Radioactive material is produced during the process that generates nuclear energy. If radioactive waste is not properly disposed of, there can be severe consequences for the environment and public health. Nuclear energy can only be designated as a transitional green energy source upon safely disposing of radioactive waste from nuclear reactors.
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The Nuclear Waste Dilemma
When electricity is generated, waste is produced. Regardless of the fuel utilized, waste generated during electricity production has to be controlled to protect public health and reduce environmental effects. Any substance regarded to have no further utility that is radioactively polluted or fundamentally radioactive is considered nuclear waste.
Unlike all other thermal electricity generation methods, nuclear power generation produces waste that is strictly regulated and cannot result in pollution. The very high quantity of energy generated from a very small amount of fuel and the comparatively small amount of waste produced during this process are the defining characteristics of nuclear power. However, since a large portion of the waste generated is radioactive, it must be handled properly. Radioactive waste is produced during every stage of the nuclear fuel cycle, and the expense of handling and removing it is included in the energy cost.
Nuclear Waste Recycling
Reprocessing spent fuel to recover fissile and fertile materials to provide new fuel for current and future nuclear power plants is a crucial and almost unique feature of nuclear energy. While many other countries have yet to adopt the idea that spent nuclear fuel is a resource rather than a waste, European nations, China, and Japan, have procedures in place to reprocess used nuclear material.
The primary motivation for reprocessing used fuel has been to obtain unused plutonium and accessible wasted uranium from the used fuel elements. This closes the fuel cycle and adds 25–30% extra energy from the original uranium. Reducing the quantity of material to be disposed of as hazardous waste to approximately one-fifth is a secondary objective.
Reprocessing spent nuclear fuel has long been used to remove fissile elements for recycling and lower the amount of high-level waste produced. Today, fissile plutonium is produced mostly by converting fertile U-238.
New recycling technologies are being developed in conjunction with fast neutron reactors, which burn all long-lived actinides, containing all uranium and plutonium, without isolating them from one another. While only a small amount of recovered uranium has been recycled thus far, a significant quantity of plutonium recovered from spent fuel is now recycled into MOX fuel.
The Benefits of Recycling Nuclear Waste
Reusing nuclear waste can increase fuel efficiency by separating the fissile material from the fission products that absorb neutrons and recycling it into fresh fuel for more reactors.
Recycling nuclear fuel in fast neutron reactors can change waste nuclides' half-lives from 10,000 to 200 years, lowering the radiotoxicity of nuclear waste over an extended period. Nuclear waste can undergo recycling to transform its physical form into one more suitable for its final disposal location.
Technologies and Innovations in Recycling Nuclear Waste
For a long time, nuclear energy has been promoted as a practical way to combat climate change and offer a reliable electricity supply. Disposal of nuclear waste, however, continues to be a major challenge. Recent developments in Generation IV and Small Modular Reactors (SMRs) have presented viable options for handling and recycling radioactive waste. Several capable Generation-IV reactor conceptions are under development worldwide:
- Molten salt reactors: Molten salt reactors (MSRs) use liquid salts fluoride or chloride as both a coolant and a fuel. They are safer by nature because they work at greater temperatures and lower pressures. By effectively burning nuclear waste, MSRs can lower the amount of radioactive elements with extended half-lives.
- Fast Neutron Reactors (FNRs): FNRs transform fertile material into fissile material by using fast neutrons. This method can more effectively use uranium resources and "burn" nuclear waste.
- High-Temperature Gas-Cooled Reactors (HTGRs): HTGRs can produce hydrogen and use waste heat among their many other uses because of their extremely high operating temperatures. Nuclear waste can be burned or recycled using its fuel stones.
- Sodium-Cooled Fast Reactors (SFRs): Fast reactors that use liquid sodium as a coolant are known as sodium-cooled fast reactors or SFRs. SFRs can recycle spent nuclear fuel, lowering waste and prolonging the useful life of uranium supplies.
Successful Nuclear Waste Recycling Program
France exemplifies a robust nuclear waste recycling program with its innovative recycling plant in La Hague. This French effort, managed by the state-owned Orano (previously Areva), has been in existence for decades. It expertly recycles spent nuclear fuel to recover valuable fissile materials such as uranium and plutonium, which are then repurposed in nuclear reactors.
The result not only reduces nuclear waste volume but also improves France's sustainable energy reserves, considering the country's heavy reliance on nuclear energy for electricity production. This recycling approach increases the life of nuclear fuel and reduces reliance on fossil fuels, demonstrating beneficial implementation.
The United Kingdom has another remarkable example of nuclear recycling at the Sellafield nuclear complex in Cumbria via the Thorp (Thermal Oxide Reprocessing Plant) facility. This facility has helped to recycle nuclear fuel and reduce waste. Originally intended for sophisticated gas-cooled reactors, it has also been used to recycle fuel from pressurized water reactors.
Future Prospects and Challenges
It is feasible to produce radioactive waste that will decay to such natural levels in 300 to 400 years, rather than the 250000 years required if spent fuel is disposed of directly. Essentially, developing an efficient nuclear power plant would significantly lessen the waste load on future generations.
However, this is a difficult task, and it is required to improve reprocessing and recycling technologies to enhance the performance of actinide separations, reduce secondary waste volume, and avoid proliferation issues. IAEA studies on fast reactor development and novel fuel cycles demonstrate that these concerns can be resolved and the nuclear industry can progress to a more sustainable new fuel cycle.
Significant research and development efforts are also focusing on using thorium rather than uranium, as well as the greater utilization of reactor designs with higher fuel burnup, such as high-temperature gas-cooled and molten salt reactors. The goal of these initiatives is to produce the same amount of electricity while using less transuranic materials.
Read More: Converting Waste PPE into Renewable Fuel
References for Further Reading
Krūmiņš, J., & Kļaviņš, M. (2023). Investigating the Potential of Nuclear Energy in Achieving a Carbon-Free Energy Future. Energies, 16(9), 3612. https://doi.org/10.3390/en16093612
Hannum, W. H., Marsh, G. E., & Stanford, G. S. (2005). Smarter use of nuclear waste. Scientific American, 293(6), 84-91. https://www.jstor.org/stable/26061261
Rehm, T. E. (2023). Advanced nuclear energy: the safest and most renewable clean energy. Current Opinion in Chemical Engineering, 39, 100878. https://www.sciencedirect.com/science/article/abs/pii/S2211339822000880
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