Suppression Method of Radionuclide Deposition on Reactor Component of Nuclear Power Plant and Ferrite Film Formation Apparatus

Abstract

A method of suppressing deposition of radionuclides on components of a nuclear power plant comprises forming a ferrite film by contacting a first chemical including iron (II) ions, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of a processing solution containing a mixture of the first and second chemicals to be 5.5 to 9.0 with the metal member surface in a time period from a finishing stage in decontamination step of removing contaminants formed on the surface of metal member composing the nuclear power plant, and suppressing deposition of radionuclides on the metal member by the ferrite film.

1 . A method of suppressing deposition of radionuclides on components of a nuclear power plant, comprising the steps of:
 forming a ferrite film on a surface of a metal member composing the nuclear power plant; and   decomposing chemicals included in a waste liquid after forming the ferrite film on the surface of the metal member.   
   
   
       2 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 1 , wherein decomposition of the chemicals is carried out with decomposition equipment. 
   
   
       3 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 1 , further comprising the steps of:
 removing contaminants including an oxide film deposited on the surface of the metal member by chemical decontamination;   decomposing reducing agent used in reductive removing included in the chemical decontamination after the reductive removing; and   carrying out formation of the ferrite film after decomposition of the reducing agent.   
   
   
       4 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 3 , wherein decomposition of the chemicals is carried out with decomposition equipment used in the decomposition of the reducing agent. 
   
   
       5 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 1 , wherein the chemicals include a first pH adjusting agent used in formation of the ferrite film and organic acid which dissolves iron for preparing iron (II) ion used in formation of the ferrite film. 
   
   
       6 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 5 , wherein the organic acid is formic acid. 
   
   
       7 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 5 , further, comprising the steps of:
 removing contaminants including an oxide film deposited on the surface of the metal member by chemical decontamination;   decomposing reducing agent and a second pH adjusting agent used in reductive removing included in the chemical decontamination after the reductive removing; and   carrying out formation of the ferrite film after decomposition of the reducing agent and the second pH adjusting agent.   
   
   
       8 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 7 , wherein decomposition of the first pH adjusting agent and the organic acid is carried out with decomposition equipment used in the decomposition of the reducing agent and the second pH adjusting agent. 
   
   
       9 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 8 , wherein when the first pH adjusting agent and the organic acid are decomposed and when the reducing agent and the second pH adjusting agent are decomposed, oxidizer is supplied into the decomposition equipment. 
   
   
       10 . A method of suppressing deposition of radionuclides on components of a nuclear power plant, comprising the steps of:
 forming a ferrite film on a surface of a metal member composing the nuclear power plant with solution including iron (II) ion, oxidizer for oxidizing the iron (II) ion to iron (III) ion, and a first pH adjusting agent; and   decomposing the first pH adjusting agent including in the solution after forming the ferrite film on the surface of the metal.   
   
   
       11 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 10 , wherein decomposition of the first pH adjusting agent is carried out with decomposition equipment. 
   
   
       12 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 10 , wherein when the solution includes organic acid which dissolves iron for preparing iron (II) ion, the organic acid is decomposed after formation of the ferrite film. 
   
   
       13 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 12 , wherein decomposition of the first pH adjusting agent and the organic acid is carried out with decomposition equipment. 
   
   
       14 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 10 , further comprising the steps of:
 removing contaminants including an oxide film deposited on the surface of the metal member by chemical decontamination;   decomposing reducing agent and a second pH adjusting agent used in reductive removing included in the chemical decontamination after the reductive removing; and   carrying out formation of the ferrite film after decomposition of the reducing agent and the second pH adjusting agent.   
   
   
       15 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 14 , wherein decomposition of the first pH adjusting agent is carried out with decomposition equipment used in the decomposition of the reducing agent and the second pH adjusting agent. 
   
   
       16 . An apparatus for forming a ferrite film on components of a nuclear power plant, comprising:
 a first tank for storing a first chemical including iron (II) ion;   a second tank for storing a second chemical for oxidizing the iron (II) ion to iron (III) ion;   a third tank for storing a third chemical for adjusting pH of a solution including the first and second chemicals;   piping through which the solution is introduced, connected with the first, second and third tanks, and being connected with the nuclear power plant;   a pump provided with the piping; and   decomposition equipment for decomposing the third chemical, and connected with the piping.   
   
   
       17 . An apparatus for forming a ferrite film on components of a nuclear power plant according to  claim 16 , wherein the decomposition equipment decomposes organic acid which dissolves iron for preparing the iron (II) ion and which is included in the first chemical. 
   
   
       18 . An apparatus for forming a ferrite film on components of a nuclear power plant according to  claim 16 , further comprising:
 oxidizer supply apparatus for supplying oxidizer to the decomposition equipment.   
   
   
       19 . A method of suppressing deposition of radionuclides on components of a nuclear power plant, comprising the steps of:
 forming a ferrite film on a surface of a metal member composing the nuclear power plant; and   depositing noble metal on the ferrite film by conducting noble metal deposition treatment after formation of the ferrite film.   
   
   
       20 . A method of suppressing deposition of radionuclides on components of a nuclear power plant according to  claim 19 , further comprising the steps of:
 removing contaminants including an oxide film deposited on the surface of the metal member by chemical decontamination; and   carrying out the formation of the ferrite film after the chemical decontamination.