Method of depositing noble metal on structure member of nuclear plant

摘要

A noble metal injection apparatus is connected to a piping of a nuclear plant at the time of stop of the nuclear plant before start of the nuclear plant. In chemical decontamination, oxidation decontamination agent decomposition, and reduction decontamination on an inner surface of the pipe system are executed. After reduction decontamination, a part of an oxalic acid included in a reduction decontamination solution is decomposed and platinum is injected into the reduction decontamination solution of pH 3.5 or higher. When the platinum concentration becomes a preset concentration, a reduction agent is injected and the reduction decontamination solution including the platinum and reduction agent is brought into contact with the inner surface of the piping. The platinum is deposited on the inner surface of the piping. The injection of the platinum and reduction agent is stopped and the platinum and reduction agent are decomposed.

主权项

1. A method of depositing a noble metal on a structure member of a nuclear plant, comprising:
1) executing reduction decontamination of a surface of a structure member of a nuclear plant in contact with reactor water by using a first aqueous solution including a reduction decontamination agent; and 2) bringing a second aqueous solution including noble metal ions, a reduction agent, and said reduction decontamination agent into contact with said surface of said structure member on which said reduction decontamination is executed and depositing said noble metal on said surface; wherein said second aqueous solution is generated by injecting chemical including said noble metal ions and said reduction agent into said first aqueous solution, wherein step 2 is performed in a period that at least part of said reduction decontamination agent from step 1 remains in said second aqueous solution and has not been decomposed, wherein steps 1 and 2 are executed after operation stop of said nuclear plant but before start of said nuclear plant, and wherein the noble metal is selected from the group consisting of platinum, palladium, rhodium, ruthenium, osmium, and iridium.