FAQ

START (Subcritical Transmuting Accelerated Regenerative Technology) is an advanced transmutation plant that transforms nuclear waste into clean energy and fresh fuel, adhering to the highest safety standards. Offered to national power plant operators, it includes full support from procurement to maintenance. START enables scalable, carbon-free energy production while reducing nuclear waste, providing a sustainable solution for both developed and developing countries.

Yes, the system eliminates long-lived radioactive waste, including transuranics and long-lived fission fragments (LLFF) that last over 800,000 years. Transuranics form when uranium captures a neutron, while LLFFs result from uranium atom fission. In our reactor, these elements are broken down into lighter, more stable forms. In the end, only 20% of the original waste remains as short- and medium-lived waste, which can be safely managed using existing disposal methods, like those for radiotherapy equipment.

Transmutation is a physical process of changing one nucleus (a core of an atom composed of protons and neutrons) into a different type of nucleus by changing the number of protons and/or neutrons inside. This can happen naturally (such as in radioactive decay) or can be induced. Induced transmutation involves changing the nucleus of an atom by bombarding it with particles such as neutrons. This can be done in nuclear reactors or with the support of particle accelerators.

While renewable sources like solar and wind are essential for green energy, their intermittent nature requires stable, continuous energy sources to ensure grid reliability. Nuclear power is set to play a critical role in the future global energy mix by providing this baseload supply. Currently, fission is the primary commercial method, while fusion and transmutation are in development. Transmutation offers unique advantages by reducing nuclear waste and converting it into usable fuel while producing carbon-free energy. This enhances sustainability, reduces reliance on limited natural resources, and maximizes the use of existing materials. Together with fission and fusion, transmutation will be an essential component of future energy systems.

Our system is designed in such a way that it stays subcritical, which means that the nuclear chain reaction in the transmuter core cannot sustain itself without using an external neutron source. In the case of Transmutex, the neutron source comes from the spallation reaction. When a beam of protons, positively charged particles, is accelerated to high energy and directed into a metal target, which is placed inside the transmutation reactor, they release the neutrons through a process called spallation. These neutrons initiate the transmutation process in the fuel, which generates massive amounts of energy. When the accelerator is switched off, the fission chain reaction stops and thanks to this feature the nuclear system is perceived as inherently safe.

The particle accelerator ensures the subsequent delivery of protons and hence spallation neutrons needed to sustain the chain reaction inside the core. No beam, no power. That’s the operating principle of Spallation Enhanced Transmuters (SETs). There are several accelerator technologies that can be used for this purpose. Transmutex has decided to use a cyclotron due to its capability to achieve very high energy-efficiency and very compact footprint, enhancing the sustainability and eco-friendship of its solution. Furthermore, our design is inspired by the existing and successfully operating machine of the Paul Scherrer Institute, which helps us to significantly decrease the R&D time and cost of prototyping.

Contrary to uranium which is a fissile element (can sustain a chain reaction), thorium is a fertile element. This means that it needs to capture one neutron (to be converted into U-233) before being usable as fuel. This difference is the main reason why thorium is not used as fuel in conventional nuclear plants. However, thorium can efficiently be used in our technology since the neutrons generated by the spallation source are calibrated to maximize its conversion into fuel. Under such conditions, thorium offers several key advantages over uranium. It does not produce plutonium, significantly reducing the risk of nuclear weapons proliferation. It generates minimal long-lived radioactive waste, enhancing environmental safety. Thorium is also three times more abundant and more evenly distributed in the Earth's crust compared to uranium, making it a more sustainable and accessible resource for nuclear energy production. Due to its abundance and distribution, thorium mining has a lower environmental impact compared to uranium mining, and it makes thorium a more practical and long-term solution for meeting global energy needs. Finally, our thorium-based fuel cycle is more efficient a uranium-based one, as it allows for a near-complete fuel utilization.

The theory of transmutation was formulated in the 1990s by Carlo Rubbia and his team at CERN (Conseil Européen pour la Recherche Nucléaire - the European Organization for Nuclear Research). It emerged from his broader work in particle physics. After his significant contributions to the discovery of the W and Z bosons, for which he was awarded the Nobel Prize in Physics in 1984 (with Simon van der Meer), prof. Rubbia turned his attention to the potential of accelerators in nuclear energy and waste management. In the mid-1990s, prof. Rubbia proposed the concept of the Energy Amplifier, which uses a particle accelerator to produce a neutron flux through spallation reactions. This neutron flux can then be used to sustain a sub-critical nuclear reactor, which can transmute long-lived radioactive waste into shorter-lived isotopes, thereby reducing the hazard and longevity of nuclear waste. One of his notable experiments in this field was the Transmutation by Adiabatic Resonance Crossing (TARC) experiment at CERN, which demonstrated the feasibility of using accelerators for transmutation purposes. Prof. Rubbia's work in this area has been foundational in demonstrating feasibility for both energy production and nuclear waste management. Key breakthroughs in our technology include the development of high-current, high-energy accelerators capable of producing neutrons from heavy elements, and the successful demonstration of neutron spallation processes. These advancements have enabled the practical applications for both waste transmutation and energy production, particularly using thorium as a fuel source.

Thorium offers a sustainable fuel cycle, waste treatment and waste reduction. Given the large potential for worldwide expansion in nuclear generation it is likely that, in the medium term, the demand for uranium will increase. Although at present the effect of this on the uranium price is only marginal, in the future this is likely to change with demand-led price rises predicted. Hence the option to utilize alternative fuels such as thorium will become more attractive. Thorium reserves are currently estimated to be three to five times more abundant than uranium, with the advantage of being used at 100% instead of .7% for the uranium in conventional reactors. A side benefit of using thorium fuel is non-proliferation as uranium enrichment technology is not required. Additionally, using thorium in a breeding cycle as a nuclear fuel also generates isotopes which are high energy gamma emitters, therefore making handling and subsequent diversion of materials to bomb-making much more difficult.

The essential engineering aspects have been successfully demonstrated at CERN and the Paul Scherrer Institute (PSI) in Switzerland, and corroborated by numerous research institutes, including the French CEA, over a ten-year period from 1995 to 2006.Below you will find the most significant experimental validations: FEAT (First Energy Amplifier Test), 1995, demonstrated a substantial energy gain factor (x30) in line with predictions, paving the way for the possibility of industrial-scale energy production. TARC (Transmutation by Adiabatic Resonance Crossing), 1997, clarified the phenomenology of neutron physics in a large volume of lead and demonstrated the efficient transmutation of long-lived fission fragments (99 Tc,129 I). The n_TOF facility at CERN, following on from the TARC experiment, has dramatically enriched neutron data, enabling much more accurate simulations. MEGAPIE (MEGAwatt Pilot Experiment), 2002, was the first megawatt-class liquid metal neutron spallation target designed by PSI, Subatech and CEA. MEGAPIE operated successfully for four months at PSI. High-power 600MeV cyclotron operating at PSI since the early 1990s. The current was increased from a 0.1 mA to 2.3 mA of protons at 600 MeV. Its power is now close to START's performance target. Electrorefining at Argonne National Laboratory (ANL), a pilot plant for spent fuel reprocessing and actinide separation by electrorefining developed in the USA. A prototype processed 2 tonnes of spent fuel, and a plan was drawn up for a plant capable of processing 100 tonnes a year. It should be noted that electrorefining can be carried out on hot fuel after six months' storage. In addition to these experimental validations of system components, a simulation software package, GEANT4, was developed at CERN. This open-source software is the basis of most simulations at CERN, and of the Transmutex simulation software. We are also developing a deterministic code for sub-critical systems in collaboration with the École Fédérale Polytechnique de Lausanne, and a digital twin infrastructure reproducing the functions of the entire system. This infrastructure will be the digital realization of the project, reproducing as closely as possible its behavior in normal and accidental operating situations. All that remains is to assemble the various technologies into a functional whole. This means all that is required is an engineering effort to construct the system rather than any fundamental scientific research.

The nuclear fuel cycle refers to the series of processes involved in producing nuclear energy from uranium or thorium, including mining, enrichment, fuel fabrication, reactor operation, spent fuel reprocessing, and waste disposal. Open Fuel Cycle: Spent nuclear fuel is considered waste and is not reprocessed. It is stored and eventually disposed of in a geological repository. Closed Fuel Cycle: Spent nuclear fuel is reprocessed to extract usable materials, which are then recycled into new fuel. This reduces waste and makes better use of resources. Benefits: Reduces the volume and toxicity of high-level radioactive waste. Increases the utilization of uranium resources. Extracts valuable isotopes like plutonium and minor actinides for reuse in reactors.

The Transmutation Reactor achieves full closure of the thorium fuel cycle, enabling resource utilization and minimization of long-lived radioactive waste. The transmutation reactor reaches an equilibrium state after undergoing long-term operation, where the reactivity and fuel mass flow remain identical over successive fuel sub-cycles. The separated and recycled actinides can be re-used in the transmutation reactor by supplementing the fuel with a feed of fresh thorium and transuranics coming from the spent fuel from LWRs to preserve the initial mass of the fuel. The START fuel cycle is based on periodic fuel management involving multi-batch refueling and reshuffling schemes, reprocessing and recycling of the spent fuel, and separation of fission products.

Both particle accelerators and nuclear reactors are among the primary tools for producing radioisotopes for medical or industrial applications. They can be obtained by bombarding stable isotopes either with neutrons in a reactor or with charged particles, like electrons or protons, in a particle accelerator. Some radioisotopes are byproducts of nuclear fission. The START system that combines an accelerator and a nuclear reactor can synergize the strengths of both technologies to enhance the production of radioisotopes.

Transmuting waste is crucial because it significantly reduces both the volume and the longevity of high-level radioactive waste. While a deep geological repository is still necessary, transmutation shortens the required isolation period from hundreds of thousands of years to just a few centuries. Within this manageable timeframe, we can ensure safe isolation of the waste, thereby eliminating the burden on future generations and addressing environmental concerns more effectively, while producing carbon-free energy.

Dealing with nuclear waste is a significant challenge due to its long-lived radiotoxicity. The current most considered solution is placing the waste in deep geological repositories (DGRs), which means burying nuclear waste deep underground in stable geological formations. Countries like Finland, Switzerland, Sweden, and France are at the forefront of developing DGRs. The idea is to isolate the waste from the biosphere for hundreds of thousands of years, allowing radioactivity to decay naturally. However, finding suitable geological formations that are stable over the required timescales (hundreds of thousands of years) is difficult. The site must be free from significant seismic activity, groundwater flow, and other geological risks. Additionally, constructing and maintaining a DGR requires advanced engineering to ensure the integrity of barriers and containers over long periods. If containment barriers fail, there is a risk of radioactive materials leaking into groundwater, potentially affecting ecosystems and human health. All these challenges make construction and maintenance of DGRs technically demanding and extremely expensive. Transmutex solution eases the stringent requirements on deep geological repository ensuring the highest level of safety and cost reduction.

Our approach sets us apart from competitors who usually choose to build, own, and operate their plants. Moreover, their primary focus is energy production, not waste management. Transmutex provides design expertise on all aspects of the nuclear process, then we grant customers full control over the implementation process. In that fashion, our customers own the final facilities and are free to select the operators they desire. With this unique approach, we enable our technology for any country, highly adaptable to local regulations, political and economic environments. We believe that flexibility is key to efficiently deploy our technology in many parts of the globe, and to increase our chances of success.