Method of repairing housing of control rod driving system

A method of repairing the housing of a control rod driving system of a nuclear reactor, said housing being inserted through the wall of a pressure vessel of said reactor into a cylindrical sleeve secured to the inner surface of said vessel which housing is jointed by welding to said cylindrical sleeve, said method comprising the steps of:

• cutting said housing in the circumferential direction of the housing at a portion thereof positioned between the weld joint and the inner surface of said vessel and surrounded by said cylindrical sleeve, thereby to divide said housing into a first housing part still secured to the weld joint and another removable housing part;
• removing said removable housing part;
• inserting a second housing part into said cylindrical sleeve through the wall of said nuclear reactor vessel, and forming a weld groove defined between the cut end of said first housing part and the adjacent end of said second housing part;
• and
• effecting a welding on said groove to unite said first housing part, second housing part and said cylindrical sleeve, thereby to form a new housing of said control rod driving system.

A method of repairing the housing of a control rod driving system of a boiling water reactor, said housing being inserted through the lower end plate of the pressure vessel of said reactor into a cylindrical sleeve secured to the inner surface of said vessel which housing is jointed to said cylindrical sleeve by welding, said housing accommodating a control rod and a control rod driving member detachably connected to said control rod, said method comprises the steps of:

• detaching the connection between said control rod and said control rod driving member and removing the latter from said housing;
• cutting said housing in the circumferential direction of the housing at a portion thereof positioned between the weld joint and the inner surface of said lower end plate and surrounded by said cylindrical sleeve, thereby to cut said housing into a first housing part fixed to said weld joint and another removable housing part;
• removing said removable housing part;
• inserting a second housing part into said cylindrical sleeve through said lower end plate;
• and
• uniting said first housing part and said second housing part thereby to form a new housing for said control rod driving system.

A method of repairing the housing of a control rod driving system of a boiling water reactor, said housing being inserted through the lower end plate of the pressure vessel of said reactor into a cylindrical sleeve secured to the inner surface of said vessel which housing is jointed to said cylindrical sleeve by welding, said housing accommodating a control rod and a control rod driving member detachably connected to said control rod, said method comprises the steps of:

• detaching the connection between said control rod and said control rod driving member and removing the latter from said housing;
• cutting said housing in the circumferential direction of the housing at a portion thereof positioned between the weld joint and the inner surface of said lower end plate and surrounded by said cylindrical sleeve, thereby to divide said housing into a first housing part attaching to the weld joint and another removable housing part;
• removing said removable housing part;
• inserting a second housing part into said cylindrical sleeve through said lower end plate and forming a weld groove between the cut end of said first housing part and the adjacent end of said second housing part;
• effecting an inert gas arc welding at said groove to unit said first housing part, second housing part and said cylindrical sleeve thereby to form a new housing for the control rod driving system.