An apparatus including a lower end fitting having a top planar surface, a bottom planar surface, a counterbore defined therebetween, an opening extending from the counterbore to the top planar surface, and a lock recess that extends both radially outwardly from the counterbore and extends inwardly into the lower end fitting from the bottom planar surface. The apparatus includes a guide tube having a lower end and an end plug configured to connect with the lower end of the guide tube. The end plug has a threaded shaft sized to pass through the opening of the lower end fitting, and a female lock nut has a deformable side wall configured to be swaged into the recess of the lower end fitting. The lock recess remains visible as viewed from the bottom planar surface of the lower end fitting when the female lock nut is fully disposed in the counterbore.

An apparatus including a lower end fitting having a top planar surface, a bottom planar surface, a counterbore defined therebetween, an opening extending from the counterbore to the top planar surface, and a lock recess that extends both radially outwardly from the counterbore and extends inwardly into the lower end fitting from the bottom planar surface. The apparatus includes a guide tube having a lower end and an end plug configured to connect with the lower end of the guide tube. The end plug has a threaded shaft sized to pass through the opening of the lower end fitting, and a female lock nut has a deformable side wall configured to be swaged into the recess of the lower end fitting. The lock recess remains visible as viewed from the bottom planar surface of the lower end fitting when the female lock nut is fully disposed in the counterbore.

A novel head device generally consisting of at least one aperture that is capable of excepting different sizes of safety wire, at least one cam-locking lever, which may incorporate a spring return mechanism, is disclosed. The body may be rotated by a mechanical means which twists the safety wire. In preferred embodiment, the various elements of the safety wire twister device are each configured with means of limiting torque or twists of safety wire to eliminate possibility of over torqueing or twisting of safety wire.

A novel head device generally consisting of at least one aperture that is capable of excepting different sizes of safety wire, at least one cam-locking lever, which may incorporate a spring return mechanism, is disclosed. The body may be rotated by a mechanical means which twists the safety wire. In preferred embodiment, the various elements of the safety wire twister device are each configured with means of limiting torque or twists of safety wire to eliminate possibility of over torqueing or twisting of safety wire.

An apparatus including a lower end fitting having a top planar surface, a bottom planar surface, a counterbore defined therebetween, an opening extending from the counterbore to the top planar surface, and a lock recess that extends both radially outwardly from the counterbore and extends inwardly into the lower end fitting from the bottom planar surface. The apparatus includes a guide tube having a lower end and an end plug configured to connect with the lower end of the guide tube. The end plug has a threaded shaft sized to pass through the opening of the lower end fitting, and a female lock nut has a deformable side wall configured to be swaged into the recess of the lower end fitting. The lock recess remains visible as viewed from the bottom planar surface of the lower end fitting when the female lock nut is fully disposed in the counterbore.

A fuel assembly includes a plurality of fuel rods comprising fissile material, a plurality of guide tubes interspersed amongst the fuel rods, an upper end fitting connected with upper ends of guide tubes, and a lower end fitting. End plugs are connected with the lower ends of the guide tubes. The end plugs have threaded male shafts extending from the lower ends of the guide tubes which pass through openings of the lower end fitting. Female lock nuts are threaded onto the threaded male shafts of the end plugs and lock with the lower end fitting to secure the lower end fitting to the lower ends of the guide tubes. The female lock nuts suitably have locking portions that are outwardly deformed into recesses of the lower end fitting to lock the lock nuts in place after tightening. Dashpot tubes may be disposed in the lower ends of the guide tubes and connected to the end plugs.

A fuel assembly includes a plurality of fuel rods comprising fissile material, a plurality of guide tubes interspersed amongst the fuel rods, an upper end fitting connected with upper ends of guide tubes, and a lower end fitting. End plugs are connected with the lower ends of the guide tubes. The end plugs have threaded male shafts extending from the lower ends of the guide tubes which pass through openings of the lower end fitting. Female lock nuts are threaded onto the threaded male shafts of the end plugs and lock with the lower end fitting to secure the lower end fitting to the lower ends of the guide tubes. The female lock nuts suitably have locking portions that are outwardly deformed into recesses of the lower end fitting to lock the lock nuts in place after tightening.