A research group based at North-West University to direct and manage thorium and new nuclear material research in partnership with Necsa and Nelson Mandela Metropolitan University is actively developing new materials and working to improve existing nuclear materials for future new build nuclear power plants.
Nuclear technology for electricity production has received increased attention in South Africa, especially after government published the Integrated Resource Plan (IRP) 2010. A slight growth in the nuclear power industry is expected, owing to the amplified focus on depleting coal resources and the drive to use carbon-free power sources.
The nuclear industry needs to be equipped with sufficient resources to succeed in the enormous responsibility of sustainability. Uranium cannot carry this load alone and other nuclear fuel sources need to be introduced, says NWU, a multicampus university with a footprint spanning the North West and Gauteng.
"Fuel cycles that use thorium have been studied during the 1950s, but were not commonly employed as a result of the achievement of uranium fuel cycles and because thorium does not contain a fissile isotope. However, there is a renewed interest in thorium as a nuclear fuel and the International Atomic Energy Agency has released several reports on thorium," explains the university.
The feasibility of thorium-plutonium and thorium-uranium fuel in pressurised water reactors (PWRs) has been the focus of some recent studies, especially to improve the plutonium destruction rate. The total thorium resources in South Africa are estimated at around 55 000 t. Utilising thorium-based fuels in PWRs, says NWU, results in longer refuelling cycles with reduced initial excess reactivity, ultimately producing more efficient nuclear reactors.
When refuelling cycles are extended from 18 to 24 months with the use of thorium-based fuels, the effects of the extended burn-up or radiation damage on the zirconium fuel-cladding materials needs to be studied and quantified, notes the university. "Knowledge about radiation damage in nuclear reactor materials is also important for the design and management of safe nuclear reactors. In a reactor, neutrons, electrons, gamma rays, fission products and ions produce radiation damage."
In the light of the Fukushima Daiichi nuclear accident in Japan in 2011, fuel-cladding materials with improved oxidation resistance need to be developed, says NWU, adding that coating zirconium fuel tubes with zirconium carbide could provide this improved safety benefit as well as enhanced resistance to radiation damage.
"Other materials such as oxide dispersion strengthened steel is a promising nuclear reactor fuel cladding material owing to its high swelling resistance and high temperature strength. Zirconium nitride ceramic can also be considered for an inert matrix fuel host for fast reactors."
South African Nuclear Energy Corporation (Necsa) and the Department of Science and Technology (DST) have identified thorium as a strategic nuclear fuel source for future nuclear plants in South Africa.
School of Mechanical and Nuclear Engineering
Mechanical Engineering specialises in systems reliability and systems optimising by focusing on innovative design, integrity and automation. Research is carried out in the fields of aeroplane and glider design, manufacturing and biobeneficiation in the areas of extrusion and extrusion machine design and supercritical fluid extraction, energy systems in the areas of power generation, heat pumps, and coal combustion efficiency.
This work and research is carried out through the implementation of computational fluid dynamics and finite element analysis or other types of modelling, analysis, materials testing and characterisation and/or improved materials selection for design, vibration monitoring and analysis.
Nuclear Engineering specialises in engineering physics and focuses on neutronics and thermal fluid systems.
Research is carried out in the fields of power generation in the areas of process heat, nuclear materials and fuel cycles, and nuclear safety and policy by implementing modelling and experimentation, materials selection and characterisation of nonradiated materials and creative design.
The research in the School is carried out by the:
• sail plane design and manufacturing group;
• thorium and nuclear materials application group;
• vibration and vibration analysis and modelling group;
• biobeneficiation group;
• energy systems group;
• coal combustion and efficiency group; and
• mining and agriculture machine design group.
All groups are funded by NWU, the Department of Trade and Industries, the National Research Foundation or Industry and the DST, which also funds the well-established South African Research Chairs Initiative Chair in Nuclear Engineering.
Apart from this research, work is also carried out by an engineering education group and in the field of techno-economic studies; applicable to both nuclear and mechanical engineering.