Abstract: An unlatching tool which can be used to uncouple and grapple standard handle and extended handle control rods from their associated control rod drives. The unlatching tool is lowered onto the handle of a control rod residing in the reactor core. Due to differences in the shapes of the handles of the standard handle and extended handle control rods, the tool is able to sense the type of control rod present and, through the use of a pneumatically actuated cylinder, position the unlatching mechanism at the appropriate elevation. In particular, a four-way valve, that is actuated by contact with the top corner of the handle of the extended handle control rod and is not contacted by the handle of the standard handle control rod, is used to differentiate between control rod types. The unlatching mechanism is positioned relative to the unlocking handle on the control rod using a pneumatic cylinder activated by the four-way valve.