Method and device for unlatching control rod drive shafts in pressurized water reactors

An unlatching tool configured for actuating a movable section of a control rod drive shaft in a pressurized water reactor, the unlatching tool extending longitudinally along a center axis and comprising:

• a base;
• an outer assembly rotatably fixed to the base;
• an inner support assembly non-rotatably fixed to the base;
• a gripper assembly movably coupled to the base and configured for gripping the movable section of the control rod drive shaft;
• a latch rotatably coupled to the inner support assembly for rotation about a latch axis extending parallel to a center axis of the unlatching tool;
• and
• a latch actuator fixed to the outer assembly and configured for rotating the outer assembly in a first rotational direction about the center axis of the unlatching tool such that the latch is rotated about the latch axis radially inward with respect to the center axis of the unlatching tool,
• the outer assembly being configured such that an inner circumferential surface of the outer assembly contacts a tip of the latch to hold the latch against an outer circumferential surface of a stationary section of the control rod drive shaft.