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AssigneesHitachi, Ltd., Kurita Engineering Co., Ltd.
InventorsKazushige Ishida, Kazumi Anazawa, Yoshiyuki Takamori, Naohito Uetake, Makoto Nagase, Hiroo Yoshikawa, Tadashi Tamagawa
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To suppress a decrease of thickness due to corrosion of structural members and to achieve a removal of radionuclides with good efficiency in a nuclear power plant, oxidation decontamination is first conducted. An aqueous potassium permanganate solution is supplied from a circulation line to a reactor pressure vessel, which is a stainless steel structural member, and a reactor water cleanup system piping and a drain piping, which are carbon steel structural members. These structural members are oxidation-decontaminated by the action of potassium permanganate. Then the above-mentioned structural members are reduction-decontaminated by using an aqueous oxalic acid solution. The aqueous oxalic acid solution contains hydrazine.
A method of chemical decontamination which comprises, in a boiling water reactor nuclear power plant provided with a first structural member having a surface which contacts with a coolant and is made of stainless steel and a second structural member having a surface which contacts with a coolant and is made of carbon steel or an iron-based alloy containing chromium and being inferior in corrosion resistance to the stainless steel, pretreating the second structural member with an oxidation decontaminating solution containing an oxidation decontaminating agent applied to both the first structural member and the second structural member, thereby increasing corrosion resistance of the second structural member, and thereafter decontaminating the first structural member and the second structural member with a reduction decontaminating solution containing a reduction decontaminating agent applied to the first structural member and the second structural member, to remove radionuclides from both the first structural member and the second structural member.
A method of chemical decontamination which comprises, in a boiling water reactor nuclear power plant provided with a first structural member having a surface which contacts with a coolant and is made of stainless steel and a second structural member having a surface which contacts with a coolant and is made of carbon steel or an iron-based alloy containing chromium and being inferior in corrosion resistance to the stainless steel, pretreating the second structural member with an oxidation decontaminating solution containing an oxidation decontaminating agent applied to both the first structural member and the second structural member at a state that the first structural member and the second structural member are communicated to each other, thereby increasing corrosion resistance of the second structural member, and thereafter decontaminating the first structural member and the second structural member with a reduction decontaminating solution containing a reduction decontaminating agent applied to the first structural member and the second structural member at a state that the first structural member and the second structural member are communicated to each other, to remove radionuclides from both the first structural member and the second structural member.
Dependencies are inferred from the claim text.