| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability of a plant and prolong service life or the like, by realizing surface reform execution of the weld zone of a core spray sparger or the like, and by reducing the possibility of generation of a stress corrosion cracks of the core spray sparger. SOLUTION: The upper part of a reactor pressure vessel is opened, and instruments on the reactor upper part such as a steam drier, a steam separator or the like and a fuel are dismantled. Piping in a core spray system, arranged over a core shround and connected to the core spray sparger through inlet piping, is cut and dismantled. Hereby, the upper part of the core shroud is opened, and the inlet pipe part of the core spray sparger is opened. A surface reforming device is inserted in this state into the core spray sparger via the cut opening part of the piping in the core spray system, and the surface reforming execution with respect to the stress corrosion crack is executed from the inner surface side of the core spray sparger.
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