The key causes that led the Republic of South Africa to become the first, and thus far only, nuclear state to disarm were the reversal of the causes that had led to its arming in the first place:
The first sign of a change in direction for South Africa was in 1987 when President Botha announced that South Africa was considering signing the 1968 Nuclear Nonproliferation Treaty (NPT) and would begin discussions with other countries toward that end.
The crucial year was 1989. Just before the start of that year, the Angolan War in which Cuban had played a major role came to an end with the signing of the tripartite agreement between South Africa, Angola and Cuba on 22 December 1988. During 1989 a phased withdrawal of the 50,000 Cuban troops from Angola occurred. Namibia - called South-West Africa by South Africa, which occupied it and used it as a staging ground for intervention in the Angolan War - became independent after UN Security Council resolution 435/9978 was put into operation on 1 April 1989. The waning of Soviet power was starkly revealed by the complete collapse of the Iron Curtain in Europe. And in September 1989 a new President took office -- FW de Klerk, who immediately set into motion fundamental political reforms of South Africa's domestic policies towards full democracy.
Waldo Stumpf, chief executive officer of the state-controlled Atomic Energy Corporation (AEC), recounts de Klerk's actions on disarmament as follows:
Shortly after his assumption of office in September 1989, the former State President, therefore, instructed that an investigation be carried out to dismantle the nuclear deterrent completely with the aim of acceding to the NPT as a state without a nuclear weapons capability. This first report was submitted to him in November 1989 and was approved in principle. In the light of internal and external political factors, it was also decided that an announcement of South Africa's past nuclear deterrent capability, would not take place before accession to the NPT and that the dismantling project would, therefore, for the time being, also be classified as top secret. A steering committee of senior officials of the AEC, ARMSCOR and the SA Defence Force and under the chairmanship of the author, was appointed by the State President, with the following brief: A steering committee of senior officials of the AEC, ARMSCOR and the SA Defence Force and under the chairmanship of the author, was appointed by the State President, with the following brief:[Stumpf 1995].
- To dismantle the six completed gun type devices at ARMSCOR under controlled and safe conditions;
- To melt and recast the HEU from these six devices as well as the partially completed seventh device and return it to the AEC for safe keeping;
- To decontaminate the ARMSCOR facilities fully and to return severely contaminated equipment to the AEC (such as a melting furnace);
- To convert the ARMSCOR facilities to conventional weapon and non-weapon commercial activities;
- To destroy all hardware components of the devices as well as technical design and manufacturing information;
- To advise the Government of a suitable time table of accession to the NPT, signature of a Comprehensive Safeguards Agreement with the IAEA and submission of a full and complete national initial inventory of nuclear material and facilities, as required by the Safeguards Agreement; and
- To terminate the operation of the Y Plant at the earliest moment.
Although the Y Plant was actually closed down on 1 February 1990, actual written confirmation of these instructions was received from the former State President on 26 February 1990 and this date should, therefore, stand as the official date of implementation of termination of South Africa's nuclear deterrent capability.
At its closure the Y Plant had logged some 3000 cascade-days of operation.
Albright provides an excellent account of the decommissioning operation:
Dismantling started in July 1990. By 6 September 1991, all of the HEU had been removed from the weapons, melted down, and sent back to the AEC for storage. During the dismantlement process at Circle, criticality-safe shelves were installed in one vault to store recast HEU ingots.
To insure secrecy, HEU was shipped from Circle to Pelindaba at night. Initially, Armscor had military guards patrolling the road, but stopped when the guards attracted the attention of people living in the area. One person demanded to know what was happening. Subsequent shipments aroused less curiosity.
Soon after sending the last material to the AEC, the Circle building was completely decontaminated and the equipment that had been used for the re-melting and casting of HEU sent to the AEC. The main uranium processing section of Circle was carefully decontaminated. Walls were removed, and the concrete floor was jacked out.
Radioactive contamination was reduced to background levels. An Armscor official said that they wanted the room clean enough so that they could plausibly deny the existence of the program. Several did not believe that the weapons program would ever be revealed.
Although all the HEU had not gone to the AEC when South Africa acceded to the NPT on July 10, 1991, all of it had been sent before the safeguards agreement entered into force on September 16, 1991. The first IAEA inspection team arrived in South Africa in November 1991.
The major non-nuclear components of the weapons, detailed design drawings, and photos of components remained. Destruction of many of these items began in 1992. By March 24, 1993, when de Klerk announced the program's existence, most of the classified documents had been shredded and the sensitive weapon components destroyed or damaged beyond repair. Destruction of less important components continued into 1994.
Along with the destruction of the bombs themselves, and the tooling required to produce them, South Africa also destroyed all design, production, and other technical documentation generated by the weapons-related part of the program. This makes it impossible for subsequent (black-led) governments to recreate the arsenal without duplicating much of the research and development work. It also makes it difficult or impossible to investigate or verify many claims about the program, and questions that remain. In particular it appears that much of information about the collaboration with Israel is lost.
South Africa officially entered the NPT with its ratification on 10 July 1991. The NPT safeguards entered into force immediately on 16 September 1991 with the signing of a Comprehensive Safeguards Agreement (INFCIRC/394).
On 30 October 1991 South Africa submitted its initial inventory of nuclear materials and facilities to the International Atomic Energy Agency (IAEA) and the first verification team from the Agency arrived on site in November 1991. IAEA inspectors found an inventory of about 400 kg of weapon-grade enriched uranium at Pelindaba (roughly 100 kg enriched to about 80 percent; the rest enriched to 90-95 percent). Suspicion immediately arose that this highly enriched material had been previously used in nuclear weapons. But - to encourage full disclosure - the IAEA inspections are conducted confidentially and are not disclosed the details of the inspections publicly. South Africa insisted on strict secrecy but hints of their findings soon began leaking out [Baeckmann et al 1995], [Albright 1994a].
By late 1992, as preparations for South Africa's first all-race elections proceeded, the African National Congress (ANC) was pressing the government for full disclosure of its previous weapons activity. In a 24 March 1993 speech, President de Klerk revealed that South Africa had produced nuclear weapons. De Klerk claimed - incorrectly - that the arsenal had been destroyed before 10 July 1991, when South Africa joined the NPT. In fact the destruction process was not complete at that point, although it was by the time the NPT actually entered force.
The IAEA declared in late 1994, after it had completed its inspection around the end of August, that it had verified that South Africa's nuclear weapons facilities had been dismantled.
The total inventory of enriched uranium was about 1500 kg, with an average enrichment of 37 percent. Taking into account the highly enriched portion, the remaining 1100 kg would have an enrichment a trifle under 20 percent. The seven weapons for which HEU cores were fabricated would have combined mass of 390 kg, essentially matching the quantity of weapon grade material found.
South Africa has investigated other uranium enrichment processes over the years, since the vortex enrichment process has never been commercially competitive. Centrifuge enrichment was investigated from the 1970s until 1991, when it was terminated due to the difficulty of competing with the advanced centrifuge operations in Europe. Since 1983 South Africa has been investigating more advanced techniques like molecular and atomic vapor laser isotope separation (MLIS and AVLIS). A prototype 6000 SWU per year MLIS module has been under development at the decommissioned Y-Plant site.
On 24 February 2000 a new Nuclear Energy Act (No. 46 of 1999) came into effect, it partially repealing the previous Nuclear Energy Act and reorganizing the former AEC (Atomic Energy Corporation) into NECSA (the Nuclear Energy Corporation of South Africa Ltd).