Radioactive Wastes and its Disposal | Civil Engineering Optional Notes for UPSC PDF Download

What is Nuclear Waste?

Radioactive waste, or nuclear waste, is a byproduct originating from nuclear reactors, fuel processing facilities, medical institutions, and research centers. It can manifest in various states, including gas, liquid, and solid forms, with its radioactivity levels varying according to the specific waste material. The duration of radioactivity persistence can range from a matter of hours to several months, or even extend over hundreds of thousands of years.

Types of Nuclear Waste

• Exempt Waste: This category encompasses waste that conforms to the criteria for exemption, clearance, or exclusion from regulatory control with respect to radiation protection.
• Low and Intermediate-Level (LIL) Waste: LIL waste is characterized by low levels of radioactivity. It includes materials such as those used for handling highly radioactive components of nuclear reactors (e.g., cooling water pipes and protective clothing) and waste generated from medical procedures involving radioactive treatments or diagnostic X-rays, among others.
• High-Level Waste: High-level waste possesses substantial levels of radioactivity and is primarily generated during the reprocessing of spent nuclear fuel. This waste comprises elements like uranium, plutonium, and other intensely radioactive isotopes formed through nuclear fission. Notably, high-level waste materials have exceedingly long half-lives, with some extending beyond 100,000 years. Consequently, it takes a significant amount of time for these materials to reach a safer level of radioactivity.

Nuclear Waste In India

India has a growing nuclear energy sector and a significant nuclear weapons program, both of which contribute to the production of nuclear waste. Here are some key points related to nuclear waste in India:

• Nuclear Power: India has a growing nuclear power sector, with several nuclear power plants operational and more under construction. These power plants generate low and intermediate-level radioactive waste in the form of spent nuclear fuel, contaminated materials, and various other byproducts.
• Reprocessing: India has facilities for reprocessing spent nuclear fuel, such as the Bhabha Atomic Research Centre (BARC) and the upcoming Advanced Fuel Fabrication Facility. Reprocessing is done to recover fissile material and reduce the volume of nuclear waste.
• High-Level Waste: Reprocessing facilities generate high-level radioactive waste, which includes materials with long-lived radioactive isotopes like plutonium. Proper disposal of high-level waste is a significant concern in India, as it requires long-term management and isolation.
• Radioactive Medical and Industrial Waste: India also generates radioactive waste from medical and industrial applications, including radiation therapy, radiography, and industrial radiography. These sources contribute to the low and intermediate-level waste inventory.

Nuclear Waste in World Statistics

• In 2022, about 2.32 million cubic feet and 154 thousand curies of low-level radioactive waste were disposed of.
• The International Atomic Energy Agency (IAEA) estimates that about 370,000 metric tonnes of heavy metal (MTHM) of spent fuel has been produced since the start of civil nuclear power production. Of this, 120,000 MTHM has been reprocessed.
• The IAEA estimates that 392,000 tonnes of heavy metal (tHM) in the form of used fuel have been discharged since the first nuclear power plants began operation.
• More than a quarter million metric tons of highly radioactive waste is stored near nuclear power plants and weapons production facilities worldwide. Over 90,000 metric tons are in the US alone.
• Around 80 percent of this waste (close to 2 million m3) has been disposed of.
• The amount of nuclear waste is constantly increasing with no full disposal route anywhere.

Nuclear Waste Related Concern

Nuclear waste is associated with several significant concerns, and addressing these concerns is essential for the safe management and disposal of radioactive waste materials. Some of the key concerns related to nuclear waste include:

• Radioactive Contamination: Nuclear waste contains radioactive isotopes, some of which can remain hazardous for thousands or even millions of years. Radioactive materials can emit ionizing radiation, which can damage living organisms and the environment if not properly contained and isolated.
• Health and Safety Risks: Improper handling and storage of nuclear waste can pose health and safety risks to workers, the public, and future generations. Exposure to radiation can lead to various health issues, including cancer and genetic mutations.
• Long-Term Storage: High-level nuclear waste, in particular, requires secure long-term storage solutions. Identifying suitable sites for deep geological repositories and ensuring their long-term integrity are complex challenges. The waste must be isolated from the environment for an extended period.
• Transportation Risks: Transporting nuclear waste from its point of origin to storage or disposal facilities can present risks. Accidents or security breaches during transportation could lead to radioactive material release, which is a significant concern.
• Proliferation Risks: Reprocessing nuclear waste to extract fissile materials, such as plutonium and uranium, can have proliferation risks. These materials could potentially be diverted for the production of nuclear weapons, which is a global concern.
• Environmental Impact: Improper disposal of nuclear waste can lead to contamination of soil, water, and ecosystems. The long-lived nature of some radioactive isotopes makes this a concern for future generations.

Nuclear Waste Management

Nuclear waste management refers to the systematic handling, storage, and ultimate disposal of radioactive materials produced by nuclear power generation, research, and other nuclear-related activities. Proper management is essential to ensure the safety of both humans and the environment. Here are the key components of nuclear waste management:

• Generation: Nuclear waste is generated as a byproduct of nuclear processes, including nuclear power generation, reprocessing, and nuclear research. It can be in various forms, such as spent fuel, contaminated equipment, or radioactive liquids.
• Collection and Segregation: Radioactive waste is collected, segregated, and categorized based on its level of radioactivity and physical form. It is then properly packaged to prevent leakage and ensure safe handling.
• Storage: Radioactive waste is initially stored at the point of generation in secure containers and facilities. This can be short-term storage while awaiting transportation to more permanent storage or disposal sites.
• Transportation: Waste is transported from its generation site to interim or permanent storage and disposal facilities. This involves stringent safety measures to prevent accidents or radioactive material release during transit.
• Interim Storage: Low and intermediate-level waste is often placed in interim storage facilities, while a suitable long-term disposal solution is identified. These facilities are designed to safely contain waste for decades.
• Deep Geological Repositories: For high-level radioactive waste, the preferred method of disposal is deep geological repositories. These repositories are located deep underground in stable geological formations. The waste is placed in specially engineered containers and stored in such a way that it remains isolated from the environment for thousands of years.
• Reprocessing: In some cases, reprocessing is considered as a method to extract valuable materials from spent nuclear fuel and reduce the volume of waste. However, reprocessing also presents proliferation risks and complex challenges.
• Regulatory Oversight: Governments establish and enforce regulatory frameworks to oversee nuclear waste management, setting strict safety standards and guidelines to protect the public and the environment.
• Public Engagement: Public engagement and community involvement are critical in the decision-making process for selecting waste management sites. Building trust and addressing concerns are essential to successful waste management projects.
• International Cooperation: Given the global nature of nuclear waste issues, international cooperation is crucial. Organizations like the International Atomic Energy Agency (IAEA) work to establish best practices and standards for nuclear waste management.

Waste Management Challenges

• Spent Fuel Handling: Initially, spent fuel is highly radioactive and hot, necessitating up to several decades of underwater cooling before it can be safely transferred to dry cask storage for longer-term containment.
• Longevity: The radioactive nature of nuclear waste requires isolation from human contact for durations far exceeding the existence of anatomically modern humans, with some materials needing containment for millennia.
• Liquid Waste Treatment: Nuclear facilities also produce liquid waste, which, depending on the radionuclide content, may be treated and discharged, evaporated, chemically precipitated, absorbed, or incinerated.
• High-Level Waste Vitrification: High-level liquid waste, containing the majority of fission products, is turned into glass for safer, long-term storage.

Nuclear Waste Treatment Technologies

Nuclear waste treatment technologies include:

• Radioactive waste disposal:Uses bioremediation technology to treat waste with microbes and plants
• Electrochemical treatment of radioactive waste:Uses high-temperature thermal treatment to reduce waste volume, retain toxic substances, and recover valuable substances
• Radioactive waste characterization: Determines important waste parameters and enables segregation of radioactive waste
• Deep geological disposal: Provides multiple barriers to prevent radionuclides from reaching the environment and exposing humans to radiation
• Vitrification: Immobilizes high-level liquid waste into inert vitrified borosilicate glasses
• Integrated waste management: Implements radioactive waste management solutions

Other nuclear waste treatment technologies include:

• Incineration of solid waste
• Evaporation of liquid waste
• Conditioning