The decision to completely destroy weapons related technology and information may have been made in part to keep nuclear weapons out of the hands any future black-lead government. Suspicion immediately arose that this material had been previously used in nuclear weapons, confirmed three years later by De Klerk. South Africa developed a unique technology for enriching U-235 called UCOR during the 1960s and 70s based on aerodynamic forces produced by vortex tubes. Research on weapons began in 1971, and in 1974 the decision was made to develop and manufacture nuclear weapons. The equipment for the final stages of separation was subsequently dismantled.
Some uncertainty surrounds the fate of the first nuclear device built by South Africa.
This device was used in one zero-yield test, the only nuclear test of the entire program. This story is now known definitely to be false in at least some important ways. In April 1997 South African Deputy Foreign Minister Aziz Pahad admitted that an unexplained nuclear explosion detected in the Indian Ocean on 22 September 1979 was a South African nuclear test, making South Africa the seventh nation known to have exploded a nuclear device. See the Vela Incident article for full details about this event. In light of this, it would seem that the first batch was indeed ready in September 1979, but was instead quickly loaded into a bomb prototype and then exploded in a covert naval operation.