Suppression method of radionuclide deposition on reactor component of nuclear power plant and ferrite film formation apparatus

A method of suppressing deposition of radionuclides on components of a nuclear power plant, comprising the steps of:

• removing contaminants including an oxide film deposited on an inner surface of piping in the nuclear power plant by chemical decontamination;
• supplying a processing solution into the piping through a pipe having a pump for pressurizing the processing solution and a heating apparatus for heating the processing solution after removing the contaminants, wherein the processing solution:
• includes a first chemical including iron (II) ions and formic acid, a second chemical for oxidizing the iron (II) ions to iron (III) ions, and a third chemical for adjusting the pH of the processing solution,
• is adjusted to a temperature within 60° C. to 100° C. by the heating apparatus, and
• has a pH adjusted within 5.5 to 9.0,
• wherein the first, second and third chemicals are individually supplied to the pipe;
• forming a ferrite film on the inner surface of the piping by contacting the processing solution with the inner surface of the piping at a temperature between 60° C. and 100° C.;
• and
• decomposing the formic acid and the third chemical for adjusting pH into gas and water after formation of the ferrite film is finished,
• wherein the steps of removing contaminants, supplying the processing solution, forming the ferrite film, and decomposing the formic acid and the third chemical are carried out after the nuclear power plant is stopped and before restarting the nuclear power plant.