The world-renowned South African nuclear facility that supplies critical cancer medicine globally
Pelindaba in the North West is home to one of the world’s most commercially important nuclear research reactors, which contributes 20%–30% of the world’s critical supply of the molybdenum-99 radioisotope.
The facility sits about 40 minutes from Pretoria, near Hartbeespoort, and houses South Africa’s SAFARI-1 research reactor.
SAFARI-1 turned 60 years old in 2025, after first achieving criticality on 18 March 1965 at the Pelindaba nuclear research complex.
The reactor is operated by the South African Nuclear Energy Corporation (Necsa), the state-owned company responsible for South Africa’s nuclear research and technology development.
Necsa’s commercial subsidiaries include NTP Radioisotopes, which relies on SAFARI-1 to supply radiation-based products and services.
NTP is a major global supplier of molybdenum-99 (Mo-99), a parent isotope used to produce technetium-99m for nuclear medicine scans.
Technetium-99m is widely used in diagnostic imaging, including cancer, cardiac, and other medical procedures, where doctors need to see how organs and tissues function.
NTP also supplies other radioisotopes, including iodine-131 and lutetium-177, which are used in nuclear medicine applications, including cancer diagnostics and treatment.
According to NTP, SAFARI-1 is operational for about 300 days a year and is one of the most highly commercially utilised research reactors in the world.
It produces about a quarter of the global demand for Mo-99 alongside other radioisotopes, but the proportion can vary depending on outages at similar facilities globally.
Pelindaba’s setting was unusual for a nuclear technology hub. NTP described its headquarters as being housed in the heart of a nature reserve.
The site was once part of a farm owned by renowned Afrikaans academic and writer Gustav Preller.
It was also an occasional retreat for the naturalist, poet, and writer Eugene Marais, a family friend of the Prellers.
Despite its location in a quiet nature reserve, SAFARI-1 has become one of South Africa’s most important scientific exports.
In the late 1950s, Pelindaba was selected as the home of South Africa’s expanding national nuclear technology programme.
Many of the complex’s distinctive concrete buildings date from this period, including the SAFARI-1 reactor building designed by Pretoria architect Brian Sandrock.
The name Pelindaba comes from the isiZulu expression “phelile indaba”, which means “end of discussion” or “we will not talk about this anymore”.
The legend goes that an elderly farm labourer uttered the phrase after plans to develop a township on the farmland were abandoned in the 1920s.
After 1969, the phrase was adapted for the apartheid government’s secret uranium enrichment plant, Y-Plant, also known as Valindaba.
Valindaba meant “we do not talk about this at all”, reflecting the secrecy surrounding South Africa’s nuclear weapons and enrichment programme.
That history gives Pelindaba unique global significance. South Africa remains the only country to have voluntarily dismantled its atomic weapons and ended its nuclear weapons programme.
The enrichment plants were later decommissioned, decontaminated, and dismantled after South Africa signed the Treaty on the Non-Proliferation of Nuclear Weapons in 1991.
Pelindaba also gave its name to the African Nuclear-Weapon-Free Zone Treaty, known as the Treaty of Pelindaba. The treaty opened for signature in Cairo on 12 April 1996 and came into force on 15 July 2009.
SAFARI-1 research reactor
SAFARI-1 is a 20MW tank-in-pool, high-flux research reactor. Unlike a power reactor, it is not used to generate electricity.
When SAFARI-1 was commissioned in 1965, it initially operated at 6.67MW using highly enriched uranium (HEU) fuel procured from the United States, and soon ramped up to 20MW.
A decade later, political pressure and international sanctions reshaped its history, as the United States stopped supplying fuel for SAFARI-1 in 1977.
This forced the reactor to operate at 5MW and only on weekdays for many years, limiting its output but extending its eventual life.
To ensure Pelindaba had a sustainable source of fuel, the South African government approved the construction of Valindaba, a facility where the country would produce its own weapons-grade uranium.
Locally manufactured medium-enriched uranium fuel was supplied for the first time in 1981, allowing continued operation under restricted conditions.
NTP said SAFARI-1 came under pressure to justify its expensive infrastructure and operating costs during South Africa’s democratic transition.
Scientists and engineers who had developed and operated the facility argued that peaceful nuclear applications could make an essential contribution to democratic South Africa.
As a result, NTP said many batches of radiochemicals were produced using enriched uranium that had once been contained in South Africa’s nuclear armaments.
Move away from weapons-grade uranium
Since 2009, SAFARI-1’s reactor core has been fuelled entirely by low-enriched uranium (LEU), which NTP said made it the first commercial reactor in the world to successfully make the conversion.
Regulatory approval for the commercial production of Mo-99 from LEU target plates was granted in 2010.
“As of December 2015, more than three-quarters of target plates used in the production of medical radioisotopes have also been made with LEU targets,” NTP stated.
“That made SAFARI-1 and NTP pioneers in the commercial production of all-LEU radioisotopes.”
SAFARI-1’s importance has prompted work on a successor. Cabinet approved the Multi-Purpose Research Reactor project in September 2021.
Necsa said the new reactor would eventually succeed SAFARI-1 while continuing isotope production, irradiation services, beam-line facilities, and research capabilities.
It announced in February 2025 that it had secured approval from government, as well as R1.2 billion in funding, for the design phase of its multipurpose reactor.
More Pelindaba and SAFARI-1 photos
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