Hitachi, Ltd.

Babcock-Hitachi Kabushiki Kaisha

Kasunori Sato

Kunio Enomoto

Ren Morinaka

Koichi Kurosawa

Masahiro Otaka

Shigeo Hattori

Eisaku Hayashi

Kazuo Amano

Low temperature water in a low temperature water tank 12 installed outside a reactor pressure vessel 9 is pumped by a high pressure pump 15 and supplied through a conductor 17 under pressure. The supplied water is ejected, as a stream of cold water jet 8, from a nozzle 14 connected to the conductor 17 and introduced into the reactor pressure vessel 9 by a driving mechanism. The stream of cold water jet 8 ejected from the nozzle 14 is directed to impinge against a predetermined position of a core shroud 13 in reactor water 11 filled in the reactor pressure vessel 9 and being at temperature higher than the low temperature water. Then, while continuing to eject the cold water jet 8 from the nozzle 14, the nozzle 14 is moved away from the predetermined position, or the ejection of the cold water jet 8 from the nozzle 14 is stopped, allowing the predetermined position to be heated again with the temperature of the reactor water 11. A thermal shock is thereby applied to the predetermined position for improvement in residual stress of the core shroud 13.

Residual stress improving method for members in reactor pressure vessel

Growing community of inventors

Kure, Japan

Kasunori Sato