In order to make nuclear energy safer, STL is designing a Generation 4 reactor that is meltdown-proof.
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Steenkampskraal Thorium Ltd. (STL) is a South African company that is dedicated to the development and commercialization of clean, safe and sustainable nuclear energy.
The Thorium Fuel Cycle In order to make nuclear energy cleaner, STL is developing the thorium fuel cycle. The spent fuel from the uranium fuel cycle contains plutonium which creates risks from a proliferation point of view; spent uranium fuel also contains minor actinides which create problems from a waste management and storage point of view, as they remain radioactive for many thousand years. In contrast, the thorium fuel cycle can consume plutonium and creates less minor actinides in its waste, and this fact substantially reduces the problems associated with the management and storage of spent fuel. The thorium fuel cycle produces mainly fission products in its waste; these fission products remain radioactive for a few hundred years and they do not present a similar proliferation risk. |
Leader: Trevor Blench Headquarters: Centurion, South Africa Reactor type: High Temperature Reactor Start of operations: 2005 Market entry: Three years Budget: EUR 1m Employees: 20 Main investors: Companies and private individuals Website: Thorium100.com |
The modular Pebble Bed reactor being transported to site
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Steenkampskraal’s Core Activities
STL is undertaking several activities in order to introduce the thorium fuel cycle. Firstly, STL owns the rights to the thorium that will be produced at the Steenkampskraal rare earths and thorium mine in South Africa. STL has designed a thorium refinery that it plans to build in South Africa for the production of reactor-grade thorium. Secondly, STL has invested in Thor Energy AS (Thor) in Norway, a company that has conducted research and development into thorium fuels, that has registered several patents on these fuels, that has manufactured thorium fuels and that is now conducting a qualification program to license and commercialize these fuels. Thirdly, Thor has commenced discussions with several utilities about the use of these thorium fuels in commercial light water reactors (LWRs) and is conducting feasibility studies with one utility. Fourthly, Thor has commenced discussions with several regulators about the licensing of thorium fuels for use in these (LWRs). |
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Generation 4 Reactor Design
In order to make nuclear energy safer, STL is designing a Generation 4 reactor that is meltdown-proof. Water-cooled reactors will always run the risk of a meltdown in the event of a loss of water, even with thorium fuel. STL’s Generation 4 reactor is a high-temperature, gas-cooled, pebble-bed reactor, the HTMR100 (100MWth high-temperature modular reactor). The HTMR100 will be cooled with helium gas and operate at temperatures around 750 degrees C. This reactor design has been demonstrated on several occasions, under the supervision of the International Atomic Energy Agency, to be safe in the event of a loss of the coolant. This type of reactor is therefore intrinsically safe. |
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The melting point of the silicon carbide coating is higher than the temperature of the fuel, even when the fuel is not cooled; the coated particles therefore prevent the meltdown of the fuel under any circumstances, even in accident conditions. |
Pebble Fuel Characteristics
The safety of the HTMR100 is partly due to the reactor design and partly due to the design of the fuel. The fuel is in the form of particles that are coated with silicon carbide and then pressed into a sphere, or pebble. The melting point of the silicon carbide coating is higher than the temperature of the fuel, even when the fuel is not cooled; the coated particles therefore prevent the meltdown of the fuel under any circumstances, even in accident conditions. These coated particles also provide a secure and permanent containment for the fuel both during the residence time in the reactor and subsequently during the storage of the spent fuel. These coated particles are designed to retain all the fission products that are produced by the fission of the fuel over a long period of time and have been demonstrated to retain these fission products during the residence time of the fuel in the reactor and during subsequent storage. Thorium was used for many years in coated particle fuel in pebble-bed reactors in Germany and this coated particle fuel design is very well suited for the use of thorium. |
Aiming for Sustainable Nuclear Energy
STL is trying to make nuclear energy sustainable in several different ways. Firstly, uranium supplies are limited and, in view of the many reactors that will be built over the next twenty years, there could be a shortage of uranium at some time in the future. Thorium is several times more abundant than uranium and the development and introduction of the thorium fuel cycle will provide a sustainable alternative to uranium for a long time into the future. Secondly, the combination of the high-temperature gas-cooled reactor and the TRISO coated particle pebble fuel enables high burnups to be achieved, with the result that the HTMR100 can extract much more energy from each kilo of uranium or thorium fuel than LWRs. Thirdly, there is increasing resistance to the accumulation of waste from the uranium fuel cycle, with its content of plutonium and minor actinides, and the storage and disposal of this waste is problematic. Thorium is capable of incinerating plutonium, while simultaneously generating energy, and therefore also offers a possible solution to the uranium waste problem. Fourthly, the possibility of developing a closed thorium fuel cycle with the breeding of U233 offers the possibility of generating energy almost indefinitely.
STL is trying to make nuclear energy sustainable in several different ways. Firstly, uranium supplies are limited and, in view of the many reactors that will be built over the next twenty years, there could be a shortage of uranium at some time in the future. Thorium is several times more abundant than uranium and the development and introduction of the thorium fuel cycle will provide a sustainable alternative to uranium for a long time into the future. Secondly, the combination of the high-temperature gas-cooled reactor and the TRISO coated particle pebble fuel enables high burnups to be achieved, with the result that the HTMR100 can extract much more energy from each kilo of uranium or thorium fuel than LWRs. Thirdly, there is increasing resistance to the accumulation of waste from the uranium fuel cycle, with its content of plutonium and minor actinides, and the storage and disposal of this waste is problematic. Thorium is capable of incinerating plutonium, while simultaneously generating energy, and therefore also offers a possible solution to the uranium waste problem. Fourthly, the possibility of developing a closed thorium fuel cycle with the breeding of U233 offers the possibility of generating energy almost indefinitely.
Achievements in 2014 - Steenkampskraal Thorium Ltd
Conceptual Designs
During 2014, STL completed the conceptual designs of the thorium refinery that STL plans to build in South Africa, the HTMR100 reactor and the pebble fuel factory. STL also commenced the basic designs of these facilities and the detailed designs of some of the components. STL started working with component manufacturers and started to establish a supply chain for these projects. STL acquired the nuclear codes that are necessary for the detailed analysis of the core.
During 2014, STL completed the conceptual designs of the thorium refinery that STL plans to build in South Africa, the HTMR100 reactor and the pebble fuel factory. STL also commenced the basic designs of these facilities and the detailed designs of some of the components. STL started working with component manufacturers and started to establish a supply chain for these projects. STL acquired the nuclear codes that are necessary for the detailed analysis of the core.
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Once-Through-Then-Out
STL also developed the know-how to employ the Once-Through-Then-Out (OTTO) procedure, which will allow the pebbles to pass slowly only once through the reactor during a residence time of about three years rather than the previous procedure that involved the rapid movement of the pebbles through the reactor and the multiple recycling of the pebbles. The OTTO procedure simplifies the loading and the unloading of the fuel and reduces the size and the complexity of the fuel loading and unloading machines. The OTTO procedure also reduces the amount of friction on the pebbles and the risk of dust creation. Cogeneration Capabilities STL prepared numerous studies about the versatility of the HTMR100 and its cogeneration capabilities. As the HTMR100 operates at temperatures of around 750 degrees C, it is capable of producing electricity, high-temperature steam, hydrogen and it is capable of efficiently purifying contaminated water or desalinating sea water. |
Goals for 2015 - Steenkampskraal Thorium Ltd
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STL has several objectives for 2015.
Design and Manufacturing STL will continue to prepare the basic designs of the thorium refinery, the HTMR reactor and the pebble fuel factory. The company will also continue to do the detailed engineering of some of the components of this equipment. STL has made some advances in the designs of these components and plans to standardize them for possible future manufacture. STL may start to make some prototypes of these components in 2015 and to qualify the manufacturers of these components. Performance Studies STL will do several studies related to the performance of the HTMR100 reactor. One of these studies will analyse the load-following capability of the reactor. Another study will analyse the co-generation capabilities of the reactor, especially at higher temperatures of around 900 degrees C. STL plans to design a co-generation system and a simplified system only for desalination. STL will also study the capability of the HTMR100 reactor to produce medical isotopes. Fuel Development Program STL has a thorium fuel development programme. During 2015, STL plans to develop, manufacture and test a Thorium/LEU fuel that will achieve a high burn-up. STL will develop a programme to compare the safety features of thorium fuels compared to uranium fuels. STL will analyse the spent fuel that results from the Thorium/LEU fuel cycle and study how to reduce the volume of this spent fuel. STL will also investigate the possibility of using an external neutron source as the driver for the thorium fuel. Quality Assurance System STL plans to introduce a Quality Assurance system into all of the work that the company performs. |
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Burning billions of tons of coal, billions of barrels of oil and billions of cubic metres of gas to generate electricity causes air pollution, climate change, environmental degradation and millions of deaths each year. This burning of fossil fuels will eventually have to stop. Thorium is a plentiful resource that could produce much of the energy we need in a sustainable way with negligible carbon emissions and minimum impact on the environment. Thorium could eventually replace fossil fuels. |
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