Title:
PREVENTIVE MAINTENANCE EQUIPMENT FOR REACTOR PRESSURE VESSEL INTERNAL STRUCTURE
Document Type and Number:
Japanese Patent JP3779416
Kind Code:
B
Abstract:
PROBLEM TO BE SOLVED: To efficiently remove surface residual stress being the cause of stress corrosion cracking of welding part on shroud inner surface and the like by providing a nozzle to a pole mounted in vertical direction from a preventive maintenance device main body rotatably placed on a fixing body placed on the shroud upper part in a reactor pressure vessel.
SOLUTION: A preventive maintenance device 1 is provided with detectors detecting the velocity and rotational position of the motor driving each part, potensiometer, etc. The detection signal is sent to a control panel and the running velocity and spray position of a spray nozzle 10 are controlled in optimum conditions. The water pressurized by a high pressure pump is sprayed out of the spray nozzle 10 via a high pressure hose. At this moment, cavitation bubbles are generated by using the pressure difference between the surrounding reactor water and the spray water, shearing work, etc. With the shock pressure generated during collapse of the bubbles on the surface and in the vicinity of the upper flange 4, the upper flange 4 and whole upper shroud 3 below it are peened and residual stress is removed.
Inventors:
Kurosawa, Koichi
Otaka, Minoru
Enomoto, Kunio
Satou, Kazunori
Hayashi, Eisaku
Kume, Tadashi
Otaka, Minoru
Enomoto, Kunio
Satou, Kazunori
Hayashi, Eisaku
Kume, Tadashi
Application Number:
JP1997000075730
Publication Date:
March 10, 2006
Filing Date:
March 27, 1997
Export Citation:
Assignee:
HITACHI LTD
BABCOCK HITACHI KK
BABCOCK HITACHI KK
International Classes:
G21C19/02; H01G2/06; G21C19/02; H01G2/00; (IPC1-7): G21C19/02
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