Civilian HEU: South Africa

July 1, 2019

Part of the
Civilian HEU Reduction and Elimination Resource Collection


South Africa has several hundred kilograms (kg) of HEU, including HEU produced for use in South Africa’s former nuclear weapons program. [1] This stockpile is now considered a strategic national asset. [2] Some of the HEU stockpile has been used to fuel the SAFARI-1 research reactor and to manufacture targets for medical isotope production. SAFARI-1 also received 33 kg of HEU in the form of fuel elements from the United States in the late 1960s and early 1970s; in 2011, South Africa sent 6.3 kg of U.S.-origin HEU back to the United States. [3]

In 1990, before the fall of the apartheid regime and in the context of the end of the Cold War, South Africa swiftly proceeded with dismantlement of its nuclear weapons-related programs, after shuttering its pilot enrichment plant (Y-plant). Three years later, President F. W. de Klerk publicly admitted the country’s past nuclear weapons efforts.

South Africa disclosed its material inventory to the International Atomic Energy Agency (IAEA) as part of its Initial Safeguards declaration in 1991. The exact amount of HEU is classified to this day, though experts estimate that approximately 800 kg of HEU (most of it unirradiated) was declared and placed under safeguards. [4] Of the materials produced for the weapons program at the Y-plant, approximately 400 kg had reportedly been enriched to 80% U-235 and above. Out of this amount, 350 kg had reportedly been enriched to 90% U-235 or higher levels. [5] The rest of the HEU stockpile came from the pipes and filters of the Y-plant, and was manufactured as fuel elements for the SAFARI-1 reactor.

In 2005, Albright and Kramer estimated that following the declaration, approximately 200 kg of HEU had been used for fueling the SAFARI-1 reactor and for target production, although approximately 50 kg could have since been recovered. Further, they assessed that South Africa had blended down approximately 150 kg of HEU in this stock of 800 kg to low enriched uranium (LEU). Thus, as of the end of 2002, South Africa had an unirradiated HEU stockpile of 450 to 600 kg. [6] By the end of 2003, South Africa’s overall HEU stock (irradiated and unirradiated) had decreased to between 610 and 760 kg. [7] The HEU stock is kept in a secured vault at the Pelindaba site, and is under 24-hour IAEA surveillance. In addition, IAEA teams inspect South African nuclear facilities, including the HEU, on a regular basis, to verify that the stockpile is not being used for any weapons-related purposes.

HEU Production, Use, and Commerce

South Africa does not produce HEU and currently has no enrichment capabilities.

South Africa has only one research reactor, the SAFARI-1 (South African Fundamental Reactor Installation), operated by Necsa at its site in Pelindaba. [8] SAFARI is a 20-MW tank-in-pool materials test reactor, commissioned in 1965, and has been converted to LEU fuel. Today, the reactor is utilized for fission production of the medical isotope molybdenum-99; Necsa’s NTP Radioisotopes (NTP) supplies about 20% of world demand of Mo-99. Another successful commercial project is the irradiation of high purity single crystal silicon ingots for international clients in the semiconductor industry. [9]

The SAFARI-1, constructed with U.S. assistance under the Atoms for Peace program, was originally powered with U.S.-origin HEU enriched to 90%. Following a 1975 U.S. halt in all sales of nuclear fuel over concerns of a South African nuclear weapons program, the AEC initiated indigenous production of fuel in 1977. [10] Since that time, the reactor has been running on fuel from South Africa’s HEU stockpile. [11]

In 1981, the South African government raised the possibility of conversion of the SAFARI-1 reactor with help from the United States. [12] Over the next two decades, several feasibility studies were conducted for potentially converting the reactor to LEU fuel, but it wasn’t until 2005 when the South African Department of Minerals and Energy announced its decision to convert SAFARI-I’s core. The conversion began in 2006 with an eye towards completing the process within three years. [13] By September 2008, the U.S. National Nuclear Security Administration (NNSA) considered the conversion complete. [14] The SAFARI reactor’s core was subsequently fueled with LEU.

After initiating the conversion of the nuclear fuel in its SAFARI reactor in 2006, South Africa continued to use HEU from its stockpile to manufacture HEU targets for medical isotope production. An official from the Nuclear Energy Corporation of South Africa, Necsa, the organization that succeeded South Africa’s Atomic Energy Corporation (AEC), indicated in 2005 that all HEU materials remaining in Necsa’s inventory would be used for this purpose. [15] Some sources had suggested that some of the HEU might also be blended down to LEU for use in the 110 MW Pebble Bed Modular Reactor (PBMR) program; however, government funding for the development of the PBMR ceased in 2010. [16]

South Africa currently does not export or import HEU. Between 1965 and 1975, the United States supplied approximately 33 kg of HEU fuel (30 kg of U-235) for the SAFARI-1 reactor. [17] The repatriation of this material began with an August 2011 shipment of 6.3 kg of HEU spent fuel; additional shipments of "gap" materials are pending. [18]

Efforts to Eliminate or Reduce Civilian HEU

Following the dismantlement of its nuclear weapons and the fall of the Apartheid regime, South Africa became a non-nuclear weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) in 1991 and has remained in good standing. In 2002, Pretoria signed the IAEA Additional Protocol. The country is also a leading proponent of a Fissile Material Treaty. However, as a leader of the Non-Aligned Movement, South Africa has frequently used its HEU stockpile as leverage to promote disarmament goals. For example, in a 2006 Symposium on HEU minimization held in Norway, South Africa’s Abdul Samad Minty noted the "linkage between the need to minimize and/or eliminate civilian HEU and, at the very least, the HEU declared as excess in the military stockpiles of the weapon states." "In South Africa’s view," Minty stated, "the threat to our very existence constituted by the continued utilization of such material for weapons purposes remains as real as ever." [19]

South Africa’s President Jacob Zuma attended the Nuclear Security Summits in 2010 and 2012. After a meeting with Zuma in 2010, U.S. President Barack Obama noted South Africa’s leadership on nonproliferation. "South Africa has special standing in being a moral leader on this issue… [We] are looking forward toward the possibility of them helping to guide other countries down a similar direction of non-proliferation," stated Obama. [20] At the 2012 and 2016 Nuclear Security Summits, South Africa reiterated its views on the linkage between civilian HEU minimization and disarmament efforts, with Zuma stating that the successful LEU isotope production process was "a welcome addition to the capability to produce such isotopes using highly enriched uranium." [21] The choice of words heralded back to South Africa’s ability to maintain HEU stores as a way to galvanize other producers to convert, as well as to prod the nuclear weapon states on disarmament.

As an incentive to develop LEU-based Mo-99 production, the NNSA awarded NTP a $25 million grant to "secure the sustainability of the transition of its Mo-99 production capability" from HEU to LEU in October 2010. [22] In December of that year, NNSA and Necsa "announced that the first shipment of Mo-99 produced with LEU and approved for patient use had arrived in the United States, making South Africa the world’s first large-scale producer to supply Mo-99 using LEU." [23] Although sustaining 100% "LEU-LEU" Mo-99 (use of both LEU targets and fuel) production proved to be a challenge for some time due to the Mo-99 licensing delays in some of the states importing South Africa’s product, [24] in August 2017, the NNSA and the NTP completed converting South Africa’s Mo-99 production process from HEU to LEU. [25] Despite the fact that South Africa still maintains significant HEU stocks and considers them to have strategic national value, the country has effectively eliminated its civilian use of HEU.

Security of HEU Stocks

In November 2007, four armed attackers raided an emergency control center at Pelindaba, reportedly intent on stealing computers. [26] Security measures and requirements at Pelindaba are relatively strong for a civilian facility and have been improved several times since another theft at the site in 2005. In January 2007, South Africa hosted an IAEA security review team, which reportedly found no evidence to conclude that sensitive nuclear areas were under any threat during the latest break-in. [27]

However, some U.S. experts have expressed concern regarding the security of HEU stocks at the facility. Harvard University’s Matthew Bunn has pointed out that South Africa has delayed establishment and implementation of a design basis threat (DBT), as recommended by the IAEA. [28] In a 2010 report, Bunn noted that the country "privately agreed to cooperate on security upgrades for the Pelindaba site, to prevent a recurrence of the 2007 break-in." [29] However, an April 2012 security breach at the facility suggested the need for additional improvements of material security requirements and procedures. [30]

[1] Since the exact amount of HEU is classified in light of South Africa’s safeguards agreement with the IAEA, various estimates exist.
[2] Jean DuPreez authored an early draft of this profile while at the James Martin Center for Nonproliferation Studies.
[3] National Nuclear Security Administration, "NNSA Announces Return of U.S.-Origin Highly Enriched Uranium Spent Fuel from South Africa," NNSA Press Release, 17 August 2011,
[4] "South Africa: Ex-Military Stocks of Fissile Material, end of 2003 (in kilograms)," Institute for Science and International Security,
[5] David Albright, "South Africa’s Secret Nuclear Weapons," ISIS Report, May 1994,; Mark Hibbs, "Y-plant MUF ‘enough for a bomb,’ 350 kg was enriched to 90% U-235," NuclearFuel, 14 February 1994, p. 7.
[6] "South Africa: Ex-Military Stocks of Fissile Material, end of 2003 (in kilograms)," Institute for Science and International Security,
[7] David Albright and Kimberly Kramer, "Civil HEU Watch: Tracking Inventories of Civil Highly Enriched Uranium," ISIS, revised August 2005,
[8] W.E. Stumpf, A.P. Vermaak, G. Ball, "Key Considerations of the Conversion to LEU of a Mo-99 Commercially Producing Reactor: SAFARI-1 of South Africa," paper presented at the 2000 RERTR International Meeting, October 2000, This paper also provides a brief overview of Necsa.
[9] See: H. Bonet, "Security of Supply for Fission Medical Radio-Isotopes Based on the Optimal Use of the Test Reactor Network," paper presented at RRFM 2009 Conference, March 2009, p. 71,; NESCA, Necsa Annual Report 2011, p. 5,; Nicky Smith, "Second Reactor Mooted," Financial Mail, 23 November 2007, p. 76; Also see Cristina Hansell, "Nuclear Medicine’s Double Hazard," Nonproliferation Review, Vol. 15.2, July 2008, pp. 197-198,
[10] Department for Disarmament Affairs Report of the Secretary-General, United Nations, "South Africa’s Nuclear-Tipped Ballistic Missile Capability," New York, 1991, pp.8-9,; D. L. Tillwick, J. F. Du Bruyn, A. J. D’Arcy, "Operation and Maintenance at SAFARI-1 Research Reactor in South Africa," paper presented at the International Conference on Research Reactors: Safe Management and Effective Utilization, Rabat, Morocco, 14-18 November 2011, p. 2,
[11] Charles Piani, "SAFARI-1: Adjusting Priorities During the LEU Conversion Program," paper presented at the 2006 RERTR International Meeting, Cape Town, South Africa, October 2006, p.1,
[12] Communication with Jean DuPreez, Monterey, CA, April 2009.
[13] Ann MacLachlan, "Converting SAFARI-1 to LEU fuel," NuclearFuel, 9 October 1995, p. 10.; Ann MacLachlan, "New Study Finds Little Financial Loss in Converting SAFARI to LEU," NuclearFuel, 1 October 2001, p. 3; Ann MacLachlan and Daniel Horner, "Safari-1 reactor to use LEU in landmark conversion," Nucleonics Week, 21 July 2005, p. 16.
[14] Chloe Colby, "The Conversion of South Africa’s Medical Isotope Production from HEU to LEU: Policy Implications for Global Conversion," May 2011,
[15] Ann MacLachlan and Daniel Horner, "Safari-1 reactor to use LEU in landmark conversion," Nucleonics Week, 21 July 2005, p. 16.
[16] Fuel for this new type of reactor would not have been readily accessible from other suppliers due to its unique form and level of enrichment. For additional information, see: Pebble Bed Modular Reactor (SOC), "Future Energy," 20 March 2013,; World Nuclear Association, "Nuclear Power in South Africa," 30 November 2013,
[17] U.S. Department of Energy, National Nuclear Security Administration, Office of the Deputy Administrator for Defense Programs, Highly Enriched Uranium: Striking a Balance, released January 2001, revision 1, p. 100,; Mark Hibbs, "South Africa’s Nuclear Program: The Dismantling," NuclearFuel, 24 May 1993, p. 9.
[18] National Nuclear Security Administration, "NNSA announces return of U.S.-origin highly enriched uranium spent fuel from South Africa," NNSA Press Release, 17 August 2011,; Also see: Todd Jacobson, "NNSA makes plans to ship more spent nuclear fuel to SRS," Nuclear Weapons & Materials Monitor, 2 February 2009, p. 7.
[19] Abdul Samad Minty, "South African Perspectives on Highly Enriched Uranium (HEU)," presentation for the International Symposium on HEU Minimization, June 2006,
[20] Embassy of the Republic of South Africa, "Obama lauds SA for quitting nuclear program," 12 April 2010,
[21] Peter Fabricius, "SA playing both sides of the nuclear coin," The Star, 30 March 2012,; "Statement by the President of the Republic of South Africa on Occasion of the Nuclear Security Summit, Washington D.C. March/April 2016," National Statement: South Africa, Nuclear Security Summit 2016, 1 April 2016.
[22] National Nuclear Safety Administration, "GTRI: Reducing nuclear threats," NNSA Fact Sheet, 1 February 2011,
[23] National Nuclear Safety Administration, "Record levels of non-HEU-based Mo-99 supplied to the United States," NNSA Press Release, 2 June 2011,
[24] Chloe Colby, "The Conversion of South Africa’s Medical Isotope Production from HEU to LEU: Policy Implications for Global Conversion," May 2011,
[25] “NNSA collaborates with South African Firm on Groundbreaking Conversion to Low-Enriched Uranium-Based Molybdenum-99 Production,” National Nuclear Security Administration, 22 September 2017,
[26] South African Nuclear Energy Corporation (Necsa), "Press Release- Security Breach at Necsa," NECSA website, November 13, 2007,; Cristina Hansell, "Nuclear Medicine’s Double Hazard," Nonproliferation Review, Vol. 15.2, July 2008, p. 186,
[27] Eleanor Momberg, "Pelindaba breach still a mystery," The Sunday Independent, 21 December 2008.
[28] Matthew Bunn, Securing the Bomb 2008 (Cambridge, Mass. and Washington, D.C.: Project on Managing the Atom, Belfer Center for Science and International Affairs, Harvard Kennedy School and Nuclear Threat Initiative), 18 November 2008, pp. 3-4,
[29] Matthew Bunn, Securing the Bomb 2010 (Cambridge, Mass. and Washington, D.C.: Project on Managing the Atom, Belfer Center for Science and International Affairs, Harvard Kennedy School and Nuclear Threat Initiative), April 2010, p. 89,
[30] "Another Infiltration Reported at South African Atomic Site," Global Security Newswire, 13 July 2012,

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