Apparatus for exchanging control rod drive mechanism in a nuclear reactor

In apparatus for exchanging a control rod drive mechanism of a nuclear reactor of the type comprising a horizontal platform supported to be rotatable in a working chamber disposed below a reactor pressure vessel and a traveling carriage traveling on a rail assembly laid on said platform, the improvement which comprises a beam attached to said traveling carriage to be swingable between the vertical and horizontal portions and provided with a carrier for vertically moving said control rod drive mechanism, bolt mounting means for loosening and clamping bolts which are used to connect said control rod drive mechanism to a housing in the reactor pressure vessel;

• holding means secured to said beam for carrying one end of said control rod drive mechanism when said control rod mechanism is separated from said bolt mounting means and holding said control rod drive mechanism when said beam is swung to said horizontal position, said holding means being received in a position where said holding means is not interferred with said carrier when said carrier passes near said holding means;
• means for conveying said bolt mounting means in and out of the passage of movement of said carrier so that said control rod drive mechanism can easily be withdrawn vertically without being interferred with said bolt mounting means;
• and means for receiving said control rod drive mechanism when said beam has been moved to said horizontal position and for conveying said control rod drive mechanism into an inspection chamber for inspecting said control rod drive mechanism through a passage provided for the peripheral wall of said working chamber.