NUCLEAR WASTE
1. Context
Recently, India loaded the core of its long-delayed Prototype Fast Breeder Reactor (PFBR) vessel, bringing the country to the cusp of stage II powered by uranium and plutonium of its three-stage nuclear programme. By stage III, India hopes to be able to use its vast reserves of thorium to produce nuclear power and gain some energy independence. However, the large-scale use of nuclear power is accompanied by a difficult problem: waste management.
2. About Nuclear Waste
- Nuclear waste refers to the radioactive byproducts generated during the operation of nuclear reactors. In a fission reactor, neutrons collide with the nuclei of specific elements, causing them to become unstable and split, releasing energy and producing different elements.
- For instance, when uranium-235 (U-235) absorbs a neutron, it can split into barium-144, krypton-89, and three neutrons. The non-fissile components, such as barium-144 and krypton-89, form part of the nuclear waste.
- One of the primary sources of nuclear waste is the spent fuel itself. "The spent fuel contains all the radioactive fission products generated during each nucleus's break-up to produce energy, along with the radioactive elements produced during the conversion of uranium into heavier elements after absorbing neutrons and undergoing radioactive decay,".
- Due to its high radioactivity, nuclear waste requires careful storage in specially designed facilities to prevent leaks or contamination of the surrounding environment.
3. Handling Nuclear Waste
- Spent Fuel Management: The main challenge in handling nuclear waste lies in managing spent fuel, which is both hot and highly radioactive. Typically, spent fuel is stored underwater for several decades to allow it to cool down. Once cooled, it can be transferred to dry casks for long-term storage. Countries with extensive nuclear power programs, such as the United States, Canada, and Russia, have accumulated significant amounts of spent fuel over the years.
- Storage Periods and Challenges: Depending on the level of radioactivity, the storage period for nuclear waste can extend to many millennia. This necessitates the need for secure storage facilities that can isolate the waste from human contact for durations longer than the existence of modern humans on Earth.
- Liquid Waste Treatment: Nuclear power plants are equipped with liquid waste treatment facilities to manage radioactive liquid waste. Small quantities of aqueous wastes containing short-lived radionuclides may be discharged into the environment after treatment. Other waste materials may be evaporated, chemically precipitated to form a sludge for storage, absorbed on solid matrices, or incinerated based on their hazard levels.
- High-Level Waste Management: Liquid high-level waste contains a majority of the fission products produced in nuclear fuel. To manage this waste, it is vitrified to form a stable glass that can be stored safely. However, certain challenges remain, especially in cases where reprocessing of spent fuel is involved, as some fission products cannot be used as fuel and must be stored as liquid waste, posing potential accident hazards.
4. Dealing with Nuclear Waste
- Dry-Cask Storage: Once spent fuel has sufficiently cooled in a spent-fuel pool for at least a year, it can be transferred to dry-cask storage. In this method, the fuel is placed inside large steel cylinders and surrounded by inert gas. These cylinders are then sealed shut and placed within larger steel or concrete chambers for additional protection.
- Geological Disposal: Some experts advocate for geological disposal, where the waste is sealed in special containers and buried underground in geological formations such as granite or clay. This approach offers long-term storage away from human activity. However, there are concerns about the potential risks of radioactive material exposure if the containers are disturbed, such as by nearby excavation activities.
- Reprocessing: Reprocessing involves technologies to separate fissile from non-fissile material in spent fuel. Through chemical treatment, fissile material is separated from the non-fissile components. Reprocessing facilities require specialized protection and personnel due to the hazardous nature of spent fuel. While reprocessing offers higher fuel efficiency, it is also an expensive process.
- Plutonium Management: An important aspect of reprocessing is the management of plutonium, which can be weapons-usable. The International Atomic Energy Agency (IAEA) strictly regulates facilities handling plutonium, specifying thresholds for plutonium concentration to ensure non-proliferation efforts are maintained.
5. Issues Associated with Nuclear Waste
- Environmental Contamination Concerns: One of the significant issues associated with nuclear waste is the potential for environmental contamination. Instances such as the Asse II salt mine in Germany, where nuclear waste storage led to concerns about groundwater contamination, highlight the challenges of managing and containing radioactive materials. Decontamination efforts can be extremely costly and time-consuming, as seen in the case of the Asse II mine.
- Operational Risks and Unknown Factors: The operational risks and uncertainties associated with nuclear waste facilities pose another set of challenges. For example, the Waste Isolation Pilot Plant (WIPP) in the U.S. initially served as a model for nuclear waste management. However, an accident in 2014 resulted in the release of radioactive materials, exposing serious maintenance failures and highlighting the unpredictable nature of such facilities.
- Liquid Waste Treatment Challenges: Treating liquid nuclear waste, particularly high-level and intermediate-level waste, presents specific challenges. Questions arise regarding the effectiveness of vitrification plants in reprocessing facilities and the amount of remaining liquid waste yet to be treated. These uncertainties add complexity to the overall management of nuclear waste.
- Repository Failures and Ethical Concerns: Many countries have faced challenges in successfully setting up repositories for nuclear waste. Failures in repository projects underscore the difficulty of finding suitable long-term storage solutions. Moreover, ethical concerns arise regarding the export of nuclear waste, highlighting issues of environmental justice and the responsibility of nations benefiting from nuclear power to bear the associated costs and risks.
6. Cost of Waste Handling in Nuclear Power
According to Dr Tsyplenkov's analysis in a 1993 feature, the cost of waste handling in nuclear power is significant and distributed across various stages of the fuel cycle and plant operation.
| Stage of Waste Management | Percentage of Total Cost | Description |
| Front-End Waste Management | 10% | Handling depleted uranium and front-end waste |
| Power Plant Operation | 24% | Managing wastes generated during plant operation |
| Decommissioning | 15% | Costs associated with power plant decommissioning |
| Back-End of Fuel Cycle | 50% | Spent fuel management and disposal |
Overall Cost Estimate
In total, waste management imposes a cost ranging from $1.6 to $7.1 per megawatt-hour (MWh) of nuclear energy generated, considering factors such as plant capacity, operational efficiency, and waste handling practices throughout the fuel cycle. These costs reflect the comprehensive efforts required to manage radioactive waste responsibly and safely in the nuclear power industry.
7. Nuclear Waste Management in India
India employs various strategies and facilities to handle nuclear waste generated from its nuclear power and research activities.
- Reprocessing Facilities: India has reprocessing plants located in Trombay, Tarapur, and Kalpakkam. These facilities play a crucial role in reprocessing spent nuclear fuel to extract plutonium for use in stage II reactors and nuclear weapons production. The Trombay facility processes 50 tonnes of heavy metal per year (tHM/y) from research reactors, while the Tarapur facilities handle 100 tHM/y each from pressurized heavy water reactors. The Kalpakkam facility also processes 100 tHM/y of spent fuel.
- On-Site Waste Management: According to statements made by government officials, nuclear waste generated during operations at nuclear power stations in India is categorized as low and intermediate-activity level waste. These wastes are managed on-site, treated, and stored within dedicated facilities located at the respective nuclear power stations. The surrounding areas are continuously monitored for radioactivity to ensure public safety.
- Challenges and Complications: There have been observations regarding delays and operational issues with certain facilities, such as the PFBR (Prototype Fast Breeder Reactor) in India. These delays suggest potential operational challenges and inefficiencies in managing nuclear waste. Additionally, the discharge of spent fuel from PFBR may introduce new complexities due to differences in the distribution of fission products and transuranic elements compared to other reactors.
8. The Way Forward
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Previous Year Questions 1. To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this on text, what advantage, does thorium hold over uranium? (UPSC 2012)
Which of the statements given above is/are correct? (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 2. Which among the following has the world’s largest reserves of Uranium? (UPSC 2009) (a) Australia Answers: 1-D, 2-A |
Source: The Hindu
