A retention system adapted to prevent axial movement of a plurality of turbine buckets located in respective mating slots in a turbine rotor wheel, the retention system comprising: a plurality of first circumferentially-oriented retention slots formed in outer peripheral portions of the turbine wheel; a plurality of second circumferentially-oriented retention slots formed in wheel mounting portions of said buckets, said first and second retention slots aligned to form an annular lockwire retention slot; a lockwire (46,46A) located within said annular lockwire retention slot, said lockwire having free ends (38,40); at least one axially-extending first surface feature provided on said turbine rotor wheel or on one or more of said plurality of turbine buckets; and a second surface feature (48,48A) on said lockwire adapted to circumferentially engage with the at least one first surface feature on said turbine rotor wheel or on one or more of said plurality of turbine buckets for preventing circumferential rotation of said lockwire beyond predetermined limits, characterized in that said at least one first surface feature comprises a plurality of circumferentially-spaced pins protruding into said annular retention slot radially inwardly of the lockwire for radially holding said lockwire (46,46A) in said annular retention slot; in that said second surface feature comprises at least one radially-extending tab (48,48A); and in that some circumferential rotation of said lockwire in either direction during turbine operation is permitted and undesirable circumferential rotation in either direction is stopped by said engagement of said at least one tab with one of said pins. a plurality of first circumferentially-oriented retention slots formed in outer peripheral portions of the turbine wheel; a plurality of second circumferentially-oriented retention slots formed in wheel mounting portions of said buckets, said first and second retention slots aligned to form an annular lockwire retention slot; a lockwire (46,46A) located within said annular lockwire retention slot, said lockwire having free ends (38,40); at least one axially-extending first surface feature provided on said turbine rotor wheel or on one or more of said plurality of turbine buckets; and a second surface feature (48,48A) on said lockwire adapted to circumferentially engage with the at least one first surface feature on said turbine rotor wheel or on one or more of said plurality of turbine buckets for preventing circumferential rotation of said lockwire beyond predetermined limits, characterized in that said at least one first surface feature comprises a plurality of circumferentially-spaced pins protruding into said annular retention slot radially inwardly of the lockwire for radially holding said lockwire (46,46A) in said annular retention slot; in that said second surface feature comprises at least one radially-extending tab (48,48A); and in that some circumferential rotation of said lockwire in either direction during turbine operation is permitted and undesirable circumferential rotation in either direction is stopped by said engagement of said at least one tab with one of said pins.