Chemical Technology Archive

Alpha emitters are small particles used in the treatment of cancer. They are nuclear particles that typically travel short distances and attack cancer cells only.
New research has produced alpha particles with a special coating enabling them to differentiate between healthy cells and cancer cells. The coating identifies the cancer cell and focuses on the cell. When inside the cell, the alpha emitter gives off radiation and destroys the cancer cell. After 27 hours the alpha particle stops emitting, causing no collateral damage to the healthy cells.

Physicist Studying Alpha Rays GPN 2000 000381However, there is a shortage of these alpha emitters, which can only be manufactured in a nuclear reactor. At the NECSA Safari reactor at Pelindaba medical isotopes are being produced, but worldwide production is insufficient to meet the growing demand.

A physicist observes alpha particles from the decay of a polonium source in a cloud chamber (Photo: NASA)

Now a solution has been found to produce these alpha particles in the natural decay of thorium, which emits alpha particles. In a world first, Thor Energy in Norway is studying the feasibility of producing alpha emitters as a by-product of the natural thorium decay process.

Trevor Blench, chairman of Steenkampskraal, which owns the Steenkampskraal rare earths and thorium mine in the Western Cape, says the company is gearing to supply thorium to Thor Energy. SHL owns 12,5% of Thor Energy.

“Our relationship started with Thor Energy some years ago with our involvement in the qualification of a safe thorium/uranium pellet fuel for existing light water reactors (LWR),” he says.

“Thor Energy is now in the fourth year of a five-year qualification period of the fuel, and to date, the tests have proceeded well. South Africa is therefore in a good position to supply low-cost thorium for the production of these alpha particles.

The latest mineral resource estimate indicates the presence of 11 700 tons of thorium in the Steenkampskraal deposit. In October 2014, the Colorado School of Mines published a report entitled ‘Thorium: Does Crustal Abundance Lead to Economic Availability?’ The report considers the possibility that thorium could be used as a nuclear fuel and that the demand for thorium could eventually rise to nearly 4 000 tons per year.

The report includes studies of where this thorium would be sourced and states that the Steenkampskraal mine in South Africa will be the lowest cost producer of thorium in the world, with an estimated production cost of USD3,56 per kilo.

Steenkampskraal is also designing a small, modular, low-cost, helium-cooled thorium pebble-bed modular reactor known as the HTMR100. It will use the thorium mined at Steenkampskraal and Steenkampskraal’s locally designed thorium/uranium pebble fuel.

Steenkampskraal is designing the factory to produce the pebble fuel for the HTMR100. The fuel presents no risk of meltdown, such as that experienced at Fukushima.

Steenkampskraal’s strategy covers four key areas: mining thorium and rare earths at Steenkampskraal: designing a safe thorium-based nuclear reactor; designing the thorium/uranium pebble fuel for this new HTMR100 reactor; and testing and then the supply of a safe thorium/uranium and thorium/plutonium pellet fuel for existing light water reactors. (LWRs).

For more information contact David Boyes on tel: +27 12 667 2141; email:; or go to



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