SA marks twentieth anniversary of move from nuclear weapons to nonproliferation

Engineering News: SA marks twentieth anniversary of move from nuclear weapons to nonproliferation


On July 10, 1991, South Africa signed the Treaty on the Non Proliferation of Nuclear Weapons, better known as the Non Proliferation Treaty and most usually referred to simply as the NPT. This marked the final step in South Africa’s transition from a nuclear weapons State to a country with a nuclear programme that was and is exclusively and verifiably devoted to peaceful ends.

In the process, South Africa became the first country with nuclear weapons to give them up. That nuclear weapons programme, whatever its political or military advisability (or lack thereof), represented a very significant South African scientific, technological and engineering achievement.

DEEP ROOTS

“South Africa is one of the oldest nuclear countries in the world,” affirms Stratek Business Strategy Consultants CEO, nuclear physicist and Engineering News columnist Dr Kelvin Kemm. “This is something we should be proud of.”

During the Second World War, the US, with the active participation of the UK and Canada, driven by fear of Nazi German research into nuclear fission, launched what came to be called the Manhattan Project, to develop and deploy atomic bombs which employed the principle of nuclear fission – splitting the atom. Uranium, the most abundant radioactive element on earth, was the basis of these weapons.

To digress a little, 99% of all naturally occurring uranium is in the form of the isotope uranium-238 (U-238) and 0,7% is uranium-235 (U-235). But it is U-235 that can be easily subjected to fission, and so essential to make the bomb work. U-235 cannot be chemically separated from U-238; this must be achieved using physical processes, which require large, complex and energy-intensive machinery. This process is called enrichment.

Uranium for use in weapons needs to be very highly enriched – the U-235 content must exceed 90%. (Uranium for use in civil nuclear power reactors needs only low enrichment levels – less than 20% U-235 content – indeed, it is usually around 5%; reactor fuel cannot produce a nuclear explosion: it is physically impossible.) Alternatively, U-238 can be put into a nuclear reactor, where it undergoes a nuclear transformation and becomes plutonium-239 (Pu-239). (The reactor itself is powered by low-enriched uranium.) Pu-239 is also easily fissionable, and so very suitable for use in a weapon.

The Manhattan Project developed both U-235 and Pu-239 bombs, the former being used on Hiroshima (August 6, 1945) and the latter on Nagasaki (August 9, 1945). But all this depended on a secure supply of uranium, and South Africa, where uranium was a by-product of gold mining, was one of the countries that the metal was sourced from – Canada was another. (Uranium ore from what is today the Democratic Republic of the Congo was also used.)

Then South African Prime Minister Jan Smuts was apparently briefed on the atomic bomb programme in London in mid-1944. In 1945, in response to requests from Washington and London regarding the supply of uranium, Smuts’ administration set up a Uranium Committee, headed by Dr Basil Schonland. In 1948 came the establishment of the Atomic Energy Board (AEB), to oversee the production and trading of uranium.

That year also saw, in May, the general election in which the then opposition National Party won a majority of seats in Parliament, despite winning fewer votes than Smuts’ United Party. This marked the beginning of the implemen- tation of apartheid in South Africa.

In July 1957, South Africa and the US signed a nuclear cooperation agreement within the framework of the American Atoms for Peace programme. Subsequently, in 1959, the Act governing the AEB was amended to permit the board to also carry out nuclear research and development and to employ nuclear technology. The very next year, and under the Atoms for Peace programme, planning for the construction of a nuclear research reactor was started in South Africa. The year after that – 1961 – a nuclear research centre was established among the hills at Pelindaba, west of Pretoria.

In 1965, the country’s first nuclear reactor, the US supplied 20 MWt research unit formally designated South African Fundamental Atomic Research Installation 1, inevitably acronymed to Safari 1, was commissioned. As a research reactor, Safari 1 originally employed highly enriched uranium – enriched to a level of 93%.

(In the past few years, the reactor was modified by South African scientists and engineers to employ low-enriched uranium and now uses fuel enriched to 19.5%. The 20% enrichment level is internationally regarded as marking the division between low-enriched uranium, which is useless for weapons, and the start of the high-enrichment zone.)

BENEFICIATION

“Safari 1 was not obtained to build nuclear weapons,” stresses Kemm. “The development of a local nuclear enrichment capability was originally, basically, a purely scientific and technological project. It was not a military or political one.” It should be noted that Safari 1 was always monitored by the International Atomic Energy Agency (IAEA) and always subject to IAEA safeguards.

Writing in the December 1995/January 1996 edition of the journal Arms Control Today, the then CEO of the Atomic Energy Corporation of South Africa (the successor organisation to the AEB), Dr Waldo Stumpf, stated that, as the country “was – and still is – a prominent producer of uranium, it was almost inevitable that the AEB would explore uranium enrichment technology as a means to mineral beneficiation”.

The conversion of uranium ore to usable uranium (whether low enriched for power plants or highly enriched for research or weapons) involves a number of steps. Firstly, the ore is milled and leached with acid, separating out the uranium oxide from the rest of the ore.

The uranium oxide is then precipitated, dried, and (usually) heated to produce another oxide, U308, which is popularly called yellowcake. This is internationally traded. The yellowcake is then refined into uranium dioxide. As uranium can only be enriched if it is in gaseous form, the uranium dioxide is converted into uranium hexafluoride gas and it is this that is used as the feedstock for the enrichment process.

The development of a South African enrichment tech- nology was led by the University of Pretoria’s Professor Pierre Haarhoff. His team developed a unique enrichment process, known as the Helikon Aero-dynamic Vortex Tube. “Haarhoff did all the theoretical calculations for the Vortex Tube,” highlights Kemm. “The South African nuclear programme joined very front-end science – theoretical nuclear physics – through applied science to engineering. All too often in South Africa there is a gap between scientists and engineers. Good science can help engineers.”

“The design, only superficially similar to the so-called German Becker process, was much closer to the ordinary centrifuge process except that the centrifuge wall was stationary and a vortex mechanism rapidly spun the uranium hexafluoride and hydrogen gas inside a stationary tube,” explained Stumpf in his article. “The uranium isotopes were separated by centrifugal force and exited through different concentric holes in the ends of the tube.”

Following success in laboratory experiments, in 1969, the government authorised the setting up of a pilot plant at Pelindaba to test the process on an industrial scale. This decision was made public in 1970 and construction of the pilot plant, known as the Y-Plant, started in 1971. Respons-ibility for this programme was vested in a new body, set up in 1970 – the Uranium Enrichment Corporation (Ucor). (In 1985, Ucor was merged with the AEB to form the AEC.)

The Y-Plant became fully operational in 1977 and the first highly enriched uranium was obtained in January 1978. This was enriched to 80%, which was not as high as desired, owing to the fact that the“enrichment gradient” of the plant had not reached “full equilibrium”.

Meanwhile, in parallel, and starting in 1971, the AEB had been, with government permission, secretly (because it was a sensitive topic) examining the possibility of using “peaceful nuclear explosives” (PNEs) in mining and construction projects. The PNE concept was not originally a cover for a weapons programme. The idea was seriously pursued by the US from 1957 to 1975 and by the then Soviet Union (USSR) from 1965 to 1989. Between them, these two countries carried out 151 PNE experiments. The Russians actually used five PNEs to construct water reservoirs, 21 to stimulate oil and gas recovery, and five for controlling runaway oil and gas fires.

By 1974, the AEB was certain it could construct a device for use as a PNE. But that same year, India detonated a nuclear device, claiming it was for peaceful purposes, and the hostile world reaction to the Indian action helped persuade the South African government to abandon the PNE idea in practice, although research continued.

Separately, South Africa also developed a facility at Pelindbaba to produce low-enriched uranium fuel – including the fuel elements and fuel assemblies – for the country’s solitary nuclear power station at Koeberg, near Cape Town, which started operation in 1984.
This plant, designated the Z-Plant, started commissioning in 1984 and reached full production in 1988. This was a major technological achievement for South Africa. Like Safari 1, the Z-Plant was never involved in the nuclear weapons programme. This was a major technological achievement for South Africa. Technically successful, but uneconomic to operate, the Z-Plant was closed in 1995 as South Africa was again able to buy nuclear fuel on the international market.

THE BOMB

The second half of the 1970s saw South Africa increasingly isolated because of its apartheid policies and facing a very major deterioration in its strategic position. The year 1974 also saw the Portuguese ‘Carnation Revolution’ in which the army overthrew the basically Fascist ‘New State’ regime. The result was the independence of Portugal’s African territories in 1975, followed by civil war in Angola, which led to intervention by both Cuba and South Africa; the first stage of this conflict ended in 1976 with South African forces withdrawing from Angola and Cuban forces staying in the country.

Also in 1976, then US President Jimmy Carter banned the export of fuel elements for Safari 1, despite the reactor being under IAEA safeguards. In addition, Carter refused to refund South Africa the payment it had already made for the fuel (according to Stumpf, South Africa got the money back five years later, during the administration of President Ronald Reagan).

“The Americans assumed that Safari would close down within a few months,” says Kemm. “Instead, South Africa used the expertise it had developed in uranium enrichment to produce fuel for Safari 1 in a programme called Beva (Brandstoff Element Vervaardiger – Fuel Element Manufacturer).”

Still formally under the aegis of the PNE project, South Africa had carried out a scale model test of a nuclear device using unenriched uranium (which cannot produce a nuclear explosion) in May 1974 and a full-scale device – but again equipped only with unenriched uranium – was tested in 1976. These were effectively tests of device design and detonation systems, and not of actual devices or weapons themselves.

Faced by a dramatically more dangerous strategic situation, in 1977, Pretoria decided to turn this research into a formal nuclear weapons programme. The highly enriched uranium required would come from the Y-Plant, originally intended to supply Safari 1 and research projects once it had achieved full equilibrium in its enrichment gradient.

But, in 1979, the Y-Plant suffered a major accident, and came to a total halt. Stumpf described this event as “a massive catalytic in-process gas reaction between the UF6 (uranium hexafluoride) and the hydrogen carrier gas, a mixture that is thermodynamically unstable, and, when contaminated by certain impurities, can react to form uranium tetrafluoride plus hydrochloric acid.” As a result of this accident, a “massive” amount of gas was lost. The subsequent repairs and modifications (to eliminate the impurities) meant that the Y-Plant did not resume operations until April 1980 and the first highly enriched uranium was not obtained from it until July 1981.

Meanwhile, the design of actual weapons went ahead, although there was no highly enriched uranium to arm them. In 1977, South Africa excavated an under- ground nuclear weapons test chamber at Vastrap, in the Kalahari desert, but this was detected by the USSR and the US. Intense international pressure led to Pretoria abandoning the Vastrap site.

In fact, South Africa was never to undertake a full nuclear weapons test. The infamous ‘double flash’ detected over the South Atlantic by a US satellite on September 22, 1979, which was, at the time, claimed to be evidence of a nuclear test, had nothing to do with South Africa, nor was any nuclear fallout ever detected, suggesting that the event was a natural phenomenon.

The country’s first nuclear weapon was produced in 1982. In all, six were completed, at a rate of fewer than one a year – in line with the output of the Y-Plant. Each, Kemm adds, was individually built and ranged in yield from 10 kilotons (Kt) to 18 Kt – the Hiroshima bomb was about 15 Kt.

All were to the same basic design, being of ‘gun tube’ type. In this design, the enriched uranium is divided into two elements, each too small to have the critical mass needed to produce an explosion. These two elements are positioned at opposite ends of a tube. At detonation, a conventional high explosive is used to blast one of these elements down the tube and into the other, creating critical mass and so generating a nuclear explosion.

The deterrence concept underlying the development of nuclear weapons was, first, to create uncertainty about whether the country had nuclear weapons or not, thereby complicating the strategic planning of the country’s foes. Secondly, if South Africa was subject to a major invasion anyway, Pretoria would secretly reveal the existence of the weapons to Western powers in the hope it would force them to intervene in the crisis.

Finally, the country could carry out a test detonation of a weapon as a warning.

“South African high government politicians and officials thought it would be crazy to actually use nuclear weapons – what would they be used against?” affirms Kemm. “And, if they were used, the USSR would retaliate.” Which raises a lot of questions – for example, if they were never meant to be used, why didn’t South Africa just resort to the much cheaper and simpler option of faking nuclear weapons? (Stumpf estimated the cost of the weapons programme to have been under R680-million in 1995 values.)

In 1989, FW de Klerk became President and, faced by a rapidly changing world, within a short period terminated the nuclear weapons programme. In line with the President’s decision, the Y-Plant was closed in February 1990 and the weapons were dismantled by June 1991. In July 1991, South Africa joined the NPT and supplied the IAEA with an initial inventory of its nuclear material (the highly enriched uranium retrieved from the weapons had been returned to the AEC) in October 1991.

SWORDS INTO PLOUGHSHARES

What advantages has South Africa gained from renouncing nuclear weapons and joining the NPT? For one thing, it eased the way to the conclusion of the African Nuclear Weapons Free (or Pelindaba) Treaty of 2009.

“The NPT forms the basis of global nuclear security,” points out South African Nuclear Energy Corporation (Necsa) CEO Dr Rob Adam. (The AEC was restructured into Necsa in 1999.) “By being part of the NPT club, we contribute to global security. The primary advantage to South Africa was the achievement of the moral high ground by being the first country to voluntarily dismantle a nuclear weapons programme. At the same time, South Africa, through Necsa, transferred the expertise and the highly enriched uranium from the weapons programme into bene- ficial, peaceful applications of nuclear technology by becoming a global market leader in the supply of radioisotopes for medical applications. The signing of the NPT also opened doors for the South African government and the nuclear industry to be accepted into a variety of international collaborative programmes relating to advanced nuclear energy technologies, such as the Generation IV International Forum and various IAEA programmes.”

“As a result of joining the NPT, South Africa got great credibility. It also gave South African nuclear science a great boost,” states Kemm. “The NPT allows South Africa to access various nuclear capabilities and nuclear facilities around the world. We’ve been a model of compliance. As a result, the world would not be afraid of South Africa going back into the business of uranium enrichment. We are now trusted.”