Title:
PREVENTION AND MAINTENANCE DEVICE FOR NARROWED PART WITHIN REACTOR PRESSURE VESSEL
Document Type and Number:
Japanese Patent JP3175570
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To efficiently improve the residual stress of a narrowed weld by installing a second arm to the tip of a first arm, rotating it or moving it radially and vertically, and injecting cavitation bubbles through an injection nozzle on the tip of the second arm.
SOLUTION: The intermediate drum 21 of a rotating body is connected to the lower tip of a fixed structure installed to a CRD guide pipe in the lower part of a reactor core support plate. A vertically movable core 22 is mounted on the intermediate drum 21, and the base of a first arm 24 is installed thereto. The arm 24 is made radially expansible and contractible, so that a second arm 28 having an injection nozzle 27 is drawn into the device by contracting the arm 24. The nozzle 27 is raised and lowered through the arms 24, 28 by the core 22. When the arm 28 is radially extended by the arm 24, and reaches near a shroud wall, the arm 28 is vertically inserted to a narrowed part by the core 22. Cavitation bubbles are injected and collided to a weld narrowed part between the shroud inner wall, and an upper lattice plate through the nozzle 27 at the tip.
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Inventors:
Katsuhiko Hirano
Kunio Enomoto
Kazuo Amano
Eisaku Hayashi
Ren Morinaka
Sadato Shimizu
Kunio Enomoto
Kazuo Amano
Eisaku Hayashi
Ren Morinaka
Sadato Shimizu
Application Number:
JP34031195A
Publication Date:
June 11, 2001
Filing Date:
December 27, 1995
Export Citation:
Assignee:
株式会社日立製作所
International Classes:
G21C19/02; G21D1/00; (IPC1-7): G21C19/02; G21D1/00
Attorney, Agent or Firm:
Yasuo Sakuta