South African private-sector company Steenkampskraal Thorium Limited (STL) is developing a design for a small modular reactor (SMR) which it calls the high temperature modular reactor (HTMR). This is being done using expertise developed in the country by the now effectively abandoned pebble bed modular reactor (PBMR) project. Like the PMBR, the smaller HTMR will use small spherical fuel elements, or ‘pebbles’.

STL, which also owns the Steenkampskraal thorium and rare earths mine, in the Western Cape, is developing the 100 MWt HTMR-100, the concept design of which has been completed. This would be able to produce up to 35 MWe.

“What we are trying to do is design a reactor that is adapted to Africa’s circumstances,” explained STL chairperson Trevor Blench at the recent Nuclear Africa 2016 conference, in Centurion, west of Pretoria. “Almost every country in Africa needs power, needs water, needs food.” But most cannot afford large-scale nuclear power plants. “A small reactor like ours could cost about $300-million. That’s affordable for many African countries.”

However, he pointed out that STL is “a tiny company” and the HTMR project needs “money, people and resources. We want to assemble a consortium to make this project possible”. The reactor would be able to generate power and/or produce process heat, not least for desalination.

The HTMR shares the inherent safety of the other PBMR designs, demonstrated in practice in both the German original and the Chinese HTR-10 small experimental reactor. Unlike the concept that was being developed for the South African PBMR project, with the HTMR, each fuel sphere will go through the reactor only once. This significantly simplifies the design. The 100 MWt version would produce about 120 used fuel spheres a day. The intent is that these would be stored, on site, in a helium-filled secure storage area, until a national high-level waste repository is approved.

The HTMR has been designed to be able to use uranium fuel, thorium-uranium fuel or thorium-plutonium fuel (an option for those countries which possess plutonium; this option would not be relevant to Africa). Like other SMR designs, the HTMR could be manu- factured in a factory and the reactor vessel could be transported to the site by road.

Currently, the company is focused on making, testing and qualifying (for licensing purposes) thorium-uranium fuel. This is being done in Norway by an associate company of STL, Thor Energy. The results have been most encouraging. “We can make fuel at least equivalent to the best German fuel,” reported STL consultant, Pretoria University professor Johan Slabber. “That’s the crucial thing.”