1/25, and it was confirmed that the construction time could be shortened.

  The inventors contact an aqueous solution containing a first agent containing cerium ions, a second agent having an oxidizing ability, and a third agent that is an acidic solution with a metal surface of a component of a nuclear power plant, and It has been found that, instead of forming a cerium film on the metal surface, cerium particles can be adhered to the metal surface even when an aqueous solution containing a drug containing cerium ions and a pH adjusting agent is brought into contact with the metal surface. When hydrazine is used as the pH adjuster, the construction time required to attach the cerium particles in the form of a film to the surface of the constituent member is the second chemical agent having an oxidizing ability and an acidic solution as shown in FIG. When the third chemical is used, the construction time required for forming the cerium film is reduced to about 1/3. This is because the addition of hydrazine (pH adjusting agent) causes the pH of the aqueous solution to increase, so that cerium ions are likely to precipitate as cerium oxide on the surface of the component member, and as a result, precipitate on the surface of the component member. This is because adhesion of cerium oxide is promoted.

  The present invention is most preferably used in a reactor water recirculation system and a reactor water purification system of a boiling water nuclear power plant, but is not limited to this, and is widely used on the surface of a component of a nuclear plant in contact with reactor water. I can do it. Moreover, this invention can be similarly used not only for the boiling water type nuclear power plant but also for the components contacting the reactor water of the pressurized water type nuclear power plant.

  A first embodiment which is a preferred embodiment of the present invention will be described with reference to FIGS. Example 1 has shown the example which gave the formation method of the particle | grains and film | membrane which contain cerium in the recirculation system piping member of a boiling water nuclear power plant.

  First, the configuration of a boiling water nuclear power plant as a nuclear power plant to which the present embodiment is applied will be described with reference to FIG. The boiling water nuclear power plant includes a nuclear reactor 1, a turbine 3, a condenser 4, a recirculation system, a reactor purification system, a water supply system, and the like as main components.

  Among these, the nuclear reactor 1 has a nuclear reactor pressure vessel 12 containing a reactor core 13, and a jet pump 14 is installed in the nuclear reactor pressure vessel 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 nuclear reactor 1 is installed in a nuclear reactor containment vessel 11 arranged in a nuclear reactor building (not shown).

  The recirculation system includes a recirculation system pipe 22 and a recirculation pump 21 installed in the recirculation system 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, and a feed water pump connected to a feed water pipe 10 that connects the condenser 4 and the reactor pressure vessel 12. 7 and the high-pressure feed water heater 9 are arranged in the order shown in the figure from the condenser 4 toward the reactor pressure vessel 12.

  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 boiling water nuclear power plant configured as described above is operated as shown below. First, the cooling water in the reactor pressure vessel 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. Cooling water supplied to the core 13 is heated by heat generated by fission of nuclear fuel material in the fuel rods. Some of the heated cooling water becomes steam.

  This steam is guided from the reactor pressure vessel 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 to the reactor pressure vessel 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 reactor pressure vessel 12. In addition, the extraction steam extracted from the turbine 3 by the extraction piping 15 is supplied to the low-pressure feed water heater 8 and the high-pressure feed water heater 9, respectively, and becomes a heating source of the feed water.

  Further, 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 in the regenerative heat exchanger 25 and the non-regenerative heat exchanger 26. After cooling, it 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 reactor pressure vessel 12 through the purification system pipe 20 and the water supply pipe 10.

  In the configuration of the above general boiling water nuclear power plant, in the first embodiment of the present invention, the film forming apparatus 30 is temporarily installed in the recirculation system. Hereinafter, the operation of the boiling water nuclear power plant to which the present invention is applied will be described focusing on the relationship between the film forming apparatus 30 and the reactor purification system.

  In a boiling water nuclear power plant, the reactor water is usually recirculated by a recirculation system, and a part of the reactor water is introduced into the reactor purification system to purify the reactor water. That is, the valve 23 is open to the reactor purification system side, and 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. doing. At this time, the valve 23 closes the film forming apparatus 30 side.

  However, when the operation of the nuclear reactor 1 is stopped, for example, the bonnet of the valve 23 provided in the reactor water purification system pipe 20 branched from the reactor water recirculation pipe 22 is opened and the reactor water purification device 27 side is opened. Close. Further, the temporary piping is connected using the flange of the valve 23 to form the inflow path 35 to the film forming apparatus 30.

  On the other hand, drain piping, instrumentation piping, and the like on the downstream side of the recirculation pump 21 are disconnected. In order to allow the treatment liquid to circulate in the separated branch pipe, a temporary pipe is connected to form an outflow path 36 of the film forming apparatus 30. In this example, the film forming apparatus 30 is connected to the recirculation system pipe. However, the present invention is not limited to this, and a water supply system, a coolant purification system, a condensate system, an auxiliary cooling water system, a cooling water system using a cooling tower, etc. The film forming apparatus 30 may be applied to portions where reactor water is in contact with members of the system constituting the plant (the members of these portions are collectively referred to as constituent members of the nuclear power plant).

  As shown in FIG. 2, in Example 1, a cerium particle and film deposition apparatus 30 to which the present invention is applied is connected to a recirculation system pipe 22 of a boiling water nuclear power plant. FIG. 3 shows a specific configuration of the film forming apparatus 30. In FIG. 2, the film forming apparatus 30 is connected to the recirculation system pipe 22 by a temporary pipe.

  The film forming apparatus 30 is connected to the recirculation system pipe 22 by a temporary pipe via the inflow side valve Vi and the outflow side valve Vo. The outflow side valve Vo is connected downstream of the recirculation pump 21 in the recirculation system pipe 22, and the inflow side valve Vi is connected upstream of the recirculation pump 21 in the recirculation system pipe 22. In the example of FIG. 5, the inflow side valve Vi of the film forming apparatus 30 is connected to a valve 23 provided in the reactor water purification system pipe 20 connected to the recirculation system pipe 22 upstream of the recirculation pump 21. ing.

  The film forming apparatus 30 of the present embodiment is configured to be used for chemical decontamination processing. For the chemical decontamination process, as shown in FIG. 3, the film forming apparatus 30 extracts a surge tank 31 filled with water used for the process, the water from the surge tank 31, and opens the valve V <b> 1 and the outflow valve Vo. And a circulation pump P <b> 1 that is supplied to one end of the recirculation pipe 22. Further, a return flow path L2 is formed from the discharge side of the circulation pump P1 to the surge tank 31 via the valve V2 and the ejector EJ. The ejector EJ has a hopper for injecting potassium permanganate for oxidizing and dissolving contaminants in the pipe, or oxalic acid for reducing and dissolving contaminants in the pipe.

  The detailed configuration of the film forming apparatus 30 will be described below with reference to FIG. The film forming apparatus 30 includes a surge tank 31, a circulation pipe L1, and a cation exchange resin tower 60.

  An inflow side valve Vi, a circulation pump P2, a valve V3, a heater H, valves V4, V5 and V6, a surge tank 31, a circulation pump P1, a valve V1 and an on-off valve Vi are provided in the circulation pipeline L1 in this order from the upstream. ing.

  Further, a valve V7 and a filter F are installed in a pipe L3 that bypasses the valve V3 and is connected to the circulation pipe L1. A pipe L4 that bypasses the heater H and the valve V4 is connected to the circulation pipe L1, and a cooler C and a valve V8 are installed in the pipe L4.

  Furthermore, a cation exchange resin tower 60 and a valve V9 are installed in a pipe L5 that is connected to the circulation pipe L1 at both ends and bypasses the valve V5. Similarly, the mixed bed resin tower 62 and the valve V10 are installed in a pipe L6 that is connected to the pipe L1 at both ends and bypasses the cation exchange resin tower 60 and the valve V9.

  Further, a pipe L7 in which the valve V11 and the decomposition device 64 are installed bypasses the valve V6 and is connected to the circulation pipe L1. 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 L1 between the valve V6 and the circulation pump P1. A pipe L2 provided with a valve V2 and an ejector EJ is connected to the circulation pipe L1 between the valve V1 and the circulation pump P1, and is further connected to the surge tank 31. The ejector EJ is provided with a hopper (not shown). From the hopper, potassium permanganate (oxidative decontamination agent) used to oxidize and dissolve contaminants on the inner surface of the recirculation system pipe 22 and further used to reduce and dissolve contaminants on the inner surface of the recirculation system pipe 22. Oxalic acid (reductive decontamination agent) is charged and supplied into the surge tank 31 via the ejector EJ. At this time, hydrazine may be injected.

  The cerium ion implantation apparatus 85 includes a chemical liquid tank 45, an injection pump P3, a valve V12, and an injection pipe L8. The chemical tank 45 is connected to the circulation pipe L1 by an injection pipe L8 having an injection pump P3 and a valve V12. The chemical tank 45 is filled with a medicine (first medicine) prepared by dissolving cerium carbonate or cerium nitrate in water. In addition, as a chemical | medical agent which dissolves cerium, an organic acid salt or an inorganic acid salt can be used. Alternatively, an individual containing cerium such as cerium carbonate may be dissolved in an organic acid such as formic acid or oxalic acid.

  The oxidant injection device 86 has a chemical tank 46, an injection pump P4, a valve V13, and an injection pipe L9. The chemical tank 46 is connected to the circulation pipe L1 by an injection pipe L9 having an injection pump P4 and a valve V13. The chemical tank 46 is filled with an aqueous solution of hydrogen peroxide or potassium permanganate as an oxidizing agent (second chemical).

  The acidic liquid injection device 87 includes a chemical liquid tank 40, an injection pump P5, a valve V14, and an injection pipe L10. The chemical tank 40 is connected to the circulation pipe L1 by an injection pipe L10 having an injection pump P5 and a valve V14. The chemical tank 40 is filled with an organic acid such as formic acid and oxalic acid, which is an acidic solution (third drug), and an inorganic acid such as nitric acid.

  A pipe line L11 is formed between the outlet of the injection pump P4 of the oxidizer injection device 86 and the inlet side of the decomposition device 64 via a valve V15.

  The decomposing device 64 can decompose an organic acid (for example, formic acid) to be used and a pH adjusting agent hydrazine used at the time of decontamination. That is, as the counter anion of the cerium ion, an organic 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.

  A method for forming particles and a film containing cerium in this example will be described in detail with reference to FIGS. The procedure shown in FIG. 1 includes not only the process of forming particles and films containing cerium, but also the process of the chemical decontamination solution as a pretreatment.

  In the procedure shown in FIG. 1, first, in process step S1, the film forming apparatus 30 is connected to the piping system to be coated. That is, in the operation stop period after the boiling water nuclear power plant is stopped for the periodic inspection, as described above, the recirculation system pipe in which the circulation pipe L1 in FIG. 22 is connected.

  Next, in process step S2, chemical decontamination is performed on the film formation target portion. In this case, the film formation target portion is a recirculation system in contact with the reactor water. An oxide film is formed on the inner surface of the recirculation pipe 22. In a boiling water nuclear power plant, this oxide film contains a radionuclide. In an example of the processing step S2, a process of removing the oxide film from the inner surface of the recirculation piping 22 that is a film formation target portion is performed by a chemical process.

  The formation of cerium-containing particles and coating on the piping system to be coated is intended to suppress corrosion of the inner surface of the recirculation piping. It is preferable to carry out chemical decontamination in advance. Since it is sufficient that the surface of the member on which the film is to be formed is exposed before forming the particles containing cerium and the film, it is possible to apply mechanical decontamination treatment instead of chemical decontamination.

  An example of chemical decontamination applied in processing step S2 will be briefly described. As this method, the method described in JP 2000-105295 A can be used. The case of realizing the configuration of FIG. 6 will be described as an example. First, in FIG. 3, the valves Vi, V3, V4-V6, V1, and Vo are opened to form the circulation piping L1, and the other valves are closed. In the state, the circulation pumps P1 and P2 are driven. Thereby, the water in the surge tank 31 is circulated in the recirculation piping 22 shown in FIG. At this time, the circulating water is heated by the heater H, and when the temperature of the water reaches 90 ° C., the valve V2 provided in the return pipe L2 is opened.

  As a result, the required amount of potassium permanganate supplied from the hopper connected to the ejector EJ is introduced into the surge tank 31 by the hot water flowing in the pipe L2. The first step S21 in chemical decontamination is an oxidative decontamination process using potassium permanganate as shown in FIG. FIG. 10 shows a series of processing steps in the chemical decontamination (processing step S2) of FIG.

  Potassium permanganate is dissolved in water in the surge tank 31, and an oxidative decontamination solution (potassium permanganate aqueous solution) is generated. This oxidative decontamination liquid is supplied into the recirculation system pipe 22 from the surge tank 31 through the circulation pipe L1 by driving the circulation pump P1. The oxidative decontamination solution oxidizes and dissolves contaminants such as an oxide film formed on the inner surface of the recirculation pipe 22.

  In FIG. 10, after the oxidative decontamination with the potassium permanganate aqueous solution, which is the first stage treatment (treatment step S21) in the chemical decontamination, the reductive decontamination with the oxalic acid aqueous solution, which is the second stage treatment in the chemical decontamination ( Processing step S22) is carried out. Here, oxalic acid is injected into the surge tank 31 from the hopper connected to the ejector EJ. 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 P1 and exists on the inner surface of the recirculation system pipe 22. Reduces and dissolves corrosion products. At this time, the acidic liquid injection device 87 functions to adjust the pH of the reductive decontamination liquid with hydrazine supplied from the chemical liquid tank 40 into the circulation pipe L1. The pH control of the reductive decontamination liquid in the acidic liquid injection device 8 is performed by returning the detection location of the pH detector 76.

  A part of the reductive decontamination liquid discharged from the recirculation pipe 22 and returned to the circulation pipe L1 is guided to the cation exchange resin tower 60 by a necessary valve operation in order to remove metal cations.

  In FIG. 10, after completion of reductive decontamination with an oxalic acid aqueous solution, which is the second stage process (process step S22) in chemical decontamination, recovery of the reductive decontamination liquid, which is the third stage process (process step S23) in chemical decontamination. Perform disassembly. In the recovery and decomposition process, the valve V11 is opened to adjust the opening of the valve V6, and a part of the reductive decontamination liquid flowing in the circulation pipe L1 is supplied to the decomposition device 64. Oxalic acid and hydrazine contained in the reductive decontamination solution are hydrogen peroxide introduced from the chemical solution tank 46 in the oxidizer injection device 86 to the decomposition device 64 through the valve V15 and the pipe L11, and the activated carbon catalyst in the decomposition device 64. It is decomposed by the action of

  After decomposition of oxalic acid and hydrazine, the valve V4 is closed to stop heating by the heater H, and at the same time, the valve V8 is opened to cool the decontamination solution by the cooler C. The cooled decontamination liquid (for example, 60 ° C.) is supplied to the mixed bed resin tower 62 in order to remove impurities.

  The above is a series of processing steps in the chemical decontamination (processing step S2) of FIG. This treatment step does not need to be carried out when particles and a film containing cerium are formed in piping (recirculation piping etc.) of a new plant, for example, a new boiling water nuclear power plant. The chemical decontamination process in the processing step S2 is performed when particles and a film containing cerium are formed in piping (recirculation piping etc.) of an existing boiling water nuclear power plant.

  After the chemical decontamination of the member is completed, a process for forming particles and a film containing cerium is performed. After the decontamination of the film formation target portion is completed, the temperature of the aqueous solution is adjusted in the processing step S3 of FIG. For this reason, after the decontamination of the film formation target portion, that is, after the final purification operation by the film forming apparatus 30 is completed, the following valve operation is performed.

  The valve V7 is opened and the valve V3 is closed, and water flow to the filter F is started. Water flow to the mixed bed resin tower 62 is stopped by opening the valve V5 and closing the valve V10. Further, the valve V4 is opened and the water in the circulation pipe L1 is heated to a predetermined temperature by the heater H. In this state, the valves Vo, V6, V1 and Vi are open, and valves other than the above are closed. Water passing through the filter F removes fine solids remaining in the water, and particles and films containing cerium are also formed on the surface of the solids, so that chemicals are wasted. This is to prevent it.

  The temperature of the aqueous solution is preferably maintained at about 75 ° C. while the film is formed on the inner surface of the recirculation pipe 22, but is not limited to this temperature. In short, it is only necessary that the formed cerium-containing particles and the crystal structure of the coating can be densely formed to such an extent that corrosion of members during operation of the nuclear reactor can be suppressed. Therefore, the temperature of the aqueous solution to be formed is preferably not more than the maximum use temperature of the recirculation pipe 22, that is, not more than 280 ° C. The temperature of the forming aqueous solution is preferably at least 200 ° C. or lower, and the lower limit may be 20 ° C., but is preferably 60 ° C. or higher at which the production rate of particles containing cerium and the film is within the practical range. When the temperature is 100 ° C. or higher, pressure must be applied to suppress boiling of the aqueous solution to be formed, and pressure resistance of the temporary equipment is required and the equipment becomes large, which is not preferable. Accordingly, the temperature of the aqueous solution in the film formation treatment is more preferably 100 ° C. or lower, and it is desirable to control the temperature within the range of 60 ° C. or higher and 100 ° C. or lower.

  Next, in process step S4, the chemical | medical solution (1st chemical | medical agent) containing a cerium ion is inject | poured into formation aqueous solution. At this time, the valve V12 in the cerium ion implantation apparatus 85 is opened to drive the injection pump P3, and the cerium ion chemical liquid (first chemical) flows from the chemical liquid tank 45 through the injection pipe L8 through the circulation pipe L1. Inject into water. The 1st chemical | medical agent inject | poured here contains the cerium ion which melt | dissolved and adjusted cerium carbonate with water, for example.

  In process step S5, an oxidizing agent is inject | poured into formation aqueous solution. At this time, the valve V13 in the oxidant injection device 86 is opened to drive the injection pump P4, and hydrogen peroxide as an oxidant flows from the chemical tank 46 through the injection pipe L9 to the inside of the circulation pipe L1. Inject into a forming aqueous solution containing. As the oxidizing agent, potassium permanganate may be used in addition to hydrogen peroxide.

  In processing step S5, an acidic aqueous solution (third drug) is injected into the forming aqueous solution. At this time, by opening the valve V14 in the acidic liquid injection device 87 and driving the injection pump P5, an acidic solution (for example, formic acid aqueous solution) flows from the chemical liquid tank 40 through the injection pipe L10 through the circulation pipe L1. Pour into the forming aqueous solution.

  As a result, the formed aqueous solution containing cerium ions (cerium ion implantation device 85), oxidant (oxidant injection device 86), and acidic solution (acid solution injection device 87) flows in the recirculation system pipe 22, so that the nuclear power plant. The cerium ions adsorbed on the inner surface of the recirculation pipe 22 that is a constituent member of the above change to cerium oxide that is an oxide. As a result, particles and a film (cerium oxide particles and this film) containing cerium are formed on the inner surface of the recirculation pipe 22.

  At this time, since the circulation pumps P1 and P2 are driven on the circulation pipe L1, an aqueous solution containing cerium ions, an oxidant, and an acidic solution is recirculated through the valve Vo by the circulation pipe L1. Supplied in. This formed aqueous solution flows through the recirculation pipe 22 and is returned to the valve Vi side of the circulation pipe L1.

  By carrying out the processing steps S4 to S6, a formed aqueous solution containing a chemical solution (first chemical) containing cerium ions, hydrogen peroxide (second chemical) and an acidic solution (third chemical) is added to the recirculation system pipe 22. Supplied and brought into contact with the inner surface of the recirculation pipe 22. In particular, it is preferable to continuously inject each medicine in steps S4, S5, and S6.

  In process step S7, it is determined whether the formation process of the particle | grains and film | membrane which contain cerium was completed. This determination is performed based on the elapsed time after the start of the formation process of the particles containing cerium and the film. Until this elapsed time reaches the time required to form particles and a film containing cerium having a predetermined thickness on the inner surface of the recirculation system pipe 22, the determination in the processing step S7 is “NO”. The operations of processing steps S4 to S6 are repeated. When the determination in process step S7 is “YES”, the control device (not shown) stops the infusion pumps P3, P4, P5 (or valves V12, V13, V14) and circulates each medicine. Stop pouring into the forming aqueous solution. Thereby, the formation work of particles and a film containing cerium on the inner surface of the recirculation pipe 22 is completed.

  Injection of a chemical solution containing cerium ions (first drug), hydrogen peroxide (second drug), and an acidic solution (third drug) into a forming aqueous solution forms particles and a film containing cerium with a set thickness. Until it is done.

  Thereafter, in the processing step S8, the chemical contained in the aqueous solution is decomposed. The aqueous solution used for forming the particles and the film containing cerium on the inner surface of the recirculation pipe 22 contains formic acid, which is an organic acid, even after the formation of the particles containing cerium and the film.

  The formic acid contained in the forming aqueous solution is decomposed by the decomposition apparatus 64 in the same manner as the decomposition of oxalic acid that is a reducing decontamination agent. In the chemical decomposition process, the opening degree of the valves V6 and V11 is adjusted, and a part of the aqueous solution in the circulation pipe L1 is supplied to the decomposition device 64.

  Further, by opening the valve V15, hydrogen peroxide is supplied from the chemical solution tank 46 to the decomposition device 64 through the pipe L11. Formic acid is decomposed in the decomposition apparatus 64 by the action of hydrogen peroxide and activated carbon catalyst. Formic acid breaks down into carbon dioxide and water. After the decomposition of the chemical contained in the aqueous solution is completed, the circulation pipe L1 is removed from the recirculation system pipe 22, and the valves Vo, Vi, etc. are restored to their original positions. Thereby, the operation of the boiling water nuclear power plant can be started.

  In addition, it is also possible to use an ultraviolet irradiation apparatus instead of the decomposition processing apparatus 64 using a catalyst. An ultraviolet irradiation device can also decompose hydrazine, formic acid and oxalic acid in the presence of an oxidizing agent.

  By decomposing hydrazine and formic acid into gas and water in the decomposition apparatus 64 as described above, removal of hydrazine and formic acid by the mixed bed resin tower 62 by the cation exchange resin tower 60 can be avoided. The amount of used ion exchange resin discarded in the floor resin tower 62 can be significantly reduced.

  In this example, the same kind of hydrogen peroxide is used as the oxidizing agent necessary for the formation of particles and films containing cerium and the oxidizing agent used in the decomposition of hydrazine and formic acid contained in the aqueous solution. The chemical liquid tank 46 filled with the agent and the infusion pump P4 for transferring it can be shared. For this reason, the structure of the film forming apparatus 30 can be simplified.

  In this embodiment, since the chemicals used for forming the particles and the film containing cerium do not contain any chemicals containing chlorine, the soundness (for example, corrosion resistance) of the components of the boiling water nuclear power plant is impaired. There is no. In order to suppress the amount of drug used, it is preferable to separate and remove excess reaction products, collect unreacted drug, and reuse the unreacted drug after recovery.

  In the present embodiment, since cerium particles adhere to the inner surface of the recirculation system pipe 22 in the form of a film, it is possible to suppress the attachment of a radionuclide such as cobalt 60 to the inner surface of the recirculation system pipe 22. Furthermore, in this embodiment, since an aqueous solution containing cerium ions, hydrogen peroxide (oxidizing agent) and formic acid (third drug) is brought into contact with the inner surface of the recirculation system pipe 22, a predetermined thickness is formed on the inner surface of the recirculation system pipe 22. The construction time until cerium adheres can be shortened.

  In this embodiment, by attaching particles of cerium oxide to the inner surface of the stainless steel recirculation pipe 22, iron which is the composition of the base material of the recirculation pipe 22 on the inner surface of the recirculation pipe 22, A passive film consisting of oxides of chromium, nickel and cerium is formed.

  Another embodiment of the present invention will be described with reference to FIG. Here, the particle | grains and film | membrane formation method which contain cerium in the carbon steel member of the feed water piping of a boiling water nuclear power plant are implemented. This example is different from Example 1 in that the film forming apparatus 30 is connected to a water supply pipe of a boiling water nuclear power plant. Since other processes are the same as those in the first embodiment, detailed description thereof is omitted.

  According to the present embodiment, particles containing cerium (cerium oxide particles) can be attached to the inner surface of the water supply pipe 10. For this reason, since it is possible to suppress a very small amount of radionuclide contained in the feed water from adhering to the inner surface of the feed water pipe 10 and to suppress corrosion elution from the feed water pipe 10 of cerium, Inflow of transition metal can be prevented. Therefore, the radioactive concentration of the reactor water in the reactor pressure vessel 12 can be suppressed, and the attachment of the radionuclide to the piping (for example, the recirculation piping 22) connected to the reactor pressure vessel 12 is suppressed. be able to. In the present embodiment, each effect produced in the first embodiment can be obtained.

  Another embodiment of the present invention will be described below with reference to FIG. Here, the particle | grains containing cerium and the membrane | film | coat formation method are implemented in the purification system piping 20 of a boiling water nuclear power plant. Corrosion becomes a problem in the reactor purification system in the regenerative heat exchanger 25 into which high-temperature cooling water from the reactor pressure vessel 12 flows. Valves 100 and 101 are provided in the purification system pipe 20 upstream and downstream of the regenerative heat exchanger 25 made of carbon steel.

  During the operation stop period of the boiling water nuclear power plant, the bonnet of the valve 100 is opened and one end of the circulation pipe L1 of the film forming apparatus 30 is connected to the flange of the bonnet where the valve 100 is opened. The valve 23 provided in the purification system pipe 20 is closed. The bonnet of the valve 101 is opened to seal the flange on the non-regenerative heat exchanger 26 side. The other end of the circulation pipe L1 of the film forming apparatus 30 is connected to the flange of the bonnet where the valve 101 is opened. In this way, the film forming apparatus 30 is connected to the purification system pipe 20, and a circulation path of the aqueous solution formed by the purification system pipe 20 and the circulation pipe L1 is formed.

  Also in the present embodiment, the operations and processes in steps S1 to S8 in the first embodiment are executed. As a result, particles and a film containing cerium are formed on the inner surface of the shell of the non-regenerative heat exchanger 25 in contact with the aqueous solution to be formed, as in Example 1. After the process of step S8 is completed, and within the operation stop period of the boiling water nuclear power plant, the circulation pipe L1 is removed from the purification system pipe 20.

  Also in this embodiment, each effect produced in the first embodiment can be obtained.

  When the valve 101 does not exist between the regenerative heat exchanger 25 and the non-regenerative heat exchanger 26, an isolation valve provided in the purification system pipe 20 between the non-regenerative heat exchanger 26 and the reactor water purification device 27 is provided. What is necessary is just to connect the other end of circulation piping L1 of the film-forming apparatus 30. FIG.

  The film forming apparatus 30 is a carbon steel member in a boiling water nuclear power plant, for example, residual heat removal system piping, water supply system piping, reactor isolation cooling system piping, core spray system piping, auxiliary equipment cooling The method of forming particles and coating film containing cerium according to any one of Examples 2 and 3 may be applied by connecting to piping of a water system and piping of a cooling water system using a cooling tower.

  Furthermore, the particles containing cerium and the film forming method on the carbon steel members of Examples 2 and 3 are not limited to boiling water nuclear power plants, but also carbon steel water supply pipes of pressurized water nuclear power plants and carbon of thermal power plants. It can be applied to steel water supply pipes. At this time, the film forming apparatus 30 is connected to the water supply pipe of the corresponding plant.

  A method for suppressing radionuclide adhesion to structural members of a nuclear power plant according to embodiment 4 which is another embodiment of the present invention will be described with reference to FIGS. 11, 12 and 13. This embodiment is applied to a water supply pipe having a stainless steel member and a carbon steel member in a boiling water nuclear power plant.

  In the radionuclide adhesion suppression method for the components of the nuclear power plant according to the present embodiment, the film forming apparatus 30A shown in FIG. 13 is connected to the water supply pipe, and processing based on the procedure shown in FIG. 11 is executed.

  The procedure shown in FIG. 11 executed by the method for suppressing radionuclide adhesion to the components of the nuclear power plant according to the present embodiment is executed by the method for suppressing attachment of radionuclide to the components of the nuclear power plant according to the first embodiment. Among the procedures shown in FIG. 1, the processing steps S5 (oxidizing agent injection) and S6 (acidic solution injection) are replaced with processing step S9 (pH adjusting agent injection). Other processing steps executed in the procedure of the present embodiment are the same as the processing steps executed in the procedure of the first embodiment.

  The film forming apparatus 30A used in the present embodiment has a configuration in which the acidic liquid injection apparatus 87 is removed from the film formation apparatus 30 used in the first embodiment and a pH adjuster injection apparatus 88 is added. The piping L11 of the injection device 86 is directly connected to the piping L7 upstream of the decomposition device 64 without being directly connected to the circulation piping L1. Other configurations of the film forming apparatus 30A are the same as those of the film forming apparatus 30.

  The pH adjuster injection device 88 includes a chemical liquid tank 47, an injection pump P6, and an injection pipe L13. The chemical tank 47 is connected to the circulation pipe L1 by an injection pipe L13 having an injection pump P6 and a valve V15. The chemical tank 47 is filled with, for example, hydrazine which is a pH adjusting agent.

  The procedure of the radionuclide adhesion suppression method to the components of the nuclear power plant of the present embodiment will be described with reference to FIG. After the operation of the boiling water nuclear power plant is stopped, the respective steps of the processing steps S1 to S8 shown in FIG. 11 are performed. In the processing step S1, one end of the circulation pipe L1 of the film forming apparatus 30A is opened at the bonnet of the valve V16 provided in the water supply pipe between the condensate purification apparatus 6 and the water supply pump, and the circulation pipe of the film formation apparatus 30A is provided. One end of L1 is connected to the flange of the water supply pipe 10 on the water supply pump 7 side. One end of the circulation pipe L1 of the film forming apparatus 30A is connected to the water supply pipe 10 upstream from the connection point between the purification system pipe 20 and the water supply pipe 10 and downstream from the high-pressure feed water heater 9. Thereafter, similarly to the first embodiment, the processing steps S2, S3, and S4 are performed.

  A pH adjuster is injected (processing step S9). A chemical solution containing cerium ions (first drug) is injected from the chemical solution tank 45 of the cerium ion injection device 85 into 75 ° C. water flowing in the circulation pipe L1, and an aqueous solution containing cerium ions is added to the injection pipe L13 and the water supply pipe 10. When hydrazine is reached, hydrazine, which is a pH adjusting agent, is injected from the pH adjusting agent injection device 88 into the injection pipe L1. Hydazine is injected from the chemical liquid tank 47 through the pipe L13 by opening the valve V15 and driving the injection pump P6. By injecting hydrazine, a 75 ° C. aqueous solution that is an aqueous solution containing cerium ions and hydrazine is generated in the circulation pipe L1. The pH of the aqueous solution formed is adjusted to a pH in the range of 6 to 9.5, for example, pH 7, by injection of hydrazine. When the pH of the aqueous solution is 6 or more, cerium oxide particles are produced.

  A formed aqueous solution containing cerium ions and hydrazine is supplied into the water supply pipe 10 from the circulation pipe L1. The formed aqueous solution comes into contact with the inner surface of the water supply pipe 10, and cerium ions contained in the formed aqueous solution of pH 7 are likely to be deposited on the inner surface as cerium oxide. For this reason, cerium oxide particles adhere to the inner surface of the water supply pipe 10. The aqueous solution formed in the feed water pipe 10 is discharged to the circulation pipe L1 downstream of the high-pressure feed water heater 9, and is pressurized by the circulation pumps P2 and P1. The chemical solution containing cerium ions from the cerium ion implanter 85 and the hydrazine from the pH adjuster injector 88 are injected into this formed aqueous solution, and the formed aqueous solution is supplied to the water supply pipe 10 again.

  In the processing step S7, whether the cerium particles have adhered to the inner surface of the water supply pipe 10 with a predetermined thickness is determined as in the first embodiment. When cerium oxide particles having a predetermined thickness adhere, the valve V12 is closed, the injection pump P3 is stopped, and the injection of the chemical liquid containing cerium ions into the circulation pipe L1 is stopped. Further, the valve V15 is closed, the injection pump P6 is stopped, and injection of hydrazine into the circulation pipe L1 is stopped. Thereafter, in the processing step S8, the decomposition of the hydrazine in the decomposition device 64 is performed in the same manner as in the first embodiment. The cerium ions remaining in the forming aqueous solution are removed by the cation resin tower 60 and the mixed bed resin tower 62.

  After the processing of the processing step S8 is completed, the aqueous solution present in each of the water supply pipe 10 and the circulation pipe l1 is discharged to the radioactive waste treatment facility and processed. Thereafter, the circulation pipe L1 is removed from the water supply pipe 10, and the boiling water nuclear power plant is started.

  As a pH adjuster, ammonia may be used instead of hydrazine.

  Since the water supply pipe 10 has a portion made of stainless steel (stainless steel member) and a portion made of carbon steel (carbon steel member), particularly when the acidic solution used in Example 1 is used, carbon The surface of the base material in contact with the water supply of the steel member is dissolved by the acidic solution, making it impossible to attach cerium particles. For this reason, in a present Example, by using a pH adjuster instead of an oxidizing agent and an acidic solution, melt | dissolution of the base material surface of the feed water piping 10 which is a structural member of a nuclear power plant is suppressed, and carbon steel of the feed water piping 10 is used. Cerium particles can be adhered to the inner surface of the member.

  Since the forming aqueous solution containing cerium ions and hydrazine as a pH adjusting agent is brought into contact with the inner surface of the water supply pipe 10, the construction time until the predetermined thickness of cerium oxide adheres to the inner surface of the recirculation system pipe 22 is from Example 1. Can be further shortened. When the pH of the aqueous solution formed is increased to 6 or more using hydrazine, the cerium ions can be changed to cerium oxide, and the cerium oxide easily adheres to the inner surface of the water supply pipe 10.

  According to the present embodiment, each effect generated in the second embodiment can be obtained. In Example 1, since an oxidizing agent and an acidic solution (for example, formic acid aqueous solution) are used, if the formic acid concentration in the aqueous solution formed becomes high and the pH of the aqueous solution formed becomes too small (if the pH becomes less than 5.5). There is a possibility that a problem that the water supply pipe 10 made of carbon steel dissolves may occur. However, in this embodiment, since the oxidizing agent and the acidic solution (for example, formic acid aqueous solution) are not injected as in the first embodiment, the problem that the inner surface of the water supply pipe 10 is dissolved does not occur. In each of the above-described examples such as Example 1 in which an oxidizing agent and an acidic solution (for example, formic acid aqueous solution) are injected, the injection amount of the formic acid aqueous solution is adjusted, and cerium ions, an oxidizing agent and an acidic solution (for example, formic acid aqueous solution) The pH of the aqueous solution containing the solution must be 5.5 or higher.

  A method for suppressing attachment of radionuclide to components of a nuclear power plant according to embodiment 5 which is another embodiment of the present invention will be described with reference to FIG. This embodiment is applied to a water supply pipe having a stainless steel member and a carbon steel member in a boiling water nuclear power plant.

  In the radionuclide adhesion suppression method for the components of the nuclear power plant according to the present embodiment, the film forming apparatus 30A shown in FIG. 13 is connected to the water supply pipe, and processing based on the procedure shown in FIG. 14 is executed. The procedure shown in FIG. 14 executed in this embodiment is executed after the processing step S9 by changing the order of the processing step S4 and the processing step S9 in the procedure shown in FIG. 11 executed in the fourth embodiment. . Other processing steps shown in FIG. 14 are the same as the processing steps shown in FIG. The film forming apparatus 30A used in the present embodiment is substantially the same as the film forming apparatus 30A shown in FIG. 13, but the connection position of the pH adjusting agent injecting device 88 to the circulation pipe L1 is that of the cerium ion injecting device 85. It is located upstream from the connection position to the circulation pipe L1.

  Also in a present Example, after the driving | operation of a boiling water nuclear power plant is stopped, each process of process step S1-S3 is implemented. In processing step S9, hydrazine as a reducing agent is injected from the pH adjuster injection device 88 into 75 ° C. water flowing in the circulation pipe L1. Thereafter, in the processing step S4, when the 75 ° C. aqueous solution containing hydrazine reaches the position of the connection point between the cerium ion implanter 85 and the circulation pipe L1, the chemical solution containing the cerium ions (first drug) becomes the cerium ion implanter 85. Into the circulation pipe L1. A 75 ° C. aqueous solution that is an aqueous solution containing cerium ions and hydrazine is generated in the circulation pipe L 1 and supplied to the water supply pipe 10. Similarly to Example 4, cerium particles adhere to the inner surface of the water supply pipe 10.

  When it is determined “YES” in the processing step S7, the disassembling process in the processing step S8 is executed. After the process of this process step S8 is complete | finished, the circulation piping L1 is removed from the feed water piping 10, and a boiling water nuclear power plant is started.

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

  A method for suppressing attachment of radionuclide to components of a nuclear power plant according to embodiment 6, which is another embodiment of the present invention, will be described with reference to FIG. This embodiment is applied to a reactor purification system of a boiling water nuclear power plant, and uses a film forming apparatus 30A. In this embodiment, each process is executed based on the procedure of FIG.

  In the present embodiment, in the processing step S1, as in the third embodiment, one end of the circulation pipe L1 of the film forming apparatus 30A is connected to the flange of the bonnet in which the valve 100 of the purification system pipe 20 is opened, and the circulation pipe The other end of L1 is connected to the open hood flange of the valve 101. The valve 23 is closed. Then, each process of process steps S2-S4, S9, S7, and S8 is performed sequentially. As a result, a predetermined amount of cerium particles adheres to the inner surface of the purification system pipe 20 between the valve 100 and the valve 101 and the inner surface of the shell of the non-regenerative heat exchanger 25 made of carbon steel. After processing step S8 is completed, the circulation pipe L1 is removed from the purification system pipe 20, and the boiling water nuclear power plant is started.

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

  The forming apparatus 30A is a carbon steel member in a BWR plant, for example, residual heat removal system piping, water supply system piping, reactor isolation cooling system piping, core spray system piping, auxiliary equipment cooling water system piping, In addition, the particles may be connected to piping of a cooling water system using a cooling tower or the like, and the corresponding cerium-containing particles and the film forming method of the second and third embodiments may be applied. As shown in FIG. 2, the forming apparatus 30A may be connected to the recirculation system pipe 22 of the BWR plant, and cerium particles may be attached to the inner surface of the recirculation system pipe 22 using the forming apparatus 30A.

  Furthermore, the particle | grains and film formation method containing the cerium to the carbon steel member of Example 2 and 3 are applied not only to a BWR plant but to the carbon steel water supply pipe of a PWR plant and the carbon steel water supply pipe of a thermal power plant. can do. At this time, the forming apparatus 30 is connected to the water supply pipe of the corresponding plant.

  The present invention can be applied to stainless steel and carbon steel piping in a nuclear power plant.

  DESCRIPTION OF SYMBOLS 1 ... Reactor, 3 ... Turbine, 4 ... Condenser, 10 ... Feed water piping, 12: Reactor pressure vessel, 20 ... Purification system piping, 23 ... Valve, 30, 30A ... Film-forming apparatus, 31 ... Surge tank, P1, P2 ... circulation pump, L1 ... circulation pipe, EJ ... ejector, P3, P4, P5, P6 ... injection pump, 40, 45, 46, 47 ... chemical tank, F ... filter, H ... heater, C ... cooling 60 ... cation exchange resin tower, 62 ... mixed bed resin tower, 64 ... decomposition device, Vi ... inflow side valve, Vo ... outflow side valve, 85 ... cerium ion implantation device, 86 ... oxidant injection device, 87 ... acidic Solution injection device, 88... PH adjuster injection device.

Claims (22)

  A nuclear power plant component whose surface is in contact with reactor water of the nuclear reactor, and after the reactor is shut down, the surface in contact with the reactor water of the reactor is decontaminated and exposed, and then nuclear power and cerium-containing particles and a film are formed. Plant components. In the component of the nuclear power plant according to claim 1,
A component of a nuclear power plant that has been subjected to chemical decontamination to decontaminate and expose the surface. In the component of the nuclear power plant according to claim 2,
A component of a nuclear power plant in which reductive decontamination is performed after oxidative decontamination on the surface as the chemical decontamination, and a reductive decontamination solution used for reductive decontamination is recovered. In the component of the nuclear power plant in any one of Claims 1-3,
In order to form particles and a film containing cerium, a first agent containing cerium ions on the surface, a second agent having an oxidizing ability, and a third agent which is an acidic solution are added to water and brought into contact with each other. A component of a nuclear power plant.   A component of a nuclear power plant whose surface is in contact with the reactor water of the nuclear reactor is characterized in that particles and a film containing cerium are formed after the surface in contact with the reactor water of the nuclear reactor is decontaminated after the reactor is shut down. A method for suppressing the attachment of radionuclides to components of a nuclear power plant. In the method for suppressing attachment of radionuclide to a component of a nuclear power plant according to claim 5,
The method for suppressing radionuclide adhesion to a component of a nuclear power plant, wherein the surface decontamination is performed by chemical decontamination. In the method for suppressing attachment of radionuclide to a component of a nuclear power plant according to claim 5,
As the chemical decontamination, reductive decontamination is carried out after oxidative decontamination on the surface, and a reductive decontamination solution used for reductive decontamination is recovered. . In the radionuclide adhesion suppression method to the structural member of the nuclear power plant in any one of Claims 5-7,
In order to form particles and a film containing cerium, a first agent containing cerium ions on the surface, a second agent having an oxidizing ability, and a third agent which is an acidic solution are added to water and brought into contact with each other. A method for suppressing attachment of a radionuclide to a component of a nuclear power plant, characterized in that In the radionuclide adhesion suppression method to the component of the nuclear power plant according to claim 8,
The method for suppressing attachment of radionuclide to a component of a nuclear power plant, wherein the first chemical containing cerium ion containing cerium is an acidic film forming liquid containing cerium ion. In the method for suppressing attachment of radionuclide to a component of a nuclear power plant according to claim 9,
The method for suppressing attachment of radionuclide to a nuclear reactor component, wherein the acidic film-forming liquid contains an organic acid. In the method for suppressing radionuclide adhesion to the components of the nuclear power plant according to claim 9 or claim 10,
The method for suppressing attachment of a radionuclide to a component of a nuclear power plant, wherein the temperature of the film forming liquid is adjusted to a temperature included in a range of 60 ° C to 100 ° C. A nuclear power plant component forming apparatus for forming a film on the surface of a nuclear plant component contacting the reactor water of a nuclear reactor,
After the reactor is shut down, decontamination means for decontaminating and exposing the surfaces of the components of the nuclear power plant in contact with the reactor water of the nuclear reactor, driven after processing of the decontamination means, A film forming apparatus for a component of a nuclear power plant, comprising particles containing cerium on the surface and a film forming means for forming a film. In the film-forming apparatus of the structural member of the nuclear power plant of Claim 12,
The apparatus for depositing a component of a nuclear power plant, wherein the decontamination means for decontaminating and exposing the surface is chemical decontamination means for performing chemical decontamination. In the film-forming apparatus of the structural member of the nuclear power plant of Claim 13,
The chemical decontamination means includes a first means for supplying an oxidative decontamination liquid to the surface, a second means for supplying a reductive decontamination liquid after the first means, and a reduction decontamination after the second means. A film forming apparatus for a component of a nuclear power plant, comprising a third means for collecting and decomposing the dye liquor. In the film-forming apparatus of the structural member of the nuclear power plant in any one of Claims 12-14,
The film forming means includes a first agent containing cerium ions on a surface of a component of the nuclear power plant, a second agent having an oxidizing ability, and an acidic solution to form particles and a film containing cerium. A film forming apparatus for a component of a nuclear power plant, wherein a third chemical is added to water and supplied to the component of the nuclear power plant. In the film-forming apparatus of the structural member of the nuclear power plant of Claim 15,
A film forming apparatus for a component of a nuclear power plant, wherein the first chemical containing cerium containing cerium is an acidic film forming liquid containing cerium ions. In the nuclear power plant component forming apparatus according to claim 16,
A film forming apparatus for a component of a nuclear power plant, wherein the acidic film forming liquid contains an organic acid such as formic acid or oxalic acid. In the film-forming apparatus of the structural member of the nuclear power plant of Claim 16 or Claim 17,
A film forming apparatus for a component of a nuclear power plant, wherein the temperature of the film forming liquid is adjusted to a temperature included in a range of 60 ° C to 100 ° C. In the film-forming apparatus of the structural member of the nuclear power plant of Claim 16 or Claim 18,
The film forming apparatus is used by being installed on a pipe portion in contact with reactor water in a nuclear power plant and used. In the method for suppressing attachment of radionuclide to a component of a nuclear power plant according to claim 5,
A method for suppressing attachment of a radionuclide to a component of a nuclear power plant, wherein an aqueous solution containing cerium ions and a pH adjusting agent is brought into contact with the surface of the component and cerium is adhered to the surface. In the method for suppressing attachment of radionuclide to the structural member of the nuclear power plant according to claim 20,
A method for suppressing radionuclide adhesion to a structural member of a nuclear power plant, wherein the aqueous solution containing the cerium ion and the pH adjusting agent is brought into contact with a surface of a carbon steel member as the structural member. In the method for suppressing radionuclide adhesion to a component of a nuclear power plant according to claim 20 or 21,
The method for suppressing attachment of a radionuclide to a component of a nuclear power plant, wherein the temperature of the film forming liquid is adjusted to a temperature included in a range of 60 ° C to 100 ° C.

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