Stevens, Davis, Miller & Mosher
Method and apparatus for use to exchange O-ring interposed between in-core housing and in-core flange in nuclear reactor
 This invention concerns a method and apparatus for use to exchange an O-ring interposed between an in-core housing disposed at the lower end of a guide tube for an in-core monitor for monitoring the operation of a nuclear reactor and an in-core flange attached to the housing. The apparatus comprises a drain system adapted to be connected to the lower end of the flange for draining reactor water, a split cylindrical guide member adapted to be suspended from an upper grid located in a pressure vessel after removing the in-core monitor, an operating mechanism to be inserted into the guide member, the operating member being hung down from a platform of the reactor, and a tubular repairing tool secured to the lower portion of the operating mechanism, the repairing tool being provided with a valve member which is to be water-tightly engaged with a valve seat formed for the housing when the operating mechanism is lowered into the guide member. 
Tokyo Shibaura Denki Kabushiki Kaisha
G Y G Y
G21C Y10T G21C Y02E
inventional additional inventional additional
Teruaki Shigeru
Tsuji Watanabe