A South African company is designing a safe helium-cooled nuclear reactor that will use a locally designed pebble-based thorium/uranium fuel, replacing uranium as the primary fuel. This will provide a safer environment, without meltdown risk, such as that experienced at the Fukushima reactor in Japan.

“The pebble fuel will be based on thorium, using uranium as the fissile driver material. The by-products produced by thorium are safer than that produced by a uranium-based nuclear reactor, making it safer and extremely difficult to make a nuclear weapon,” said Trevor Blench, chairman of Steenkampskraal Thorium Limited (STL). The thorium will be mined in South Africa at the Group’s Steenkampskraal mine in the Western Cape.

“The reactor is gas cooled and will not need to be located near the sea or river. It can be built exactly where the energy is needed and requires significantly less water for cooling. The cost of the reactor is significantly less than building a large uranium reactor,” says Blench.

He says there are two types of gas reactors, carbon dioxide and helium. Carbon dioxide is the older technology now surpassed by helium. “Helium is an inert gas, cannot burn, and is therefore safe. Carbon dioxide is used in older nuclear reactors and can present health and safety risks, including fire and harmful emissions. Helium exhibits none of these risks,” he says.

STL’s reactor, known as the HTMR100 (High Temperature Modular Reactor), uses a once-through fuel-cycle process, meaning that the fuel passes through the reactor only once and slower than a normal high-temperature pebble-bed reactor.

“The combination of these factors make the design of the pebble-fuel nuclear reactor a world first,” says Mr Blench. “No other nuclear reactor offers a combination of these features which contribute to safety, efficiency, reduced cost and reduction in the risk of nuclear proliferation.”

In addition to the local development of the pebble-based thorium fuel for its new reactor, STL is also involved in the testing of a pellet-based thorium/uranium fuel for existing uranium nuclear power stations.

This is being done in co-operation with its associate company Thor Energy in Norway. Tests are being conducted at the Norwegian government-owned Halden reactor. There are potentially over 350 nuclear power stations around the world that could use this fuel composition.

Thor Energy has completed three years of a five-year test qualification period for the world’s first commercial thorium/uranium pellet fuel for light water reactors (LWRs). “This will revolutionise the nuclear industry by improving safety,” says Blench.

The pellet fuel could be used in most light-water reactors around the world as a safe alternative to uranium-only fuels and no modifications are needed to existing nuclear reactors.

“Overall, our strategy covers designing a safe nuclear reactor; designing a thorium/uranium pebble fuel for this new reactor; and testing a safe thorium/uranium pellet fuel for existing reactors.”