Method for Depositing Noble Metal to Carbon Steel Member of Nuclear Power Plant and Method for Suppressing Radionuclide Deposition on Carbon Steel Member of Nuclear Power Plant

Abstract

A film forming apparatus is connected to a carbon steel purification system piping of a BWR plant (S 1 ). Formic acid (surface purification agent) is injected into a circulation piping of the film forming apparatus (S 4 ). A surface purification agent aqueous solution containing 30000 ppm of formic acid is contacted with the inner surface of the purification system piping, and a large amount of Fe 2+ is dissolved from the purification system piping, and a large amount of electrons are generated by this dissolution. Thereafter, a formic acid Ni aqueous solution is injected into the surface purification agent aqueous solution to produce a film forming aqueous solution (S 5 ). The film forming aqueous solution storing the electrons is contacted with the inner surface of the purification system piping, and Ni ions incorporated into the inner surface are reduced by the electrons, and a Ni metal film is formed on the inner surface. Platinum ions and a reducing agent are injected into the circulation piping (S 9 , S 10 ), and an aqueous solution containing the platinum ions and the reducing agent is supplied to the purification system piping to deposit platinum on the surface of the Ni metal film.

What is claimed is: 
     
         1 . A method for depositing a noble metal on a carbon steel member of a nuclear power plant, the method comprising:
 contacting a film forming solution containing nickel ions and a surface purification agent and having a pH within a range of 1.8 or more to 2.5 or less with a first surface of a carbon steel member of a nuclear power plant that contacts reactor water; and   forming a nickel metal film on the first surface; and   depositing a noble metal on a second surface of the formed nickel metal film,   wherein the forming the nickel metal film and the depositing the noble metal are performed after shut-down of the nuclear power plant and before start-up of the nuclear power plant.   
     
     
         2 . A method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 ,
 wherein the formation of the nickel metal film including the first step of contacting the film forming solution containing the nickel ions and the surface purification agent with the first surface and the second step of forming the a nickel metal film on the first surface is performed by steps of:   contacting a surface purification agent solution containing a surface purification agent and having a pH within a range of 1.8 or more to 2.5 or less with a first surface of a carbon steel member of a nuclear power plant that contacts reactor water;   after a set time is elapsed since the surface purification agent solution is contacted with the first surface of the carbon steel member, injecting nickel ions into the surface purification agent solution to produce a film forming solution to produce the film forming solution; and   contacting the produced film forming solution with the first surface of the carbon steel member to form a nickel metal film on the first surface.   
     
     
         3 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 , wherein any one of formic acid, malonic acid, and ascorbic acid is used as the surface purification agent. 
     
     
         4 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 , wherein the forming the nickel metal film is performed by reducing the nickel ions incorporated into the first surface of the carbon steel member by using electrons generated when iron ions are dissolved from the carbon steel member by the surface purification agent. 
     
     
         5 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 4 , wherein the depositing the noble metal on the second surface of the nickel metal film is performed by contacting an aqueous solution containing noble metal ions and a reducing agent with the second surface of the nickel metal film. 
     
     
         6 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 , wherein the contacting the film forming solution with the first surface of the carbon steel member is performed after removing an oxide film formed on the carbon steel member. 
     
     
         7 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 2 , wherein the contacting the surface purification agent solution with the first surface of the carbon steel member is performed after removing an oxide film formed on the carbon steel member. 
     
     
         8 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 6 , wherein the removing the oxide film is performed by contacting an oxalic acid aqueous solution with the first surface of the carbon steel member, wherein an oxidant is injected into the oxalic acid aqueous solution. 
     
     
         9 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 , comprising decomposing the surface purification agent contained in the film forming solution after the nickel metal film is formed and before the noble metal is deposited on the second surface of the nickel metal film. 
     
     
         10 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 1 , wherein the forming the nickel metal film is performed by supplying, through a second piping, the film forming solution to a first piping which is connected to a reactor pressure vessel and which is the carbon steel member, and by contacting the film forming solution with an inner surface of the first piping, which is the first surface of the carbon steel member. 
     
     
         11 . The method for depositing a noble metal on a carbon steel member of a nuclear power plant according to  claim 2 , wherein the contacting the surface purification agent solution with the first surface of the carbon steel member is performed by supplying, through a second piping, the surface purification agent solution to a first piping which is connected to a reactor pressure vessel and which is the carbon steel member, and by contacting the surface purification agent solution with an inner surface of the first piping, which is the first surface of the carbon steel member, and
 the forming the nickel metal film is performed by supplying the film forming solution produced in the second piping by injecting the nickel ions into the surface purification agent solution to the first piping and by contacting the produced film forming solution with the inner surface of the first piping, which is the first surface of the carbon steel member.   
     
     
         12 . A method for suppressing deposition of radionuclides on a carbon steel member of a nuclear power plant, the method comprising:
 contacting a film forming solution containing nickel ions and a surface purification agent and having a pH within a range of 1.8 or more to 2.5 or less with a first surface of a carbon steel member of a nuclear power plant that contacts reactor water; and   forming a nickel metal film on the first surface; and   depositing a noble metal on a second surface of the formed nickel metal film,   wherein the forming the nickel metal film and the depositing the noble metal are performed after shut-down of the nuclear power plant and before start-up of the nuclear power plant, and   contacting oxygen-containing water having a temperature range of 130° C. or more and 330° C. or less with a second surface of the nickel metal film on which the noble metals are deposited.   
     
     
         13 . The method for suppressing deposition of radionuclides on a carbon steel member of a nuclear power plant according to  claim 12 , the method comprising:
 starting the nuclear power plant after the noble metals are deposited on the second surface; and   using reactor water as the oxygen-containing water having the temperature range of 130° C. or more and 330° C. or less.