Vibration suppressing device for jet pump, jet pump and vibration suppressing method therefor

摘要

A vibration suppressing device for a jet pump is provided in a reactor pressure vessel of a boiling water reactor for causing forced circulation of cooling water in the reactor pressure vessel. The jet pump includes an inlet mixer pipe coupled to a riser pipe and a diffuser coupled to the inlet mixer pipe by a slip joint, in which a clearance flow channel in the slip joint is formed between an inner surface of the diffuser and an outer surface of the inlet mixer pipe. The vibration suppressing device includes an extension sleeve mounted on the diffuser and shaped to have a smaller inner diameter in an upper portion thereof than in a lower portion thereof and forms, above an upper end of the diffuser, an extension clearance flow channel between an inner surface thereof and the outer surface of the inlet mixer pipe. The extension clearance flow channel is shaped to be narrower in an upper portion thereof than in a lower portion thereof because of the shape of the extension sleeve.