| 摘要 |
PROBLEM TO BE SOLVED: To mitigate stress corrosion cracking at metal structure part by injecting a solution of compound containing noble metals into cooling water during no generation of nuclear heat and decomposing under radiating condition in reactor and discharging the noble metal atoms. SOLUTION: A solution of compound containing noble metals, for example palladium acetylacetonate, is injected in cooling water in reactor shutdown period or during heatup. Though the cooling water temperature is as low as ca. 120 deg. F in shutdown period, it rises to ca. 400 to 450 deg. F by pump heating and the noble metal compound is decomposed byγ-ray radiated from fuel. The decomposition is promoted also by radioactive isotopes in material in core structure to be protected. By this, noble metal compounds are decomposed to discharge noble metal atoms, which mixes in deposits on oxide coating formed on the structure part of such alloy as stainless steel and mitigates stress corrosion cracking.
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