METHOD FOR SUPPRESSING RADIOACTIVE NUCLIDE DEPOSITION TO CARBON STEEL MEMBER OF NUCLEAR POWER PLANT

• Main Authors: ITO TAKESHI, HOSOKAWA HIDEYUKI
• Format: Patent
• Language: English; Japanese
• Published: 19.09.2019
• Subjects: NUCLEAR ENGINEERING; NUCLEAR PHYSICS; NUCLEAR POWER PLANT; PHYSICS

To provide a method for suppressing radioactive nuclide deposition to the carbon steel member of a nuclear power plant, capable of reducing the number of processes.SOLUTION: A method for suppressing radioactive nuclide deposition to the carbon steel member of a nuclear power plant comprises: connecting a coating forming apparatus to a carbon steel purification pipe line of a nuclear power plant during the stopping (S1); reductively decontaminating the purification pipe line by an oxalic acid aqueous solution (S2); decomposing a part of oxalic acid (S3B); supplying a coating formation aqueous solution formed by nickel ion injection (S4) to the purification pipe line to form a nickel metal coating on the inner surface of the purification pipe line; supplying an aqueous solution including nickel ions, Pt ions and hydrazine to the purification pipe line from a circulation pipe line to deposit Pt particles including nickel metal on the nickel metal coating (S4-S6); removing the coating forming apparatus from the purification pipe line (S15); starting the nuclear power plant (S16); and converting the nickel metal coating having deposited Pt particles into a stable nickel ferrite coating without eluting even when Pt acts by contacting furnace water including oxygen and having a temperature of 130°C or more and 330°C or less (S12).SELECTED DRAWING: Figure 1 【課題】工程数を低減できる原子力プラントの炭素鋼部材への放射性核種付着抑制方法を提供する。【解決手段】停止中の原子力プラントの炭素鋼製の浄化系配管に皮膜形成装置を接続する（Ｓ１）。シュウ酸水溶液により浄化系配管の還元除染を実施し（Ｓ２）、シュウ酸の一部の分解後（Ｓ３Ｂ）、Ｎｉイオン注入（Ｓ４）で生成した皮膜形成水溶液を浄化系配管に供給し、Ｎｉ金属皮膜を浄化系配管の内面に形成する。その後、Ｎｉイオン、Ｐｔイオン及びヒドラジンを含む水溶液を循環配管から浄化系配管に供給し、そのＮｉ金属皮膜上にＮｉ金属を含むＰｔ粒子を付着させる（Ｓ４〜Ｓ６）。皮膜形成装置を浄化系配管から取り外し（Ｓ１５）、原子力プラントを起動する（Ｓ１６）。１３０℃以上３３０℃以下の酸素を含む炉水の接触により（Ｓ１２）、Ｐｔ粒子が付着したＮｉ金属皮膜を、Ｐｔが作用しても溶出しない安定なＮｉフェライト皮膜に変換する。【選択図】図１