Method of removing retainer of jet pump and jet pump

Abstract

A retainer provided at lower portion of a pump beam of a jet pump for circulating cooling water to a reactor core or a bolt for fastening the retainer is cut through an underwater-remote control to remove the bolt and the retainer is removed through the underwater-remote control.

1 . A method of removing a jet pump retainer disposed in a reactor pressure vessel of a boiling water reactor and configured to connect a pump beam of a jet pump for circulating coolant in a reactor core to an elbow portion, the method comprising the steps of:
 annularly cutting a peripheral portion excluding a welded portion of the retainer and a retainer mounting bolt fastening the retainer to the elbow portion;   inserting a bolt retainer, for preventing the retainer from falling down, between the retainer and the elbow portion after loosening the retainer mounting bolt;   removing the retainer mounting bolt with the bolt retainer being inserted;   rotating a head bolt mounted on the pump beam to tightly fastening the retainer to the pump beam;   grasping and removing the pump beam outside the reactor pressure vessel; and   removing thereafter the retainer through an under water operation by a remote control.   
   
   
       2 - 7 . (canceled)