Control rod drive apparatus utilizing alloys with low to zero cobalt content

A control rod drive apparatus, comprising:

• a cylindrical housing structure including a proximal end and an opposing distal end;
• a drive assembly within the cylindrical housing structure, the drive assembly including a drive piston and an index tube;
• a flange connected to the proximal end of the cylindrical housing structure, the flange defining a vacancy therein;
• and
• a check valve ball disposed within the vacancy defined by the flange, the vacancy configured to facilitate a displacement of the check valve ball between an open position which allows a first flow in a first direction to facilitate movement of the drive piston toward the distal end of the cylindrical housing structure and a closed position which halts a second flow in an opposite second direction, the check valve ball being made of an alloy having less than 2% cobalt by weight.