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 . An apparatus for forming a ferrite film on a surface of component composing a nuclear power plant, comprising:
 a surge tank for storing a processing solution;   a recirculation pump sucking the processing solution in the surge tank;   processing solution supply piping for supplying the processing solution sucked by said recirculation pump to piping for film formation;   a first chemical tank for storing iron (II) ions injected into the processing solution in said processing solution piping;   a second chemical tank for storing oxidizer injected in the processing solution in said processing solution supply piping;   a third chemical tank for storing pH adjuster adjusting the pH of the processing solution in said processing solution supply piping to 5.5 to 9.0;   processing solution return piping for returning the processing solution returned from said piping for film formation to said surge tank; and   a heating means for heating the processing solution to be a temperature of 60-100° C.   
   
   
       2 . An apparatus for forming a ferrite film according to  claim 1 , wherein a chemical tank for oxidizer and reducer is fluidly communicated with said processing solution piping. 
   
   
       3 . An apparatus for forming a ferrite film according to  claim 2 , wherein an ion exchange resin tower and a mixed bed resin tower each for removing contaminants in the processing solution are inserted in said processing solution return piping. 
   
   
       4 . An apparatus for forming a ferrite film according to  claim 3 , wherein a filter for removing solid substances contained in the processing solution is installed in said processing solution supply piping or said piping for film formation. 
   
   
       5 . An apparatus for forming a ferrite film according to  claim 3 , wherein the oxidizer stored in said second chemical tank generates oxygen-containing bubbles in the solution. 
   
   
       6 . An apparatus for forming a ferrite film according to  claim 3 , wherein decomposition equipment for at least a part of organic acid and nitrogen compound contained in the processing solution in said processing solution return piping. 
   
   
       7 . An apparatus for forming a ferrite film according to  claim 6 , wherein said decomposition equipment is a decomposer employing at least one of active carbon catalyst, hydrogen peroxide, ultraviolet rays, and ozone. 
   
   
       8 . An apparatus for forming a ferrite film according to  claim 3 , wherein a chemical tank for storing noble metal or compound containing noble metal is connected to said processing solution supply piping.